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PurposeAfrican Americans experience greater prostate cancer risk and mortality than do Caucasians. An analysis of pooled phase III data suggested differences in overall survival (OS) between African American and Caucasian men receiving sipuleucel-T. We explored this in PROCEED (NCT01306890), an FDA-requested registry in over 1900 patients with metastatic castration-resistant prostate cancer (mCRPC) treated with sipuleucel-T.Patients and methodsOS for patients who received ≥1 sipuleucel-T infusion was compared between African American and Caucasian men using an all patient set and a baseline prostate-specific antigen (PSA)-matched set (two Caucasians to every one African American with baseline PSAs within 10% of each other). Univariable and multivariable analyses were conducted. Survival data were examined using Kaplan-Meier and Cox proportional hazard methodologies.ResultsMedian follow-up was 46.6 months. Overall survival differed between African American and Caucasian men with hazard ratios (HR) of 0.81 (95% confidence interval [CI]: 0.68-0.97, P = 0.03) in the all patient set and 0.70 (95% CI: 0.57-0.86, P

Androgen receptor (AR) is a main driver for castration-resistant prostate cancer (CRPC). c-Myc is an oncogene underlying prostate tumorigenesis. Here, we find that the deubiquitinase USP11 targets both AR and c-Myc in prostate cancer (PCa). USP11 expression was up-regulated in metastatic PCa and CRPC. USP11 knockdown (KD) significantly inhibited PCa cell growth. Our RNA-seq studies revealed AR and c-Myc as the top transcription factors altered after USP11 KD. ChIP-seq analysis showed that either USP11 KD or replacement of endogenous USP11 with a catalytic-inactive USP11 mutant significantly decreased chromatin binding by AR and c-Myc. We find that USP11 employs two mechanisms to up-regulate AR and c-Myc levels: namely, deubiquitination of AR and c-Myc proteins to increase their stability and deubiquitination of H2A-K119Ub, a repressive histone mark, on promoters of AR and c-Myc genes to increase their transcription. AR and c-Myc reexpression in USP11-KD PCa cells partly rescued cell growth defects. Thus, our studies reveal a tumor-promoting role for USP11 in aggressive PCa through upregulation of AR and c-Myc activities and support USP11 as a potential target against PCa. [ABSTRACT FROM AUTHOR]

PurposeZoledronic acid decreases the risk for skeletal-related events (SREs) in men with castration-resistant prostate cancer and bone metastases but its role earlier in the natural history of the disease is unknown. This phase III study evaluated the efficacy and safety of earlier treatment with zoledronic acid in men with castration-sensitive metastatic prostate cancer.Patients and methodsMen with castration-sensitive prostate cancer and bone metastases whose androgen-deprivation therapy was initiated within 6 months of study entry were randomly assigned in a blinded 1:1 ratio to receive zoledronic acid (4 mg intravenously every 4 weeks) or a placebo. After their disease progressed to castration-resistant status, all patients received open-label treatment with zoledronic acid. The primary end point was time to first SRE, defined as radiation to bone, clinical fracture, spinal cord compression, surgery to bone, or death as a result of prostate cancer. Target accrual was 680 patients. Primary analysis was planned after 470 SREs. The study was discontinued prematurely (645 patients; 299 SREs) after the corporate supporter withdrew study drug supply.ResultsEarly zoledronic acid was not associated with increased time to first SRE. The median time to first SRE was 31.9 months in the zoledronic acid group (95% CI, 24.2 to 40.3) and 29.8 months in the placebo group (95% CI, 25.3 to 37.2; hazard ratio, 0.97; 95% CI, 0 to 1.17; one-sided stratified log-rank P = .39). Overall survival was similar between the groups (hazard ratio, 0.88; 95% CI, 0.70 to 1.12; P = .29). Rates of adverse events were similar between the groups.ConclusionIn men with castration-sensitive prostate cancer and bone metastases, early treatment with zoledronic acid was not associated with lower risk for SREs.

Simple Summary: Advanced prostate cancer that has progressed after standard therapies such as hormone therapy and taxane-based chemotherapies is an invariably lethal disease state with limited treatment options. There remains an important need to continue to identify new treatment approaches for such patients. We used two cell culture models of prostate cancer that are resistant to hormonal therapy and chemotherapy, and which also manifest some characteristics that are often associated with advanced prostate cancer, such as neuroendocrine differentiation, to evaluate the potential anti-cancer effects of targeting the key molecules, ErbB receptors and AKT. Using several complementary approaches, we found that the concurrent targeting of ErbB receptors and AKT with specific inhibitors was more effective than targeting each of them individually, independent of the underlying molecular characteristics or relative degrees of resistance to the taxanes that defined the prostate cancer models that were studied. Enhanced anti-tumor responses occurred both in vitro and in vivo with dual targeting, with the consistent inhibition particularly of AKT occurring in both settings. These studies provide a framework to evaluate the role of signal pathway modulation as a potential therapeutic strategy in treatment-refractory prostate cancer. Using two representative models of androgen-independent prostate cancer (PCa), PC3 and DU145, and their respective paclitaxel- and docetaxel-resistant derivatives, we explored the anti-tumor activity of targeting the ErbB receptors and AKT using small-molecule kinase inhibitors. These cells manifest varying degrees of neuroendocrine differentiation characteristics and differ in their expression of functional PTEN. Although the specific downstream signaling events post the ErbB receptor and AKT co-targeting varied between the PC3- and DU145-lineage cells, synergistic anti-proliferative and enhanced pro-apoptotic responses occurred across the wild-type and the taxane-resistant cells, independent of their basal AKT activation state, their degree of paclitaxel- or docetaxel-resistance, or whether this resistance was mediated by the ATP Binding Cassette transport proteins. Dual targeting also led to enhanced anti-tumor responses in vivo, although there was pharmacodynamic discordance between the PCa cells in culture versus the tumor xenografts in terms of the relative activation and inhibition states of AKT and ERK under basal conditions and upon AKT and/or ErbB targeting. The consistent inhibition, particularly of AKT, occurred both in vitro and in vivo, independent of the underlying PTEN status. Thus, co-targeting AKT with ErbB, and possibly other partners, may be a useful strategy to explore further for potential therapeutic effect in advanced PCa. [ABSTRACT FROM AUTHOR]

Formation of the androgen receptor splicing variant 7 (AR-V7) is one of the major mechanisms by which resistance of prostate cancer to androgen deprivation therapy occurs. The histone demethylase JMJD1A (Jumonji domain containing 1A) functions as a key coactivator for AR by epigenetic regulation of H3K9 methylation marks. Here, we describe a role for JMJD1A in AR-V7 expression. While JMJD1A knockdown had no effect on full-length AR (AR-FL), it reduced ARV7 levels in prostate cancer cells. Reexpression of AR-V7 in the JMJD1A-knockdown cells elevated expression of select AR targets and partially rescued prostate cancer cell growth in vitro and in vivo. The AR-V7 protein level correlated positively with JMJD1A in a subset of human prostate cancer specimens. Mechanistically, we found that JMJD1A promoted alternative splicing of AR-V7 through heterogeneous nuclear ribonucleoprotein F (HNRNPF), a splicing factor known to regulate exon inclusion. Knockdown of JMJD1A or HNRNPF inhibited splicing of AR-V7, but not AR-FL, in a minigene reporter assay. JMJD1A was found to interact with and promote the recruitment of HNRNPF to a cryptic exon 3b on AR pre-mRNA for the generation of AR-V7. Taken together, the role of JMJD1A in AR-FL coactivation and AR-V7 alternative splicing highlights JMJD1A as a potentially promising target for prostate cancer therapy. [ABSTRACT FROM AUTHOR]

Purpose/Objective(s): Skeletal-related events (SREs), which include radiation to the bone (RtB), can occur among patients with bone metastasis (BM). There is a recognized potential for misclassification of RtB when using claims data. We compared alternative measures of RtB to better understand their impact on SRE prevalence and SRE-related mortality. Methods and materials: We analyzed data for stage IV prostate cancer (PCa) cases identified between 2005 and 2009 in the Surveillance, Epidemiology, and End Results registry linked with Medicare claims. We created two measures of RtB: 1) a literature-based measure requiring the presence of a prior claim with a BM code; 2) a new measure requiring either that the BM code coincided with the radiation episode or that the duration of the radiation episode was less than or equal to 4 weeks. We estimated adjusted hazard ratios of an SRE using both measures among stratified samples: no metastasis (M0), metastasis to bone (M1b) and other sites (M1c). Results: The study sample included 5,074 men with stage IV PCa (median age 77 years), of whom 22% had M0, 54% had M1b, and 24% had M1c disease at time of PCa diagnosis. Based on Approaches 1 and 2, the proportion with probable RtB was 5% and 8% among M0, 30% and 30% among M1b, and 25% and 27% among M1c patients. Among M0 patients, the adjusted hazard ratio (AHR) associated with an SRE was 1.27 when using Approach 1 (95% confidence interval, CI: 0.95–1.7) and 1.49 when using Approach 2 (95% CI: 1.14–1.96). However, the impact of SREs on mortality did not differ between both approaches among M1b and M1c patients. Conclusion: We found that alternative measures used to define RtB as SRE in claims data impact conclusions regarding the effect of SREs on mortality among M0 but not M1 patients. [ABSTRACT FROM AUTHOR]

The purpose of this study was to estimate the risk of developing skeletal-related events ( SREs) based on site of metastasis at diagnosis and identify other predictors of developing SREs among metastatic prostate cancer patients. We conducted a retrospective cohort study using linked SEER (Surveillance, Epidemiology, and End Results) and Medicare data and identified men over the age of 65 with incident metastatic prostate cancer diagnosed during 2005-2009. SREs included radiation ( RAD), pathological fractures ( PF), bone surgery ( BS), and spinal cord compression ( SCC). The association between site of metastasis at diagnosis and SRE was examined using a Cox proportional hazards model that accounts for death as a competing risk. Among 4404 men (median age: 79 years) with incident metastatic prostate cancer, 44% experienced SREs at a median of 9.6 months post diagnosis. Compared to bone metastasis only, our model showed that patients were significantly less likely to develop SREs if they had LN-only metastasis at diagnosis (Sub-Hazard Ratio [ SHR] 0.56; 95% Confidence Interval [ CI]: 0.43-0.72) or unknown site of metastasis ( SHR: 0.79; CI: 0.64-0.97). Other predictors of reduced SRE risk were age 80+ years ( SHR: 0.83; CI: 0.75-0.91), non-Hispanic Black ( SHR: 0.77; CI: 0.65-0.90), or being diagnosed in year 2009 ( SHR: 0.85; CI: 0.72-0.99). Patients were significantly more likely to develop SREs if they received androgen deprivation therapy ( SHR: 1.73; CI: 1.48-2.02) or had Gleason score 8-10 disease ( SHR: 0.79; CI: 0.64-0.97). Compared to patients who present with bone metastasis only at diagnosis, patients presenting with other metastatic sites have similar risk of developing SREs, with the exception of those presenting with lymph node only metastasis who have a significantly reduced risk of SREs. [ABSTRACT FROM AUTHOR]

Phosphorylated cyclic-AMP (cAMP) response element binding protein (p-CREB) is a downstream effector of a variety of important signaling pathways. We investigated whether the human BCRP promoter contains a functional cAMP response element (CRE). 8Br-cAMP, a cAMP analogue, increased the activity of a BCRP promoter reporter construct and BCRP mRNA in human carcinoma cells. Epidermal growth factor receptor (EGFR) pathway activation also led to an increase in p-CREB and in BCRP promoter reporter activity via two major downstream EGFR signaling pathways: the phosphotidylinositol-3-kinase (PI3K)/AKT pathway and the mitogen-activated protein kinase (MAPK) pathway. EGF treatment increased the phosphorylation of EGFR, AKT, ERK and CREB, while simultaneously enhancing BCRP mRNA and functional protein expression. EGF-stimulated CREB phosphorylation and BCRP induction were diminished by inhibition of EGFR, PI3K/AKT or RAS/MAPK signaling. CREB silencing using RNA interference reduced basal levels of BCRP mRNA and diminished the induction of BCRP by EGF. Chromatin immunoprecipitation assays confirmed that a putative CRE site on the BCRP promoter bound p-CREB by a point mutation of the CRE site abolished EGF-induced stimulation of BCRP promoter reporter activity. Furthermore, the CREB co-activator, cAMP-regulated transcriptional co-activator (CRTC2), is involved in CREB-mediated BCRP transcription: androgen depletion of LNCaP human prostate cancer cells increased both CREB phosphorylation and CRTC2 nuclear translocation, and enhanced BCRP expression. Silencing CREB or CRTC2 reduced basal BCRP expression and BCRP induction under androgen-depletion conditions. This novel CRE site plays a central role in mediating BCRP gene expression in several human cancer cell lines following activation of multiple cancer-relevant signaling pathways. [ABSTRACT FROM AUTHOR]

BACKGROUND Factors contributing to the lower likelihood of urologist follow-up among African American (AA) men diagnosed with prostate cancer may not be strictly related to patient factors. The authors investigated the relationship between crime, poverty, and poor housing, among others, and postdiagnosis urologist visits among AA and white men. METHODS The authors used linked cancer registry and Medicare claims data from 1999 through 2007 for men diagnosed with American Joint Committee on Cancer stage I to III prostate cancer. The USA Counties and County Business Patterns data sets provided county-level data. Variance components models reported the percentage of variation attributed to county of residence. Postdiagnosis urologist visits for AA and white men were investigated using logistic and modified Poisson regression models. RESULTS A total of 65,635 patients were identified; 87% of whom were non-Hispanic white and 9.3% of whom were non-Hispanic AA. Approximately 16% of men diagnosed with stage I to III prostate cancer did not visit a urologist within 1 year after diagnosis (22% of AA men and 15% of white men). County of residence accounted for 10% of the variation in the visit outcome (13% for AA men and 10% for white men). AA men were more likely to live in counties ranked highest in terms of poverty, occupied housing units with no telephone, and crime. AA men were less likely to see a urologist (odds ratio, 0.65 [95% confidence interval, 0.6-0.71]; rate ratio, 0.94 [95% confidence interval, 0.92-0.95]). The sign and magnitude of the coefficients for the county-level measures differed across race-specific regression models of urologist visits. CONCLUSIONS Among older men diagnosed with stage I to III prostate cancer, the social environment appears to contribute to some of the disparities in postdiagnosis urologist visits between AA and white men. Cancer 2014;120:3385-3392. © 2014 American Cancer Society. [ABSTRACT FROM AUTHOR]

Background To assess concordance between Medicare claims and Surveillance, Epidemiology, and End Results (SEER) reports of incident BM among prostate cancer (PCa) patients. The prevalence and consequences of bone metastases (BM) have been examined across tumor sites using healthcare claims data however the reliability of these claims-based BM measures has not been investigated. Methods This retrospective cohort study utilized linked registry and claims (SEER-Medicare) data on men diagnosed with incident stage IV M1 PCa between 2005 and 2007. The SEER-based measure of incident BM was cross-tabulated with three separate Medicare claims approaches to assess concordance. Sensitivity, specificity and positive predictive value (PPV) were calculated to assess the concordance between registry- and claims-based measures. Results Based on 2,708 PCa patients in SEER-Medicare, there is low to moderate concordance between the SEER- and claims-based measures of incident BM. Across the three approaches, sensitivity ranged from 0.48 (0.456 - 0.504) to 0.598 (0.574 - 0.621), specificity ranged from 0.538 (0.507 - 0.569) to 0.620 (0.590 - 0.650) and PPV ranged from 0.679 (0.651 - 0.705) to 0.690 (0.665 - 0.715). A comparison of utilization patterns between SEER-based and claimsbased measures suggested avenues for improving sensitivity. Conclusion Claims-based measures using BM ICD 9 coding may be insufficient to identify patients with incident BM diagnosis and should be validated against chart data to maximize their potential for population-based analyses. [ABSTRACT FROM AUTHOR]

BACKGROUND: The treatment for prostate cancer patients with biochemical failure after local therapy remains controversial. Peripheral androgen blockade using a combination of a 5-alpha reductase inhibitor and an antiandrogen may allow control of the prostate-specific antigen (PSA). Because testosterone levels are not suppressed, this approach may be associated with less morbidity than conventional gonadal androgen suppression. METHODS: All patients had undergone previous definitive local therapy and had evidence of a rising PSA >1ng/mL, with no evidence of recurrent disease. Patients received both finasteride, 5 mg orally per day, and flutamide, 250 mg orally 3× a day. Patients were followed for a PSA response and quality of life assessment. RESULTS: Ninety-nine of 101 accrued patients were eligible. A ≥80% PSA decline was seen in 96 (96%) patients. The median time to PSA progression was 85 months. With a median follow-up of 10 years, the median survival time had not been reached, and the 5-year overall survival rate was 87%. Toxicity was mild, with 18 patients stopping for toxicity; 15 had diarrhea, 4 had gynecomastia, and 3 had transaminase elevation. Baseline Functional Assessment of Cancer Therapy Prostate Module and Treatment Outcome Index scores decreased by 5 points each at 6 months after enrollment. CONCLUSIONS: The use of the finasteride/flutamide combination is feasible, and results in PSA declines of ≥80% in 96% of patients with serologic progression after definitive local therapy. There were no unexpected toxicities, and the change in quality of life was mild. Further evaluation of this or a similar regimen in a controlled clinical trial is warranted. Cancer 2012. © 2011 American Cancer Society. [ABSTRACT FROM AUTHOR]

Purpose: We report the long-term results of a prospective, Phase II study of long-term androgen deprivation (AD), pelvic radiotherapy (EBRT), permanent transperineal prostate brachytherapy boost (PB), and adjuvant docetaxel in patients with high-risk prostate cancer. Methods and Materials: Eligibility included biopsy-proven prostate adenocarcinoma with the following: prostate-specific antigen (PSA) > 20 ng/ml; or Gleason score of 7 and a PSA >10 ng/ml; or any Gleason score of 8 to 10; or stage T2b to T3 irrespective of Gleason score or PSA. Treatment consisted of 45 Gy of pelvic EBRT, followed 1 month later by PB with either iodine-125 or Pd-103. One month after PB, patients received three cycles of docetaxel chemotherapy (35 mg/m2 per week, Days 1, 8, and 15 every 28 days). All patients received 2 years of AD. Biochemical failure was defined as per the Phoenix definition (PSA nadir + 2). Results: From August 2000 to March 2004, 42 patients were enrolled. The median overall and active follow-ups were 5.6 years (range, 0.9–7.8 years) and 6.3 years (range, 4–7.8 years), respectively. Grade 2 and 3 acute genitourinary (GU) and gastrointestinal (GI) toxicities were 50.0% and 14.2%, respectively, with no Grade 4 toxicities noted. Grade 3 and 4 acute hematologic toxicities were 19% and 2.4%, respectively. Of the patients, 85.7% were able to complete the planned multimodality treatment. The 5- and 7-year actuarial freedom from biochemical failures rates were 89.6% and 86.5%, and corresponding rates for disease-free survival were 76.2% and 70.4%, respectively. The 5- and 7-year actuarial overall survival rates were 83.3% and 80.1%, respectively. The 5- and 7-year actuarial rates of late Grade 2 GI/GU toxicity (no Grade 3–5) was 7.7%. Conclusions: The trimodality approach of using 2 years of AD, external radiation, brachytherapy, and upfront docetaxel in high-risk prostate cancer is well tolerated, produces encouraging long-term results, and should be validated in a multi-institutional setting. [Copyright &y& Elsevier]

Simple Summary: In the present study, we sought to determine whether a commonly used oral drug to treat adult-onset diabetes, metformin, which has a longstanding clinical history and known safety and tolerability profile, can improve the anti-cancer effects of two well-established oral agents currently in use to treat advanced prostate cancer, abiraterone and enzalutamide. We used androgen-sensitive cell culture models of human prostate cancer to test our hypothesis. We found that metformin and the oral anti-prostate cancer agents together are more effective in inhibiting prostate cancer cell growth and inducing prostate cancer cell death than when used alone. We identified new pathways by which the enhanced anti-cancer effects occur with the combination treatments. The present work suggests that incorporating metformin with abiraterone or enzalutamide may improve treatment outcomes in hormone sensitive prostate cancer. We explored whether the anti-prostate cancer (PC) activity of the androgen receptor-axis-targeted agents (ARATs) abiraterone and enzalutamide is enhanced by metformin. Using complementary biological and molecular approaches, we determined the associated underlying mechanisms in pre-clinical androgen-sensitive PC models. ARATs increased androgren receptors (ARs) in LNCaP and AR/ARv7 (AR variant) in VCaP cells, inhibited cell proliferation in both, and induced poly(ADP-ribose) polymerase-1 (PARP-1) cleavage and death in VCaP but not LNCaP cells. Metformin decreased AR and ARv7 expression and induced cleaved PARP-1-associated death in both cell lines. Metformin with abiraterone or enzalutamide decreased AR and ARv7 expression showed greater inhibition of cell proliferation and greater induction of cell death than single agent treatments. Combination treatments led to increased cleaved PARP-1 and enhanced PARP-1 activity manifested by increases in poly(ADP-ribose) (PAR) and nuclear accumulation of apoptosis inducing factor (AIF). Enhanced annexin V staining occurred in LNCaP cells only with metformin/ARAT combinations, but no caspase 3 recruitment occurred in either cell line. Finally, metformin and metformin/ARAT combinations increased lysosomal permeability resulting in cathepsin G-mediated PARP-1 cleavage and cell death. In conclusion, metformin enhances the efficacy of abiraterone and enzalutamide via two PARP-1-dependent, caspase 3-independent pathways, providing a rationale to evaluate these combinations in castration-sensitive PC. [ABSTRACT FROM AUTHOR]

Increasing evidence suggests a role of epigenetic mechanisms at chromosome 8q24, an important cancer genetic susceptibility region, in prostate cancer. We investigated whether MYC DNA methylation at 8q24 (six CpG sites from exon 3 to the 3′ UTR) in prostate tumor was associated with tumor aggressiveness (based on Gleason score, GS), and we incorporated RNA expression data to investigate the function. We accessed radical prostatectomy tissue for 50 Caucasian and 50 African American prostate cancer patients at the University of Maryland Medical Center, selecting an equal number of GS 6 and GS 7 cases per group. MYC DNA methylation was lower in tumor than paired normal prostate tissue for all six CpG sites (median difference: −14.74 to −0.20 percentage points), and we observed similar results for two nearby sites in The Cancer Genome Atlas (p < 0.0001). We observed significantly lower methylation for more aggressive (GS 7) than less aggressive (GS 6) tumors for three exon 3 sites (for CpG 212 (chr8:128753145), GS 6 median = 89.7%; GS 7 median = 85.8%; p-value = 9.4 × 10−4). MYC DNA methylation was not associated with MYC expression, but was inversely associated with PRNCR1 expression after multiple comparison adjustment (q-value = 0.04). Findings suggest that prostate tumor MYC exon 3 hypomethylation is associated with increased aggressiveness. [ABSTRACT FROM AUTHOR]

These studies compared the efficacies of our clinical agent galeterone (Gal) and the FDA-approved prostate cancer drug, enzalutamide (ENZ) with two lead next generation galeterone analogs (NGGAs), VNPP414 and VNPP433-3β, using prostate cancer (PC) in vitro and in vivo models. Antitumor activities of orally administered agents were also assessed in CWR22Rv1 tumor-bearing mice. We demonstrated that Gal and NGGAs degraded AR/AR-V7 and Mnk1/2; blocked cell cycle progression and proliferation of human PC cells; induced apoptosis; inhibited cell migration, invasion, and putative stem cell markers; and reversed the expression of epithelial-to-mesenchymal transition (EMT). In addition, Gal/NGGAs (alone or in combination) also inhibited the growth of ENZ-, docetaxel-, and mitoxantrone-resistant human PC cell lines. The NGGAs exhibited improved pharmacokinetic profiles over Gal in mice. Importantly, in vivo testing showed that VNPP433-3β (at 7.53-fold lower equimolar dose than Gal) markedly suppressed (84% vs. Gal, 47%; p < 0.01) the growth of castration-resistant PC (CRPC) CWR22Rv1 xenograft tumors, with no apparent host toxicity. ENZ was ineffective in this CRPC xenograft model. In summary, our findings show that targeting AR/AR-V7 and Mnk1/2 for degradation represents an effective therapeutic strategy for PC/CRPC treatment and supports further development of VNPP433-3β towards clinical investigation. [ABSTRACT FROM AUTHOR]

Re-activation of androgen receptor (AR) activity is the main driver for development of castration-resistant prostate cancer. We previously reported that the ubiquitin ligase Siah2 enhanced AR transcriptional activity and prostate cancer cell growth. Among the genes we found to be regulated by Siah2 was AKR1C3, which encodes a key androgen biosynthetic enzyme implicated in castration-resistant prostate cancer development. Here, we found that Siah2 inhibition in CWR22Rv1 prostate cancer cells decreased AKR1C3 expression as well as intracellular androgen levels, concomitant with inhibition of cell growth in vitro and in orthotopic prostate tumors. Re-expression of either wild-type or catalytically inactive forms of AKR1C3 partially rescued AR activity and growth defects in Siah2 knockdown cells, suggesting a nonenzymatic role for AKR1C3 in these outcomes. Unexpectedly, AKR1C3 re-expression in Siah2 knockdown cells elevated Siah2 protein levels, whereas AKR1C3 knockdown had the opposite effect. We further found that AKR1C3 can bind Siah2 and inhibit its self-ubiquitination and degradation, thereby increasing Siah2 protein levels. We observed parallel expression of Siah2 and AKR1C3 in human prostate cancer tissues. Collectively, our findings identify a new role for AKR1C3 in regulating Siah2 stability and thus enhancing Siah2-dependent regulation ofARactivity in prostate cancer cells. [ABSTRACT FROM AUTHOR]

Abstract: Cells with increasing resistance to the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitor thapsigargin (TG), ranging from 60-fold (PC3/TG10 cells) to 1350-fold (PC3/TG2000 cells), were derived from PC3 cells. SERCA2 is overexpressed in all PC3/TG cells but retains sensitivity to TG. siRNA-mediated downregulation of SERCA completely or partially reverses TG resistance in PC3/TG10 or PC3/TG2000 cells, respectively; thus SERCA overexpression mediates resistance in PC3/TG10 cells but is not the only resistance mechanism in PC3/TG2000 cells. By contrast, SERCA is not overexpressed in TG-resistant DU145/TG cells derived from DU145 cells. DU145/TG cells retain resistance while in PC3/TG cells resistance decreases upon removal of TG selection. The transport proteins PGP/BCRP/MRP1 and anti-apoptotic proteins Bcl2/BclXL are not involved in mediating resistance in either cell line. PARP and caspase 3 cleavage in response to other drugs demonstrate that the apoptotic pathways tested remain intact in these cells. Further, no cross-resistance occurs to other drugs. Thus, novel TG-specific resistance mechanisms are recruited by these cancer cells. [Copyright &y& Elsevier]

Introduction: Men diagnosed with metastatic prostate cancer (PCa) are at increased risk for skeletal complications which are associated with significant morbidity and mortality. Although both the urologist and the medical oncologist play important roles in the management of patients with advanced PCa, there is limited information regarding their role in the context of skeletal complications. The current study investigated these relationships among newly diagnosed metastatic patients with PCa.Methods and Materials: This retrospective cohort study used Surveillance, Epidemiology and End Results cancer registry data for incident stage IV metastatic (M1) cases diagnosed from 2000 to 2007 with linked Medicare claims. Postdiagnosis urologist and medical oncologist visits were identified using billing codes. We considered skeletal-related events (SREs) that occurred after the urologist or medical oncologist visit. We used Cox proportional hazards models to examine the relationship between a physician visit and the timing of the first SRE with and without propensity-score matching to account for observable selection.Results: The sample included 5,572 patients with stage IV M1 prostate cancer. Seventy-six percent of the patients were non-Hispanic White, 16% were non-Hispanic African American, and 8% were of other races; 75% of patients saw a urologist (median time to first visit = 19 days) and 44% saw an oncologist (median = 80 days), whereas 41% experienced at least one SRE (median = 309 days). Covariate-adjusted Cox models showed a longer time to an SRE for patients with only a medical oncologist visit (hazard ratio [HR] = 0.53, 95% CI: 0.45-0.61), only a urologist visit (HR = 0.35, 95% CI: 0.31-0.39) or both a urologist and medical oncologist visit (HR = 0.34, 95% CI: 0.31-0.38), compared to individuals without these visits. Among men with a urologist visit, a medical oncologist visit was not associated with the time to the first SRE (HR = 0.97, 95% CI: 0.90-1.05). Among those without a urologist visit a medical oncologist visit was associated with a longer time to an SRE (HR = 0.54, 95% CI: 0.46-0.64). Results were comparable using propensity-score matched samples.Conclusion: Among men newly diagnosed with metastatic PCa, 4 of 10 patients experienced an SRE. Patients experienced a delay in skeletal complications when managed by a urologist or a medical oncologist compared to patients who did not see either specialist. [ABSTRACT FROM AUTHOR]

Background: The urologist generally manages the treatment of men immediately following the diagnosis of prostate cancer (PCa). The role of other physician specialists in this setting is less clear. We investigated whether involvement of other physician specialty types immediately following diagnosis affects initiation of cancer-directed treatment.Methods: This is a retrospective cohort study using linked cancer registry and claims data from 1999 to 2009, excluding stage I/II PCa. A physician visit index (PVI) served as the exposure variable and captured the "dispersion of care" across specialties, that is, the extent to which patient care involved different types of physician specialties such as the primary care physician, urologist, or oncologist. The PVI score was calculated using visits occurring within 30 days postdiagnosis. This score was dichotomized to measure "low PVI" (reflects seeing multiple specialist types). Competing risk Cox proportional hazard regression models provided adjusted hazard ratios (HR) for treatment receipt associated with a low PVI.Results: The sample included 33,380 patients: 4,910 metastatic and 28,470 nonmetastatic groups. The top 3 visit categories within 30 days postdiagnosis were "urologist only" (59%) and "urologist plus primary care physician" (21%) and no visit (6%). The median time to receipt of cancer-directed treatment was 51 days. Overall, 29% of individuals in the metastatic group and 38% in the nonmetastatic group were categorized as low PVI. A low PVI was associated with a shorter time to treatment receipt in the nonmetastatic (HR = 1.12 [95% CI: 1.09-1.15]) and metastatic (HR = 1.21 [95% CI: 1.14-1.29]) groups.Conclusions: Multispecialist involvement in the weeks following diagnosis is associated with a shorter time to treatment initiation, highlighting a role for exposure to different specialty types in the weeks following an initial diagnosis of PCa. This study provides important baseline data for future studies examining coordination of care across cancer and noncancer specialists. [ABSTRACT FROM AUTHOR]