Punctuated evolution of prostate cancer genomes.

The analysis of exonic DNA from prostate cancers has identified recurrently mutated genes, but the spectrum of genome-wide alterations has not been profiled extensively in this disease. We sequenced the genomes of 57 prostate tumors and matched normal tissues to characterize somatic alterations and to study how they accumulate during oncogenesis and progression. By modeling the genesis of genomic rearrangements, we identified abundant DNA translocations and deletions that arise in a highly interdependent manner. This phenomenon, which we term "chromoplexy," frequently accounts for the dysregulation of prostate cancer genes and appears to disrupt multiple cancer genes coordinately. Our modeling suggests that chromoplexy may induce considerable genomic derangement over relatively few events in prostate cancer and other neoplasms, supporting a model of punctuated cancer evolution. By characterizing the clonal hierarchy of genomic lesions in prostate tumors, we charted a path of oncogenic events along which chromoplexy may drive prostate carcinogenesis.

Author Correction: FOXA1 mutations alter pioneering activity, differentiation and prostate cancer phenotypes.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

FOXA1 mutations alter pioneering activity, differentiation and prostate cancer phenotypes.

Mutations in the transcription factor FOXA1 define a unique subset of prostate cancers but the functional consequences of these mutations and whether they confer gain or loss of function is unknown1-9. Here, by annotating the landscape of FOXA1 mutations from 3,086 human prostate cancers, we define two hotspots in the forkhead domain: Wing2 (around 50% of all mutations) and the highly conserved DNA-contact residue R219 (around 5% of all mutations). Wing2 mutations are detected in adenocarcinomas at all stages, whereas R219 mutations are enriched in metastatic tumours with neuroendocrine histology. Interrogation of the biological properties of wild-type FOXA1 and fourteen FOXA1 mutants reveals gain of function in mouse prostate organoid proliferation assays. Twelve of these mutants, as well as wild-type FOXA1, promoted an exaggerated pro-luminal differentiation program, whereas two different R219 mutants blocked luminal differentiation and activated a mesenchymal and neuroendocrine transcriptional program. Assay for transposase-accessible chromatin using sequencing (ATAC-seq) of wild-type FOXA1 and representative Wing2 and R219 mutants revealed marked, mutant-specific changes in open chromatin at thousands of genomic loci and exposed sites of FOXA1 binding and associated increases in gene expression. Of note, ATAC-seq peaks in cells expressing R219 mutants lacked the canonical core FOXA1-binding motifs (GTAAAC/T) but were enriched for a related, non-canonical motif (GTAAAG/A), which was preferentially activated by R219-mutant FOXA1 in reporter assays. Thus, FOXA1 mutations alter its pioneering function and perturb normal luminal epithelial differentiation programs, providing further support for the role of lineage plasticity in cancer progression.

Prostate cancer genetic alterations in Hispanic men.

BACKGROUND: Differences in DNA alterations in prostate cancer among White, Black, and Asian men have been widely described. This is the first description of the frequency of DNA alterations in primary and metastatic prostate cancer samples of self-reported Hispanic men. METHODS: We utilized targeted next-generation sequencing tumor genomic profiles from prostate cancer tissues that underwent clinical sequencing at academic centers (GENIE 11th). We decided to restrict our analysis to the samples from Memorial Sloan Kettering Cancer Center as it was by far the main contributor of Hispanic samples. The numbers of men by self-reported ethnicity and racial categories were analyzed via Fisher's exact test between Hispanic-White versus non-Hispanic White. RESULTS AND LIMITATIONS: Our cohort consisted of 1412 primary and 818 metastatic adenocarcinomas. In primary adenocarcinomas, TMPRSS2 and ERG gene alterations were less common in non-Hispanic White men than Hispanic White (31.86% vs. 51.28%, p = 0.0007, odds ratio [OR] = 0.44 [0.27-0.72] and 25.34% vs. 42.31%, p = 0.002, OR = 0.46 [0.28-0.76]). In metastatic tumors, KRAS and CCNE1 alterations were less prevalent in non-Hispanic White men (1.03% vs. 7.50%, p = 0.014, OR = 0.13 [0.03, 0.78] and 1.29% vs. 10.00%, p = 0.003, OR = 0.12 [0.03, 0.54]). No significant differences were found in actionable alterations and androgen receptor mutations between the groups. Due to the lack of clinical characteristics and genetic ancestry in this dataset, correlation with these could not be explored. CONCLUSION: DNA alteration frequencies in primary and metastatic prostate cancer tumors differ among Hispanic-White and non-Hispanic White men. Notably, we found no significant differences in the prevalence of actionable genetic alterations between the groups, suggesting that a significant number of Hispanic men could benefit from the development of targeted therapies.

Randomized phase II trial of MRI-guided salvage radiotherapy for prostate cancer in 4 weeks versus 2 weeks (SHORTER).

BACKGROUND: Ultra-hypofractionated image-guided stereotactic body radiotherapy (SBRT) is increasingly used for definitive treatment of localized prostate cancer. Magnetic resonance imaging-guided radiotherapy (MRgRT) facilitates improved visualization, real-time tracking of targets and/or organs-at-risk (OAR), and capacity for adaptive planning which may translate to improved targeting and reduced toxicity to surrounding tissues. Given promising results from NRG-GU003 comparing conventional and moderate hypofractionation in the post-operative setting, there is growing interest in exploring ultra-hypofractionated post-operative regimens. It remains unclear whether this can be done safely and whether MRgRT may help mitigate potential toxicity. SHORTER (NCT04422132) is a phase II randomized trial prospectively evaluating whether salvage MRgRT delivered in 5 fractions versus 20 fractions is non-inferior with respect to gastrointestinal (GI) and genitourinary (GU) toxicities at 2-years post-treatment. METHODS: A total of 136 patients will be randomized in a 1:1 ratio to salvage MRgRT in 5 fractions or 20 fractions using permuted block randomization. Patients will be stratified according to baseline Expanded Prostate Cancer Index Composite (EPIC) bowel and urinary domain scores as well as nodal treatment and androgen deprivation therapy (ADT). Patients undergoing 5 fractions will receive a total of 32.5 Gy over 2 weeks and patients undergoing 20 fractions will receive a total of 55 Gy over 4 weeks, with or without nodal coverage (25.5 Gy over 2 weeks and 42 Gy over 4 weeks) and ADT as per the investigator's discretion. The co-primary endpoints are change scores in the bowel and the urinary domains of the EPIC. The change scores will reflect the 2-year score minus the pre-treatment (baseline) score. The secondary endpoints include safety endpoints, including change in GI and GU symptoms at 3, 6, 12 and 60 months from completion of treatment, and efficacy endpoints, including time to progression, prostate cancer specific survival and overall survival. DISCUSSION: The SHORTER trial is the first randomized phase II trial comparing toxicity of ultra-hypofractionated and hypofractionated MRgRT in the salvage setting. The primary hypothesis is that salvage MRgRT delivered in 5 fractions will not significantly increase GI and GU toxicities when compared to salvage MRgRT delivered in 20 fractions. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04422132. Date of registration: June 9, 2020.

Impact of Left-Digit Age Bias in the Treatment of Localized Prostate Cancer.

PURPOSE: Left-digit bias is a phenomenon in which the leftmost digit of a number disproportionately influences decision making. We measured the effect of left-digit age bias on treatment recommendations for localized prostate cancer. MATERIALS AND METHODS: We included men with clinically localized prostate adenocarcinoma in Surveillance, Epidemiology, and End Results from 2004 to 2018 and the National Cancer Database from 2004 to 2016. Primary outcomes were recommendations for radiation therapy and radical prostatectomy. Regression discontinuity was used to assess whether age increase from 69 to 70 years was associated with disproportionate changes in treatment recommendations. RESULTS: In Surveillance, Epidemiology, and End Results, discontinuities were found in the proportion of patients recommended for radiation among the entire cohort (effect size 2.2%, P < .01) and among patients with Gleason 6 (1.6%, P < .01), Gleason 7 (2.5%, P < .01), and Gleason ≥8 (2.1%, P < .01) cancer, while the proportion recommended for prostatectomy decreased in the entire cohort (-1.4%, P < .01) and in patients with Gleason 7 cancer (-2.4%, P < .01). In the National Cancer Database, discontinuity from age 69 to 70 was found in recommendations for radiation in the entire cohort (effect size: 3.1%, P < .01) and in patients with Gleason 6 (2.2%, P < .01), Gleason 7 (4.0%, P < .01), and Gleason ≥8 (2.3%, P < .02) cancer, while the proportion recommended for prostatectomy decreased at this cutoff in the entire cohort (effect size: -2.7%, P < .01) and patients with Gleason 6 (-2.2%, P < .01) and Gleason 7 (-3.7%, P < .01) cancer. CONCLUSIONS: In patients with localized prostate cancer, left-digit age change from 69 to 70 was associated with disproportionately increased recommendations for radiation and decreased recommendations for prostatectomy.

Active Surveillance for Men with Intermediate Risk Prostate Cancer.

PURPOSE: Optimal treatment of intermediate risk prostate cancer remains unclear. National Comprehensive Cancer Network® guidelines recommend active surveillance, prostatectomy or radiotherapy. Recent trials demonstrated no difference in prostate cancer specific mortality for men undergoing active surveillance for low risk prostate cancer compared to prostatectomy or radiotherapy. The use of active surveillance for intermediate risk prostate cancer is less clear. In this study we characterize U.S. national trends for demographic, clinical and socioeconomic factors associated with active surveillance for men with intermediate risk prostate cancer. MATERIALS AND METHODS: This retrospective cohort study examined 176,122 men diagnosed with intermediate risk prostate cancer from 2010 to 2016 in the National Cancer Database. Temporal trends in demographic, clinical and socioeconomic factors among men with intermediate risk prostate cancer and association with the use of active surveillance were characterized. The analysis was performed in April 2020. RESULTS: In total, 176,122 men were identified with intermediate risk prostate cancer from 2010 to 2016. Of these men 57.3% underwent prostatectomy, 36.4% underwent radiotherapy and 3.2% underwent active surveillance. Active surveillance nearly tripled from 1.6% in 2010 to 4.6% in 2016 (p <0.001). On multivariate analysis use of active surveillance was associated with older age, diagnosis in recent years, lower Gleason score and tumor stage, type of insurance, treatment at an academic center and proximity to facility, and attaining higher education (p <0.05). Race and comorbidities were not associated with active surveillance. CONCLUSIONS: Our findings highlight increasing active surveillance use for men with intermediate risk prostate cancer demonstrating clinical and socioeconomic disparities. Prospective data and improved risk stratification are needed to guide optimal treatment for men with intermediate risk prostate cancer.

Intraductal carcinoma of the prostate in the absence of high-grade invasive carcinoma represents a molecularly distinct type of in situ carcinoma enriched with oncogenic driver mutations.

Intraductal carcinoma of the prostate (IDC-P) most often appears associated with high-grade invasive prostate carcinoma (PCa), where it is believed to represent retrograde spread. However, IDC-P rarely occurs as an isolated finding at radical prostatectomy or with concurrent low-grade (Grade Group 1) invasive carcinoma. We hypothesized that isolated IDC-P (iIDC-P) in these unusual cases may represent a distinct in situ lesion and molecularly profiled 15 cases. iIDC-P was characterized by copy number alteration (CNA) profiling and targeted next generation sequencing in cases with sufficient tissue (n = 7). Immunohistochemistry for PTEN and ERG was performed on the total cohort (n = 15), where areas of iIDC-P and associated invasive disease were evaluated separately (n = 9). By copy number profiling, iIDC-P alterations were similar to those previously described in high-grade invasive PCa (PTEN, RB1, and CHD1 loss; MYC gain). However, in four cases, targeted sequencing revealed a striking number of activating oncogenic driver mutations in MAPK and PI3K pathway genes, which are extraordinarily rare in conventional PCa. In addition, pathogenic mutations in DNA repair genes were found in two cases of iIDC-P (BRCA2, CHEK2, CDK12) and other known PCa-associated mutations (FOXA1, SPOP) in two cases. Overall, ERG was expressed in 7% (1/15) of the iIDC-P lesions and PTEN was lost in 53% (8/15). Discordance for ERG or PTEN status between IDC-P and the low-grade PCa was observed in five of nine cases, with intact PTEN in the invasive tumor and PTEN loss in IDC-P in four. Despite a CNA profile similar to conventional PCa, iIDC-P is enriched with potentially targetable oncogenic driver mutations in MAPK/PI3K genes. Based on PTEN and ERG status, iIDC-P is not likely a precursor to the associated low-grade invasive PCa, but represents a molecularly unique in situ tumor of unclear clinical significance. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The Clinical Utility of the Genomic Prostate Score in Men with Very Low to Intermediate Risk Prostate Cancer.

PURPOSE: We retrospectively investigated the Genomic Prostate Score® assay in clinical practice at an urban tertiary care academic center. MATERIALS AND METHODS: We reviewed all Genomic Prostate Score results acquired during a 3-year period. Changes in patient NCCN® (National Comprehensive Cancer Network®) risk group, including very low, low, intermediate or high risk, and ultimate management decisions were recorded. RESULTS: Genomic Prostate Score risk stratification was performed in 134 men. According to the NCCN Guidelines®, 31 of the 134 men (23.1%) were at very low risk, 45 (33.6%) were at low risk and 58 (43.3%) were at intermediate risk. After adding the score the risk group changed in 32 of 134 patients (23.9%). The risk group did not change in the 31 men at very low risk. However, in the low risk group the risk changed in 19 of the 45 men (42.2%), including in 15 to very low and in 4 to intermediate risk. Also, in the intermediate risk group the risk changed in 13 of the 58 men (22.4%), including to low in 12 and to high risk in 1. Nine of the 15 men (60%) in whom risk changed from low to very low elected active surveillance. Nine of the 12 patients (75%) at intermediate risk in whom risk changed to low risk elected active surveillance, 2 (16.7%) elected definitive therapy and in 1 (8.3%) the choice was unknown. Of the 45 men at intermediate risk in whom risk was unchanged 28 (62.2%) elected definitive therapy, 12 (26.0%) elected active surveillance and in 5 (11.1%) the choice was unknown. Of the 4 men upgraded from low to intermediate risk after adding the genomic prostate score 2 elected definitive therapy and 2 chose active surveillance. CONCLUSIONS: The Genomic Prostate Score has limited clinical usefulness in patients at very low risk since the NCCN risk group did not change. While it may be more useful for men at low and intermediate risk, for 32 (31%) of whose risk group was reclassified, clinical management decisions did not always appear to reflect these changes.

Impact of Pelvic Radiation Therapy on Inflatable Penile Prosthesis Reoperation Rates.

INTRODUCTION: Considering that radiation therapy (RT) compromises soft tissue microvasculature, impairs wound healing, and causes cavernosal fibrosis, inflatable penile prosthesis (IPP) outcomes may be adversely affected in men treated with RT. AIM: To compare IPP outcomes among those who had undergone prior RT vs a cohort who underwent radical prostatectomy (RP) before insertion of IPP. METHODS: The Surveillance, Epidemiology, and End Results (SEER)-Medicare Database was queried for men with prostate cancer (PCa) who underwent RT (n = 83,277) or RP (n = 32,608) with subsequent IPP insertion between 2002 and 2013. Men who had undergone both RT and RP were excluded from the analysis. MAIN OUTCOME MEASURE: The primary outcome was reoperation, defined by removal, revision, or replacement of the IPP. RESULTS: We identified 350 men who received an IPP following RT and 653 who received an IPP following RP. Men who underwent RT were older (P < .01) and had more comorbidities (P < .01). There were no significant differences in overall reoperation rates at 90 days (P = .78), 1 year (P = .52), or 3 years (P = .48). Time-to-event analysis demonstrated that RT was not associated with an increased likelihood of overall reoperation (hazard ratio [HR] 1.46, 95% confidence interval [CI] 0.94-2.29, P = .09). There was no association between time from RT to IPP and overall reoperation rates. CLINICAL IMPLICATIONS: Prior RT for the treatment of PCa does not impact the revision or removal rates of IPPs as compared with a cohort of non-radiated patients who underwent RP. STRENGTH & LIMITATIONS: The strength includes the analysis of outcomes among a contemporary, nationwide cohort with robust follow-up. Using diagnosis and procedure codes, we were thoroughly able to capture reoperations. Limitations include the lack of specific indications for reoperation and inability to control for surgeon experience or technique. CONCLUSION: IPP is a safe and effective treatment of erectile dysfunction that should be offered to men with a history of pelvic radiation who have failed medical therapy. Golan R, Patel NA, Sun T, et al. Impact of pelvic radiation therapy on inflatable penile prosthesis reoperation rates. J Sex Med 2018;15:1653-1658.

Molecular Subtypes of Prostate Cancer.

PURPOSE OF REVIEW: This review will examine the taxonomy of PCa subclasses across disease states, explore the relationship among specific alterations, and highlight current clinical relevance. RECENT FINDINGS: Prostate cancer (PCa) is driven by multiple genomic alterations, with distinct patterns and clinical implications. Alterations occurring early in the timeline of the disease define core subtypes of localized, treatment-naive PCa. With time, an increase in number and severity of genomic alterations adds molecular complexity and is associated with progression to metastasis. These later events are not random and are influenced by the underlying subclasses. All the subclasses of localized disease initially respond to androgen deprivation therapy (ADT), but with progression to castrate-resistant PCa (CRPC), mechanisms of resistance against ADT shift the molecular landscape. In CRPC, resistance mechanisms largely define the biology and sub-classification of these cancers, while clinical relevance and opportunities for precision therapy are still being defined.

Quantification of mutant SPOP proteins in prostate cancer using mass spectrometry-based targeted proteomics.

BACKGROUND: Speckle-type POZ protein (SPOP) is an E3 ubiquitin ligase adaptor protein that functions as a potential tumor suppressor, and SPOP mutations have been identified in ~10% of human prostate cancers. However, it remains unclear if mutant SPOP proteins can be utilized as biomarkers for early detection, diagnosis, prognosis or targeted therapy of prostate cancer. Moreover, the SPOP mutation sites are distributed in a relatively short region with multiple lysine residues, posing significant challenges for bottom-up proteomics analysis of the SPOP mutations. METHODS: To address this issue, PRISM (high-pressure, high-resolution separations coupled with intelligent selection and multiplexing)-SRM (selected reaction monitoring) mass spectrometry assays have been developed for quantifying wild-type SPOP protein and 11 prostate cancer-derived SPOP mutations. RESULTS: Despite inherent limitations due to amino acid sequence constraints, all the PRISM-SRM assays developed using Arg-C digestion showed a linear dynamic range of at least two orders of magnitude, with limits of quantification ranged from 0.1 to 1 fmol/µg of total protein in the cell lysate. Applying these SRM assays to analyze HEK293T cells with and without expression of the three most frequent SPOP mutations in prostate cancer (Y87N, F102C or F133V) led to confident detection of all three SPOP mutations in corresponding positive cell lines but not in the negative cell lines. Expression of the F133V mutation and wild-type SPOP was at much lower levels compared to that of F102C and Y87N mutations; however, at present, it is unknown if this also affects the biological activity of the SPOP protein. CONCLUSIONS: In summary, PRISM-SRM enables multiplexed, isoform-specific detection of mutant SPOP proteins in cell lysates, providing significant potential in biomarker development for prostate cancer.

Prognostic Significance of a Negative Prostate Biopsy: An Analysis of Subjects Enrolled in a Prostate Cancer Screening Trial.

PURPOSE: To our knowledge the optimal treatment of patients following a negative prostate biopsy is unknown. Consequently, resources are increasingly being directed toward risk stratification in this cohort. However, the risk of prostate cancer mortality in this group before the introduction of supplemental biomarkers and imaging techniques is unclear. MATERIALS AND METHODS: The PLCO (Prostate, Lung, Colorectal and Ovarian Cancer) Screening Trial provides survival data prior to the implementation of new diagnostic interventions. We divided men with an initial positive screen and a subsequent prostate biopsy into cohorts based on positive or negative results. Prostate cancer specific mortality was then compared to that in the trial control arm to estimate the prognostic significance of biopsy results relative to the general population. RESULTS: A total of 36,525 and 36,560 patients comprised the screening and control arms, respectively. Of 4,064 subjects with a positive first screen 1,233 underwent a linked biopsy, of which 473 were positive and 760 were negative. At a median followup of 12.9 years, 1.1% of men in the negative biopsy cohort had died of prostate cancer. The difference in mortality rates between the negative biopsy and control arms was 0.734 deaths per 1,000 person-years. The proportional subhazard ratios of prostate cancer specific mortality for negative biopsy and positive biopsy relative to the control arm were 2.93 (95% CI 1.44-5.99) and 18.77 (95% CI 12.62-27.93), respectively. CONCLUSIONS: After a negative prostate biopsy, men face a relatively low risk of death from prostate cancer when followed with traditional markers and biopsy techniques. This suggests limited potential for new diagnostic interventions to improve survival in this group.

Prostate size, nocturia and the digital rectal examination: a cohort study of 30 500 men.

OBJECTIVES: To evaluate the utility of the digital rectal examination (DRE) in estimating prostate size and the association of DRE with nocturia in a population-based cohort. SUBJECTS AND METHODS: We identified all men randomized to the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening (PLCO) trial for whom DRE results were available. Men were excluded if they had a history of prostate surgery or incident prostate cancer. Prostate posterior surface area was derived from DRE sagittal and transverse estimates. Relationships between prostate posterior surface area, transrectal ultrasonography (TRUS), prostate-specific antigen (PSA) and nocturia were analysed using intraclass correlation coefficients (ICCs), Spearman's rank correlation and multivariable logistic regression. RESULTS: A total of 30 500 men met the inclusion criteria, with 103 275 screening visits containing paired DRE and PSA data. Digital rectal examination posterior surface area estimates had an ICC of 0.547 (95% CI 0.541-0.554) and were significantly yet modestly correlated with elevated PSA level (rs = 0.18, P < 0.001) and TRUS prostate volume (rs = 0.32, P < 0.001). Prostate posterior surface area was significantly associated with nocturia on multivariable analysis, but was not significant in stratified analysis of men with cardiovascular risk factors (hypertension, diabetes, high body mass index, stroke). In men without these risk factors, the highest quintile of DRE posterior surface area had 22% greater odds of nocturia than the lowest quintile (odds ratio 1.216, 95% CI 1.036-1.427). CONCLUSIONS: Digital rectal examination is a modestly accurate tool for measuring prostate volume. While DRE posterior surface area represents a statistically significant predictor of nocturia, the magnitude of effect suggests it has limited clinical utility for assessing this condition, particularly in the presence of cardiovascular risk factors.

Decline in Prostate Cancer Screening by Primary Care Physicians: An Analysis of Trends in the Use of Digital Rectal Examination and Prostate Specific Antigen Testing.

PURPOSE: Prostate cancer screening by digital rectal examination and prostate specific antigen testing has been routine clinical practice in the United States for the last 25 years. Recent studies have shown a national decline in prostate specific antigen testing following the USPSTF (United States Preventive Services Task Force) recommendation against routine prostate specific antigen screening. However, to our knowledge the effect of this recommendation on digital rectal examination utilization remains unknown. MATERIALS AND METHODS: We used NAMCS (National Ambulatory Medical Care Survey) to characterize trends in the rate of digital rectal examination and prostate specific antigen testing by primary care physicians in men older than 40 years presenting for preventive care. From 2005 to 2012 NAMCS contained 3,368 such visits (unweighted) for the study of digital rectal examination trends and 4,035 unweighted visits from 2002 to 2012 for the study of prostate specific antigen trends. RESULTS: Following the USPSTF recommendation the proportion of visits where digital rectal examination was performed decreased from 16.0% (95% CI 13.1-19.5) to 5.8% (95% CI 4.0-8.3, p <0.001). Similarly, the proportion of visits where prostate specific antigen testing was performed decreased from 27.3% (95% CI 24.5-30.3) to 16.7% (95% CI 12.9-21.2, p <0.001). This represents a relative 64% decrease in digital rectal examination and a 39% decrease in prostate specific antigen testing. Among men 55 to 69 years old the number of visits where digital rectal examination and prostate specific antigen testing were performed decreased 65% and 39%, respectively (p <0.001). CONCLUSIONS: Utilization of digital rectal examination and prostate specific antigen has declined significantly following the release of the USPSTF recommendation against prostate specific antigen screening. This suggests that prostate cancer screening is rapidly disappearing from primary care practice.

Molecular subtyping of prostate cancer.

PURPOSE OF REVIEW: The recent publication of The Cancer Genome Atlas molecular taxonomy of primary prostate cancer highlights the increased understanding of the genomic basis of human prostate cancer, but also emphasizes the complexity and heterogeneity of prostate cancer. RECENT FINDINGS: Seven molecular subclasses have been defined on the basis of early genomic alterations, which are largely mutually exclusive. SUMMARY: We review the recent advances in the genomic understanding of human prostate cancer, with focus on molecular subclassification. Broadly, prostate cancer can be classified based upon whether specific genomic rearrangements, such as the Transmembrane Protease, Serine 2-ETS-related gene fusion occur or whether specific alterations such as Speckle-type POZ protein and forkhead box A1 mutations occur. The molecular drivers remain to be identified in a further quarter of human prostate cancers. Depending upon the molecular subclassification and the coincident genomic alterations, specific clinical insights can be gained from this information, including associations with pathologic factors, race, and prognosis, as well as the possibility for future precision therapies.

Prostate cancer-associated mutations in speckle-type POZ protein (SPOP) regulate steroid receptor coactivator 3 protein turnover.

The p160 steroid receptor coactivators (SRCs) SRC-1, SRC-2 [nuclear receptor coactivator (NCOA)2], and SRC-3 [amplified in breast cancer 1 (AIB1)/NCOA3] are key pleiotropic "master regulators" of transcription factor activity necessary for cancer cell proliferation, survival, metabolism, and metastasis. SRC overexpression and overactivation occur in numerous human cancers and are associated with poor clinical outcomes and resistance to therapy. In prostate cancer (PC), the p160 SRCs play critical roles in androgen receptor transcriptional activity, cell proliferation, and resistance to androgen deprivation therapy. We recently demonstrated that the E3 ubiquitin ligase adaptor speckle-type poxvirus and zinc finger (POZ) domain protein (SPOP) interacts directly with SRC-3 and promotes its cullin 3-dependent ubiquitination and proteolysis in breast cancer, thus functioning as a potential tumor suppressor. Interestingly, somatic heterozygous missense mutations in the SPOP substrate-binding cleft recently were identified in up to 15% of human PCs (making SPOP the gene most commonly affected by nonsynonymous point mutations in PC), but their contribution to PC pathophysiology remains unknown. We now report that PC-associated SPOP mutants cannot interact with SRC-3 protein or promote its ubiquitination and degradation. Our data suggest that wild-type SPOP plays a critical tumor suppressor role in PC cells, promoting the turnover of SRC-3 protein and suppressing androgen receptor transcriptional activity. This tumor suppressor effect is abrogated by the PC-associated SPOP mutations. These studies provide a possible explanation for the role of SPOP mutations in PC, and highlight the potential of SRC-3 as a therapeutic target in PC.