Prostate Cancer Disease Progression Research Articles

An inverted CAV1 (caveolin 1) topology defines novel autophagy-dependent exosome secretion from prostate cancer cells

ABSTRACT CAV1 (caveolin 1) expression and secretion is associated with prostate cancer (PCa) disease progression, but the mechanisms underpinning CAV1 release remain poorly understood. Numerous studies have shown CAV1 can be secreted within exosome-like vesicles, but antibody-mediated neutralization can mitigate PCa progression; this is suggestive of an inverted (non-exosomal) CAV1 topology. Here we show that CAV1 can be secreted from specific PCa types in an inverted vesicle-associated form consistent with the features of bioactive CAV1 secretion. Characterization of the isolated vesicles by electron microscopy, single-molecule fluorescence microscopy and proteomics reveals they represent a novel class of exosomes ~40 nm in diameter containing ~50-60 copies of CAV1 and, strikingly, are released via a non-canonical secretory macroautophagy/autophagy pathway. This study provides novel insights into a mechanism whereby CAV1 translocates from a normal plasma membrane distribution to an inverted secreted form implicated in PCa disease progression. Abbreviations: 3-MA: 3-methyladenine; APEX: a modified soybean ascorbate peroxidase; ATG5: autophagy related 5; ATG9A: autophagy related 9A; ATG12: autophagy related 12; BHK: baby hamster kidney; C-exosomes: caveolin-exosomes; CAMKK2/CAMKKβ: calckum/calmodulin dependent protein kinase kinase 2; CAV1: caveolin 1; DAB: 3,3′-diaminobenzidine; DAPK: death associated protein kinase; EEA1: early endosome antigen 1; EM: electron microscopy; FCS: fluorescence correlation spectroscopy; GBP: GFP/YFP-binding peptide; GFP: green fluorescent protein; GOLGA2: golgin A2; ILVs: intralumenal vesicles; LC3: microtubule-associated protein 1 light chain 3; MBP: maltose binding protein; MTORC1: mechanistic target of rapamycin kinase complex 1; MVBs: multivesicular bodies; PBS: phosphate-buffered saline; PCa: prostate cancer; PI3K: phosphoinositide 3-kinase; PM: plasma membrane; SFM: serum-free medium; TSG101: tumor susceptibility 101; WCL: whole cell lysates; WT: wild type; YFP: yellow fluorescent protein; βoG: β-octylglucoside

545P Preclinical profile of EPI-7386, a second-generation N-terminal domain androgen receptor inhibitor for the treatment of prostate cancer

Disease progression in metastatic castration-resistant prostate cancer (mCRPC) patients largely remains androgen receptor (AR) dependent. Resistance inevitably arises to current anti-androgens through numerous ligand binding domain (LBD)-associated mechanisms. EPI-7386 is a second-generation aniten which inhibits AR transcriptional activity by binding to the AR N-terminal domain (NTD), thus bypassing these resistance mechanisms. A phase I trial in patients with anti-androgen resistant mCRPC is currently being initiated. The preclinical anti-tumor and safety profile of EPI-7386 will be presented. EPI-7386 potency and selectivity was assessed using reporter and viability assays in cellular models. Pharmacodynamic markers were measured by qPCR, NanoString and RNAseq. The pre-clinical safety profile was assessed both in in vitro assays and in rat and dog toxicology studies. EPI-7386 has an IC50 of 421 nM in LNCaP reporter assays, it inhibited both AR full-length and AR-V7 dependent gene expression and maintained antitumor activity in AR-V7-expressing tumor models, including in in vivo models resistant to enzalutamide (ENZ). Transcriptomic analysis of EPI-7386 revealed on-target anti-AR activity, with a profile overlapping but distinct from ENZ, while the combination of the two agents demonstrated broader and deeper AR pathway inhibition. IND-enabling studies in rats and dogs showed on-target activity with good tolerability at drug exposures several fold higher than those active in tumor xenograft models. PK simulations suggest predicted tolerated and active doses can be achieved during the phase I dose escalation. EPI-7386, a second-generation aniten, is a potent AR NTD inhibitor, with a favorable safety and ADME profile, good pharmaceutical characteristics, and a long predicted human half-life supporting once-daily oral dosing with tablets. In vivo, EPI-7386 demonstrated anti-tumor activity as a single agent in the setting of anti-androgen clinical resistance and enhanced efficacy in combination therapy. A phase I study is scheduled to begin Q2 2020.

Caveolin-1-mediated sphingolipid oncometabolism underlies a metabolic vulnerability of prostate cancer

Plasma and tumor caveolin-1 (Cav-1) are linked with disease progression in prostate cancer. Here we report that metabolomic profiling of longitudinal plasmas from a prospective cohort of 491 active surveillance (AS) participants indicates prominent elevations in plasma sphingolipids in AS progressors that, together with plasma Cav-1, yield a prognostic signature for disease progression. Mechanistic studies of the underlying tumor supportive onco-metabolism reveal coordinated activities through which Cav-1 enables rewiring of cancer cell lipid metabolism towards a program of 1) exogenous sphingolipid scavenging independent of cholesterol, 2) increased cancer cell catabolism of sphingomyelins to ceramide derivatives and 3) altered ceramide metabolism that results in increased glycosphingolipid synthesis and efflux of Cav-1-sphingolipid particles containing mitochondrial proteins and lipids. We also demonstrate, using a prostate cancer syngeneic RM-9 mouse model and established cell lines, that this Cav-1-sphingolipid program evidences a metabolic vulnerability that is targetable to induce lethal mitophagy as an anti-tumor therapy.

Abstract 3520: Immunogenomic landscape of grade group 5 prostate cancer predicts risk of lethal outcomes and may inform treatment response

Abstract Introduction Prognostic and therapeutic implications of the immunogenomic landscape in poorly differentiated Grade Group 5 (GG5) prostate cancer (PCa) remains largely unknown. While novel treatment strategies including immuno-radiotherapy have been hypothesized to attenuate disease progression in advanced PCa, limited data exist to show underlying mechanisms related to immunogenomcis and its role in the management of GG5 PCa. Method This retrospective analysis includes 822 PCa patients who underwent radical prostatectomy (RP) with pathologic GG5 disease. Immunogenomic interaction between the immune content score (ICS) and Decipher score was used to predict the metastasis and Prostate cancer specific mortality (PCSM). Immunogenomic interaction categories were used to assess patient response to radiation therapy, measured by the PORTOS score. Additionally, 135 biopsy based tumor samples were also used to validate the immunogenomic correlation between ICS and Decipher as well as the association with PORTOS score. A Kruskal-Wallis test was used to compare median scores whereas methods of survival analysis were used for time dependent endpoints. Principal component analysis (PCA) was used to show sample clustering based on PORTOS score. Results Among GG5 patients 64.8% had high Decipher risk score (> 0.60) whereas 35.5% had low-average risk score (≤ 0.60). When comparing Decipher risk categories with ICS, a linear association was observed with the highest ICS quartile showing the highest Decipher score (Spearman's correlation 0.23, p < 2.4e−11). In a multivariable model, high Decipher score was associated with risk metastasis (HR = 1.63, 95% CI: 1.12 - 2.37, p = 0.01) and PCSM (HR = 1.61, 95% CI: 0.93 – 2.78, p = 0.08) whereas high ICS did not show significant effect on lethal outcomes. However, in the interaction model, effect of decipher on lethal outcomes was augmented in relation with higher ICS. Patients with ICSHigh and DecipherHigh showed significantly higher risk of metastasis (HR = 3.29, 95% CI: 1.53 - 7.07, p = 0.002) and PCSM (HR = 4.15, 95% CI: 1.55 - 11.0, p = 0.004). Additionally, ICSHigh and DecipherHigh also showed higher PORTOS score compared to those with ICSLow and DecipherLow (p < 2.2e−16). Similar to RP cases, in the validation biopsy data Decipher score and ICS were associated (p = 0.01). Likewise, the association of immunogenomic categories with PORTOS score was also consistent in the validation dataset (p = 0.0002). PCA in both RP and validation data using other T cells (i.e. CD4+, CD8+ and Treg) along with ICS, showed separation of high and low PORTOS score categories in relation to immune cells. Conclusions The immunogenomic landscape of GG5 disease has major prognostic and therapeutic implications in aggressive PCa. Immunogenomic interaction between immune content and genomic risk classifiers can be used to identify subsets of patients who are at increased risk of metastasis and PCSM, and may have enhanced response to radiotherapy. Citation Format: Kosj Yamoah, Shivanshu Awasthi, Brandon Mahal, Shuang G. Zhao, Julieta Abraham-Miranda, Travis A. Gerke, Elai Davicioni, Robert J. Rounbehler, Anders E. Berglund, Daniel G. Grass, Jong Y. Park, Julio M. Pow-Sang, Daniel Fernandez, Rohit K. Jain, Edward M. Schaeffer, Stephen Freedland, Daniel E. Spratt, Robert B. Den, Manish Kohli, Timothy R. Rebbeck, Felix Y. Fang. Immunogenomic landscape of grade group 5 prostate cancer predicts risk of lethal outcomes and may inform treatment response [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3520.

Abstract 2612: Neuropilin-2 promotes enzalutamide-resistant neuroendocrine prostate cancer

Abstract Background: Neuroendocrine prostate cancer (NEPC) is a lethal subtype of prostate cancer (PC) that emerges after androgen deprivation therapy in advanced PC patients, with incidence significantly increased in recent years due to the widespread use of highly potent antiandrogens such as enzalutamide (ENZ). This study investigated the role of neuropilin-2 (NRP2) in the development and progression of ENZ-induced NEPC. Methods: Human PC tissue microarrays with different characteristics, including hormone naïve, castration resistant (CR) and neuroendocrine (NE), were analyzed for NRP2 expression by immunohistochemistry. Human PC cells were manipulated for stable knockdown or overexpression of NRP2, and then subjected to cell proliferation, cell colony formation and tumorsphere formation assays, and Western blot/RT-qPCR examination of NE marker expression. Results: NRP2 expression was elevated in CRPC and NEPC patient samples compared to hormone-naïve counterparts, which was supported by association of higher NRP2 expression with hormone-refractory and NE status of PC from additional clinical data sets. Increased NRP2 expression was found in LNCaP cells treated with ENZ (10 µM, up to 7 days) as well as in the ENZ-resistant C4-2BENZR cells (with acquired resistance to ENZ at 20 µM). Both cell lines exhibited treatment-induced NEPC features, including NE differentiation cell morphology, AR suppression and NE marker induction. Silencing of NRP2 in C4-2BENZR and 22Rv1 (with inherent ENZ resistance and NE traits) cells decreased cell proliferation by 50% and 75% respectively, which was corroborated in colony formation and tumorsphere assays. Silencing of NRP2 also increased apoptosis in both cell lines. NRP2 silencing further led to reduced expression of NE markers, including CHGA, SYP, CD56 and SOX2. Conversely, enforced expression of NRP2 in LNCaP and 22Rv1 cells accelerated cell proliferation by up to 4-fold, which was paralleled by increased cell colony and tumorsphere formation, reduced cell apoptosis, upregulation of NE marker expression (CHGA, SYP, NSE, CD56 and SOX2), and downregulation of AR and AR target genes (PSA, TMPRSS2, FKBP5 and KLK2). Mechanistically, NRP2 induced phosphorylation of STAT3 in C4-2BENZR and 22Rv1 cells as revealed by phospho-kinase antibody arrays, which will be further investigated for downstream effectors mediating NRP2's function in NEPC. Conclusion: NRP2 contributes to PC disease progression towards a NE phenotype following ENZ treatment and subsequent emergence of ENZ resistance, which provides new insights into understanding the mechanism underlying development of antiandrogen-induced NEPC and developing a new target for treating this lethal disease. Citation Format: Jing Wang, Jingjing Li, Boyang Wu, Lijuan Yin. Neuropilin-2 promotes enzalutamide-resistant neuroendocrine prostate cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2612.

Combined α-methylacyl-CoA racemase inhibition and docetaxel treatment reduce cell proliferation and decrease expression of heat shock protein 27 in androgen receptor-variant-7-positive prostate cancer cells.

BackgroundDisease progression in castrate-resistant prostate cancer (PCa) is most commonly driven by the reactivation of androgen receptor (AR) signaling and involves AR splice variants including ARV7.Materials and methodsWe used the ARV7-positive PCa cell line, 22Rv1, to study the relationship of the PCa marker α-methylacyl-CoA racemase (AMACR), AR, and ARV7 in PCa.ResultsDocetaxel addition but not AMACR inhibition decreased the proliferation of 22Rv1 cells. The combination of AMACR inhibition and docetaxel treatment resulted in a maximum reduction of cell proliferation. The Western blotting analysis revealed that both AR and ARV7 expression were significantly decreased with the use of charcoal-stripped serum following AMACR inhibition and docetaxel treatment. AMACR inhibition and docetaxel treatment in the charcoal-stripped serum condition reduced the proliferation of 22Rv1, possibly via the downregulation of the heat shock protein 27.ConclusionUsing cell proliferation and Western blot analysis, we demonstrated that AMACR inhibition and docetaxel treatment, under androgen deprivation conditions, significantly reduced the proliferation of ARV7 positive cancer cells and decreased the levels of AR and ARV7 expression, possibly via downregulation of heat shock protein 27.

MicroRNAs as Guardians of the Prostate: Those Who Stand before Cancer. What Do We Really Know about the Role of microRNAs in Prostate Biology?

Prostate cancer is the second leading cause of cancer-related deaths of men in the Western world. Despite recent advancement in genomics, transcriptomics and proteomics to understand prostate cancer biology and disease progression, castration resistant metastatic prostate cancer remains a major clinical challenge and often becomes incurable. MicroRNAs (miRNAs), about 22-nucleotide-long non-coding RNAs, are a group of regulatory molecules that mainly work through post-transcriptional gene silencing via translational repression. Expression analysis studies have revealed that miRNAs are aberrantly expressed in cancers and have been recognized as regulators of prostate cancer progression. In this critical review, we provide an analysis of reported miRNA functions and conflicting studies as they relate to expression levels of specific miRNAs and prostate cancer progression; oncogenic and/or tumor suppressor roles; androgen receptor signaling; epithelial plasticity; and the current status of diagnostic and therapeutic applications. This review focuses on select miRNAs, highly expressed in normal and cancer tissue, to emphasize the current obstacles faced in utilizing miRNA data for significant impacts on prostate cancer therapeutics.

Aberrant Expression of Citrate Synthase is Linked to Disease Progression and Clinical Outcome in Prostate Cancer.

PurposeCitrate synthase (CS) is a rate-limiting enzyme in the citrate cycle and is capable of catalyzing oxaloacetate and acetyl-CoA to citrate. CS has been uncovered to be upregulated in a variety of cancers, and its expression and clinical significance in prostate cancer (PCa) remain unknown.MethodsIn this study, we examined the association between CS expression level and clinicopathological features of prostate cancer patients in a TMA cohort and the public cancer database (The Cancer Genome Atlas-Prostate Adenocarcinoma, TCGA-PRAD). The CS knockdown cell lines were constructed to study the effects of CS downregulation on proliferation, colony formation, migration, invasion, and cell cycle of prostate cancer cells in vitro. And the effect of CS downregulation on tumor growth in mice was studied in vivo. In addition, the metabolomics and mitochondrial function were detected in the CS knockdown cell lines.ResultsCS expression level in PCa tissues was higher than that in normal tissues (P < 0.05). CS upregulation was significantly associated with high Gleason score (P < 0.05), advanced pathological stage (P < 0.001), and biochemical recurrence (P < 0.001). Functionally, decreased expression of CS inhibited PCa cell proliferation, colony formation, migration, invasion and cell cycle in vitro, and inhibited tumor growth in vivo. In addition, CS downregulation exerted potential inhibitory effects on the lipid metabolism and mitochondrial function of PCa cells.ConclusionIn conclusion, these findings suggested that CS upregulation may contribute to the aggressive progression and poor prognosis of PCa patients, which might be partially associated with its influences on the cell lipid metabolism and mitochondrial function.

Testosterone Replacement Therapy in Men with Untreated or Treated Prostate Cancer: Do We Have Enough Evidences?

PurposeTo investigate the oncologic safety of testosterone replacement therapy (TRT) in men with untreated or treated prostate cancer.Materials and MethodsWe systematically searched PubMed, Embase, and Cochrane library database from January 1941 to March 2019.ResultsIn total, 36 articles met the eligibility criteria for this systematic review. They included a total of 2,459 TRT-treated patients, with a median of 20 patients per study (range: 1–1,142). Except for four studies, all were single-armed studies with poor quality scores (median MINOR, 9 of 24). Of the 36 studies, prostate cancer was managed through active surveillance (AS), in 5 studies; radical prostatectomy, in 11 studies; radiation therapy, in 5 studies; multiple intervention modalities, in 5 studies; and systemic therapy, in 9 studies. In comparison with TRT-treated and untreated patients, the pooled risk ratio (RR) was not significantly higher than one in comparisons of risk for disease progression (pooled RR, 0.83; 95% confidence interval, 0.57–1.21). The results of systematic review implied that TRT might be harmful in men with advanced disease (progression rate: 38.5%–100.0%), who undergo AS (15.4%–57.1%), and who successfully treated but having high-risk disease (0.0%–50.0%).ConclusionsCompared to TRT-untreated patients, TRT-treated patients may not have increased risks for disease progression in prostate cancer. However, the quality of currently available evidence is extremely poor. TRT may be harmful in men with advanced disease burden, in those with untreated prostate cancer undergoing AS, and in those with successfully treated prostate cancer but having high-risk disease.

Association between low prostate-specific antigen levels and greater disease progression in high-grade locally-advanced prostate cancer

In advanced or high-grade prostate cancer (PCa), prostate-specific antigen (PSA) is usually elevated, however, some patients may present with low initial PSA (iPSA) levels. The objective of this study was to evaluate whether different iPSA levels were associated with dissimilar clinical outcomes among men with high-grade PCa and advanced disease after robot-assisted laparoscopic radical prostatectomy (RaLRP). This study enrolled 69 PCa patients with initial Gleason score ≥8 and pathologic T-stage ≥3a from April 2012 to December 2018. Patients were stratified into 3 groups based on iPSA levels at diagnosis: <5.0, 5.0-9.9, and ≥10.0. The patients' related parameters were compared among these groups. The median follow-up period was 33.1 months (IQR: 12.1-48.1). There was no difference in biochemical recurrence (BCR) between the 3 groups (Log-rank test, p=0.484). We found a higher risk of biochemical recurrence in patients with positive surgical margins (HR: 5.04, 95% CI: 1.64-15.50, p=0.005). In addition, patients with low iPSA levels (<5.0ng/mL) had poor radiographic progression-free survival (Log-rank test, p=0.001) and a higher risk of disease progression (HR: 12.2, 95% CI: 1.18-1260.99, p=0.036) compared with patients with higher iPSA levels (≥10ng/mL). In patients with high-grade locally-advanced PCa, a low iPSA level was associated with a higher risk of disease progression, but not with biochemical recurrence. In this unique population, serum PSA may not be a reliable marker to detect disease progression. Monitoring of these patients may warrant other biomarkers or imaging.

Abstract C023: Annexin A2 expression level correlates with adverse pathology and disease progression in prostate cancer

Abstract Background: Annexin A2 (ANXA2) is absent or expressed focally in the prostate epithelium of moderately differentiated tumors but is highly expressed in a subset of poorly differentiated tumors. We observed earlier that ANXA2 transcription is negatively regulated by ERG in prostate cancer (CaP) cells. Here we examined whether Annexin A2 expression in prostate tumors correlates with aggressive CaP or disease progression, whether prostate tumors of Caucasian American (CA) and African American (AA) patients have distinct Annexin A2 expression profiles, and if the levels of Annexin A2 in sera is correlated to its expression in tumor tissues. We also speculated on the underlying mechanism likely to regulate ANXA2 expression in the absence of ERG. Methods: We evaluated Annexin A2 and ERG expression in index tumors on whole-mounted prostate sections and tissue microarrays derived from radical prostatectomies of 176 patients by immunohistochemistry. Both cohorts were matched for post RP follow-up, pathologic stage, and race. ERG and Annexin A2 expression status in tumors were correlated to Gleason score, biochemical recurrence and metastasis. We measured, by enzyme-linked immunosorbent assay (ELISA), Annexin A2 proteins levels in sera of 94 controls and 222 patients, matched for race and Gleason sum. Correlation between promoter methylation and gene expression profiles of ANXA2 from TCGA studies were also examined. Results: A significant association was found between ANXA2(+) index tumors and higher Gleason Grade Group (GG) 4 and 5, and worse pathologic stage (pT 3-4). Moreover, ERG(-)/ANXA2(+) tumors were found to be associated with Gleason GG 4 and 5, and ERG(+)/ANXA2(-) tumors with Gleason GG 1 and 2. However, unlike ERG expression, which is more prevalent in prostate tumors of CA men, Annexin A2 expression was not associated with race. Trends toward earlier occurrence of BCR and worse metastasis-free survival were observed among ANXA2(+) cases. Significantly higher levels of secreted Annexin A2 were detected in the sera healthy controls than in CaP patients. Analysis of TCGA prostate cancer dataset revealed an inverse association between methylation of the ANXA2 promoter region and ANXA2 expression in prostate tumor tissues. Conclusion: The association between high Annexin A2 expression in prostate tumors with higher grade and stage suggests a potential for its use as a biomarker for aggressive CaP and to stratify patients after radical prostatectomy. Citation Format: Shyh-Han Tan, Denise Young, Wei Huang, Amina Ali, Lakshmi Ravindranath, Kurt Christen, Kevin Babcock, Huai-Ching Kuo, Yongmei Chen, Jacob Kagan, Sudhir Srivastava, Albert Dobi, Srinivasan Alagarsamy, Gyorgy Petrovics, David G. McLeod, Jennifer Cullen, Inger L. Rosner, Isabell A. Sesterhenn, Shiv Srivastava. Annexin A2 expression level correlates with adverse pathology and disease progression in prostate cancer [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 C023.

Prospective Study of the Clinical Impact of Epithelial and Mesenchymal Circulating Tumor Cells in Localized Prostate Cancer.

BackgroundAlthough circulating tumor cells (CTCs) are considered as a surrogate marker in monitoring disease progression and treatment response in late stage prostate cancer (PCa), its clinical impact in localized PCa remains unclear, indicating the limitation that is simply based on cell count. This perspective observational study aimed to detect the epithelial-to-mesenchymal transition (EMT) subtypes of CTCs in localized PCa and analyze their clinical relevance and application in predicting PCa stages before surgery compared with the Partin table.Patients and MethodsBetween August 2017 and April 2019, 80 newly diagnosed localized PCa patients were enrolled in the study. Peripheral blood samples (5 mL) were collected prior to surgery. The CanPatrolTM CTC enrichment technique, a size-based isolation method, was used to detect the EMT CTCs. Clinical relevance of the CTCs was analyzed with Spearman’s rank correlation test. Models to predict pathological were built with multivariate logistic regression. Receiver operating characteristic (ROC) curve and area under the curve (AUC) analysis were performed to evaluate the accuracy of the prediction model.ResultsCTCs were detected in 55% of all patients. The biophenotypic CTCs were most valuable and closely correlated with PSA, Gleason score, D’Amico risk classification, and pathological stage in localized PCa. The mesenchymal subtype was rare in this population but associated with seminal vesicle invasion, while the epithelial subtype had limited clinical significance. In addition, the biophenotypic CTCs combined with traditional clinical variables were analyzed by multivariate logistic regression to predict organ-confined disease before surgery, of which the AUC reached 0.818 and was superior to the Partin table 2017 in our cohort.ConclusionThis study highlights the clinical impact of the biophenotypic CTCs in localized PCa, which was most closely related to clinical variables and could help to predict pathology outcomes before surgery.

Uptake of high-density lipoprotein by scavenger receptor class B type 1 is associated with prostate cancer proliferation and tumor progression in mice

High-density lipoprotein (HDL) metabolism is facilitated in part by scavenger receptor class B, type 1 (SR-B1) that mediates HDL uptake into cells. Higher levels of HDL have been associated with protection in other diseases, however, its role in prostate cancer is not definitive. SR-B1 is up-regulated in prostate cancer tissue, suggesting a possible role of this receptor in tumor progression. Here, we report that knockout (KO) of SR-B1 in both human and mouse prostate cancer cell lines through CRISPR/Cas9-mediated genome editing reduces HDL uptake into the prostate cancer cells and reduces their proliferation in response to HDL. In vivo studies using syngeneic SR-B1 WT (SR-B1+/+) and SR-B1 KO (SR-B1-/-) prostate cancer cells in WT and apolipoprotein-AI KO (apoA1-KO) C57BL/6J mice revealed that WT hosts, containing higher levels of total and HDL-cholesterol, grew larger tumors than apoA1-KO hosts with lower levels of total and HDL-cholesterol. Furthermore, SR-B1-/- prostate cancer cells formed smaller tumors in WT hosts than SR-B1+/+ cells in the same host model. Increased tumor volume was overall associated with reduced survival. We conclude that knocking out SR-B1 in prostate cancer tumors reduces HDL-associated increases in prostate cancer cell proliferation and disease progression.

Predicting prostate cancer death among 98,994 veterans: Differences by race/ethnicity.

e17609 Background: Prostate cancer mortality is higher in Blacks than Whites, but existing prognostic indices fail to account for race/ethnicity. Using data from the national U.S. Veterans Affairs Healthcare System (VA), we compared prediction of prostate cancer death by race/ethnicity. Methods: Men with biopsy confirmed prostate cancer from 2002-2016 were included. We excluded those with lymph node or distant metastatic disease at diagnosis and those not classified as Non-Hispanic White (NHW), Non-Hispanic Black (NHB), or Hispanic (HSP). We set aside 20% for future validation. Cox models estimated hazard ratios (HR) for prostate cancer death, stratified by age and race/ethnicity. Each was adjusted for age, Gleason score, tumor (T) stage, PSA at diagnosis, and calendar year. Results: Among 98,994 veterans with localized disease, 64% were NHW, 30% were NHB, and 6% were HSP. At diagnosis, median age differed by race/ethnicity (NHW 66 [IQR 62-71] yrs.; NHB 63 [58-68] yrs.; HSP 66 [61-73] yrs.). During follow-up 23,316 men died, 3484 (15% overall, and by race/ethnicity) by prostate cancer. Among those &lt; 65 yrs at diagnosis, HR for Gleason score were much stronger among NHW than NHB; associations for PSA level were stronger among NHB than NHW. HRs for HSP and NHW were similar. T stage HRs were similar by age and race/ethnicity. Conclusions: Risk associated with Gleason score and PSA varied by age and race/ethnicity. Prognostic models for prostate cancer disease progression must be evaluated in diverse populations and across age strata. [Table: see text]

A Glutaminase Isoform Switch Drives Therapeutic Resistance and Disease Progression of Prostate Cancer

Cellular metabolism in cancer is significantly altered to support the uncontrolled tumor growth. How metabolic alterations contribute to the hormonal therapy resistance and disease progression of prostate cancer (PCa) remains poorly understood. Here we report a glutaminase isoform switch mechanism that mediates the initial therapeutic effect but eventual failure of hormonal therapy of PCa. Androgen deprivation therapy inhibits the expression of kidney-type glutaminase (KGA), a splicing isoform of glutaminase 1 (GLS1) upregulated by androgen receptor (AR), to achieve therapeutic effect by suppressing glutaminolysis. Eventually the tumor cells switch to the expression of glutaminase C (GAC), a shorter splicing isoform of GLS1that is upregulated by MYC (c-MYC and N-Myc) with more potent in glutaminolysis, under the androgen-deprived condition. This switch leads to increased glutamine utilization, hyper-proliferation and aggressive behavior of tumor cells. Pharmacological inhibition or RNA interference of GLS1 isoforms differentially suppresses the growth of hormone sensitive prostate cancer and castration resistant prostate cancer in vitro and in vivo. Therefore, we have identified a metabolic function of AR action in PCa and discovered that the GLS1 isoform switch is a key mechanism in therapeutic resistance and disease progression.

MiR-484 is associated with disease recurrence and promotes migration in prostate cancer.

BACKGROUND: microRNAs (miRs) regulate the expression of protein-coding genes and play key roles in various biological processes, including development and immunity. However, dysregulation of miR expression is also involved in disease biology, including cancer.METHODS: We utilized The Cancer Genome Atlas (TCGA) and other publicly available databases for miRs and mRNA expression in prostate cancer, selected miR-484 and investigated its role in prostate cancer biology and disease progression using in vitro studies.RESULTS: Our data mining efforts revealed that increased miR-484 in prostate tumors associates with early disease recurrence, while miR-484 expression in human prostate cancer cells enhances cancer cell mobility. Using RNAseq and bioinformatics, we identified candidate target genes of miR-484 and generated a list of potential tumor suppressors. One candidate in this list was PSMG1. We applied luciferase assays and immunoblotting to confirm that miR-484 directly targets PSMG1. Additional in vitro assays with cancer cell lines showed that PSMG1 knockdown rescued the reduction in mobility brought on by miR-484 inhibition, pointing toward the existence of a miR-484–PSMG1 axis in prostate cancer.CONCLUSIONS: We hypothesize that miR-484 is an oncogene in the prostate that increases cancer cell mobility, with PSMG1 being a mir-484 target in this process.

Impact of upstream use of novel hormonal therapy on progression of patients (pts) to metastatic castration-resistant prostate cancer (mCRPC) in the United States (US).

92 Background: Novel hormonal therapies (nHTs) provide significant delay in disease progression in metastatic castration-sensitive prostate cancer (mCSPC) and non-metastatic (nm)CRPC. The impact of earlier use of these agents on the epidemiological burden of PC in the US was assessed. Methods: A disease stage transition model capturing pt flow through eight clinical states and tracking pt treatment history was used, with each nHT being used once. Progression-free survival (PFS) and overall survival (OS) data for each drug/regimen were derived from published sources where available. We analyzed scenarios 1) no nHTs and 2) with nHTs: (abiraterone acetate + prednisone [AAP], apalutamide [APA] and enzalutamide [ENZA] in high-risk mCSPC, and APA and ENZA in low-risk mCSPC and in high-risk nmCRPC). Resultant state progression parameters were compared, evaluating the impact of nHTs. The assumed nHT utilization was 17.2% in high-risk mCSPC, 7.1% in low-risk mCSPC, and 60.0% in high-risk nmCRPC. Results: For 2018, the model resulted in PC incidence of 240,150 and prevalence of 2,445,173; 49,450 pts progressed to mCRPC, 42% from PSA biochemical recurrence, 31% from mCSPC, and 27% from nmCRPC states. Longer PFS and OS afforded by novel treatments extended the mean time spent from 4.4 to 4.7 yrs in mCSPC and from 2.4 to 3.0 yrs in nmCRPC. This further resulted in reduction in inflow to mCRPC over 2019 – 2025 (table). Conclusions: Novel hormonal therapies are currently used earlier in PC, a trend anticipated to intensify. The disease model shows this change in the treatment paradigm to result in delaying progression to mCRPC and increasing OS in PC.[Table: see text]

Non-rising PSA disease progression on C-11 choline PET/CT imaging in patients receiving second generation hormone therapies (2nd-HT).

144 Background: Despite having well-recognized limitations, urologists often rely on serial PSA testing as a marker for treatment response or disease progression. To determine if PSA was indeed a reliable marker for treatment response or disease progression, we compared PSA levels against C-11 choline PET/CT in the evaluation of patients with advanced prostate cancer treated with second generation hormonal therapy (2nd-HT). Methods: We retrospectively identified 239 patients who were undergoing treatment with 2nd-HT (enzalutamide or abiraterone) for advanced prostate cancer. While on treatment, patients underwent serial PSA testing and C-11 choline PET/ CTs every 3 – 6 months. Paradoxical response was defined as increasing blood pool-corrected SUVmax of known choline-avid lesions and/or identification of new choline-avid lesions, despite stable or down-trending PSA. Results: Median (IQR) age was 70.4(64.3 – 75.7) years and median (IQR) primary Gleason Score was 8 (7 – 9). In our study, 19% of patients (n = 46/239) who were receiving 2nd-HT exhibited paradoxical response. Median (IQR) PSA and corrected SUVmax at baseline evaluation were 1.3 ng/mL (0.3 – 12.8 ng/mL) and 3.5 (1.8 – 5.8), respectively. Median (IQR) PSA and corrected SUVmax at the time of paradoxical response were 0.4 ng/mL (0.1 – 5.4 ng/mL) and 4.5 (2.8 – 6.8), respectively. The median duration of 2nd-HT treatment prior to detection of paradoxical response was 4.8 months (2.9 – 10.1 months). No significant difference was noted between patients receiving enzalutamide versus abiraterone (p = 0.35). Independent predictors of paradoxical response were prior primary systemic treatment (i.e. hormonal/chemo-hormonal therapy versus local therapy) and patient’s age at time of 2nd-HT initiation on univariate and multivariate analysis. Conclusions: Our retrospective review demonstrated prostate cancer disease progression discordant with PSA down-trending in 19% of patients receiving 2nd-HT. We conclude that in this subset of patients with advanced prostate cancer, PSA may not be a reliable marker of treatment response of disease progression, and routine radiographic evaluation in these patients is warranted.

Multi-omic serum biomarkers for prognosis of disease progression in prostate cancer

BackgroundPredicting the clinical course of prostate cancer is challenging due to the wide biological spectrum of the disease. The objective of our study was to identify prostate cancer prognostic markers in patients ‘sera using a multi-omics discovery platform.MethodsPre-surgical serum samples collected from a longitudinal, racially diverse, prostate cancer patient cohort (N = 382) were examined. Linear Regression and Bayesian computational approaches integrated with multi-omics, were used to select markers to predict biochemical recurrence (BCR). BCR-free survival was modeled using unadjusted Kaplan–Meier estimation curves and multivariable Cox proportional hazards analysis, adjusted for key pathologic variables. Receiver operating characteristic (ROC) curve statistics were used to examine the predictive value of markers in discriminating BCR events from non-events. The findings were further validated by creating a training set (N = 267) and testing set (N = 115) from the cohort.ResultsAmong 382 patients, 72 (19%) experienced a BCR event in a median follow-up time of 6.9 years. Two proteins—Tenascin C (TNC) and Apolipoprotein A1V (Apo-AIV), one metabolite—1-Methyladenosine (1-MA) and one phospholipid molecular species phosphatidic acid (PA) 18:0-22:0 showed a cumulative predictive performance of AUC = 0.78 [OR (95% CI) = 6.56 (2.98–14.40), P < 0.05], in differentiating patients with and without BCR event. In the validation set all four metabolites consistently reproduced an equivalent performance with high negative predictive value (NPV; > 80%) for BCR. The combination of pTstage and Gleason score with the analytes, further increased the sensitivity [AUC = 0.89, 95% (CI) = 4.45–32.05, P < 0.05], with an increased NPV (0.96) and OR (12.4) for BCR. The panel of markers combined with the pathological parameters demonstrated a more accurate prediction of BCR than the pathological parameters alone in prostate cancer.ConclusionsIn this study, a panel of serum analytes were identified that complemented pathologic patient features in predicting prostate cancer progression. This panel offers a new opportunity to complement current prognostic markers and to monitor the potential impact of primary treatment versus surveillance on patient oncological outcome.

Impact of clinical versus radiographic progression on clinical outcomes in metastatic castration-resistant prostate cancer

ObjectivesUnequivocal clinical progression (UCP)—a worsening of clinical status with or without radiographic progression (RAD)—represents a distinct mode of disease progression in metastatic prostate cancer. We evaluated the prevalence, risk factors and the impact of UCP on survival outcomes.MethodsA post-hoc analysis of the COU-AA-302, a randomised phase 3 study of abiraterone plus prednisone (AAP) versus prednisone was performed. Baseline characteristics were summarised. Cox proportional-hazards model and Kaplan-Meier method were used for survival and time to event analyses, respectively. Iterative multiple imputation method was used for correlation between clinicoradiographic progression-free survival (crPFS) and overall survival (OS).ResultsOf 736 patients with disease progression, 280 (38%) had UCP-only and 124 (17%) had UCP plus RAD. Prognostic index model high-risk group was associated with increased likelihood of UCP (p<0.0001). Median OS was 25.7 months in UCP-only and 33.0 months for RAD-only (HR 1.39; 95% CI 1.16 to 1.66; p=0.0003). UCP adversely impacted OS in both treatment groups. Lowest OS was seen in patients with prostate specific antigen (PSA)-non-response plus UCP-only progression (median OS 22.6 months (95% CI 20.7 to 24.4)). Including UCP events lowered estimates of treatment benefit—median crPFS was 13.3 months (95% CI 11.1 to 13.8) versus median rPFS of 16.5 months (95% CI 13.8 to 16.8) in AAP group. Finally, crPFS showed high correlation with OS (r=0.67; 95% CI 0.63 to 0.71).ConclusionsUCP is a common and clinically relevant phenomenon in patients with metastaticcastration-resistant prostate cancer (mCRPC) treated with AAP or prednisone. UCP is prognostic and associated with inferior OS and post-progression survival. A combination of PSA-non-response and UCP identifies patients with poorest survival. When included in PFS analysis, UCP diminishes estimates of treatment benefit. Continued study of UCP in mCRPC is warranted.