European American Prostate Cancer Research Articles

Abstract B92: Metabolomic landscape of African American prostate cancer: Insights into the biologic basis of the racial disparity

Abstract African American (AA) men have an approximately 60% higher incidence of prostate cancer (PCa) and have about two times greater risk of dying of the disease than their European American (EA) counterparts. Despite this staggeringly unequal burden of PCa incidence and outcome between AA and EA men, there is limited insight into the molecular mechanisms associated with this racial disparity. Using state-of-the-art mass spectrometry platform, we uncovered the very first metabolic and lipidomics landscape in PCa/benign adjacent tissue pairs and paired plasma and urine containing epidemiologic meta-data from ancestry-typed AA and EA men. A total of 190 polar and mid-polar metabolites and 495 lipids were measured in tissues and 183 metabolites and lipids were examined in the plasma and urine samples. AA PCa tissue and plasma signatures had unique alterations in metabolites and key enzymes associated with the methionine-homocysteine pathway, including adenosine and inosine levels, compared to corresponding tissues and plasma from EA case controls and EA PCa tissues. Intriguingly, methionine levels in AA PCa were also portrayed by distinct dietary practices in these patients. In addition, AA PCa tissues demonstrated unique patterns of bioenergetic metabolites and accumulated lipids reflecting impaired mitochondrial activity and TCA cycle. Further characterization of these first-in-the-field findings demonstrating reprogrammed metabolism in AA PCa relative to EA tumors could reveal insights into the biologic basis of PCa disparities and novel areas for therapeutic intervention. Citation Format: Stacy M. Lloyd*, Jie H. Gohlke*, Sumanta Basu*, Vasanta Putluri,Shaiju K Vareed, Rebeca San Martin, Thekkelnaycke Rajendiran, Tiffany A. Dorsey, Bandana Prasad, Rajni Sonavane, Uttam Rasaily, James Henderson, Balasubramanyam Karanam, Harene Venghatakrishnan, Salil Bhowmik, Alexander Zaslavsky,Nilanjan Guha, Rick Kittles, Stefan Ambs, Michael Ittmann,David Rowley, Ganesh Palapattu, Nagireddy Putluri,George Michailidis, Arun Sreekumar. Metabolomic landscape of African American prostate cancer: Insights into the biologic basis of the racial disparity [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr B92.

MicroRNAs differentially expressed in prostate cancer of African-American and European-American Men

African-American (AA) men have higher rates of prostate cancer incidence and mortality compared with European-American (EA) men. Although several socioeconomic and environmental factors may contribute to the disparity, recent studies suggest a biological component, including differential microRNA (miRNA) expression, to the disparity. miRNAs comprise a large family of about 22-nucleotide-long nonprotein coding RNAs that regulate gene expression posttranscriptionally and participate in the regulation of almost every known cellular process investigated to date. miRNAs have been associated with prostate cancer progression, and recent studies indicate that they are differentially expressed between AA and EA. They could therefore contribute, at least in part, to the disparity in prostate cancer between the two groups. In this review, existing evidence on differential miRNA expression between AA and EA prostate cancer patients or cell lines is summarized.

Abstract 2328: Race specific hyper-activation of CCR9-mediated survival signals and its impact on efficacy of docetaxel in prostate cancer

Abstract Current approaches to treat and manage prostate cancer (PCa) have failed to reduce racial disparity primarily due to undefined molecular mechanism. We have shown higher expression of chemokine receptor-9 in PCa cells and CCR9 expression was higher in PCa cells (MDA-PCa-2b) derived from African American (AA) patient compared to PCa cells derived form European American (EA) patients (LNCaP and PC3). Using antibody microarray we observed hyper activation of survival molecules and down-regulation of apoptotic molecules in AA PCa cells compared to EA PCa cell lines, following CCL25 stimulation. Comparative heat map analysis showed significant increase (~2-3 fold) in phosphorylation of pro-survival proteins in AA cells compared to EA cells treated with CCL25, which was further confirmed by western blot analysis. Furthermore, CCL25 treated PCa cells showed decreased expression of pro-apoptotic proteins (Bim, Bid, Bak), which was significantly abrogated by CCR9 shRNA. This effect was more pronounced in AA cells compared to EA cells. Efficacy of docetaxel (DTX) was higher after CCR9 blockade in presence of CCL25 compared to cells treated with CCL25 without blocking CCR9. Improvement in efficacy of DTX was due to inhibition of cell survival and activation of pro-apoptotic signals following CCR9 blockade. These observations suggest potential involvement of CCR9 mediated molecular pathways in disparity associated with outcome of PCa. Citation Format: Neeraj Kapur, Hina Mir, Guru Sonpavde, Shailesh Singh. Race specific hyper-activation of CCR9-mediated survival signals and its impact on efficacy of docetaxel in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2328. doi:10.1158/1538-7445.AM2017-2328

Abstract 4139: Role of zinc transporters in prostate cancer and a potential association with racial disparity

Abstract Optimal intracellular zinc concentration is essential for many cellular functions as it serves as a catalytic and/or structural cofactor for a variety of proteins. Although, a number of proteins are tangled in regulating cellular zinc homeostasis, the most important are two protein families of zinc transporters, 14 members of solute carrier family 39 (SLC39A) and 10 members of solute carrier family 30 (SLC30A). These two families are known to transport zinc into- and out of- the cytoplasm, respectively. Prostate cells accumulate a high amount of zinc to sustain a metabolic condition unique to the prostate which is characterized by a truncation of the Krebs cycle and production of high amounts of citrate. Zinc depletion has frequently been noted in the progression of prostate cancer (PCa). Whether zinc transporters are a steering cause of zinc depletion in PCa development and progression and/or are key determinants in the racial disparity in PCa is not well studied. In this study, we determined the connection of zinc transporters (SLC39A 1-14 and SLC30A 1-10) in PCa, in the perspective of racial health disparity in human PCa samples taken from African-American (AA) and European-American (EA) patients and compared them with respective adjacent benign samples. We also assessed the mRNA level of zinc transporters in normal prostate epithelial cells (NrPEC and RWPE1) and among PCa cells derived from AA (MDA PCa 2b, E006AA-PAR, E006AA-HT) and EA patients (DU145, PC3, 22Rν1, LNCaP, C4-2B). In addition, we performed a dataset analysis of the Oncomine database for differential expression profile of zinc transporters in PCa versus normal prostate. We found that SLC39As mRNA levels were differentially expressed in PCa with a significant downregulation of SLC39A1, SLC39A10, SLC39A11, SLC39A13 and SLC39A14, and upregulation of SLC39A3, SLC39A5, SLC39A6 and SLC39A8. Further, SLC30As showed a significant downregulation of SLC30A5 and SLC30A6 and upregulation of SLC30A1, SLC30A9 and SLC30A10, in PCa. Further, compared to EA samples, the AA PCa showed an increasing trend of SLC39A5, SLC39A6 and SLC30A9. In addition, compared to AA samples, the EA PCa showed a trend of increasing SLC30A1 and SLC30A9 and decreasing SLC39A10. These data provide evidence that the zinc transporters may be linked to racial disparity of PCa in AA versus EA. Moreover, Ingenuity Pathway Analysis revealed regulatory interactions between zinc transporters and tumor suppressor/promoter genes proven to be modulated in PCa. These genes are HOXB13, ELAVL1, DIRAS3, ALPP, CSF2, CCL4, INSR, AKT, IL6, TGFBP1, CHI3L1, EGFR and HNF4A. Overall, our study provides interesting data about the expression profiles of zinc transporters and their interaction with tumor suppressor and promoter genes in PCa, which may offer novel strategies for the management of PCa by pharmacologically modulating zinc transporters. Citation Format: Chandra K. Singh, Kareem M. Malas, Caitlin Tydrick, Kenneth A. Iczkowski, Nihal Ahmad. Role of zinc transporters in prostate cancer and a potential association with racial disparity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4139. doi:10.1158/1538-7445.AM2017-4139

Alternative splicing promotes tumour aggressiveness and drug resistance in African American prostate cancer

Clinical challenges exist in reducing prostate cancer (PCa) disparities. The RNA splicing landscape of PCa across racial populations has not been fully explored as a potential molecular mechanism contributing to race-related tumour aggressiveness. Here, we identify novel genome-wide, race-specific RNA splicing events as critical drivers of PCa aggressiveness and therapeutic resistance in African American (AA) men. AA-enriched splice variants of PIK3CD, FGFR3, TSC2 and RASGRP2 contribute to greater oncogenic potential compared with corresponding European American (EA)-expressing variants. Ectopic overexpression of the newly cloned AA-enriched variant, PIK3CD-S, in EA PCa cell lines enhances AKT/mTOR signalling and increases proliferative and invasive capacity in vitro and confers resistance to selective PI3Kδ inhibitor, CAL-101 (idelalisib), in mouse xenograft models. High PIK3CD-S expression in PCa specimens associates with poor survival. These results highlight the potential of RNA splice variants to serve as novel biomarkers and molecular targets for developmental therapeutics in aggressive PCa.

Abstract C42: Alternative splicing of FGFR3 as a mechanism for African American prostate cancer health disparities

Abstract Introduction: In this study, we investigate the role of differential expression of splicing factors and exon skipping in the receptor tyrosine kinase family on prostate cancer health disparities in African American men. Background: Prostate cancer (PCa) is the most diagnosed cancer in men and the second leading cause of male-cancer related deaths in the U.S. Dramatic ethnic disparities have been observed in PCa patients, as African American (AA) men are 60% more likely to be diagnosed with PCa and have a 2.4 fold higher mortality rate compared to European American (EA) men. Increasing evidence suggests that, after accounting for epidemiological factors, a remaining component of this disparity is due to intrinsic genetic and biological factors. Interestingly, recent exon array data from our lab suggest that differential expression of splicing factors (SFs) and differential alternative splicing may be occurring in AA PCa. We hypothesize that differential alternative splicing involving exon 14 of the FGFR3 gene is generating a shorter, more oncogenic variant in AA PCa, which is absent or weakly expressed in EA PCa. Differential splicing of FGFR3 and increased expression of SFs in AA patients may be mechanisms contributing to AA PCa health disparities. Results: Exon array data suggested FGFR3 as a candidate for differential alternative splicing. Exon profiling and RT-PCR validated enriched expression of a short variant of FGFR3 due to skipping of exon 14 in AA patient samples and cell lines. Cloning confirmed the presence of the FGFR3-L variant (containing exon 14) and the FGFR3-S variant (without exon 14) from an EA and AA PCa cell line, respectively. Enrichment of FGFR3-S resulted in increased cell proliferation in an AA cell line. RNA-seq data analysis suggests decreased survival of PCa patients with high FGFR3-S/-L expression ratios. Additionally, our exon array data predicted increased expression of seven SFs in AA patients. RT-PCR and IHC analysis validated increased expression in AA specimens. Knockdown of these SFs resulted in decreased invasion and FGFR3 splice switching in an AA cell line. Conclusions: We have identified an oncogene of interest, FGFR3, which undergoes exon skipping that is specific to AA PCa. In cell lines, this shorter isoform of FGFR3 leads to an increased oncogenic phenotype based on proliferation assays. We have shown that AA PCa patient specimens have increased expression of specific SFs compared to EA specimens and knockdown of SFs reduces AA PCa cell invasion and causes splice switching of FGFR3. Thus, differential expression of SFs and exon skipping in FGFR3 may be one mechanism contributing to the increased aggressiveness of PCa in AA patients. Citation Format: Jacqueline Olender, Bi-Dar Wang, Norman H. Lee. Alternative splicing of FGFR3 as a mechanism for African American prostate cancer health disparities. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr C42.

Prevalence and Prognostic Significance of PTEN Loss in African-American and European-American Men Undergoing Radical Prostatectomy

African-American (AA) men have a higher risk of lethal prostate cancer (PCa) compared to European-American (EA) men. However, the molecular basis of this difference, if any, remains unclear. In EA PCa, PTEN loss, but not ERG rearrangement, has been associated with poor outcomes in most studies. Although ERG rearrangement is less common in AA compared to EA PCa, the relative frequency of PTEN loss and the association of PTEN/ERG molecular subtypes with outcomes is unknown for AA PCa. We examined PTEN/ERG status by immunohistochemistry in self-identified AA patients undergoing radical prostatectomy at Johns Hopkins with tumor tissue available on tissue microarray (TMA; n=169) and matched these cases by pathologic parameters to 169 EA patients from the same TMAs. The rate of PTEN loss was significantly lower in AA compared to EA PCa (18% vs 34%; p=0.001), similar to the lower rate of ERG expression (25% vs 51%; p<0.001). To examine the association of PTEN/ERG status with oncologic outcomes, we created an additional TMA of 87 AA tumors with Gleason score > 4 + 3 = 7. Among the total population of AA men with outcome data from all TMAs (n=222), PTEN loss was associated with higher risk of biochemical recurrence (hazard ratio [HR] 2.25, 95% confidence interval [CI] 1.33–3.82) and metastasis (HR 3.90, 95% CI 1.46–10.4) in multivariable models. Patient summaryPTEN and ERG alterations in prostate cancer are less likely in African-American than in European-American men. However, PTEN loss remains associated with poor prostate cancer outcomes among African-American men.

Abstract C73: A relationship between mast cells and the racial disparity of prostate cancer

Abstract Prostate cancer afflicts African American men to a greater degree than European American men, with a 60% greater incidence and 2-3 times greater mortality. In addition, studies have shown that the incidence rate of distant metastasis is 4 times greater in African American men than in European American men, consistent with the notion that prostate cancer is more aggressive in African Americans. Of interest, African American men are also significantly more likely to present with inflammation in benign prostate biopsies, and studies have shown higher expression of a number of inflammatory markers in prostate cancer tissue from African Americans compared to European Americans. One immune cell type of particular interest in the context of prostate cancer are mast cells, which have the potential to play a number of roles in cancer, and have also been shown to increase in number in prostate cancer versus benign regions of the prostate. In the present study, immunohistochemistry (IHC) was used to directly visualize and localize mast cells in the prostate microenvironment of African American and European American men in a tissue microarray (TMA) containing tumor and benign tissues from 75 African American and 75 European American prostate cancer patients matched on tumor grade and stage. Automated counting of mast cell numbers as well as the calculation of mast cell-to-epithelial ratio (MC/Ep) and mast cell numbers per total tissue area (density) was aided by novel digital image analysis using a software framework integrating whole slide imaging, virtual microscopy, and ImageJ based analysis algorithms. Key results to date include the finding that mast cell density in prostate tumor tissues of African American men is significantly lower than that of Caucasian Americans (p &amp;lt; 0.0001). This same trend was observed for total mast cell numbers and MC/Ep (p=0.001). These results suggest the intriguing possibility that a decrease in tumor-infiltrating mast cells may contribute to the racial disparity observed in association with prostate cancer and additional studies are underway to determine the biological function of mast cells in the prostate tumor microenvironment. Citation Format: Heidi A. Hempel, Ibrahim Kulac, Nathan S. Cuka, Toby C. Cornish, Angelo M. De Marzo, Karen S. Sfanos. A relationship between mast cells and the racial disparity of prostate cancer. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr C73.

Identification and Functional Validation of Reciprocal microRNA-mRNA Pairings in African American Prostate Cancer Disparities.

African Americans (AA) exhibit higher rates of prostate cancer incidence and mortality compared with European American (EA) men. In addition to socioeconomic influences, biologic factors are believed to play a critical role in prostate cancer disparities. We investigated whether population-specific and -enriched miRNA-mRNA interactions might contribute to prostate cancer disparities. Integrative genomics was used, combining miRNA and mRNA profiling, miRNA target prediction, pathway analysis, and functional validation, to map miRNA-mRNA interactions associated with prostate cancer disparities. We identified 22 AA-specific and 18 EA-specific miRNAs in prostate cancer versus patient-matched normal prostate, and 10 "AA-enriched/-depleted" miRNAs in AA prostate cancer versus EA prostate cancer comparisons. Many of these population-specific/-enriched miRNAs could be paired with target mRNAs that exhibited an inverse pattern of differential expression. Pathway analysis revealed EGFR (or ERBB) signaling as a critical pathway significantly regulated by AA-specific/-enriched mRNAs and miRNA-mRNA pairings. Novel miRNA-mRNA pairings were validated by qRT-PCR, Western blot, and/or IHC analyses in prostate cancer specimens. Loss/gain of function assays performed in population-specific prostate cancer cell lines confirmed miR-133a/MCL1, miR-513c/STAT1, miR-96/FOXO3A, miR-145/ITPR2, and miR-34a/PPP2R2A as critical miRNA-mRNA pairings driving oncogenesis. Manipulating the balance of these pairings resulted in decreased proliferation and invasion, and enhanced sensitization to docetaxel-induced cytotoxicity in AA prostate cancer cells. Our data suggest that AA-specific/-enriched miRNA-mRNA pairings may play a critical role in the activation of oncogenic pathways in AA prostate cancer. Our findings also suggest that miR-133a/MCL1, miR-513c/STAT1, and miR-96/FOXO3A may have clinical significance in the development of novel strategies for treating aggressive prostate cancer.

Abstract B69: Effects of obesity and neighborhood socioeconomic status on prostate cancer stage and grade

Abstract Background: Obesity has been shown to increase the risk for advanced prostate cancer. Although linked to both obesity and advanced cancer, neighborhood socioeconomic status (SES) has not been studied as a modifier of obesity effects in prostate cancer patients. Ethnic differences in obesity among men are less pronounced in lower SES environments. It is possible that the relationship between obesity and prostate cancer outcomes varies by neighborhood characteristics. Objective: The goal of this project was to study neighborhood SES as an effect modifier of obesity on prostate cancer characteristics. Neighborhood SES differences may help to explain ethnic differences observed in prostate cancer outcomes. Our general hypotheses are that (1) neighborhood SES differs for African-American and European American prostate cancer patients recruited from the same medical center and (2) neighborhood SES modifies the effects of obesity on prostate cancer outcomes. Methods: A case-case design was proposed to examine the relationship between neighborhood SES and prostate cancer severity. The residential addresses of prostate cancer patients from the University of Pennsylvania were geocoded. Census tract data was downloaded from the Census Bureau website and merged with patient data. Obesity was defined as a Body Mass Index (BMI) ≥30 kg/m2 and non-obese as BMI &amp;lt;30 kg/m2. Median cut-points for census tract variables were determined for all patients combined. Census tract variables included per capita income, percent poverty, median household income, education and employment. Outcomes for this study included tumor stage and tumor grade. Age-adjusted multivariate models were used to examine obesity effects on stage and grade stratified by neighborhood SES. Analyses were stratified by ethnicity. Results: 1000 European American and 144 African-American prostate cancer patients were included in these analyses. We observed no ethnic differences in patient-level variables except for those related to obesity. The African-American sample had a higher mean BMI (29 vs. 27 kg/m,2 p=0.001) compared to European Americans. Neighborhood SES characterized by below median census tract income and education was more prevalent among African-Americans. (&amp;lt;0.001) There was no difference in stage at diagnosis by obesity status for African-Americans or European Americans. However, odds ratios increased to significance among men in either group who lived in neighborhoods below median SES characteristics (i.e., below median per capita income: OR=2.60, 95% CI=1.06-6.36 for African Americans; OR=1.77, 95% CI=1.14-2.76 for European Americans). Obesity was associated with tumor grade at baseline in European Americans (OR=1.52, 1.09-2.11). Stratification by neighborhood SES demonstrated general associations of obesity on tumor grade for European Americans. Conclusions: Lower neighborhood SES is more common among African-American prostate cancer patients than European American cases. The relationship between obesity and tumor stage may be influenced by lower neighborhood SES. Modification of obesity effects by neighborhood SES may suggest strategies for prostate cancer intervention in high-risk communities. Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):B69.

Abstract 512: Gene expression profiling reveals tumor immunobiological differences in prostate cancer between African-American and European-American men

Abstract The incidence and mortality rates of prostate cancer are significantly higher in African-American men when compared to European-American men. We tested the hypothesis that differences in tumor biology contribute to this survival health disparity. Using microarray technology, we obtained gene expression profiles of primary prostate tumors resected from 33 African-American and 36 European-American patients. These tumors were matched on clinical parameters. We also evaluated 18 non-tumor prostate tissues from 7 African-American and 11 European-American patients. The resulting datasets were analyzed for expression differences on the gene and pathway level comparing African-American with European-American patients. Our analysis revealed 162 transcripts to be differentially expressed between African-American and European-American prostate cancer patients at a false discovery rate of 5% or less. Using a disease association analysis, we identified a common relationship of these transcripts with autoimmunity and inflammation. These findings were corroborated on the pathway level with numerous differentially expressed genes clustering in immune response, defense response, antigen presentation, B-cell/T-cell function, cytokine signaling, and inflammatory response pathways. Most commonly, the genes involved in these pathways were more highly expressed in tumors of African-American patients when compared with those of European-American patients. Amongst the immune-specific genes over-expressed by African-American patients was indoleamine 2,3-dioxygenease, HLA-E, and HLA-G. All three of these genes are well-known contributors of immunologic tolerance in tumors. Furthermore, a distinctive interferon signature was identified in the African-American prostate tumors, suggesting the possibility of viral involvement in disease etiology in this African-American population. In conclusion, the gene expression profiles of prostate tumors indicate prominent differences in tumor immunobiology between African-American and European-American men. The profiles portray the existence of a distinct tumor microenvironment in these two patient groups.