Prostate Cancer In African American Men Research Articles

MP12-18 RACIAL DISPARITY IN PROSTATE CANCER DIAGNOSIS: A COMPARISON OF PROSTATE BIOPSY RESULTS IN AFRICAN AMERICAN AND WHITE MEN USING AN MRI-BASED BIOPSY STRATEGY.

You have accessJournal of UrologyCME1 Apr 2023MP12-18 RACIAL DISPARITY IN PROSTATE CANCER DIAGNOSIS: A COMPARISON OF PROSTATE BIOPSY RESULTS IN AFRICAN AMERICAN AND WHITE MEN USING AN MRI-BASED BIOPSY STRATEGY. Ali Kasraeian, Miguel Alcantara, Kaitlyn Mola Alcantara, Adam Brochert, Joshua Yellin, Eliana Namen, Sean Parsons, Jamie Cesaretti, and Ahmad Kasraeian Ali KasraeianAli Kasraeian More articles by this author , Miguel AlcantaraMiguel Alcantara More articles by this author , Kaitlyn Mola AlcantaraKaitlyn Mola Alcantara More articles by this author , Adam BrochertAdam Brochert More articles by this author , Joshua YellinJoshua Yellin More articles by this author , Eliana NamenEliana Namen More articles by this author , Sean ParsonsSean Parsons More articles by this author , Jamie CesarettiJamie Cesaretti More articles by this author , and Ahmad KasraeianAhmad Kasraeian More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003227.18AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: African American (AA) men in the United States have an increased burden of morbidity and mortality from prostate cancer (PCa). The roles of factors related to both racial disparities and intrinsic biological traits remain to be determined. We quarried our prospective database of standard and MRI fusion prostate biopsies (tMRI/US FPB) to determine if any pre-biopsy characteristics predicted adverse tumor pathology. METHODS: Between January 2017 and September 2022, 828 men underwent prostate biopsy (PBx) using an MRI-based algorithm. Men with negative MRI underwent standard PBx (n=440), while those with lesion on mpMRI underwent tMRI/US FPB (n=388). All patients underwent mpMRI of the prostate, interpreted by a single radiologist using the PIRADS scoring system. 3D rendering of the regions of interest was performed by the radiologist prior to tMRI/US FPB performed by a single urologist using the Invivo UroNav Fusion Biopsy System. A standard 14-core PBx was performed at the same time in all tMRI/US FPB cases. Prospective data was collected and analyzed. RESULTS: Of the 828 men who underwent standard and tMRI/US FP with 14Bx (tMRI/US FP-14Bx), 593 presented with a rise in PSA, while 235 had a suspicious digital rectal exam. Prostate Cancer was found in 367/608 (60%) of the White men and 104/147 (70.8%) of AA men in our series (p=0.02). 224/608 (36.8%) of White men and 74/147 (50.3%) of AA men had a Gleason score of 7-10 (p=0.003). Age, DRE status, PIRADS score, and the incidence of Gleason 6 PCa were not found to be significantly different by race. 163/608 (26.8%) of White men and 20/147 (13.6%) of AA men had a PSA upon presentation of 0-3.9 ng/ml (p=0.001). The PSA levels of 4.0-9.9 ng/ml and PSA > 10 ng/ml at presentation were not significantly different. Of the 73/828 (8.8%) of men who identify as not White and not Black no significant difference was found for any tested factor but interestingly 19/73 (26%) presented with a PSA between 0-3.9 ng/ml versus Black men (p=0.02) which was almost identical to the effect seen relative to White men. CONCLUSIONS: In this dataset, it appears that AA men present with a higher PSA than White men. It is likely that this is related to disparities in access to care rather than biological intrinsic factors. Also, we did observe a higher incidence of Gleason 7-10 PCa in AA men, which one would expect in a cohort of patients who presented for biopsy in the community with a significantly higher PSA at initial presentation. Continuing education of primary care providers regarding the importance of PSA testing in the AA community should be emphasized by both the urological and primary care professional medical societies. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e140 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ali Kasraeian More articles by this author Miguel Alcantara More articles by this author Kaitlyn Mola Alcantara More articles by this author Adam Brochert More articles by this author Joshua Yellin More articles by this author Eliana Namen More articles by this author Sean Parsons More articles by this author Jamie Cesaretti More articles by this author Ahmad Kasraeian More articles by this author Expand All Advertisement PDF downloadLoading ...

Abstract C045: Investigating molecular and genetic contributions to racial disparities in prostate cancer by integrating multi-omic datasets available in public

Abstract African-American males are disproportionately affected by prostate cancer in comparison to other racial and ethnic groups. African-American males have increased risk for the disease, experience higher incidence and mortality rates, and present higher grade and stage prostate tumors than Caucasian men. To determine molecular mechanisms beyond racial disparities in prostate cancer, molecular and genetic profiles of prostate tumor samples from different ethnic groups are developed. For example, DNA sequencing in the form of target-based array or whole exome and genome sequencing revealed SNPs, genetic mutations, deletions, and amplifications linked to prostate cancer subgroups. Comparative analysis of DNA sequences of prostate cancer cells have pinpointed areas of interest that suggest race specific mutations. Moreover, differentially expressed genes between prostate tumor tissue samples from African and Caucasian ancestries are identified using RNA sequencing and microarray-based methods. Abnormal levels of gene expression are measured by the levels of mRNA. Furthermore, epigenetic modifications, such as DNA methylation levels were examined, identifying CpG sites that are differentially methylated among ethnic groups. To comprehensively examine molecular and genetic contributions to racial disparities in prostate cancer, we compiled over 200 published studies that profiled genome, epigenome, and transcriptome in prostate tumor tissues from diverse ethnic groups. Specifically, we categorized studies according to their method and organized the identified features that offer insight into racial disparities in prostate cancer. For instance, we reviewed over 100 studies that identify reproducible genetic alterations found in prostate cancer patients from African ancestry from DNA sequencing experiments. We also reviewed over 50 studies that utilized RNA sequencing to measure gene expression levels in prostate tumor tissues from African-American male samples, identifying genes and signaling pathways abnormally dysregulated in the disease. In addition, we reviewed over 25 studies quantifying epigenetic modifications to determine key and reproducible epigenetic alterations linked to aggressiveness of the disease from African American. Subsequently, we identified socioeconomic factors that are associated with molecular features contributing to the increased risk for prostate cancer in African-American men. Overall, we evaluated multiple molecular and genetic features that contribute to racial disparities in prostate cancer. This may provide researchers with valuable background knowledge and perspective for identifying biomarkers for specific prostate cancer subgroups. Citation Format: Alexandria J. Hightower, Suhn K. Rhie, Sara M. Falzarano, Sarah Buxbaum. Investigating molecular and genetic contributions to racial disparities in prostate cancer by integrating multi-omic datasets available in public [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C045.

Abstract A081: Epigenetic regulation of SPDEF gene in RCC7/T cells, a line of malignant African-American prostate epithelial cells

Abstract Background: Prostate cancer (PCa) in African American (AA) men has an earlier onset, more aggressiveness with higher metastasis and mortality rate than in Caucasian men. SAM-pointed domain-containing Ets-like factor (SPDEF) has been identified as a possible suppressor of metastasis in castration-resistant prostate cancer (CRPC) in earlier investigations. Ongoing studies in our lab are focused on deciphering the role of SPDEF in PCa progression and metastasis with special emphasis on PCa in AA men. We discovered that SPDEF expression is lost in RCC7/T cells, and re-expression of SPDEF limits metastatic properties of these cells, however, the regulatory mechanisms underlying the loss of SPDEF have not been elucidated. In the current study, we investigated the role of epigenetic modulators (DNA methylation and histone modifications) in driving the loss of SPDEF. Methods: We analyzed publicly available data sets from TCGA (GDC TCGA Prostate Cancer, and TCGA Prostate Cancer (PRAD) for DNA methylation using Xena UCSC genome browser (https://xena.ucsc.edu/). We also analyzed histone ChIP-seq data from PCa cell lines using cistrome project (http://cistrome.org/db/#/). RCC7/T cells were grown in DMEM and maintained at 37°C in a humidified incubator. We used bisulfite sequencing (BSP) to examine DNA methylation in SPDEF gene in SPDEF proficient (LNCaP) and deficient (RCC7/T) cells. We also employed the ChIP-qPCR to reveal the active and repressive key histone marks (H3K4me3, H3K27ac, and H3K27me3) across the SPDEF gene. Results: In the clinical cohorts, SPDEF expression showed an inverse correlation with the degree of DNA methylation and expression of the epigenetic writer enzymes such as DNMT1 and EZH2. Our results revealed that the CpG islands in SPDEF gene are hyper-methylated in RCC7/T cells compared to LNCaP cells. Our analysis of the data from the cistrome project revealed an elevated enhancer repressive mark H3K27me3 (marked by EZH2) and a decreased promoter active mark, H3K4me3, in PC3 cells as compared with less metastatic LNCaP cells. Our results from ChIP-qPCR confirmed these findings. Moreover, we observed the methylation profiles in RCC7/T cells were similar to those of PC3 cells. Additionally, combination treatment with 5-aza-2-deoxycytidine (DNMT inhibitor) and GSK-126 (EZH2 inhibitor) increased the PDEF expressions levels and also restricted colony formation, migration and invasion in RCC7/T cells. Conclusion: Overall, these findings reveal an inverse correlation between expression of epigenetic writers (DNMT1 and EZH2) and SPDEF expression in PCa. Our results also suggest that SPDEF expression in PCa is regulated in part by epigenetic modifications, and that combined inhibition of DNMT1 and EZH2 may offer a therapeutic benefit in subsets of PCa patients including in AA men. Acknowledgements: These studies were funded in part by NIH/NCI-7R01CA242839 (HK) and unrestricted funds from the LSU-LCMC Cancer Center, School of Medicine -LSUHSC, New Orleans (HK). Grateful to LCU-LCMC Genomics core for DNA sequencing Citation Format: Mousa Vatanmakanian, Sweaty Koul, Thangavel Chellappagounder, Hari K. Koul. Epigenetic regulation of SPDEF gene in RCC7/T cells, a line of malignant African-American prostate epithelial cells [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr A081.

Racial Disparities in Prostate Cancer: Evaluation of Diet, Lifestyle, Family History, and Screening Patterns.

Racial disparities in prostate cancer incidence and mortality rates are considerable. We previously found in the Health Professionals Follow-up Study (HPFS) that African-American men had an 80% higher prostate cancer risk than White men. With 21 additional years of follow-up and four-fold increase in cases, we undertook a contemporary analysis of racial differences in prostate cancer incidence and mortality in HPFS. For 47,679 men, we estimated HRs and 95% confidence intervals (CI) for the association between race and risk of prostate cancer through 2016 using Cox proportional hazards regression. Multivariable models (mHR) were adjusted for lifestyle, diet, family history, and PSA screening collected on biennial questionnaires. 6,909 prostate cancer cases were diagnosed in White, 89 in African-American, and 90 in Asian-American men. African-Americans had higher prostate cancer incidence (mHR = 1.31; 95% CI, 1.06-1.62) and mortality (mHR = 1.67; 95% CI, 1.00-2.78), and lower PSA screening prevalence than White men. The excess risk was greater in the pre-PSA screening era (HR = 1.68; 95% CI, 1.14-2.48) than the PSA screening era (HR = 1.20; 95% CI, 0.93-1.56). Asian-Americans had lower prostate cancer risk (mHR = 0.74; 95% CI, 0.60-0.92), but similar risk of fatal disease compared with white men. Racial differences in prostate cancer incidence and mortality in HPFS are not fully explained by differences in lifestyle, diet, family history, or PSA screening. Additional research is necessary to address the disproportionately higher rates of prostate cancer in African-American men.

Abstract PO-153: ANPEP: A potential regulator of tumor-immune metabolic interactions in African American men with prostate cancer

Abstract In prostate cancer (PCa), lack of TMPRSS2-ETS gene fusion (ETSnegative) has been a hallmark of tumor in African American (AA) as compared with European American (EA) men. To elucidate biologic features associated with ETSnegative PCa in AA men, we identified aminopeptidase N (ANPEP) as ETS-regulated gene with preferential overexpression in AA. Aminopeptidase N is involved in endocytosis, cholesterol, amino acid transport and peptide hydrolysis. In the current work, we sought to investigate the role of ANPEP in a PCa development and exploit its role in PCa metabolism as a therapeutic vulnerability, particularly in AA tumors. Methods To understand the role of ANPEP in PCa progression and therapeutic vulnerability, we determined the expression of ANPEP in different component of tumor microenvironment. We also developed a consumption and release metabolomic platform to assess the impact of ANPEP on transport of cholesterol, fatty acids and a number of relevant amino acids. Additionally, we assessed the availability of these metabolites and their end products in plasma samples of PCa patients. Results Using publicly available datasets, we showed that prostate tumors form AA men harbor the highest expression of ANPEP as compared with other groups. Using further data mining and experimental approaches, we found that aminopeptidase N is predominantly expressed on macrophages compared with prostate tumor cells, T cell, B cells, neutrophils and dendritic cells. Expression of ANPEP predominantly correlated with various amino acid transporters which also tend to be differentially expressed by ETS status. We have successfully developed a metabolomics-based approach to assess the consumption of more than 15 metabolites in prostate cancer cells and patient derived explants. Conclusion We have identified ANPEP as a macrophage-related gene with a potential role in tumor metabolism. Future work will focus on investigating functional role of ANPEP in the tumor immune microenvironment using our unique metabolic consumption/release assay in explants derived from AA and EA prostate cancer patients. Citation Format: Asmaa E. El-Kenawi, Shivanshu Awasthi, Amparo N. Serna, Jasreman Dhillon, Kosj Yamoah. ANPEP: A potential regulator of tumor-immune metabolic interactions in African American men with prostate cancer [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-153.

MP60-05 MOLECULAR PROFILING OF PROSTATE CANCER REVEALS INCREASED INFLAMMATORY MARKERS AND POOR CLINICAL OUTCOMES IN AFRICAN AMERICAN COMPARED TO EUROPEAN AMERICAN MEN

You have accessJournal of UrologyProstate Cancer: Markers (MP60)1 Sep 2021MP60-05 MOLECULAR PROFILING OF PROSTATE CANCER REVEALS INCREASED INFLAMMATORY MARKERS AND POOR CLINICAL OUTCOMES IN AFRICAN AMERICAN COMPARED TO EUROPEAN AMERICAN MEN Udit Singhal, Srinivas Nallandhighal, Susan Bolton, Mark Farha, Judith Strangl-Kremser, Ganesh Palapattu, Aliccia Bollig-Fischer, Aaron Udagar, Isaac Powell, and Simpa Salami Udit SinghalUdit Singhal More articles by this author , Srinivas NallandhighalSrinivas Nallandhighal More articles by this author , Susan BoltonSusan Bolton More articles by this author , Mark FarhaMark Farha More articles by this author , Judith Strangl-KremserJudith Strangl-Kremser More articles by this author , Ganesh PalapattuGanesh Palapattu More articles by this author , Aliccia Bollig-FischerAliccia Bollig-Fischer More articles by this author , Aaron UdagarAaron Udagar More articles by this author , Isaac PowellIsaac Powell More articles by this author , and Simpa SalamiSimpa Salami More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002095.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: African American men (AAM) with prostate cancer (PCa) often harbor more aggressive disease compared to European American men (EAM). However, the underlying cause for disparities in PCa outcomes is controversial. We performed gene expression analysis to characterize differences in tumor biology in AAM and EAM with PCa and assess the impact on outcomes. METHODS: Microarray analyses using 1,507 probes were performed to assess the expression of 517 genes in PCa radical prostatectomy (RP) specimens from 270 AAM and 369 EAM from 1991-1996. The primary endpoint was biochemical recurrence (BCR) and secondary endpoint was PCa-specific mortality (PCSM). Cox proportional hazard regression analyses were performed adjusting for age, pre-treatment PSA, Gleason grade group (GG), and T-stage. Differential Gene Expression (DEG) analysis was performed using the limma R package, with correction for multiple comparisons using the Benjamini-Hochberg procedure (false-discovery rate (FDR) of <0.05 considered significant). Gene Set Enrichment Analysis (GSEA) was performed to identify enriched hallmark pathways using R package fgsea. RESULTS: The median age of AAM and EAM was 64 (IQR 56-72) and 62 (IQR 54-70) years, respectively. A total of 66 (24%) AAM and 67 (18%) EAM developed BCR (p=0.002; median follow up 10.5 and 13.8 years, respectively). Sixteen men experienced PCSM in each group (5.9% and 4.3% in AAM and EAM, respectively; p=0.080). Interestingly, among those with GG1-2 disease, AAM were more likely to develop BCR than EAM (HR 2.3, 95% CI 1.3–4, p=0.004). However, the BCR risk was not significantly different between AAM and EAM with GG3-5 disease (p=0.370). DEG and GSEA revealed upregulation of inflammation, TNF-alpha signaling, apoptosis, androgen response, and epithelial to mesenchymal transition, among other pathways, in AAM compared to EAM (Figure 1; FDR <0.05). CONCLUSIONS: AAM with GG1-2 PCa had a higher incidence of BCR compared with EAM following RP, suggesting a more aggressive biologic behavior in AAM in early disease. The molecular profile of PCa in AAM is different from that in EAM, with inflammation playing a prominent role. Prognostic gene signatures accounting for these biological differences are needed to facilitate better disease management. Source of Funding: N/A © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e1042-e1043 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Udit Singhal More articles by this author Srinivas Nallandhighal More articles by this author Susan Bolton More articles by this author Mark Farha More articles by this author Judith Strangl-Kremser More articles by this author Ganesh Palapattu More articles by this author Aliccia Bollig-Fischer More articles by this author Aaron Udagar More articles by this author Isaac Powell More articles by this author Simpa Salami More articles by this author Expand All Advertisement Loading ...

Abstract 34: High urinary thromboxane B2 associates with lethal prostate cancer in African American men and inversely correlates with aspirin use

Abstract Background: Systemic low-grade inflammation is a candidate risk factor for prostate cancer (PC) in African American (AA) men, potentially contributing to lethal PC development. We previously reported that regular aspirin use is associated with a decreased risk of advanced stage disease and disease recurrence in AA patients with PC. The cancer-preventive benefits of aspirin have been attributed to inhibition of the cyclooxygenase (COX) pathway. Thromboxane A2 (TXA2) is an eicosanoid produced by the COX1 enzyme in platelets. Aspirin can inhibit metastasis by inhibiting COX1 activity and TXA2 synthesis. Hence, we assessed the role of TXA2 in the development of lethal PC. Because TXA2 is unstable, we measured its corresponding primary metabolite, urinary thromboxane B2 (TXB2), to examine the relationship of TXA2 with PC. Method: TXB2 was measured in cases (977) and controls (1022) from the NCI-MD PC Case-Control study using a mass-spectrometry-based assay. TXB2 levels were modeled into low (≤median) and high (&amp;gt;median) levels. We calculated risk factor-adjusted odds ratios (ORs) and 95% confidence intervals (CI) using unconditional logistic regression, adjusted hazard ratios (HR) using Cox regression and sub hazard ratios (SHR) using the Fine-Gray model. Results: We observed increased TXB2 levels in cases and an inverse relationship between levels of TXB2 and aspirin use in both cases and controls. For cases who used aspirin, the odds of having high TXB2 were reduced when compared to non-users (OR 0.46 95%CI, 0.34-0.61). This observation remained significant when stratified by race/ethnicity (AA: OR 0.36 95%CI, 0.23-0.54; EA: OR 0.58 95%CI, 0.38-0.88), indicating significant inhibition of TXB2 formation by aspirin, most notably in AA men. Further analysis showed that high TXB2 is associated with a PC case status in AA men (OR 1.44 95%CI, 1.08-1.93) but not EA men (OR 1.07 95%CI, 0.83-1.93), indicating increased TXA2 synthesis in AA men with PC compared to AA men without the disease. Also, men with high TXB2 were more likely to be diagnosed with metastasis compared to men with low TXB2 (OR 4.27 95%CI, 1.48-12.29), indicating more aggressive disease for cases with high TXB2. Furthermore, high TXB2 was associated with all-cause mortality (HR 1.56 95%CI, 1.05-2.33) and PC mortality (HR 4.02 95%CI, 1.46-11.07; SHR 2.89 95%CI, 1.03-8.11) in AA men only. Our findings indicate a distinct association between TXA2 and PC outcomes in AA men. Conclusion: Aspirin use inversely associates with high TXB2. This is of clinical interest as we report that increased TXB2 associates with PC in AA men, with aggressive PC, and with PC death which disproportionally affects AA men. This is consistent with our previous findings that aspirin may reduce lethal PC in AA men and highlights the potential benefit of aspirin for prevention of lethal PC in this high-risk group of men through inhibition of TXA2 synthesis. Citation Format: Maeve Bailey-Whyte, Ginger Milne, Tsion Z. Minas, Tiffany H. Dorsey, Wei Tang, Cheryl J. Smith, Michael B. Cook, Clayton Yates, Stefan Ambs. High urinary thromboxane B2 associates with lethal prostate cancer in African American men and inversely correlates with aspirin use [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 34.

Comparative Genomics Reveals Distinct Immune-oncologic Pathways in African American Men with Prostate Cancer.

The role of immune-oncologic mechanisms of racial disparities in prostate cancer remains understudied. Limited research exists to evaluate the molecular underpinnings of immune differences in African American men (AAM) and European American men (EAM) prostate tumor microenvironment (TME). A total of 1,173 radiation-naïve radical prostatectomy samples with whole transcriptome data from the Decipher GRID registry were used. Transcriptomic expressions of 1,260 immune-specific genes were selected to assess immune-oncologic differences between AAM and EAM prostate tumors. Race-specific differential expression of genes was assessed using a rank test, and intergene correlational matrix and gene set enrichment was used for pathway analysis. AAM prostate tumors have significant enrichment of major immune-oncologic pathways, including proinflammatory cytokines, IFNα, IFNγ, TNFα signaling, ILs, and epithelial-mesenchymal transition. AAM TME has higher total immune content score (ICSHIGH) compared with 0 (37.8% vs. 21.9%, P = 0.003). AAM tumors also have lower DNA damage repair and are genomically radiosensitive as compared with EAM. IFITM3 (IFN-inducible transmembrane protein 3) was one of the major proinflammatory genes overexpressed in AAM that predicted increased risk of biochemical recurrence selectively for AAM in both discovery [HRAAM = 2.30; 95% confidence interval (CI), 1.21-4.34; P = 0.01] and validation (HRAAM = 2.42; 95% CI, 1.52-3.86; P = 0.0001) but not in EAM. Prostate tumors of AAM manifest a unique immune repertoire and have significant enrichment of proinflammatory immune pathways that are associated with poorer outcomes. Observed immune-oncologic differences can aid in a genomically adaptive approach to treating prostate cancer in AAM.

Abstract PO-157: High urinary thromboxane B2 associates with aggressive prostate cancer and inversely correlates with aspirin use

Abstract Background: Systemic low-grade inflammation is a candidate risk factor for prostate cancer (PC) in African-American (AA) men potentially contributing to aggressive disease and mortality. Regular use of the anti-inflammatory drug aspirin is associated with decreased risk of advanced stage PC and increased disease-free survival in AA men. The chemopreventive benefits of aspirin have been attributed to inhibition of the cyclooxygenase (COX) pathway. Thromboxane A2 is an eicosanoid produced by the COX 1 enzyme in platelets. Aspirin inhibits cancer metastasis by inhibiting COX1 activity and thromboxane A2 synthesis. Hence, we assessed the role of thromboxane A2 in the development of lethal PC. Because thromboxane A2 is highly unstable, we measured its corresponding primary metabolite, urinary thromboxane b2 (TXB2), to examine the relationship of thromboxane A2 levels with PC. Method: TXB2 was measured in cases (977) and controls (1023) from the NCI-MD PC Case Control study using a mass-spectrometry-based assay. We estimated odds ratios (ORs) and 95% confidence intervals (CI) using unconditional logistic regression, with TXB2 levels modeled by quartiles. Multivariable models were adjusted for PC risk factors. Results: We observed an inverse relationship between aspirin use and levels of TXB2 in both cases and controls. For cases who used aspirin, the odds of having TXB2 urinary levels in the highest quartile (Q4) were significantly reduced when compared to non-users (adjusted OR = 0.29 95%CI 0.19-0.4) and this observation remained significant when stratified by race/ethnicity (AA men: OR 0.21 95%CI 0.11-0.38) (EA men: OR 0.34 95%CI 0.19-0.61), indicating significant inhibition of TXB2 formation by aspirin. The adjusted OR for PC was 1.42 (95%CI 1.09-1.85) for men in Q4 compared to Q1 (P trend 0.002). There was an association between TXB2 and PC in AA men (Q4 adjusted OR 1.95 95%CI 1.31-2.91, P trend &amp;lt;0.000) but not EA men (Q4 adjusted OR 1.04 95%CI 0.72-1.49, P trend 0.58), indicating increased thromboxane A2 synthesis in AA men with PC when compared to AA men without the disease. Also, men with Q4 levels of TXB2 were more likely to be diagnosed with metastasis compared to men with Q1 levels of TXB2 (adjusted OR 6.98 95%CI 1.51-32.32, P trend 0.014), indicating more aggressive disease for cases with the highest levels of TXB2. Conclusion: Aspirin use is protective against high levels of urinary TXB2. This is of clinical interest as we report increased urinary TXB2 associates with PC in AA men as well as with more aggressive PC which disproportionally affects AA men. These findings are consistent with our previous findings that aspirin inhibits aggressive disease in AA men and highlights the potential benefit of aspirin as a chemoprotective agent for this population through inhibition of thromboxane A2 synthesis. Citation Format: Maeve Kiely, Ginger Milne, Tsion Z. Minas, Tiffany H. Dorsey, Wei Tang, Cheryl J. Smith, Michael B. Cook, Clayton Yates, Stefan Ambs. High urinary thromboxane B2 associates with aggressive prostate cancer and inversely correlates with aspirin use [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-157.

Abstract IA33: The immunogenomic landscape of primary prostate cancer in African-American men

Abstract African-American (AA) men have a 1.5-fold higher incidence of prostate cancer (PCa) than non-Latino White (WH) men and are nearly 2.5 times more likely to die from their disease. These disparities are likely due to a combination of social, environmental, and biological factors. Discerning the biological determinants of aggressive PCa in AA men remains a critical and unmet need in cancer health disparities research. Although there have been several large-scale genome sequencing studies that identified unique molecular drivers in primary and metastatic PCa, these have included few AA patients, even fewer with potentially lethal PCa, and have generally lacked clinical outcome data. Work by our group and others demonstrates that the most common somatic genomic alterations in primary PCa (such as ERG rearrangement and PTEN deletion) occur at significantly different frequencies in AA and WH men, providing the first direct evidence for molecular differences between PCa arising in AA and WH patients. Similarly, gene expression studies by other groups have consistently found that various immune response pathways are more highly expressed in PCa arising in AA compared to WH patients. However to date, few studies have integrated somatic molecular subtype data with immune tumor microenvironment (TME) characterization across different populations. To begin to address these knowledge gaps, we have studied primary PCa tissues from a unique cohort comprising 200 self-identified AA and 200 WH patients, matched by grade and other clinical-pathologic parameters, with long-term follow-up for biochemical recurrence and metastasis. This cohort is unique in that it is highly enriched for high-risk disease and has now been profiled for somatic genomic, epigenomic, transcriptomic and tumor microenvironment landscapes, enabling one of the first integrative molecular portraits of AA PCa. We find that tumor infiltrating T-lymphocyte density is significantly correlated with underlying tumor molecular subtype and oncologic outcomes, but does not vary by racial ancestry. In contrast, using a combination of transcriptomic, methylation and quantitative immunohistochemical analyses, we demonstrate that tumor infiltrating B-lymphocyte density is significantly higher among AA compared to WH PCa patients, irrespective of molecular subtype, and trends towards improved outcomes. Citation Format: Tamara L. Lotan. The immunogenomic landscape of primary prostate cancer in African-American men [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr IA33.

Abstract PR18: The immune landscape of prostate cancer in African-American patients is skewed towards inhibitory signatures relative to Caucasian-American patients

Abstract Prostate Cancer is a leading cause of cancer-related deaths among men in the United States. Within the general population, African-Americans who constitute a minority group suffer a higher burden of the disease compared to other racial groups. Given that immune cells recruited to the tumor micro-environment shape tumor behavior, an outstanding issue is whether the immunological landscape of prostate cancer in African-American patients is a contributory factor to disease disparity seen in this minority patient population. In this regard, the present study sought to investigate whether prostate cancer in African-American men harbor distinctive immunological features compared to their Caucasian counterparts. Fresh prostate cancer specimens were obtained from consented African-American and Caucasian patients after prostatectomy. Gleason scores were comparable between the two demographics with an average score of 7 for African-American patients and 7.5 for Caucasian patients. We analyzed both tumor and matched peripheral blood mononuclear cells from each patient using comprehensive, multi-parameter flow cytometry. We found that both CD4+ and CD8+ T cells in African-American prostate cancer displayed upregulated expression of a number of inhibitory proteins that restrain T cell response. These cells also expressed reduced levels of co-stimulatory receptors and a less activated phenotype compared to equivalent cells in the tumors of Caucasian patients. Furthermore, analysis of serum from patients in each demographic revealed an enrichment of cytokines skewed towards immunosuppressive profile which may support reduced immune cell function against tumor-associated antigens. These findings suggest that the immunological profile of prostate cancer in African-American men harbors intrinsic signatures that may contribute to muting of potential anti-tumor responses in this patient demographic, enabling tumor immune evasion to support aggressive tumor growth and progression. Collectively, our data is in support of the contributory role of immunological factors to disease behavior and associated disparity in African-American prostate cancer patients. Citation Format: Andrew Schultz, David Noyes, Arup Bag, Dennis Adeegbe. The immune landscape of prostate cancer in African-American patients is skewed towards inhibitory signatures relative to Caucasian-American patients [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PR18.

Abstract PR05: Epigenetic disruption of vitamin D receptor signaling in African American prostate cancer alters circadian signaling networks

Abstract The current study aimed to define the genomic functions of the vitamin D receptor (VDR) in African American (AA) prostate cancer (PCa) compared to European American (EA) counterparts. VDR-dependent ChIP-Seq and RNA-Seq gene was undertaken in EA (non-malignant HPr1AR and malignant LNCaP) and AA (non-malignant RC43N and malignant RC43T) prostate models, combined with analyses of three PCa cohorts. In AA prostate models the VDR is highly expressed, binds more frequently, and is enriched in active and poised enhancers. Motif analyses revealed selective enrichment, including ZBTB33/KAISO in AA cells and ERG family members in EA cells and, similarly, GIGGLE analyses revealed AA VDR cistromes were significantly overlapped with core circadian rhythm transcription factors (e.g. NONO). Combining VDR-dependent ChIP-Seq and RNA-Seq established that AA cells displayed a significantly stronger transcriptional response, compared to EA cells, and was most responsive in non-malignant RC43N. For example, RC43N transcriptional responses were enriched for circadian rhythm (NES 2.7) and inflammation, whereas in RC43T the same gene networks were repressed. To reveal how VDR/1,25(OH)2D3 signaling is corrupted in AA PCa, we mined TCGA data and revealed that the BAZ1A/SMARCA5 chromatin remodeling complex was uniquely altered in TMPRSS2:ERG fusion negative AA PCa. We are currently examining the impact of BAZ1A on the 1,25(OH)2D3 responsiveness. We also identified miRNA associated with progression from HGPIN to PCa in AA men, and that ~30% were bound by VDR and regulated by 1,25(OH)2D3, although ~5% of EA progression miRNA were VDR-responsive. For example, VDR binds to miR-199b, is uniquely 1,25(OH)2D3 up-regulated in RC43N but repressed in RC43T, and associates with AA progression from HGPIN to PCa. MiR-199b regulates expression of NPAS2, a core circadian transcription factor. Finally, leveraging a previously analyzed cohort of 1,25(OH)2D3-treated PCa patients revealed that AA tumors were intrinsically more 1,25(OH)2D3-responsive than EA counterparts, reflecting the cell line analyses. 1,25(OH)2D3 regulated circadian transcriptional regulators (e.g. NOCT and MYBBP1A) and inflammatory signals. Together, these data suggest VDR transcriptional control in AA men is more dynamic than in EA men, and is primed to govern inflammatory and circadian rhythm pathways. This is frequently disrupted, including by altered BAZ1A/SMARCA5 expression and/or reduced environmental-regulated serum vitamin D3 levels, and leads to altered regulation of circadian rhythm process, and inflammatory signals. Therefore, the VDR axis lies at the cross-roads of biopsychosocial processes that contributes to PCa health disparities. Citation Format: Manjunath Siddappa, Sajad D. Wani, Jaimie S. Gray, Mark D. Long, Hedieh Jafari, Hsuchang Wu, Honhe Wang, Rebecca Morgan, Gary Hardiman, James Marshall, Chanita Hughes-Halbert, Lara E. Sucheston-Campbell, Clayton L. Yates, Moray J. Campbell. Epigenetic disruption of vitamin D receptor signaling in African American prostate cancer alters circadian signaling networks [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PR05.

Abstract C090: Association between hypertension and prostate cancer risk in black and white men in the Atherosclerosis Risk in Communities (ARIC) study

Abstract Background: A diagnosis of hypertension (HTN) has been reported to be associated with an increased risk of total and aggressive prostate cancer (PCa) in some studies. In this study, we evaluated the association between HTN and total and lethal PCa in African-American (AA) and Caucasian-American (CA) men. Given that AA men are disproportionately burdened by both HTN and PCa, especially aggressive disease, we hypothesized that the positive association between HTN and total and lethal PCa is stronger in AA than CA men. We alternatively hypothesized that the positive association between HTN and PCa is the same in AA and CA men, but the higher HTN prevalence in AA men results in a greater PCa burden in AA men. Methods: We studied 1,590 AA men and 5,094 CA men from the Atherosclerosis Risk in Communities (ARIC) study without a history of cancer at the first study visit (1987-1989) and who were followed through 2012. HTN was defined based on clinic-measured systolic and diastolic blood pressure and self-reported use of antihypertensive drugs at Visit 1. First primary total PCa (N=266 in AA men, 565 in CA men) and lethal PCa (metastatic at baseline or progressed to death from prostate cancer, N=39 in AA men, 59 in CA men) were ascertained by cancer registry linkage, medical records, and death certificates. We used Cox proportional hazards regression to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of total and lethal PCa comparing CA men with HTN, AA men without HTN, and AA men with HTN to CA men without HTN. We adjusted for age, education, and purported risk factors including body mass index, waist to hip ratio, smoking, physical activity, diabetes, cholesterol-lowering medication use, and aspirin use. Results: AA men had a higher prevalence of HTN (54.6%) than CA men (28.6%) at baseline. Compared with CA men without HTN, CA men with HTN had a higher risk of total PCa (HR=1.23, 95% CI=1.01-1.49, p=0.040), and as expected, AA men without HTN had an elevated PCa risk (HR=2.41, 95% CI=1.94-3.01, p&amp;lt;0.001), but AA men with HTN had a similarly elevated PCa risk (HR=2.41, 95% CI=1.93-3.01, p&amp;lt;0.001). Patterns were similar for lethal PCa (versus CA men without HTN, CA men with HTN - HR=1.48, 95% CI=0.83-2.63, p=0.183, AA men without HTN - HR=3.27, 95% CI=1.79-5.95, p&amp;lt;0.001, AA men with HTN - HR=2.49, 95% CI=1.31-4.73, p=0.005). Conclusions: Our prospective findings support some prior studies that HTN is associated with an increased risk of total and possibly lethal PCa in CA men. Counter to our hypothesis, HTN was not associated with total or lethal PCa in AA men. Support: NHLBI, NCI, NPCR, UMMC Office of Research. Citation Format: Wanmei Wang, Eldrin Bhanat, Kenneth R. Butler, Corinne E. Joshu, Thomas H. Mosley, Elizabeth A. Platz, Christian R. Gomez. Association between hypertension and prostate cancer risk in black and white men in the Atherosclerosis Risk in Communities (ARIC) study [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C090.

Abstract C039: Investigation of a prostate cancer genetic susceptibility candidate region on chromosome 5 in African Americans

Abstract There are well documented, marked racial disparities in prostate cancer (PCa) incidence and mortality in the United States between African American (AA) and European American (EA) men. These disparities cannot be fully explained by differences in screening or treatment differences by race, and other environmental and biological risk factors have not been well characterized. We hypothesize that racial differences in the distribution of genetic risk factors may contribute to the observed disparities. We previously identified a region on chromosome 5q35 via admixture mapping that is associated with PCa in AA men (Bock 2009). Preliminary analyses in this region suggested two loci involved in chromatin regulation, and several genes including COL23A1, TSPAN17, and GRM6. These are genes that have not been well characterized in the literature, however hints of their role in PCa can be found within previous expression studies. Here, we examine the region on chromosome 5q35 in greater depth to first confirm the observed admixture and to leverage the admixture signal within that region to identify novel variants associated with risk of prostate cancer in African Americans. To achieve the first goal, we estimated genome-wide and local ancestry across chromosome 5 in African American subjects from the Multiethnic Cohort (MEC) and an independent case control study from the Barbara Ann Karmanos Cancer Institute (KCI). Our results validated the significance of the admixture (p=7.87*10-6). However, the ancestry odds ratio from the MEC study was in the opposite direction in comparison to our original discovery analysis. Despite this difference, after combining studies via meta-analysis, we still retained a significant admixture peak on the distal portion of the chromosome 5q (p=5.47*10-4), which stretched from 152-180Mb. Overall, this effect showed that increasing European ancestry at this locus was associated with increased risk of prostate cancer. Additionally, our admixture meta-analysis uncovered a secondary peak (p=3.66*10-4) from 64-96Mb, where increased risk of prostate cancer was again associated with increasing European ancestry at this locus. We also performed association testing using the MIXSCORE approach, which is a combined test of genotype and local ancestry association. Our most significant association results were located within our primary admixture association peak, and they clustered around a locus at 173 Mb. The lead single nucleotide polymorphism (SNP) within this region was rs6885032 (MIXSCORE p=7.83*10-4). Interestingly, this SNP was identified in a genome-wide association analysis as associated with height, and a recent meta-analysis of studies from the literature confirmed an association between height and prostate cancer risk. Furthermore, this SNP was also identified as an expression quantitative trait locus (p=3.30*10-9) in the Genotype-Tissue Expression project. This convergence of findings suggests a possible mechanism for this variant on prostate cancer risk. Citation Format: Albert M Levin, Gregory Dyson, Julie L Boerner, Julie J Ruterbusch, Cathryn H Bock. Investigation of a prostate cancer genetic susceptibility candidate region on chromosome 5 in African Americans [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr C039.

Abstract 1022: The role of dopamine signaling in prostate cancer disparities

Abstract Prostate cancer is the second leading cause of cancer-related deaths among men in western countries. Majority of prostate tumors often evolves as metastatic castration-resistant prostate cancer (CRPC) following hormonal therapy. Metastatic prostate cancer is the major cause of mortalities from this disease. African-American (AA) men have the highest incidence and mortality rate compared to any other race such as Caucasian American (CA). Despite recent advances, the cellular and molecular mechanisms that contribute to this disparity are unknown, obstructing the development of an effective therapy for this disease. Genetic and epigenetic studies have indicated that the biology of prostate cancer in AA men is substantially different from CA. Here, we investigate the dopamine (DA) signaling to better understand the mechanism of prostate cancer disparity. Our analysis of the prostate cancer public data sets showed that the dopamine receptor (DR) genes were amplified in up to 18% prostate cancer clinical cases. We have demonstrated that the levels of DR transcripts were significantly higher in the metastatic prostate cancer cell lines with African genetic ancestry than CA counters. We also demonstrate that the efficacy of pimozide, a potent DRD inhibitor and an FDA-approved antipsychotic, on AA cells was significantly higher than CA cells. In addition, we have found that L-dopa, an immediate precursor of DA differentially regulates the growth of AA and CA prostate cancer cells in a dose dependent manner. We also found that carbidopa, a potent inhibitor of the dopa decarboxylase, suppressed prostate cancer cell growth by L-dopa and showed that carbidopa re-sensitized CRPC cell line to enzalutamide, a potent inhibitor of androgen receptor (AR) signaling. These observations suggest that DA/DR signaling plays a critical role in prostate cancer disparity, making the DA/DR-AR axis a viable therapeutic target to reduce disparities in cancer mortality. Citation Format: Isaiah R. Pickett, Ava M. Boston, Marwah M. Almathkour, Camille Ragin, Mehmet A. Bilen, Adeboye O. Osunkoya, Bekir Cinar. The role of dopamine signaling in prostate cancer disparities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1022.

Prostate carcinoma in African-Americans has miRNA expression and biological markers for aggressive disease.

e16558 Background: African American (AA) men have twice the incidence and mortality in Prostate Cancer (PCa) as compared to non-Hispanic Whites. The identification of a biological basis for this disparity is crucial in providing focused treatment. In this study, we have characterized the pathological features and molecular markers of PCa in AA men. Methods: 91 proctectomies for primary PCa and 23 biopsies for metastatic PCa with their pathological data were retrieved. Tissue microarrays were constructed and the expression of Programmed Cell Death 1 (PD-1), Programmed Death Ligand 1 (PD-L1) and Mismatch Repair (MMR) (MLH1, MSH2, MSH6 and PMS2) proteins was assessed by immunohistochemistry. miRNA expression of 24 cases of primary PCa and adjacent normal prostate tissue from proctectomies was identified by microarray in situ hybridization. Spearman’s rank-correlation was used to correlate variables and p &lt; .05 was considered significant. TargetScan and DIANA analysis software were used to identify modulation in miRNA expression. Results: In a supervised heat map, overall the downregulation of microRNA was more than upregulation in tumor tissue; 11 miRNA were upregulated and 12 were downregulated, with a log fold change of 1.5. miR-345, a component of the mismatch repair and DNA Replication pathway, showed significant up-regulation (p = 9.4E-02); has been linked to more aggressive PCa. PD-L1 expression was lower in primary PCa (16%) than in metastatic PCa (35%). PD-1 expression was high in almost half of primary and metastatic PCa patients. MMR protein expression was largely intact in both primary and metastatic PCa cases. Both of these protein markers have been associated with biochemical recurrence and low survival. Conclusions: The biological characteristics (low expression of PD-L1, high expression of PD-1, intact MMR and distinct miRNA signature) identified in our cohort of exclusively AA men are indicators of aggressive PCa. These results explain the biological basis of widely documented poor prognosis of PCa in AA men.

Exosome proteomic analyses identify inflammatory phenotype and novel biomarkers in African American prostate cancer patients

African American men face a stark prostate cancer (PCa)‐related health disparity, with the highest incidence and mortality rates compared to other races. Additional and innovative measures are warranted to reduce this health disparity. Here, we focused on the identification of a novel serum exosome‐based “protein signature” for potential use in the early detection and better prognosis of PCa in African American men. Nanoparticle tracking analyses showed that compared to healthy individuals, exosome concentration (number/ml) was increased by ~3.2‐fold (P ˂ 0.05) in the sera of African American men with PCa. Mass spectrometry‐based proteomic analysis of serum exosomes identified seven unique and fifty‐five overlapping proteins (up‐ or downregulated) in African Americans with PCa compared to healthy African Americans. Furthermore, ingenuity pathway analyses identified the inflammatory acute‐phase response signaling as the top pathway associated with proteins loaded in exosomes from African American PCa patients. Interestingly, African American PCa E006AA‐hT cells secreted exosomes strongly induced a proinflammatory M2‐phenotype in macrophages and showed calcium response on sensory neurons, suggesting a neuroinflammatory response. Additionally, proteomic analyses showed that the protein Isoform 2 of Filamin A has higher loading (2.6‐fold) in exosomes from African Americans with PCa, but a lesser loading (0.6‐fold) was observed in exosomes from Caucasian men with PCa compared to race‐matched healthy individuals. Interestingly, TCGA and Taylor's dataset as well as IHC analyses of PCa tissue showed a lower Filamin A expression in tissues of PCa patients compared with normal subjects. Overall, these results support the usefulness of serum exosomes to noninvasively detect inflammatory phenotype and to discover novel biomarkers associated with PCa in African American men.

Novel Genomic Biomarker Panel Predictive of Aggressive Disease in African American Men with Prostate Cancer

Mutations in the E26 transforming specific (ETS) transcription factors occur early in the oncogenic process of prostate cancer. These mutations behave in a race dependent manner with the majority of European American (EA) men possessing ERG positive (ERG+) tumors while ≥75% of African American (AA) men have ERG negative (ERG-) tumors. In order to establish clinically relevant biomarkers in AA men, we studied ETS gene expression differences among AA men and EA men and identified race specific ETS negative (ETS-) genes that predict for clinically relevant outcomes. Previously published datasets from the Decipher Genomic Resource Information Database (GRID) were used to obtain microarray data. The validated microarray-based ETS positive (ETS+) (ERG or ETV1/4/5) over expression was used to determine ETS+ status in the GRID database. Samples with overexpression of ERG, ETV1-5, and FLI1 were categorized as ETS+. Chi square (X2)/Fisher Exact method was used to assess the race differences in clinico-pathologic endpoints such as extraprostatic extension, seminal vesicle invasion, pathologic Gleason Score, and the post-surgical Cancer of the Prostate Risk Assessment Score (CAPRA-S) . Logistic regression model was used to analyze the association between aforementioned clinico-pathologic endpoints and ETS status. Genes that showed differential expression were evaluated. On multivariable logistic regression analysis, race was found to be the strongest predictor of ETS- status. Analysis showed that AA men were four times more likely to be ETS- than EA men (p<0.001). Using a q value ≤0.05 and an expression fold change level of 0.05, we identified 3047 genes (6.6%) that were differentially expressed based on ETS status. Of these, 248 were found to be differentially expressed in a race-specific manner. Using a false-discovery rate q<0.1 we identified 143 genes that predicted for one or more clinical endpoint. In order to determine which of these race specific ETS- genes are significantly overexpressed in tumors we selected genes that met all three of the following criteria; significantly overexpressed in ETS- compared to ETS+ tumors, preferentially overexpressed in AA and not in EA, and predictive for one or more adverse outcome in a race-specific manner. Using this criteria, we have identified a 19-gene panel that includes ADAMTS1, AFF3, ANKRD20, ANPEP, CCL3, CYP4F35, FAR2P1, INPP4B, MAP1LC3, MIPEP, NPIPB7, NPNT, OPHN1, OR4K7P, PCGEM1, RLN2, SCIN, SPINK1, and TTN. In an effort to elucidate biologic features associated with aggressiveness of prostate cancer in AA men, we have identified ETS- biomarkers that predict for one or more adverse clinical outcome in AA men. Our investigation found 19 ETS- genes that are both overexpressed in AA men and predictive of clinical outcomes thus representing ideal candidates for prognostic biomarkers.

Abstract B016: MicroRNA drivers of TMPRSS2 fusion-negative prostate cancer in African Americans

Abstract TMPRSS2:ERG fusions are being pursued as genomic biomarkers to define disease state and predict treatment responses in prostate cancer (PCa). Successful biomarker exploitation depends on the frequency of TMPRSS2 fusions, which are very common in European American (EA) men with both high-grade PIN, and in at least 50% PCa patients. However, the incidence is far lower in men from other ethnicities, and as low as 10% among African American (AA) patients. Therefore in AA patients, TMPRSS2:ERG fusion events are unlikely to either explain the elevated incidence of PCa or be relevant as a biomarker. To seek novel biomarkers of TMPRSS2 fusion-negative PCa we have considered a role for miRNA drivers. Previously, we analyzed miRNA expression in various PCa cohorts, to identify differentially expressed miRNA in TMPRSS2 fusion-negative disease in AA men. These cohorts included PCa in AA men, PCa progression in EA men following surgery, and mining of TCGA-PRAD and MSKCC cohorts to identify TMPRSS2 fusion-negative associated miRNA. We have now complemented this by a genome-wide miRNA screen in serum samples using the NanoString platform of 97 aged matched EA and AA men with HGPIN, ~30% of whom progressed to PCa (SWOG S9917). Serum levels of 22 miRNA significantly distinguished AA men who progressed to PCa, from those whose HGPIN remained stable; these miRNA included miR-25-3p, miR-93-5p, and miR-423-5p. Combining the findings identified 38 miRNA, and we sought to identify shared and unique links between these miRNA associated with PCa progression and TMPRSS2 fusion-negative status. Although the PCa drivers in AA men remain obscured, strong links are emerging between vitamin D receptor (VDR) signaling and AA PCa. Epidemiologic studies have established links between low serum vitamin D3 levels and PCa incidence and progression in AA men. VDR signaling has also been linked to altered local immune responses in AA PCa patients. Remarkably, we found strong evidence from our studies and those of others that 29 of the 38 miRNA identified were regulated by 1,25(OH)2D3 in prostate cells, including the miR-25-miR-93-miR-106b cluster, miR-152 and miR-423-5p. As this regulation includes both direct and indirect effects, we examined how these miRNA genes, or host genes, were targeted by the vitamin D receptor (VDR). Previously, we identified VDR binding at the MCM7 host gene for the miR-25-miR-93-miR-106b cluster used ChIP-PCR in nonmalignant RWPE-1 cells. We have now mined publicly available VDR ChIP-Seq in LNCaP cells (GSE64656); these cells are TMPRSS2 fusion negative. Selecting all binding sites within +/- 7.5 kb of a TSS, we identified VDR associated with 8/29 miRNA, including NSRP1 (miR-423-5p host gene) and COPZ2 (miR-152 host gene). To measure associations with TMPRSS2 fusion-negative PCa, we identified the most commonly altered of the 38 miRNA in the TCGA-PRAD cohort. Specifically, we identified 18 miRNA altered by more than 2 Z scores in more than 25% tumors, which included miR-25-3p, miR-93-5p, miR-152, and miR-423-5p. Expression of these miRNA clustered tumors into two groups that significantly distinguished TMPRSS2 fusion status (p=0.007) and race (p=0.01). 15/18 miRNA were known to be regulated by 1,25(OH)2D3, and 5/8 were bound by VDR in LNCaP cells. Currently, we are measuring how these 18 miRNA are regulated by 1,25(OH)2D3 in AA and EA nonmalignant and malignant prostate cell models: AA-RC77T, RC43T; EA-HPr-1AR, LNCaP, VCaP (TMPRSS2 fusion positive), PC-3. Together these data suggest that a distinct PCa subtype, independent of TMPRSS2 fusion, arises more frequently in AA men due to reduced 1,25(OH)2D3 levels that disrupts VDR regulation of miRNA, including miR-25-3p, miR-93, miR-152, and miR-423-5p. Understanding the miRNA regulated gene networks has the potential to illuminate the cancer drivers in TMPRSS2 fusion-negative AA PCa, and expression of these miRNA may predict progression risks. Citation Format: Manjunath Siddappa, Jason White, Honghe Wang, Lara E. Sucheston-Campbell, Clayton Yates, Moray J. Campbell. MicroRNA drivers of TMPRSS2 fusion-negative prostate cancer in African Americans [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B016.

Abstract A003: Epigenetic alterations as potential biologic determinants of racial health disparities

Abstract Background: Biologic determinants of prostate cancer racial health disparities remain largely unknown. African American (AA) men are diagnosed with more aggressive prostate cancer than European American (EA) men despite presenting tumors with lower mutational burden, copy number alterations, and lacking ETS gene fusions. The purpose of our study is to investigate how DNA methylation alterations in the context of other molecular lesions contribute to aggressive prostate cancer in AA men. Methods: We measured DNA methylation and gene expression in twelve radical prostatectomy specimens from AA patients treated at Roswell Park Cancer (RPCI) Institute by Infinium DNA methylation arrays and RNA-sequencing, respectively. Additional AA (n=22)/EA (n=5) patients from RPCI and AA (n=22)/EA (n=172) patients from The Cancer Genome Atlas (TCGA) were included in the clustering analysis to raise statistical power of our study. The MethylMix pipeline was applied to DNA methylation and gene expression to identify transcripts that are potentially regulated by DNA methylation. Results: Unsupervised hierarchical clustering revealed 2 large clusters, Cluster1 (n=133) and Cluster3 (n=73). AA patients in Cluster1 presented with better overall survival (57 vs. 50 months, p=0.48) and disease-free time (47 vs. 22 months, p&amp;lt;0.05) compared to AA patients in Cluster3. We did not observe this difference in clinical outcomes for EA patients. Cluster3 consisted of hypomethylated CG sites belonging primarily to neurogenesis development and the Wnt/Hedgehog signaling pathways. TMPRSS2-ERG fusion status thought to drive aggressive prostate cancer was similar in all clusters. Interestingly, promoter DNA methylation of ERG gene was significantly lower at 5 CG sites (p&amp;lt;0.0001) and at 10 CG sites in the 5′-UTR region (p&amp;lt;0.0001) in fusion-positive EA patients as compared to fusion-negative EA patients. In tumors of AA patients, DNA methylation of ERG gene was significantly lower at 2 CG sites at the transcription start site (p&amp;lt;0.05) and at 1 CG site in the 5′-UTR region (p&amp;lt;0.05) in fusion-positive tumors as compared to fusion-negative tumors. Overall DNA methylation at the ERG negatively correlated with ERG gene expression (Pearson: -0.632). Furthermore, we used MethylMix algorithm that revealed DNA methylation as a potential negative regulator of genes involved in suppression of tumor invasion, glycosylation of mucin proteins, calcium sensing, and terminal differentiation specifically in AA patients. For a subset of these genes we observed altered transcript levels in AA tumor samples compared to EA tumor samples from the TCGA cohort. This included GALNT5 (-0.23 vs 0.15, p&amp;lt;0.05), STK39 (-0.30 vs 0.03, p&amp;lt;0.05), and TMEM63C (46.68 vs 22.65, p&amp;lt;0.05). Conclusions: Our work reveals that there are epigenetic alterations found in prostate tumors that are specific to AA men. Moreover, this differential gene methylation may have subsequent impact on gene expression and contribute to more aggressive prostate cancer. We identified novel transcripts in AA patients that are potentially regulated by DNA methylation including ERG, GALNT5, STK39, and TMEM63C. Functional validation of these genes using prostate cancer models may provide insight into whether epigenetic regulation of these genomic loci are determinants of prostate cancer racial health disparities. Citation Format: Swathi Ramakrishnan, Peng Xuan, Qianya Qi, Qiang Hu, Emily Ellman, Gissou Azabdaftari, Elena Pop, James Mohler, Kristopher Attwood, Yan Li, Jianmin Wang, Anna Woloszynska-Read. Epigenetic alterations as potential biologic determinants of racial health disparities [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A003.