Subset Of Prostate Cancer Patients Research Articles

Abstract C046: Aryl hydrocarbon receptor activity may lead to the downstream transcription of several genes relevant to prostate cancer progression, apoptosis and lipid metabolism

Abstract The aryl hydrocarbon receptor (AhR) is a nuclear transcription factor and xenobiotic sensor reported to mediate diet-induced obesity and is both upregulated and constitutively active in high-grade prostate cancer. AhR activity has also been reported to contribute to proliferation and potentially disease progression in C4-2 cells (Powell et al. 2015). To determine if the aryl hydrocarbon receptor mediates transcription of genes pertinent to cancer progression, we performed an RNA-seq analysis in C4-2 AhR knockdown cells and the vehicle control. When a fold-change cutoff of ±1.5 and an adjusted p-value (p-adj) <0.05 were used, data analyses revealed several differentially expressed genes (DEGS), i.e. LEPROT, CHAC1/2, GDF11/15, CDKN2, FAS, FASTKD, ATF1/3, CCNL2, and CCNG2 with known functions involving the cell cycle, apoptosis, epigenetic modifications, tumor aggressiveness, and interestingly – lipid metabolism. Recent evidence demonstrates significant changes in the expression profile of many of these genes in response to treatment with chemotherapeutics, specifically bromocriptine (Wu et al 2023). In murine models AhR has been shown to promote diet-induced obesity coupled with metabolic dysregulation leading to obesity, which has been reported to cause malignant behaviors in prostate cancer. Leptin, a pleiotropic obesity-associated adipokine, is significantly overexpressed in mCRPC tissues. Our lab previously reported an integrative bioinformatics analysis using TCGA data (n=498) to explore the role of AHR and leptin receptor (LEPR) in prostate cancer, which revealed AHR and LEPR mRNA expression positively correlate in a subset of prostate cancer patients (P<0.05, Pearson: 0.68, R^2=0.46). We also confirmed AhR inhibits bortezomib and docetaxel -mediated apoptosis of C4-2 cells (data not shown). Further understanding of the potential interactions between metabolism and drug treatment should lead to a better understanding of the complex network of factors influencing prostate cancer progression and lead to more effective therapeutics for patients. Citation Format: Kofi K. Khamit-Kush, Joann B. Powell, Jeffrey A. Handy, Nathan J. Bowen, Daqing Wu, Valerie Odero-Marah. Aryl hydrocarbon receptor activity may lead to the downstream transcription of several genes relevant to prostate cancer progression, apoptosis and lipid metabolism [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C046.

The Somatic Mutational Landscape of Mismatch Repair Deficient Prostate Cancer.

Prostate cancers with mismatch repair deficiency (MMR-d) have aggressive clinical and histological features, and they are potentially responsive to immunotherapy. However, its rarity prevents the analysis of the underlying biology. Here, we collected the genomic data of 2664 primary prostate tumors and 1409 metastatic prostate tumors from the GENIE and TCGA databases. A total of 69 (2.59%) primary and 60 (4.26%) metastatic MMR-d tumors were identified among these tumors. Single nucleotide variant (SNV) frequencies of 34 candidate genes (including KMT2D (46.4%), ZFHX3 (33.3%), JAK1 (31.9%), and RNF43 (27.5%)) and 16 candidate genes (including KMT2D (33.3%) and JAK1 (28.3%)) were higher in MMR-d primary tumors and MMR-d metastatic tumors, respectively. The tumor mutation burden (TMB) was higher in primary MMR-d tumors. Homozygous deletions of EPCAM and EPAS1 were enriched in MMR-d primary tumors, while EPCAM deletions were enriched in metastatic MMR-d tumors. For genomic rearrangement events, TMPRSS2-ETS fusions were less frequent in primary MMR-d tumors. Our study indicates MMR-d prostate cancers have unique genomic features. These may play an important role in providing therapeutic targets for the treatment of this subset of prostate cancer patients.

Prostate cancer castrate resistant progression usage of non-canonical androgen receptor signaling and ketone body fuel

Prostate cancer (PCa) that progresses after androgen deprivation therapy (ADT) remains incurable. The underlying mechanisms that account for the ultimate emergence of resistance to ADT, progressing to castrate-resistant prostate cancer (CRPC), include those that reactivate androgen receptor (AR), or those that are entirely independent or cooperate with androgen signaling to underlie PCa progression. The intricacy of metabolic pathways associated with PCa progression spurred us to develop a metabolism-centric analysis to assess the metabolic shift occurring in PCa that progresses with low AR expression. We used PCa patient-derived xenografts (PDXs) to assess the metabolic changes after castration of tumor-bearing mice and subsequently confirmed main findings in human donor tumor that progressed after ADT. We found that relapsed tumors had a significant increase in fatty acids and ketone body (KB) content compared with baseline. We confirmed that critical ketolytic enzymes (ACAT1, OXCT1, BDH1) were dysregulated after castrate-resistant progression. Further, these enzymes are increased in the human donor tissue after progressing to ADT. In an in silico approach, increased ACAT1, OXCT1, BDH1 expression was also observed for a subset of PCa patients that relapsed with low AR and ERG (ETS-related gene) expression. Further, expression of these factors was also associated with decreased time to biochemical relapse and decreased progression-free survival. Our studies reveal the key metabolites fueling castration resistant progression in the context of a partial or complete loss of AR dependence.

Activation of the ABCB1 Amplicon in Docetaxel- and Cabazitaxel-Resistant Prostate Cancer Cells.

Docetaxel and cabazitaxel-based taxane chemotherapy are critical components in the management of advanced prostate cancer. However, their efficacy is hindered due to de novo presentation with or the development of resistance. Characterizing models of taxane-resistant prostate cancer will lead to creation of strategies to overcome insensitivity. We have previously characterized docetaxel-resistant C4-2B and DU145 cell line derivatives, TaxR and DU145-DTXR, respectively. In the present study, we characterize cabazitaxel-resistant derivative cell lines created from chronic cabazitaxel exposure of TaxR and DU145-DTXR cells, CabR and CTXR, respectively. We show that CabR and CTXR cells are robustly resistant to both taxanes but retain sensitivity to antiandrogens. Both CabR and CTXR cells possess increased expression of ABCB1, which is shown to mediate resistance to treatment. Interestingly, we also present evidence for coordinated overexpression of additional genes present within the 7q21.12 gene locus where ABCB1 resides. This locus, known as the ABCB1 amplicon, has been demonstrated to be amplified in multidrug-resistant tumor cells, but little is known regarding its role in prostate cancer. We show that two ABCB1-amplicon genes other than ABCB1, RUNDC3B and DBF4, promote cellular viability and treatment resistance in taxane-resistant prostate cancer models. We present evidence that coordinated amplification of ABCB1-amplicon genes is common in a subset of prostate cancer patients. These data together suggest that ABCB1-amplicon activation plays a critical role in taxane resistance.

Abstract 675: Radiotherapy inhibits the antitumor immune response through release of immunosuppressive tumor-derived extracellular vesicles in prostate cancer

Abstract Stereotactic ablative radiotherapy (SABR) has shown durable response rates in a subset of prostate cancer patients presenting with low metastatic burden (oligometastasis). By delivering a highly focused dose of radiation, SABR optimizes local control and induces a systemic antitumor immune response which causes tumor regression in non-irradiated metastases at distant sites (called abscopal response). However, cases of abscopal response remain scarce and the disease in majority of patients progresses by developing wide-spread metastasis. Therefore, it is crucial to elucidate the underlying mechanisms of resistance to SABR in non-responder patients and develop more effective combination therapies. By analyzing plasma samples from metastatic castration-resistant prostate cancer (mCRPC) patients, we have observed that radiotherapy induces release of tumor fragments, called extracellular vesicles (EVs). Patients with high levels of tumor-derived EVs were more at risk of developing metastases following radiotherapy. We hypothesize that radiotherapy can inhibit a systemic antitumor immune response by inducing the release of immunosuppressive tumor-derived EVs in prostate cancer. Prostate cancer cell lines (PC3 and DU145) were treated with single dose or fractionated radiotherapy. Levels of EVs were measured with Apogee Micro60-Plus nanoscale flow cytometer and the molecular composition of EVs was analyzed by proteomics and western-blot. Co-culture of prostate cancer cells with CD8+-T cells isolated from healthy donors was used to evaluate the impact of EVs on T-cell activity.For the first time, we identified irradiated PC3 and DU145 prostate cancer cells with both single dose and fractionated radiotherapy exhibiting significant increases in B7H3 protein expression. In accordance with total B7H3 protein level changes, the levels of surface B7H3 protein expression in irradiated PC3 and DU145 cells also significantly increased. Lastly, not only did radiation cause increases in the levels of PC3 and DU145 cell EV release, but also increased B7H3 protein enrichment in those EVs. Given the increases in the B7H3 protein levels in irradiated PC3 and DU145 cell surface and EVs, B7H3 enriched- PC3 and DU145 cell EV treatment to CD8+ T-cells caused significant decreases in the proliferation rates of CD8+ T-cells compared to the proliferation rates of CD8+ T-cells without EV treatment or with non-irradiated PC3 and DU145 cell-derived EV treatment.We anticipate that this proposed study can unveil novel cellular mechanisms underscoring the role of B7H3-enriched prostate cancer cell EVs in halting the radiation-induced anti-tumor immune response. This study warrants investigation into potential therapeutic strategies paired with SABR, making more efficacious anti-metastatic prostate cancer treatments. Citation Format: Yohan Kim, Roxane R. Lavoie, Haidong dong, Sean Park, Fabrice Lucien-Matteoni. Radiotherapy inhibits the antitumor immune response through release of immunosuppressive tumor-derived extracellular vesicles in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 675.

Baseline pathogenic mutations in non-AR/non-TP53 genes and prediction of response to high-dose testosterone.

146 Background: The fact that high dose of testosterone (HDT) elicits positive responses in a subset of prostate cancer patients (pts) is surprising and puzzling. Genomics data differentiating responders (Rs) from non-responders (NRs) is sparse. Pts with mutations in DNA repair pathway genes may be particularly sensitive to HDT (see BA Teply et al. Eur Urol 71:499, 2017). Herein we perform exploratory analyses to better understand the role of pathogenic mutations (muts) in ctDNA as a predictive biomarker for patients treated with HDT. Methods: ctDNA essays were performed with the Guardant360 methodology pre-HDT. Point mutations were classified by cancervar (http://cancervar.wglab.org). Truncating mutations (frameshift and nonsense) were manually curated to assess for pathogenicity. All patients had CRPC and were pre-treated with abiraterone and/or enzalutamide. HDT was typically administered as 400 mg testosterone cypionate q 3-4 weeks. Rs were compared to NRs. All Rs had >3 more cycles of HDT and a >50% PSA decline (N = 17). Non-responders had <3 cycles and no PSA decline (N = 23). Only muts with an allelic fraction of >0.5% were analyzed given dubious importance of mutations with lower allelic fractions. Results: AR muts (4/17 vs 6/23 in Rs and NRs) and TP53 muts (10/17 vs 11/23 in Rs and NRs) were similar ( P= 0.85 and 0.49, respectively) but the number of pts with non-AR/non-TP53 muts was distinct (3/17 for Rs, and 12/23 for NRs; P= 0.026). The average number of non-AR/non-TP53 muts (Rs = 0.23 and NRs = 0.83) was higher in the NRs (P = 0.046). When analyzing DNA repair alterations, no differences were noted in those with BRCA1/BRCA2/ATM mutations in the Rs and NRs (1/17 vs 6/23 respectively; P= 0.09). Conclusions: AR and TP53 pathogenic mutations are common in both Rs and NRs but other pathogenic mutations are more common in non-responders. We hypothesize that genetic pathways outside of the AR/TP53 axis drive resistance to HDT. Additional studies are warranted to assess whether or not these pathways drive resistance to HDT. Limitations are acknowledged with regard to the Guardant assay gene selection for CRPC pts.

Development and validation of a six-gene signature for predicting prognosis in prostate cancer patients with lymph node metastasis.

e17524 Background: Prostate cancer (PCa) patients with lymph node metastasis (LNM) always exhibit poor clinical outcomes. A gene signature that could predict survival in these patients would allow for earlier detection of mortality risk and will also guide individualized therapy. Methods: A prediction model was developed using a public cohort consisting of 623 patients with clinicopathologically confirmed PCa. Data were gathered from cBioPortal and UCSC Xena. Genes expressed differentially in patients with lymph node metastasis versus those without lymph node metastasis were identified. Uni-variate Cox regression analysis and LASSO Cox regression were applied to build a prediction model. Time-dependent receiver operating characteristic (ROC) and Kaplan-Meier curves were used to assess the prognostic capacity of the model, followed by external validation using the MSKCC dataset from cBioPortal. Gene Set Enrichment Analysis (GSEA) was performed to further understand the underlying molecular mechanisms. Results: We identified a six-gene signature (covering GSDMB, SSTR1, MX1, CCBE1, MYBPC1, and FAM3D) that could effectively identify a high-risk subset of PCa patients. ROC analysis indicated that the signature had a good performance (AUC > 0.7) in survival prediction in both the training and the testing/validation cohorts. Cox regression analysis showed that the six-gene signature could independently predict disease-free survival (DFS) as well, although with lower predictive power. Subgroup analyses showed that signature-based risk score may serve as a promising marker to predict DFS in different subgroups, including stage T2 (HR = 0.12, p < 0.001), stage T3 (HR = 0.29, p < 0.001), TP53-wild-type (HR = 0.22, p < 0.001), TP53-mutated (HR = 0.07, p < 0001), AR pathways-wild-type (HR = 0.2, p < 0.001) and AR pathways-mutated(HR = 0.16, p = 0.0419). The performance of the six-gene signature in LNM+ was stable for stratifying the patients according to risk of deatch (HR = 0.23, p = 0.0333). Moreover, GSEA revealed distinct pathway enrichment features in the different risk groups, where pathways related to DNA repair were more prominently enriched in the high-risk group while the low-risk group had higher enrichment of androgen response. Conclusions: We developed a robust six-gene signature that can effectively classify PCa patients into groups with low- and high-risk group, which may help select high-risk patients who require more aggressive adjuvant target therapy or immune therapy.

Polypoidal giant cancer cells in metastatic castration-resistant prostate cancer: observations from the Michigan Legacy Tissue Program.

Despite early diagnosis and established protocols, a subset of prostate cancer patients will eventually be categorized as castration-resistant prostate cancer. Recently, it has been reported that these multi-modal therapy cases may harbor a special subset of cancer cells termed as polypoidal giant cancer cells (PGCC). These cells are phenotypically described either as possessing highly irregular polylobated nuclei or multiple pleomorphic nuclei. To identify and characterize the distribution of these cells, we created a cohort of 5 randomly selected cases of multi-modal therapy failure prostate cancer (16 selected non-osseous and osseous tumor sites) enrolled in Michigan Legacy Tissue Program. In all cases, specific "regions of interest" or "hot spots" within tumor areas showing an increased proportion of these multi-nucleated/polylobated cells under light microscopy were labeled as PGCC-rich area. On microscopic evaluation, overall mean count of PGCC was 42.4 ± 3.91 with case 2 in the study cohort with the highest number of average PGCC count of 17 ± 4.04. Site wise analysis showed retroperitoneal lymph node as the tissue with highest number of average PGCC number/site (5.0 ± 0.32). On correlating the average number of PGCC recorded with the time elapsed from last dose of chemotherapy administered to autopsy, the spearman correlation value (R) was 0.67, but the result was not statistically significant (p = 0.22). A systematic assessment of PGCC in a large stratified cohort of prostate cancer patients integrated with various histopathological and clinical parameters along with discovery of specific biomarkers for PGCC are the future studies suggested.

Radiation Biomarkers: Can Small Businesses Drive Accurate Radiation Precision Medicine?

Radiation therapy is an essential component of cancer treatment. Currently, tumor control and normal tissue complication probabilities derived from a general patient population guide radiation treatment. Its outcome could be improved if radiation biomarkers could be incorporated into approaches to treatment. A substantial number of cancer patients suffer from side effects of radiation therapy. These side effects can result in treatment interruption. Such unplanned treatment interruptions not only jeopardize anticancer treatment efficacy but also result in poor post-treatment quality-of-life. To develop and translate radiation biomarkers for clinical use, NCI's Radiation Research Program, in collaboration with the Small Business Innovation Research Development Center, funded four small businesses through the request for proposals after peer review during 2015-2019. Here, we summarize publicly available information on intellectual property rights, the status of development, ongoing clinical trials, success in obtaining financing and regulatory approval. An analysis of publicly available information indicates all four companies have completed phase I of SBIR funding and advanced to further development, validation and clinical trials with phase II SBIR funding. These biomarkers are: 1. A panel of genomic biomarkers of radiation response to predict toxicity and radioimmune response (MiraDx Inc., Los Angeles, CA); 2. A multiplex assay for single nucleotide polymorphism (SNP) biomarkers of radiation sensitivity to identify a subset of prostate cancer patients for which radiotherapy is contraindicated (L2 Diagnostics, New Haven, CT); 3. A cell-free DNA assay in blood to measure tissue damage shortly after radiation exposure (DiaCarta Inc., Richmond, CA); and 4. A metabolomic/lipidomic assay to predict late effects that adversely affect quality-of-life among patients treated with radiation for prostate cancer (Shuttle Pharmaceuticals, Rockville, MD). This work also provides a bird's eye view of the process of developing radiation biomarkers for use in radiation oncology clinics, some of the challenges and future directions.

SOX4 is activated by C-MYC in prostate cancer.

Although MYC proto-oncogene (C-MYC) amplification has been consistently reported to be a potential marker for prostate cancer (PCa) progression and prognosis, the clinicopathological and prognostic significance of C-MYC protein expression remains controversial. Overexpression of SOX4 has been shown to play important roles in multiple cancers including PCa. However, the link between these two critical genetic aberrations is unclear. In the current study, we showed that C-MYC was overexpressed in 16.2% (17/105) of Chinese patients with localized PCa. Overexpression of C-MYC was significantly associated with high Gleason scores (P = 0.012) and high Ki67 labeling index (P = 0.005). C-MYC overexpression was correlated with cancer-related mortality and suggested to be an unfavorable prognostic factor in Chinese PCa patients (P = 0.018). Overexpression of C-MYC is associated with SOX4 overexpression in PCa tissues. Notably, SOX4 is a direct target gene of C-MYC; C-MYC activates SOX4 expression via binding to its promoter. In addition, Co-IP analysis demonstrated a physical interaction between C-MYC and SOX4 protein in PCa cells. Clinically, C-MYC+/SOX4+ characterized poor prognosis in a subset of PCa patients. In total, C-MYC overexpression may contribute to PCa progression by activating SOX4. Our findings highlight an important role of C-MYC/SOX4 in PCa progression in a subset of PCa patients.

Examining the impact of a multimedia intervention on treatment decision-making among newly diagnosed prostate cancer patients: results from a nationwide RCT.

Men diagnosed with early stage prostate cancer face multiple treatment options, each with distinctive side effects that have significant implications for post-treatment quality of life. Healing Choices for Men with Prostate Cancer is a multimedia educational and decision aid program. This nation-wide randomized controlled trial evaluated the impact of Healing Choices on reducing decisional conflict and distress. Eligible prostate cancer patients who called the National Cancer Institute's Cancer Information Service (CIS) were invited to participate. After a baseline interview, participants were randomized to usual personalized consultation with a CIS specialist (comparison condition) or CIS personalized consultation plus the Healing Choices program (intervention condition). The Decision Conflict Scale and Impact of Event Scale assessed decisional conflict about prostate cancer treatment and cancer-related distress, respectively. Analyses evaluated group differences at 2 months postenrollment. Hypothesized moderation of intervention effects by demographic and clinical characteristics were evaluated. The final sample consisted of N = 349 participants (intervention: n = 181; comparison n = 168). Men were on average 64 years old, primarily White, and well educated. The difference in total decisional conflict was not significant (DCS total score; F[1,311] = .99, p = .32). The difference in cancer-related distress at 2 months between the intervention and the comparison groups was not significant (F[1,337] = .01, p = .93). Evaluation of specific decision processes indicated a significant effect on levels of perceived decisional support (intervention, M = 34.8, SD = 15.7; comparison, M = 38.3, SD = 16.1; F[1,337] = 3.74, p = .05). The intervention effect was greatest for nonwhite minority participants (b = -9.65, SE = 4.67) and those with lower educational attainment (b = 3.87, SE = 2.21). This interactive, comprehensive education and decision aid program may be most effective for a subset of prostate cancer patients in need of educational and decisional support.

Regular aspirin use and gene expression profiles in prostate cancer patients.

Pharmacoepidemiology studies suggest prognostic benefits of aspirin in prostate cancer. We hypothesized that aspirin induces transcriptional changes in tumors or normal prostate tissue. We analyzed the prostatic transcriptome from men diagnosed with prostate cancer during follow-up of the Physicians' Health Study 1 (PHS, n = 149), initially a randomized controlled trial of aspirin. Aspirin target genes were identified through systematic literature review and a drug target database. We compared target gene expression according to regular aspirin use at cancer diagnosis and used whole-transcriptome gene set enrichment analysis to identify gene sets associated with aspirin use. Results were validated in the Health Professionals Follow-up Study (HPFS, n = 254) and in Connectivity Map. Of 12 target genes identified from prior studies and 540 genes from the drug target database, none were associated with aspirin use. Twenty-one gene sets were enriched in tumor tissue of aspirin users, 18 of which were clustered around ribosome function and translation. These gene sets were associated with exposure to cyclooxygenase inhibitors in Connectivity Map. Their association with cancer prognosis was U-shaped in both cohorts. No gene sets were enriched in normal tissue. In HPFS, neither the target genes nor the gene sets were associated with aspirin use. Regular aspirin use may affect ribosome function in prostate tumors. Other putative target genes had similar expression in tumors from aspirin users and non-users. If results are corroborated by experimental studies, a potential benefit of aspirin may be limited to a subset of prostate cancer patients.

Proteotranscriptomic Measurements of E6-Associated Protein (E6AP) Targets in DU145 Prostate Cancer Cells

Prostate cancer is a common cause of cancer-related death in men. E6AP (E6-Associated Protein), an E3 ubiquitin ligase and a transcription cofactor, is elevated in a subset of prostate cancer patients. Genetic manipulations of E6AP in prostate cancer cells expose a role of E6AP in promoting growth and survival of prostate cancer cells in vitro and in vivo However, the effect of E6AP on prostate cancer cells is broad and it cannot be explained fully by previously identified tumor suppressor targets of E6AP, promyelocytic leukemia protein and p27. To explore additional players that are regulated downstream of E6AP, we combined a transcriptomic and proteomic approach. We identified and quantified 16,130 transcripts and 7,209 proteins in castration resistant prostate cancer cell line, DU145. A total of 2,763 transcripts and 308 proteins were significantly altered on knockdown of E6AP. Pathway analyses supported the known phenotypic effects of E6AP knockdown in prostate cancer cells and in parallel exposed novel potential links of E6AP with cancer metabolism, DNA damage repair and immune response. Changes in expression of the top candidates were confirmed using real-time polymerase chain reaction. Of these, clusterin, a stress-induced chaperone protein, commonly deregulated in prostate cancer, was pursued further. Knockdown of E6AP resulted in increased clusterin transcript and protein levels in vitro and in vivo Concomitant knockdown of E6AP and clusterin supported the contribution of clusterin to the phenotype induced by E6AP. Overall, results from this study provide insight into the potential biological pathways controlled by E6AP in prostate cancer cells and identifies clusterin as a novel target of E6AP.

Predictive value of epithelial-mesenchymal-transition (EMT) signature and PARP-1 in prostate cancer radioresistance.

Epithelial-mesenchymal-transition (EMT) has been previously identified as a contributor to prostate cancer progression to metastasis and therapeutic resistance to antiandrogens and radiotherapy. In this study we conducted a retrospective analysis to investigate the significance of radiation-induced EMT and consequential changes to the tumor microenvironment in biochemical recurrence and response to radiotherapy in prostate cancer patients. Expression profiling and localization for EMT effectors, E-Cadherin, N-Cadherin, β-catenin and Vimentin was assessed in human prostate tumor specimens pre- and post-radiotherapy and correlated with biochemical recurrence. In addition, immunoreactivity of the DNA repair enzyme, polymerase (PARP-1) and the cytoskeletal-remodeling regulator, cofilin was evaluated in prostate tumor specimens pre- and post-radiotherapy and correlated with pre-treatment prostate-specific antigen levels (PSA). Our findings identified that characteristic changes associated with the EMT phenotype and its reversal to mesenchymal-epithelial-transition (MET) within the tumor microenvironment correlate with biochemical recurrence and resistance to radiotherapy among prostate cancer patients. Moreover, elevated PARP-1 expression among the tumor cells undergoing EMT implicates that DNA repair mechanisms may potentially reverse the cytotoxic effects of radiotherapy-induced DNA breaks. Our results suggest that EMT programming effectors, integrated with the actin cytoskeleton regulator cofilin and mesenchymal PARP-1 expression profile provide a signature of potential predictive significance of therapeutic response to radiotherapy in a subset of prostate cancer patients.

Ultra-Low Risk Prostate Cancer Treated with Cryotherapy versus Radiation Therapy

Cryotherapy and radiation therapy are definitive local treatment approaches for prostate cancer. There is both prospective and retrospective data for definitive radiotherapy, but the use of cryotherapy has been limited primarily to single arm single institutional retrospective studies. The American Urological Association asserts that definitive cryotherapy has a role in low risk disease. Per the NCCN guidelines, ultra-low risk prostate cancer patients are candidates for active surveillance as a viable monitoring approach, but some of these patients insist on proceeding with definitive therapy. We undertook a retrospective analysis of the most favorable subset of prostate cancer patients, with ultra-low risk disease, to comparatively elucidate the utility of radiotherapy and cryotherapy. Institutional Review Board approval was obtained prior to conducting a retrospective chart review of patients treated at our institution from 1999-2014 with external beam radiation therapy (EBRT), low dose rate brachytherapy (LDR), and cryotherapy. Patients meeting inclusion criteria for the present study were diagnosed with prostate cancer and had ultra-low-risk disease as defined by all of the following conditions: stage T1c TNM classification, PSA < 10, and a combined Gleason score of 3+3, 1-3 cores positive with no more than 50% of an individual core involved by tumor. Only patients who received definitive LDR, EBRT or cryotherapy monotherapy were included in the analysis. We excluded patients who were treated with radiation for surgical salvage. Disease specifics and failure details were collected for all patients. Failure was defined as PSA nadir +2ng/mL Sixty-five patients were treated with radiation (39 with EBRT and 26 with LDR), while 40 patients were treated with cryotherapy, The EBRT dose median was 75Gy (range: 72.0-79.2Gy). LDR patients were treated with 120Gy Pd-103 or 140-145Gy I-125 implant. All cryotherapy patients were treated with 2 freeze and thaw cycles. Median cores positive were 1 (range 1-3). Ninety percent of men had unilateral disease with 10% having bilateral disease. A median of 10% maximum volume of cores were positive (range: 1-50%). Mean PSA density was 0.11ng/mL/gm (range 0.09-0.14). Mean PSA follow-up was 57.3 and 51.5 months in the radiotherapy and cryotherapy groups respectively. Eighty-nine percent (58/65) and only 67.5% (13/40) of the cryotherapy patients were free of biochemical progression (p=0.0125). There was no difference in bPFS between EBRT an LDR (p=1.0). Time to biochemical progression in failed patients was 62 months in the radiotherapy group and 11 months in the cryotherapy group. In our practice, patients undergoing definitive treatment for ultra-low risk prostate cancer appear to do better with radiation therapy than cryotherapy. We likewise do not recommend cryotherapy as definitive treatment upfront for prostate cancer.

Expression analysis of cancer-testis genes in prostate cancer reveals candidates for immunotherapy.

Prostate cancer is a prevalent disorder among men with a heterogeneous etiological background. Several molecular events and signaling perturbations have been found in this disorder. Among genes whose expressions have been altered during the prostate cancer development are cancer-testis antigens (CTAs). This group of antigens has limited expression in the normal adult tissues but aberrant expression in cancers. This property provides them the possibility to be used as cancer biomarkers and immunotherapeutic targets. Several CTAs have been shown to be immunogenic in prostate cancer patients and some of the have entered clinical trials. Based on the preliminary data obtained from these trials, it is expected that CTA-based therapeutic options are beneficial for at least a subset of prostate cancer patients.

Mutations in BRCA2 and taxane resistance in prostate cancer

Mutations in BRCA1 or BRCA2 define a subset of prostate cancer patients. Herein, we address the question whether BRCA1/2 mutations have a predictive impact on chemotherapy with docetaxel, a widely used drug in patients with metastatic castration resistant prostate cancer (mCRPC). Fifty-three men treated with docetaxel for mCRPC were tested for somatic BRCA1/2 mutations of the primary tumor. In a subgroup of patients, BRCA1/2 protein expression was tested as a potential surrogate marker for BRCA1/2 inactivation. Eight of 53 patients (15.1%) harbored a deleterious BRCA2 mutation. No BRCA1 mutation was found. Patients with a BRCA2 mutation showed a response rate of 25% to docetaxel in comparison to 71.1% in men with wildtype BRCA2 (p = 0.019). While the time to develop castration resistance was similar in both subgroups, the overall survival was significantly shorter in patients harboring a BRCA2 mutation. No correlation between the BRCA1/2 protein expression and the response to docetaxel was found. While the presence of a BRCA2 mutation does not preclude a response to docetaxel, there is overall a significant correlation between BRCA2 inactivation and a poor response rate. Our results suggest that a close oncological monitoring of patients with BRCA2 mutations for taxane resistance is warranted.

E6AP promotes prostate cancer by reducing p27 expression.

Prostate cancer (PC) is the most common cancer in men. Elevated levels of E3 ligase, E6-Associated Protein (E6AP) were previously linked to PC, consistent with increased protein expression in a subset of PC patients. In cancers, irregular E3 ligase activity drives proteasomal degradation of tumor suppressor proteins. Accordingly, E3 ligase inhibitors define a rational therapy to restore tumor suppression. The relevant tumor suppressors targeted by E6AP in PC are yet to be fully identified. In this study we show that p27, a key cell cycle regulator, is a target of E6AP in PC. Down regulation of E6AP increases p27 expression and enhances its nuclear accumulation in PC. We demonstrate that E6AP regulates p27 expression by inhibiting its transcription in an E2F1-dependent manner. Concomitant knockdown of E6AP and p27 partially restores PC cell growth, supporting the contribution of p27 to the overall effect of E6AP on prostate tumorigenesis. Overall, we unravelled the E6AP-p27 axis as a new promoter of PC, exposing an attractive target for therapy through the restoration of tumor suppression.

Epigenome-Wide Tumor DNA Methylation Profiling Identifies Novel Prognostic Biomarkers of Metastatic-Lethal Progression in Men Diagnosed with Clinically Localized Prostate Cancer.

Aside from Gleason sum, few factors accurately identify the subset of prostate cancer patients at high risk for metastatic progression. We hypothesized that epigenetic alterations could distinguish prostate tumors with life-threatening potential. Epigenome-wide DNA methylation profiling was performed in surgically resected primary tumor tissues from a population-based (n = 430) and a replication (n = 80) cohort of prostate cancer patients followed prospectively for at least 5 years. Metastasis was confirmed by positive bone scan, MRI, CT, or biopsy, and death certificates confirmed cause of death. AUC, partial AUC (pAUC, 95% specificity), and P value criteria were used to select differentially methylated CpG sites that robustly stratify patients with metastatic-lethal from nonrecurrent tumors, and which were complementary to Gleason sum. Forty-two CpG biomarkers stratified patients with metastatic-lethal versus nonrecurrent prostate cancer in the discovery cohort, and eight of these CpGs replicated in the validation cohort based on a significant (P < 0.05) AUC (range, 0.66-0.75) or pAUC (range, 0.007-0.009). The biomarkers that improved discrimination of patients with metastatic-lethal prostate cancer include CpGs in five genes (ALKBH5, ATP11A, FHAD1, KLHL8, and PI15) and three intergenic regions. In the validation dataset, the AUC for Gleason sum alone (0.82) significantly increased with the addition of four individual CpGs (range, 0.86-0.89; all P <0.05). Eight differentially methylated CpGs that distinguish patients with metastatic-lethal from nonrecurrent tumors were validated. These novel epigenetic biomarkers warrant further investigation as they may improve prognostic classification of patients with clinically localized prostate cancer and provide new insights on tumor aggressiveness. Clin Cancer Res; 23(1); 311-9. ©2016 AACR.

MUC1 is upregulated in advanced prostate cancer and is an independent prognostic factor.

MUC1 is a membrane-bound glycoprotein that belongs to the mucin family. It is involved in cell adhesion and intracellular signaling. Aberrant expression of MUC1 has been observed in different carcinomas, including prostate cancer, where it may serve as a therapeutic target. There are no data on the prognostic value of MUC1 in metastatic prostate cancer. MUC1 expression was evaluated in tissue microarrays constructed from 119 nodal positive prostate cancer patients treated by radical prostatectomy and extended lymphadenectomy. MUC1 status was correlated with various tumor features and biochemical recurrence-free (bRFS), disease-specific survival (DSS) and overall survival (OS). MUC1 expression was significantly different between primary tumors, lymph node metastases and non-neoplastic glands (scores 53.7 vs 30.1 vs 16.6; P<0.0001). High MUC1 expression in primary tumors was positively correlated with tumor volume (mean 24.4 cm(3) vs 14.5 cm(3); P=0.005) and T-stage (P=0.009); in lymph node metastases, high expression corresponded with a greater total size of metastases (mean 35.8 mm vs 12.7 mm; P<0.001) and a higher ratio of positive to examined lymph nodes (mean 0.22 vs 0.12; P=0.014). High MUC1 expression in lymph node metastases predicted unfavorable outcomes compared with low MUC1 expression (bRFS P=0.023, DSS and OS P⩽0.001), whereas in primary tumors, the same tendency was non-significant. In multivariate analyses, high MUC1 expression in primary tumors and lymph node metastases independently predicted early biochemical failure (P=0.046) and tumor-related death (P=0.0038), respectively. High MUC1 in either primary tumor or lymph node metastases correlates significantly with unfavorable tumor features and survival. Overexpression of MUC1 in the metastases of a subset of prostate cancer patients may have therapeutic potential.