Prostate Cancer Specimens Research Articles

Prostate cancer patient-derived organoids: detailed outcome from a prospective cohort of 81 clinical specimens.

Patient‐derived organoids (PDOs) represent promising preclinical models in various tumor types. In the context of prostate cancer (PCa), however, their establishment has been hampered by poor success rates, which impedes their broad use for translational research applications. Along with the necessity to improve culture conditions, there is a need to identify factors influencing outcomes and to determine how to assess success versus failure in organoid generation. In the present study, we report our unbiased efforts to generate PDOs from a cohort of 81 PCa specimens with diverse pathological and clinical features. We comprehensively analyzed histological features of each enrolled sample (Gleason score, tumor content, proliferation index) and correlated them with organoid growth patterns. We identified improved culture conditions favoring the generation of PCa organoids, yet no specific intrinsic tumor feature was broadly associated with sustained organoid growth. In addition, we performed phenotypic and molecular characterization of tumor–organoid pairs using immunohistochemistry, immunofluorescence, fluorescence in situ hybridization, and targeted sequencing. Morphological and immunohistochemical profiles of whole organoids altogether provided a fast readout to identify the most promising ones. Notably, primary samples were associated with an initial take‐rate of 83% (n = 60/72) in culture, with maintenance of cancer cells displaying common PCa alterations, such as PTEN loss and ERG overexpression. These cancer organoids were, however, progressively overgrown by organoids with a benign‐like phenotype. Finally, out of nine metastasis samples, we generated a novel organoid model derived from a hormone‐naïve lung metastasis, which displays alterations in the PI3K/Akt and Wnt/β‐catenin pathways and responds to androgen deprivation. Taken together, our comprehensive study explores determinants of outcome and highlights the opportunities and challenges associated with the establishment of stable tumor organoid lines derived from PCa patients. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Clonal hematopoiesis in prostate cancer inferred from somatic tumor profiling.

e17001 Background: Clonal hematopoiesis (CH) is a process associated with normal aging and may complicate the interpretation of liquid-biopsy genomic testing in oncology. Little is known about the prevalence of CH in prostate cancer as detected on somatic tumor profiling, or its association with clinical parameters and outcomes in prostate cancer. We sought to estimate the prevalence and clinical characteristics of patients with CH identified from tissue-based prostate cancer specimens. Methods: This was a retrospective study of men with prostate adenocarcinoma who underwent clinical somatic tissue-based next-generation sequencing using commercial platforms (n = 364). Patients with known hematologic malignancies (n = 7), and those with only liquid biopsies were excluded (n = 34), leaving 323 cases. Classical CH mutations were defined as those in DNMT3A, TET2 or ASXL1. Additional CH mutations included were defined as those in BCORL1, GNAS, SF3B1, JAK2 or PPM1D. Chi-squared tests were used to compare prevalence by categorical variables, Kruskal-Wallis tests to compare means across groups, and Cox proportional hazards were used for time-to-event analyses. Results: The prevalence of CH mutations in prostate cancer was 9% (30/323), and the prevalence of classical CH mutations was 7% (22/323)(Table). The most common mutations were in DNMT3A (n = 9), TET2 (n = 8) and ASXL1 (n = 5); other less common CH alterations were in GNAS and SF3B1 (n = 3 each), followed by CBL and JAK2 (n = 1 each). The most common site of tumor biopsy was the prostate (N = 266) followed by visceral (n = 19) and lymph node (N = 19) metastases. Men with any CH mutation were not significantly older at age of prostate cancer diagnosis (64 vs 62 years; p = 0.19) than those without; however, men with classical CH mutations were statistically older at diagnosis than those without (66 vs 62 years; p = 0.04). There was no difference in prevalence of CH mutations by Gleason sum (P = 0.67). Among men with localized disease at diagnosis, the median metastasis-free survival was 3.9 years in those with overall CH mutations and 6.6 years in those without CH mutations (HR [adjusted for age and Gleason] 1.3; 95% CI 0.7-2.3; p = 0.4). OS from the time of diagnosis to death was also numerically shorter in those with any CH mutation (median 9.7 years in those with and 14.2 years in those without CH mutations; HR 1.2, 95% CI 0.6-2.5; p = 0.6). Conclusions: CH can be detected in about 7-9% of prostate cancer patients from tissue-based tumor samples, is associated with older age, and may be linked to adverse oncological outcomes. The prognostic impact of CH in the context of specific systemic therapies (hormonal, chemotherapeutic) remains to be elucidated.[Table: see text]

Molecular Expression of Some Oncogenes and Predisposing Behaviors Contributing to the Aggressiveness of Prostate Cancer.

Prostate cancer is the second most common cancer in men in Iran. It can be treated in the early stages of the disease; therefore, early diagnosis can be lifesaving. The aim of this study was to investigate the molecular expression of some oncogenes and predisposing behaviors contributing to the aggressiveness of prostate cancer. In this case-control study, prostate cancer specimens were collected from both patients and healthy volunteers. Several factors such as age, family history, smoking, and stage of the disease, were investigated based on the criteria of this study. Real-time PCR was used to measure the expression of four oncogenes. Statistical analysis of our data was carried out using SPSS software version 22. The X2 test showed that there was a difference in the incidence of prostate cancer in different age groups (X2= 9.30; p= 0.026). Although data analysis by the X2 test showed that family history had a significant effect on prostate cancer (X2= 14.43; p= 0.001), smoking did not show a significant effect on the incidence of this disorder (X2= 4.67; p= 0.097). The T2N1M0 stage is the most common form of prostate cancer in patients with family history of prostate cancer and the habit of smoking. Also, the expression of KRAS1P, GLB1L2, SChLAP1 and PACSIN3 oncogenes reduced in prostate cancer samples compared to the control group. Overall, functional interpretation of gene expression in the prostate tissue can affect tumor progression. Yet, further practical studies are required to reveal the accurate underlying mechanisms.

Feasibility study for ex vivo fluorescence confocal microscopy (FCM) on diagnostic prostate biopsies.

Fluorescence confocal microscopy (FCM) is a novel micro-imaging technique providing optical sections of examined tissue. The method has been well established for the diagnosis of tumours in dermatological specimens. Preliminary results found good feasibility when this technique was used to examine prostate cancer (PCa) specimens. We report on the application of FCM in magnet resonance imaging (MRI)-fused prostate biopsies (10 patients, total number of biopsy specimens: n=121) and compare the results to conventional histology. Specific structures of the prostatic tissue were very well represented in the FCM images comparable to conventional histology. Prostate carcinoma was diagnosed with good sensitivity (79/68%) and high specificity (100%) by two pathologists with substantial/almost perfect levels of agreement with the results of conventional histology (kappa 0.79/0.86). Depending on the quality of the scans, malignant lesions of 1.8 mm and more in diameter were reliably diagnosed. Smaller lesions were rated as suspect for malignancy, but could not be consistently differentiated from reactive changes. Optimal image qualities were achieved in focus depths of up to 50 µm, whereas deeper scans led to insufficient representation of cytological features. Pre-treatment with acridine orange (AO) did not alter immunoreactivity of the tissue or its feasibility for fluorescence in situ hybridization (FISH) analyses and adequate amounts of DNA could be extracted for further polymerase chain reaction (PCR)-based examinations. FCM seems to be a promising tool for the timely diagnosis in cases of PCa in patients requiring therapy. In particular, this technique is a material-sparing method that conserves the biopsies as unfixed material for further analysis such as molecular tumour companion diagnosis.

Dietary Fructose Promotes Prostate Cancer Growth.

Clinical localization of primary tumors and sites of metastasis by PET is based on the enhanced cellular uptake of 2-deoxy-2-[18F]-fluoro-D-glucose (FDG). In prostate cancer, however, PET-FDG imaging has shown limited clinical applicability, suggesting that prostate cancer cells may utilize hexoses other than glucose, such as fructose, as the preferred energy source. Our previous studies suggested that prostate cancer cells overexpress fructose transporters, but not glucose transporters, compared with benign cells. Here, we focused on validating the functional expression of fructose transporters and determining whether fructose can modulate the biology of prostate cancer cells in vitro and in vivo. Fructose transporters, Glut5 and Glut9, were significantly upregulated in clinical specimens of prostate cancer when compared with their benign counterparts. Fructose levels in the serum of patients with prostate cancer were significantly higher than healthy subjects. Functional expression of fructose transporters was confirmed in prostate cancer cell lines. A detailed kinetic characterization indicated that Glut5 represents the main functional contributor in mediating fructose transport in prostate cancer cells. Fructose stimulated proliferation and invasion of prostate cancer cells in vitro. In addition, dietary fructose increased the growth of prostate cancer cell line-derived xenograft tumors and promoted prostate cancer cell proliferation in patient-derived xenografts. Gene set enrichment analysis confirmed that fructose stimulation enriched for proliferation-related pathways in prostate cancer cells. These results demonstrate that fructose promotes prostate cancer cell growth and aggressiveness in vitro and in vivo and may represent an alternative energy source for prostate cancer cells. SIGNIFICANCE: This study identifies increased expression of fructose transporters in prostate cancer and demonstrates a role for fructose as a key metabolic substrate supporting prostate cancer cells, revealing potential therapeutic targets and biomarkers.

Kinesin family member 18B regulates the proliferation and invasion of human prostate cancer cells

Expression of kinesin family member 18B (KIF18B), an ATPase with key roles in cell division, is deregulated in many cancers, but its involvement in prostate cancer (PCa) is unclear. Here, we investigated the expression and function of KIF18B in human PCa specimens and cell lines using bioinformatics analyses, immunohistochemical and immunofluorescence microscopy, and RT-qPCR and western blot analyses. KIF18B was overexpressed in PCa specimens compared with paracancerous tissues and was associated with poorer disease-free survival. In vitro, KIF18B knockdown in PCa cell lines promoted cell proliferation, migration, and invasion, and inhibited cell apoptosis, while KIF18B overexpression had the opposite effects. In a mouse xenograft model, KIF18B overexpression accelerated and promoted the growth of PCa tumors. Bioinformatics analysis of control and KIF18B-overexpressing PCa cells showed that genes involved in the PI3K–AKT–mTOR signaling pathway were significantly enriched among the differentially expressed genes. Consistent with this observation, we found that KIF18B overexpression activates the PI3K–AKT–mTOR signaling pathway in PCa cells both in vitro and in vivo. Collectively, our results suggest that KIF18B plays a crucial role in PCa via activation of the PI3K–AKT–mTOR signaling pathway, and raise the possibility that KIF18B could have utility as a novel biomarker for PCa.

Circadian Rhythm Gene PER3 Negatively Regulates Stemness of Prostate Cancer Stem Cells via WNT/β-Catenin Signaling in Tumor Microenvironment.

Prostate cancer (PCa) cells are heterogeneous, containing a variety of cancer cells with phenotypical and functional discrepancies in the tumor microenvironment, where prostate cancer stem cells (PCSCs) play a vital role in PCa development. Our earlier studies have shown that ALDHhiCD44+ (DP) PCa cells and the corresponding ALDHloCD44– (DN) PCa cells manifest as PCSCs and non-PCSCs, respectively, but the underlying mechanisms regulating stemness of the PCSCs are not completely understood. To tackle this issue, we have performed RNA-Sequencing and bioinformatic analysis in DP (versus DN) cells in this study. We discovered that, PER3 (period circadian regulator 3), a circadian rhythm gene, is significantly downregulated in DP cells. Overexpression of PER3 in DP cells significantly suppressed their sphere- and colony-forming abilities as well as tumorigenicity in immunodeficient hosts. In contrast, knockdown of PER3 in DN cells dramatically promoted their colony-forming and tumor-initiating capacities. Clinically, PER3 is downregulated in human prostate cancer specimens and PER3 expression levels are highly correlated with the prognosis of the PCa patient. Mechanistically, we observed that low levels of PER3 stimulates the expression of BMAL1, leading to the phosphorylation of β-catenin and the activation of the WNT/β-catenin pathway. Together, our results indicate that PER3 negatively regulates stemness of PCSCs via WNT/β-catenin signaling in the tumor microenvironment, providing a novel strategy to treat PCa patients.

PAX5-induced upregulation of LINC01194 exerts oncogenic properties by regulating GOLPH3 expression via miR-486-5p in prostate cancer.

Several studies have demonstrated that long non-coding RNA can act as crucial roles during the progression of various tumors, including prostate cancer (PCa). We aimed to determine lncRNA LINC01194(LINC01194) expression in prostate cancer (PCa) and examine its influence on tumor behaviors of PCa cells. RT-PCR was performed to examine LINC01194 and PAX5's expression levels in PCa tissues and cell lines. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays were performed to explore whether PAX5 could activate the transcription of LINC01194. Cell viability, migration and invasion were assessed by CCK-8, colony formation, transwell assay and Wound-healing assays. Bioinformatics and Dual-Luciferase assays were used to investigate the interaction between LINC01194 and miR-486-5p, as well as between miR-486-5p and GOLPH3. Western blot was applied for detecting the expressions of the related proteins. LINC01194 was highly expressed in PCa specimens and cell lines. PAX5 could bind directly to LINC01194 promoter region and activate its transcription. Functionally, the proliferation and metastasis of PCa cells were substantially impeded by LINC01194 silencing in vitro and in vivo. Mechanistically, LINC01194 promoted PCa progression by serving as a sponge of miR-486-5p to increase GOLPH3 expression. Our study identifies LINC01194 as a tumor promotor in PCa and implicates the LINC01194/miR-486-5p/GOLPH3 axis in the PCa progression.

Novel circular RNA circSOBP governs amoeboid migration through the regulation of the miR-141-3p/MYPT1/p-MLC2 axis in prostate cancer.

BackgroundMetastatic prostate cancer is a fatal disease despite multiple new approvals in recent years. Recent studies revealed that circular RNAs (circRNAs) can be involved in cancer metastasis. Defining the role of circRNAs in prostate cancer metastasis and discovering therapeutic targets that block cancer metastasis is of great significance for the treatment of prostate cancer.MethodsThe circSOBP levels in prostate cancer (PCa) were determined by qRT‐PCR. We evaluated the function of circSOBP using a transwell assay and nude mice lung metastasis models. Immunofluorescence assay and electron microscopic assay were applied to determine the phenotypes of prostate cancer cells’ migration. We used fluorescence in situ hybridization assay to determine the localization of RNAs. Dual luciferase and rescue assays were applied to verify the interactions between circSOBP, miR‐141‐3p, MYPT1, and phosphomyosin light chain (p‐MLC2).ResultsWe observed that circSOBP level was significantly lower in PCa specimens compared with adjacent noncancerous prostate specimens, and was correlated with the grade group of PCa. Overexpression of circSOBP suppressed PCa migration and invasion in vitro and metastasis in vivo. CircSOBP depletion increased migration and invasion and induced amoeboid migration of PCa cells. Mechanistically, circSOBP bound miR‐141‐3p and regulated the MYPT1/p‐MLC2 axis. Moreover, the depletion of MYPT1 reversed the inhibitory effect of circSOBP on the migration and invasion of PCa cells. Complementary intronic Alu elements induced but were not necessary for the formation of circSOBP. The nuclear export of circSOBP was mediated by URH49.ConclusionOur results suggest that circSOBP suppresses amoeboid migration of PCa cells and inhibits migration and invasion through sponging miR‐141‐3p and regulating the MYPT1/p‐MLC2 axis.

Single-cell analysis of cellular state heterogeneity in human localized prostate cancer.

254 Background: Prostate cancer is the second most common malignancy in men worldwide. The development of cancer from prostate tissue involves complex interactions of tumor cells with surrounding epithelial and stromal cells and can occur multifocally, suggesting that prostate epithelial cells may undergo cellular state transitions towards carcinogenesis. Previous studies on localized prostate cancer molecular changes have focused on unsorted bulk tissue samples, leaving a gap in our understanding of the cellular heterogeneity in the tumor microenvironment. Single-cell analyses of tumor specimens have the potential to reveal, at unprecedented resolution, cellular composition, as well as instructive intercellular interactions. Methods: To characterize the localized prostate cancer tumor microenvironment, we performed single-cell RNA-sequencing (scRNA-seq) on prostate biopsies, radical prostatectomy specimens, and matched patient-derived organoids from localized prostate cancer patients. Results: Within prostate epithelial cells, we identified a population of club cells that may act as progenitor cells. Furthermore, we uncovered luminal-like epithelial cellular states augmented in androgen signaling across basal and club cell populations. By classifying tumor cells based on ERG expression status, we found that ERG- tumor cells, in contrast to ERG+ cells, share transcriptomic heterogeneity with surrounding luminal epithelial cells and are associated with common stromal and immune microenvironment responses. These results suggest that specific immune niches may arise based on TMPRSS2-ERG fusion status. Finally, we generated prostate epithelial organoids derived from matched localized prostate cancer patients and characterized their transcriptomic profiles by scRNA-seq. These patient-derived organoids recapitulated tumor-associated epithelial cell states but also harbored distinct cell types and states from their parent tissues. Conclusions: Our data from localized prostate cancer specimens and organoids provide diagnostically relevant insights and will help advance our understanding of the cancer cellular states associated with prostate carcinogenesis.

Treatment-Emergent Neuroendocrine Prostate Cancer: A Clinicopathological and Immunohistochemical Analysis of 94 Cases.

PurposeThis study aimed to evaluate the pathological characteristics, immunophenotype, and prognosis of treatment-emergent neuroendocrine prostate cancer (T-NEPC).Materials and MethodsWe collected 231 repeated biopsy specimens of castration-resistant prostate cancer (CRPC) cases between 2008 and 2019. We used histopathological and immunohistochemical evaluations of Synaptophysin (SYN), ChromograninA (CgA), CD56, androgen receptor (AR), and prostate-specific antigen (PSA) to screen out T-NEPC cases. Multivariate analyses were performed to identify factors in the prognosis of T-NEPC. Further, the results were verified in the Surveillance, Epidemiology, and End Results (SEER) program.ResultsAmong the 231 CRPC cases, 94 (40.7%) cases were T-NEPC. T-NEPC were more likely to present with negative immunohistochemistry for AR (30.9%) and PSA (47.9%) than that of CRPC (8.8% and 17.5%, respectively). Kaplan-Meier analysis revealed that patients with T-NEPC (median overall survival [OS]: 17.6 months, 95% CI: 15.3–19.9 months) had significantly worse survival compared with usual CRPC patients (median OS: 23.6 months, 95% CI: 21.3-25.9 months, log-rank P = 0.001), especially in metastasis cases (median OS: 15.7 months, 95% CI: 13.3-18.0 months) and patients with small cell carcinoma component (median OS: 9.7 months, 95% CI: 8.2–11.2 months). Prostate adenocarcinoma with diffuse NE differentiation (median OS: 18.8 months, 95% CI: 15.3–22.3 months) had poor outcome than those with usual CRPC (P = 0.027), while there was no significant change in the focal NE differentiation (median OS: 22.9 months, 95% CI: 18.1–27.7 months, P = 0.136). In the unadjusted model, an excess risk of overall death was observed in T-NEPC with PSA negative (HR = 2.86, 95% CI = 1.39–6.73). Among 476 NEPC cases in the SEER database from 2004 to 2017, we observed a higher hazard of overall death in patients aged 65 years and older (HR = 1.35, 95% CI = 1.08–1.69), patients with PSA ≤ 2.5 ng/ml (HR = 1.90, 95%CI = 1.44–2.52), patients with PSA 2.6–4.0 ng/ml (HR = 2.03, 95%CI = 1.38–2.99), stage IV tumor (HR = 2.13, 95%CI = 1.47–3.08) and other races (HR = 1.85, 95%CI = 1.17–2.94) in total NEPC, adjusting for confounders. Similar hazard ratios were observed in pure NEPC, while there was no significant results among prostate adenocarcinoma with NE differentiation tumors.ConclusionT-NEPC was associated with an unfavorable prognosis, negative immunohistochemistry for PSA in T-NEPC and serum PSA level ≤ 4 ng/ml had a worse prognosis. Urologists and pathologists should recognize the importance of the second biopsy in CRPC to avoid unnecessary diagnosis and treatment delays.

Overexpression of the TRIM24 E3 Ubiquitin Ligase is Linked to Genetic Instability and Predicts Unfavorable Prognosis in Prostate Cancer.

Tripartite motif containing 24 (TRIM24) is a multifunctional protein involved in p53 degradation, chromatin binding, and transcriptional modulation of nuclear receptors. Emerging research has revealed that upregulation of TRIM24 in numerous tumor types is linked to poor prognosis, attributing an important role to TRIM24 in tumor biology. In order to better understand the role of TRIM24 in prostate cancer, we analyzed its immunohistochemical expression on a tissue microarray containing >17,000 prostate cancer specimens. TRIM24 immunostaining was detectable in 61% of 15,321 interpretable cancers, including low expression in 46% and high expression in 15% of cases. TRIM24 upregulation was associated with high Gleason grade, advanced pathologic tumor stage, lymph node metastasis, higher preoperative prostate-specific antigen level, increased cell proliferation as well as increased genomic instability, and predicted prognosis independent of clinicopathologic parameters available at the time of the initial biopsy (all P<0.0001). TRIM24 upregulation provides additional prognostic information in prostate cancer, particularly in patients with low Gleason grade tumors who may be eligible for active surveillance strategies, suggesting promising potential for TRIM24 in the routine diagnostic work-up of these patients.

MicroRNA miR-145-5p inhibits Phospholipase D 5 (PLD5) to downregulate cell proliferation and metastasis to mitigate prostate cancer

ABSTRACT Prostate cancer (PCa), a frequently detected malignant tumor, is the fifth leading global cancer mortality cause in men. Although research has improved the PCa survival rate, significantly reduced survival occurs among patients at the metastatic stage. MiRNAs, which are short non-coding proteins, are crucial for several biological roles, essential for PCa proliferation, differentiation, multiplication, and migration. The investigation aimed to explore miR-145-5p and PLD5 association and clarify their function in regulating proliferation in PCa cell lines. The study used PC-3, LNCaP, DU-145 PCa, and RWPE-1 non-cancerous cell line, PCa, and BPH tissue specimens, and nude mice to validate results. MiR-145-5p and PLD5 manifestation were assessed through RT-qPCR. PLD5 and miR-145 binding was determined through dual-luciferase reporter gene assays. Validation of cell proliferation, migration, and invasion was assessed through MTT, scratch wound, and transwell assays, respectively. The results indicated a downregulation of miR-145-5p level in PCa cell lines and tissues in comparison to the non-cancerous controls. PLD5 overexpression exerted a cancerous effect while mimicking of miR-145-5p reversed the PLD5-oncogenic effects and significantly inhibited PCa cells proliferation, migration, invasion, and metastasis. In conclusion, the study revealed that miR-145-5p upregulated apoptosis and repressed migration, invasion, and metastasis of PCa via direct PLD5 modulation.

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.

BAP1 suppresses prostate cancer progression by deubiquitinating and stabilizing PTEN.

Deubiquitinase BAP1 is an important tumor suppressor in several malignancies, but its functions and critical substrates in prostate cancer (PCa) remain unclear. Here, we report that the mRNA and protein expression levels of BAP1 are downregulated in clinical PCa specimens. BAP1 can physically bind to and deubiquitinate PTEN, which inhibits the ubiquitination-mediated degradation of PTEN and thus stabilizes PTEN protein. Ectopically expressed BAP1 in PCa cells increases PTEN protein level and subsequently inhibits the AKT signaling pathway, thus suppressing PCa progression. Conversely, knockdown of BAP1 in PCa cells leads to the decrease in PTEN protein level and the activation of the Akt signaling pathway, therefore promoting malignant transformation and cancer metastasis. However, these can be reversed by the re-expression of PTEN. More importantly, we found that BAP1 protein level positively correlates with PTEN in a substantial fraction of human cancers. These findings demonstrate that BAP1 is an important deubiquitinase of PTEN for its stability and the BAP1-PTEN signaling axis plays a crucial role in tumor suppression.

TGF-β1-regulated miR-3691-3p targets E2F3 and PRDM1 to inhibit prostate cancer progression.

Transforming growth factor-β1 (TGF-β1) acts as a tumor promoter in advanced prostate cancer (PCa). We speculated that microRNAs (miRNAs) that are inhibited by TGF-β1 might exert anti-tumor effects. To assess this, we identified several miRNAs downregulated by TGF-β1 in PCa cell lines and selected miR-3691-3p for detailed analysis as a candidate anti-oncogene miRNA. miR-3691-3p was expressed at significantly lower levels in human PCa tissue compared with paired benign prostatic hyperplasia tissue, and its expression level correlated inversely with aggressive clinical pathological features. Overexpression of miR-3691-3p in PCa cell lines inhibited proliferation, migration, and invasion, and promoted apoptosis. The miR-3691-3p target genes E2F transcription factor 3 (E2F3) and PR domain containing 1, with ZNF domain (PRDM1) were upregulated in miR-3691-3p-overexpressing PCa cells, and silencing of E2F3 or PRDM1 suppressed PCa cell proliferation, migration, and invasion. Treatment of mice bearing PCa xenografts with a miR-3691-3p agomir inhibited tumor growth and promoted tumor cell apoptosis. Consistent with the negative regulation of E2F3 and PRDM1 by miR-3691-3p, both proteins were overexpressed in clinical PCa specimens compared with noncancerous prostate tissue. Our results indicate that TGF-β1-regulated miR-3691-3p acts as an anti-oncogene in PCa by downregulating E2F3 and PRDM1. These results provide novel insights into the mechanisms by which TGF-β1 contributes to the progression of PCa.

A Genomic Approach to Integration of T Category and the Tumor Immune Microenvironment As Part of A Decision Algorithm for Radiation in Prostate Cancer

The nature of the tumor immune microenvironment (TIME) has been shown to have prognostic significance and implications for therapeutic response in many different cancers. Emerging data suggests that radiation may alter the TIME by promoting accumulation of immunosuppressive regulatory T-cells (Treg). Radiation is a mainstay of treatment for prostate cancer (PCa), but the importance of TIME composition with respect to radiation response in PCa has not been fully elucidated. Here, we leverage clinical and genomic data from The Cancer Genome Atlas (TCGA) to further characterize the TIME in a cohort of irradiated T2-T3 PCa patients, and assess relationships between stage, TIME composition, and recurrence free survival (RFS) in the setting of radiation therapy. Tumors treated with radiation were stratified by T2 vs. T3 disease, as well as “High” or “Low” values for measurement of T-regulatory (Treg) cell-specific markers, calculated relative to the mean values of 490 tissue samples. Normalized RNA Seq by expectation maximization (RSEM) values from the TCGA were collected along with expression data for Treg specific markers (CD25, FOXP3, and CTLA4). Clinical data was obtained from the Broad Institute’s Firebrowse tool. RFS was defined as length of time from end of treatment to biochemical recurrence and/or locoregional recurrence and was assessed using Kaplan-Meier estimates. Survival curves were compared using the log-rank test. 490 PCa specimens were retrieved from the TCGA Pan-Cancer Atlas. Of these, 106 tumors were treated with radiation. Patients with T3 disease (n = 67) on initial pathologic diagnosis and high intratumoral co-expression of CD25, FOXP3, and CTLA4 treated with radiation demonstrated significantly decreased estimated 8-year RFS compared to those patients with T3 disease lacking high co-expression of all three markers (p = 0.0084). There was no significant difference in estimated 8-year RFS after radiation in T2 patients (n = 39) with high co-expression of all Treg specific markers compared to those lacking high co-expression of these markers (p = 0.40). Various studies have attempted to decipher the interplay of radiation and Treg cells, the majority having been conducted on mouse models. Our analysis of human specimens revealed that radiation in PCa with extracapsular extension (T3 disease) and Treg specific marker elevation portends significantly worse prognosis than irradiated T3 disease without Treg specific marker elevations - this relationship was not seen in T2 disease. These results suggest a prognostic benefit from risk stratification of PCa patients by both T category and Treg specific activation markers, and warrant investigation into immune checkpoint inhibitors such as anti-CTLA4 antibody as part of the treatment paradigm in this patient subset to enhance anti-tumor effects by inhibiting Treg activity.

The Correlation between PSCA Expression and Neuroendocrine Differentiation in Prostate Cancer.

The prostate stem cell antigen (PSCA), as a predominantly prostate-specific marker, is overexpressed in most prostate cancer specimens, is positively correlated with prostate cancer androgen independence, and has the potential to be treated with castration-resistant prostate cancer (CRPC) as a gene therapy target. Using the typical androgen deprivation therapy, most tumors will progress to CRPC, as well as develop into neuroendocrine prostate cancer (NEPC) characterized by the expression of neuroendocrine markers such as enolase 2 (NSE). Our study was aimed at investigating the expressions of PSCA and NSE and the relationship between the two markers, as well as the correlation between the PSCA and NSE expressions and the clinicopathological parameters in prostate cancer specimens from 118 patients by using immunohistochemistry. Our results demonstrated that the PSCA and NSE protein expressions did not correlate with the prostate cancer patients' age or the hormone therapy but showed a significant correlation with the pathological tumor stage of prostate cancer, the Gleason score, and the presence of metastasis. There is a positive association between PSCA and NSE but a negative one between the prostate-specific antigen (PSA) and PSCA or between PSA and NSE. High PSCA and NSE expressions correlated with a poor prognosis in prostate cancer patients. PSCA may play an important role in the progression of neuroendocrine prostate cancer (NEPC).

Long non-coding RNA LINC00173 serves as sponge for miR-338-3p to promote prostate cancer progression via regulating Rab25.

Long non-coding RNA LINC00173 (LINC00173) has been shown to facilitate the progression of a number of malignancies. In this study, we aimed to investigate the function of LINC00173 on prostate cancer (PCa) and discover the potential regulatory mechanism. RT-PCR was used to determine the levels of LINC00173, miR-338-3p and Rab25 in PCa patients and cell lines. The clinical significance of LINC00173 was statistically analyzed in 124 PCa patients. CCK-8, colony formation, transwell, scratch wound, Ethynyldeoxyuridine (EdU) assays and flow cytometry assays were used to detect the proliferation, apoptosis, invasion and migration of PCa cells. The mechanism of LINC00173 action was explored through bioinformatics, RNA pull-down assays and Luciferase reporter assays. We observed that the expression of LINC00173 and Rab25 was distinctly upregulated in both PCa specimens and cell lines, while miR-338-3p expression was significantly down-regulated. High LINC00173 expression was associated with Gleason score, preoperative PSA level and reduced patient survivals. Functional assays revealed that knockdown of LINC00173 suppressed the proliferation, migration and invasion of PCa cells, and promoted apoptosis. Mechanistically, LINC00173 acted as a competitive endogenous RNA in PCa and increased Rab25 expressions via sponging miR-338-3p. Moreover, LINC00173 promoted PCa progression by interacting with miR-338-3p and Rab25. Our findings, for the first time, identified a novel PCa-related lncRNA, LINC00173 which might serve as an oncogene in PCa. The discovery of the LINC00173/miR-338-3p/Rab25 pathways provided new thinking for the treatments of PCa.

MiRNAs expression signature potentially associated with lymphatic dissemination in locally advanced prostate cancer

BackgroundProstate cancer is one of the most common and socially significant cancers among men. The aim of our study was to reveal changes in miRNA expression profiles associated with lymphatic dissemination in prostate cancer and to identify the most prominent miRNAs as potential prognostic markers for future studies.MethodsHigh-throughput miRNA sequencing was performed for 44 prostate cancer specimens taken from Russian patients, with and without lymphatic dissemination (N1 – 20 samples; N0 – 24 samples).ResultsWe found at least 18 microRNAs with differential expression between N0 and N1 sample groups: miR-182-5p, miR-183-5p, miR-96-5p, miR-25-3p, miR-93-5p, miR-7-5p, miR-615-3p, miR-10b, miR-1248 (N1-miRs; elevated expression in N1 cohort; p < 0.05); miR-1271-5p, miR-184, miR-222-3p, miR-221-5p, miR-221-3p, miR-455-3p, miR-143-5p, miR-181c-3p and miR-455-5p (N0-miRs; elevated expression in N0; p < 0.05). The expression levels of N1-miRs were highly correlated between each other (the same is applied for N0-miRs) and the expression levels of N0-miRs and N1-miRs were anti-correlated. The tumor samples can be divided into two groups depending on the expression ratio between N0-miRs and N1-miRs.ConclusionsWe found the miRNA expression signature associated with lymphatic dissemination, in particular on the Russian patient cohort. Many of these miRNAs are well-known players in either oncogenic transformation or tumor suppression. Further experimental studies with extended sampling are required to validate these results.