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Background: To evaluate the relationship between body composition and the oncological outcome of androgen deprivation therapy (ADT), we investigated whether body composition features including the psoas muscle may be predictive factors of ADT. Methods: This study enrolled patients with hormone-naïve metastatic prostate cancer who were treated with primary ADT from April 1996 to November 2013 at Kyushu University Hospital and who underwent a computed tomography scan before primary ADT for calculating body fat percentage, psoas muscle ratio (psoas muscle, cm3/height, cm), and body mass index. Results: Of the 178 patients enrolled, 60 patients died during follow-up. Median follow-up was 32 months, and progression-free survival and overall survival (OS) were 28 and 80 months, respectively. Multivariate analysis revealed that the psoas muscle ratio was correlated with OS (hazard ratio: 0.448; 95% confidence interval = 0.206–0.922; p = 0.028). Conclusions: This study demonstrated that higher psoas muscle ratio predicts longer OS among patients with nonlocalized prostate cancer treated with primary ADT. Keywords: Androgen deprivation therapy, Body composition, Prostate cancer, Psoas muscle, Testosterone

Objective: The outcome of the androgen-deprivation therapy (ADT) may be affected by metabolic diseases such as diabetes mellitus (DM) and dyslipidemia and/or by their treatments. We aimed to evaluate the prognostic impact of these disorders and corresponding medications in Japanese men treated with ADT for prostate cancer. Methods: This study retrospectively included 121 patients with metastatic prostate cancer who were treated with primary ADT at our hospital between 2001 and 2013. All patients received primary ADT with castration and/or an antiandrogen agent (bicalutamide or flutamide). Associations between clinicopathological factors, metabolic disease profiles, medication use, and prognosis (progression-free survival [PFS] and overall survival [OS]) were evaluated by univariate and multivariate analysis. Results: The median follow-up time was 54.9 months, and the median PFS and OS were 23.9 months and 73.0 months, respectively. High serum glucose levels at baseline (hazard ratio [HR], 95% confidence interval [CI]: 2.12, 1.16–3.76; P = 0.015), and concurrent DM (HR, 95% CI: 2.07, 1.06–3.94; P = 0.034) were significantly associated with poorer OS after adjustment for age, prostate-specific antigen levels at diagnosis, Gleason score, and clinical stage. Treatment with sulfonylurea drugs was significantly associated with a reduced risk of disease progression in men with DM (HR, 95% CI: 0.36, 0.12–0.90; P = 0.028). Conclusions: Impaired glucose tolerance and treatment with sulfonylureas have prognostic significance in prostate cancer. These findings demonstrate the importance of managing DM during ADT and point to a possible favorable effect of sulfonylureas on prostate cancer. Keywords: Androgen-deprivation therapy, Diabetes mellitus, Dyslipidemia, Metastatic prostate cancer, Prognosis

Background: We aimed to identify the candidate prostate cancer patients suitable for neoadjuvant androgen-deprivation therapy (ADT) with radical prostatectomy (RP). Materials and methods: This study included 711 Japanese patients with clinically localized prostate cancer who were treated with RP between 2000 and 2013. Patients were treated with or without neoadjuvant ADT before RP. The prognostic significance of neoadjuvant ADT on biochemical recurrence (BCR) was analyzed according to various clinicopathological characteristics. Results: BCR occurred in 186 (26.2%) of 711 patients. The group treated with neoadjuvant ADT showed higher levels of prostate-specific antigen at diagnosis and advanced clinical T-stage, but suppressed pathological T-stage. Neoadjuvant ADT was not associated with the risk of BCR. In subgroup analysis, neoadjuvant ADT was significantly associated with increased BCR in patients aged >65 years [hazard ratio (95% confidence interval), 2.04 (1.13–3.43), P = 0.020]. Among the 53 patients with available serum testosterone levels, neoadjuvant ADT was associated with the risk of BCR according to serum testosterone levels. Conclusion: This study demonstrated that neoadjuvant ADT showed potential deleterious effects in older patients and patients with lower serum testosterone levels, while a possible improved prognosis in patients with high serum testosterone levels treated with neoadjuvant ADT was suggested, warranting further exploration. Keywords: Age, Neoadjuvant androgen-deprivation therapy, Prostate cancer, Radical prostatectomy, Testosterone

Abstract Background The international, phase 3 COMPARZ study demonstrated that pazopanib and sunitinib have comparable efficacy as first-line therapy in patients with advanced renal cell carcinoma, but that safety and quality-of-life profiles favor pazopanib. Our report analyzed pazopanib and sunitinib safety in Asian and non-Asian subpopulations. Methods Patients were randomized 1:1 to receive pazopanib 800 mg once daily (continuous dosing) or sunitinib 50 mg once daily in 6-week cycles (4 weeks on, 2 weeks off). Results Safety population was composed of 363 Asian patients and 703 non-Asian patients. Asian patients had similar duration of exposure to either drug compared with non-Asian patients, although Asian patients had a higher frequency of dose modifications. Overall, hematologic toxicities, cytopenias, increased AST/ALT, and palmar-plantar erythrodysesthesia (PPE) were more prevalent in Asian patients, whereas gastrointestinal toxicities were more prevalent in non-Asian patients. Among Asian patients, hematologic adverse events and most non-hematologic AEs were more common in sunitinib-treated versus pazopanib-treated patients. Among Asian patients, the most common grade 3/4 AEs with pazopanib were hypertension (grade 3, 22%) and alanine aminotransferase increased (grade 3, 12%; grade 4, 1%); the most common grade 3/4 AEs with sunitinib were thrombocytopenia/platelet count decreased (grade 3, 36%; grade 4, 10%), neutropenia/neutrophil count decreased (grade 3, 24%; grade 4, 3%) hypertension (grade 3, 20%), and PPE (grade 3, 15%). Conclusions A distinct pattern and severity of adverse events was observed in Asians when compared with non-Asians with both pazopanib and sunitinib. However, the two drugs were well tolerated in both subpopulations. Trial registration ClinicalTrials.gov, NCT00720941, Registered July 22, 2008 ClinicalTrials.gov, NCT01147822, Registered June 22, 2010

Mineralocorticoid receptor (MR) signaling which is closely associated with hypertension plays important roles in resistance to antiandrogen therapy in prostate cancer. However, its impact on the prognosis in androgen-deprivation therapy (ADT) has not been elucidated. Then, we investigated the impact of genetic variation in MR and comorbidity with hypertension on the prognosis in ADT. This study included 182 Japanese patients with prostate cancer treated with ADT, whose comorbidity status with hypertension were available. The associations of MR polymorphism (rs5522) and comorbidity with hypertension with clinicopathological parameters as well as progression-free survival and overall survival were examined. Clinicopathological characteristics were comparable between genetic variation in MR. However, homozygous variant in MR was associated with shorter time to castration resistance (P = 0.014) and any-cause death (P = 0.024). In patients' background, presence of comorbidity with hypertension showed the trend with lower PSA level at diagnosis and lower biopsy Gleason score, as well as significant association with less incidence of N1. Comorbidity with hypertension was associated with longer time to castration resistance (P = 0.043) and any-cause death (P = 0.046), which was diminished on multivariate analysis including age, PSA level at diagnosis, biopsy Gleason score, clinical stage, and the modality of hormonal therapy. Genetic variation in MR (rs5522) and comorbidity with hypertension were significantly and potentially associated with prognosis when treated with ADT, respectively. This suggests that the individual intensity of MR signaling may be associated with resistance to ADT and a promising biomarker in ADT.

Sunitinib is a tyrosine kinase inhibitor and used as the first-line treatment for advanced renal cell carcinoma (RCC). Nevertheless, inter-individual variability of drug's toxicity was often observed among patients who received sunitinib treatment. This study is to investigate the association of a functional germline variant on ABCG2 that affects the pharmacokinetics of sunitinib with sunitinib-induced toxicity of RCC patients in the Japanese population. A total of 219 RCC patients were recruited to this pharmacogenetic study. ABCG2 421C>A (Q141K) was genotyped by using PCR-Invader assay. The associations of both clinical and genetic variables were evaluated with logistic regression analysis and subsequently receiver operating characteristic (ROC) curve was plotted. About 43% (92/216) of RCC patients that received sunitinib treatment developed severe grade 3 or grade 4 thrombocytopenia according to the National Cancer Institute-Common Terminology Criteria for Adverse Events version 3.0, the most common sunitinib-induced adverse reaction in this study. In the univariate analysis, both age (P = 7.77x10(-3), odds ratio (OR) = 1.04, 95%CI = 1.01-1.07) and ABCG2 421C>A (P = 1.87x10(-2), OR = 1.71, 95%CI = 1.09-2.68) showed association with sunitinib-induced severe thrombocytopenia. Multivariate analysis indicated that the variant ABCG2 421C>A is suggestively associated with severe thrombocytopenia (P = 8.41x10(-3), OR = 1.86, 95% CI = 1.17-2.94) after adjustment of age as a confounding factor. The area under curve (AUC) of the risk prediction model that utilized age and ABCG2 421C>A was 0.648 with sensitivity of 0.859 and specificity of 0.415. Severe thrombocytopenia is the most common adverse reaction of sunitinib treatment in Japanese RCC patients. ABCG2 421C>A could explain part of the inter-individual variability of sunitinib-induced severe thrombocytopenia.

Immunotherapy plays a significant role in the management of renal cell carcinoma (RCC) patients with metastatic disease because RCC is highly resistant to both chemotherapy and radiation therapy. Many reports illustrate various approaches to the treatment of RCC, such as cytokine-, antigen- or dendritic cell- (DC-) based immunotherapy, and the safety and effectiveness of immunotherapy have been highlighted by multiple clinical trials. Although antitumor immune responses and clinically significant outcomes have been achieved in these trials, the response rate is still low, and very few patients show long-term clinical improvement. Recently, the importance of immune regulation by antigen-presenting cells (APC) and regulatory T cells (Treg cells) has also been discussed. The authors outline the principles of cell-mediated tumor immunotherapy and discuss clinical trials of immunotherapy for RCC.

Objectives: To evaluate the efficacy and safety of cabozantinib, through a bridging study to METEOR, in Japanese patients with advanced renal cell carcinoma who had progressed after prior tyrosine kinase inhibitor therapy. Methods: This phase II, open-label, single-arm study (ClinicalTrials.gov registration number: NCT03339219) included adult Japanese patients with advanced renal cell carcinoma and measurable disease who had received one or more tyrosine kinase inhibitors. Patients received cabozantinib 60 mg orally once daily while there was clinical benefit, or until unacceptable toxicity or disease progression. The primary end-point was objective response rate per Response Evaluation Criteria in Solid Tumors Version 1.1. Secondary end-points included clinical benefit rate (complete or partial response, or ≥8- week stable disease), progression-free survival, overall survival and safety. Results: Of the 35 patients enrolled, 68.6%, 22.9% and 8.6% had previously received one, two and three prior tyrosine kinase inhibitors, respectively. The median duration of cabozantinib exposure was 27.0 weeks (range 5.1--43.0 weeks). The objective response rate was 20.0% (90% confidence interval 9.8--34.3%), and the clinical benefit rate was 85.7% (95% confidence interval 69.7--95.2%). The 6-month estimated progression-free survival was 72.3% (95% confidence interval 53.3--84.6%); the median progression-free survival and overall survival were not reached. All patients reported adverse events, which were manageable by supportive treatment or dose modification; two patients (5.7%) discontinued therapy due to adverse events. Conclusions: The results showed that findings from METEOR can be extrapolated, and that cabozantinib 60 mg/day is a viable treatment option in Japanese patients with advanced renal cell carcinoma who had progressed after prior tyrosine kinase inhibitor therapy. [ABSTRACT FROM AUTHOR]

The progression of prostate cancer to metastatic and castration-resistant disease represents a critical step. We previously showed that protein kinase C (PKC) activation followed by Twist1 and androgen receptor (AR) induction played a critical role in castration resistance, but the precise molecular mechanism remains unknown. This study aimed to elucidate the relevant molecular mechanism, focusing on NF-κB transcription factor. We examined the activity of NF-κB after PKC inhibition, and the expression of Twist1 and AR after inhibition of NF-κB in human prostate cancer cells. We also investigated the status of PKC/NF-κB after inhibition of AR signaling in cells resistant to hormonal therapy. As a result, inhibition of PKC signaling using knockdown and smallmolecule inhibition of PKC suppressed RelA activity, while blocking NF-κB suppressed Twist1 and AR expression. Conversely, inhibition of AR signaling by androgen depletion and the novel antiandrogen enzalutamide induced PKC and RelA activation, resulting in Twist1/AR induction at the transcript level. Moreover, inhibition of NF-κB signaling prevented enzalutamide-induced Twist1 and AR induction. Finally, NF-κB was activated in both castration-resistant and enzalutamide-resistant cells. In conclusion, NF-κB signaling was responsible for Twist1 upregulation by PKC in response to AR inhibition, resulting in aberrant activation of AR. NF-κB signaling thus appears to play a critical role in promoting both castration resistance and enzalutamide resistance in PKC/Twist1 signaling in prostate cancer. [ABSTRACT FROM AUTHOR]

Background: Although androgen deprivation therapy for advanced prostate cancer initially exerts excellent anticancer effects, most prostate cancer treated with androgen deprivation therapy eventually recurs as castration-resistant prostate cancer (CRPC). Although aberrant kinase activation has been proposed as a mechanism of castration resistance, comprehensive kinase profiles in CRPC remain unknown. Therefore, we aimed to elucidate the kinome in CRPC as well as the role of key molecules.Methods: We utilized a kinome array in androgen-dependent LNCaP and castration-resistant CxR cells. The effect of Y-box binding protein-1 (YB-1) on androgen receptor (AR) expression was examined by quantitative polymerase chain reaction and western blot analysis. The association between polymorphisms in the YB-1 gene determined by genotyping and YB-1 expression evaluated by immunohistochemistry in prostate cancer tissues, as well as outcome in metastatic prostate cancer, were investigated by the Cochran-Armitage test and the Cox proportional hazards model, respectively. All statistical tests were two-sided.Results: One hundred fifty-six of 180 kinase phosphorylation sites, including ERK and RSK, were activated in CRPC cells, leading to increased phosphorylation of YB-1, which is a key molecule in the progression to CRPC. YB-1 signaling regulated AR V7 expression, and YB-1 inhibition augmented the anticancer effect of enzalutamide. Moreover, polymorphism (rs12030724) in the YB-1 gene affected YB-1 expression in 93 prostate cancer tissues (YB-1 positive rate; 14.3% in TT, 40.0% in AT, and 52.9% in AA, P = .04) and associated with probability of progression in 104 metastatic prostate cancer case patients (AT/TT vs AA, hazard ratio = 0.49, 95% confidence interval = 0.32 to 0.77, P = .001).Conclusions: YB-1 appears to be a promising target to inhibit the development of castration resistance, even at the AR variant-expressing stage. Polymorphism in the YB-1 gene may be a promising predictive biomarker in hormonal therapy. [ABSTRACT FROM AUTHOR]

Although invasive and metastatic progression via the epithelial-mesenchymal transition (EMT) and acquisition of resistance to castration are both critical steps in prostate cancer, the molecular mechanism of this interaction remains unclear. In this study, we aimed to elucidate the interaction of signaling between castration resistance and EMT, and to apply this information to the development of a novel therapeutic concept using transforming growth factor-β (TGF-β) inhibitor SB525334 combined with androgen-deprivation therapy against prostate cancer using an in vivo model. This study revealed that an EMT inducer (TGF-β) induced full-length androgen receptor (AR) and AR variant expression. In addition, a highly invasive clone showed augmented full-length AR and AR variant expression as well as acquisition of castration resistance. Conversely, full-length AR and AR as well as Twist1 and mesenchymal molecules variant expression were up-regulated in castration-resistant LNCaP xenograft. Finally, TGF-β inhibitor suppressed Twist1 and AR expression as well as prostate cancer growth combined with castration. Taken together, these results demonstrate that Twist1/AR signaling was augmented in castration resistant as well as mesenchymal-phenotype prostate cancer, indicating the molecular mechanism of mutual and functional crosstalk between EMT and castration resistance, which may play a crucial role in prostate carcinogenesis and progression. [ABSTRACT FROM AUTHOR]

Background: To improve antitumor effects against metastatic renal cell carcinoma (mRCC), use of molecular target-based drugs in sequential or combination therapy has been advocated. In combination therapy, interferon (IFN)-α amplified the effect of sorafenib in our murine model (J Urol 184:2549, 2010), and cytokine-treated mRCC patients in Japan had good prognoses (Eur Urol 57:317, 2010). We thus conducted a phase II clinical trial of sorafenib plus IFN-α for untreated mRCC patients in Japan.Methods: In this multicenter, prospective study, provisionally registered patients with histologically confirmed metastatic clear cell RCC received natural IFN-α (3 dosages of 3 million U per week) for 2 weeks. Only IFN-α-tolerant patients were registered to this trial, and treated additionally with oral sorafenib (400 mg, bid). The primary end point of the study was rate of response (CR + PR) to sorafenib plus IFN-α treatment assessed using RECIST v1.0. The secondary end points were disease control rate (CR + PR + SD), progression free survival (PFS), overall survival (OS), and safety of the combined treatment. PFS and OS curves were plotted using the Kaplan-Meier method.Results: From July 2009 to July 2012, a total of 53 untreated patients were provisionally registered, and 51 patients were finally registered. Rate of Response to the combined therapy of sorafenib plus IFN-α was 26.2 % (11/42) (CR 1, PR 10). The median PFS was 10.1 months (95 % CI, 6.4 to 18.5 months), and the median OS has not been reached yet. The combined therapy increased neither the incidence of adverse effects (AE) nor the incidence of unexpected AE. A limitation was that a relatively high number of patients (9 patients) were excluded for eligibility criteria violations.Conclusion: Our data have demonstrated that sorafenib plus IFN-α treatment is safe and effective for untreated mRCC patients.Trial Registration: UMIN000002466 , 9(th) September, 2009. [ABSTRACT FROM AUTHOR]

AbstractPurpose:We evaluated the use of narrow-band imaging (NBI) cystoscopy for the detection of bladder cancer and analyzed its diagnostic efficacy in cases of carcinoma in situ(CIS) and in cases with known urine cytology results.Patients and Methods:A prospective controlled study of NBI was conducted in 104 consecutive patients with definite or suspected bladder cancer. Transurethral targeted biopsies were performed after white light imaging (WLI) and NBI cystoscopy, and the histologic outcomes were compared.Results:A total of 313 biopsies were taken, including 161 from sites identified as potentially abnormal by NBI and/or WLI cystoscopy, and 152 from apparently normal sites. The percentage of malignancies in the sites identified only by NBI was 55.7% (39/70 places). In 26.9% of patients (28/104), bladder tumors were detected only by NBI. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratio of a negative test (NLR) for the detection of bladder tumors using NBI in all patients were 92.7%, 70.9%, 63.4%, 94.7%, and 0.10, respectively. The sensitivity, specificity, PPV, NPV, and NLR for the detection of CIS using NBI were 89.7%, 74.5%, 78.8%, 87.2%, and 0.14, respectively. The sensitivity, specificity, PPV, NPV, and NLR for the detection of bladder tumors using NBI in patients with positive vsnegative urine cytology were 85.4% vs98.4%, 75.7% vs66.3%, 61.2% vs64.5%, 92.0% vs98.5%, and 0.19 vs0.02, respectively.Conclusions:NBI is a simple and effective method for identifying bladder tumors including CIS without the need for dyes because of its high sensitivity, high NPV, and low NLR. [ABSTRACT FROM AUTHOR]

Interferon-α (IFN-α) has extremely broad effects on the immune system, and the influence of IFN-α on regulatory T (Treg) cells is not fully known. In this report, Treg cells were analyzed in patients with metastatic renal cell carcinoma (RCC) following IFN-α monotherapy or treatment with IFN-α and interleukin (IL)-2. CD4and FoxP3Treg cells were significantly decreased for 2 weeks after the initiation of IFN-α monotherapy, but recovered later as treatment proceeded. Patients treated with both IFN-α and IL-2 increased their Treg cell levels during the first 2 weeks after initiation of treatment. Patients who derived complete response (CR), partial response (PR), or stable disease (SD) from IFN-α monotherapy had lower Treg cell levels before treatment than did patients whose disease progressed. Low Treg cell levels before treatment may therefore be advantageous to subsequent immunotherapy with IFN-α, and predictive for treatment results in RCC patients. [ABSTRACT FROM AUTHOR]

PurposeTo investigate the factors that affect the operative data and to evaluate the validity of a laparoscopic adrenalectomy (LA) for pheochromocytoma.Patients and MethodsBetween July 1993 and January 2008, 172 LAs were performed in this department, and 34 of them were for pheochromocytoma. The characteristics and operative data of LAs for pheochromocytoma were examined with respect to the intraoperative systolic blood pressure (SBP) and the side of tumor.ResultsThe intraoperative SBP rose to 180 mm Hg or more in 17 (50) cases of LAs for pheochromocytomas. The analysis of SBP (<180 versus >180 mm Hg), however, showed that there were no differences in the operative data between the two groups. The tumor size was significantly associated with operative time (P< 0.05) or the blood loss (P< 0.05) in an LA for pheochromocytoma. The blood loss in LAs for right adrenal tumors was greater (150 versus 79 mL) than for left tumors (P< 0.01). In particular, some procedures for right large tumors had considerable blood loss and long procedural time. In a comparison of the operative data between pheochromocytoma and other adrenal tumors, the tumor was larger (4.3 versus 2.5 cm) and the blood loss was greater (100 versus 30 mL) than for other adrenal tumors.ConclusionsThe operative data showed no correlation with the intraoperative high SBP, but they were associated with the tumor state. Although the procedure seems to be influenced by the size and state of tumor, LA is not contraindicated for pheochromocytoma, and it can therefore be performed safely. [ABSTRACT FROM AUTHOR]

Purpose To assess the quality of sound and uncompressed images during an international broadcast of live surgery using the newly developed digital video transport system (DVTS).Methods Three networks connected hospitals in Seoul, Korea, and Fukuoka, Japan. A teleconference system with bidirectional transmission over the network was set up. DVTS was used to send and receive visual and audio signals during a live broadcast of a laparoscopic partial nephrectomy to viewers at the 94th annual meeting of the Japanese Urological Association. A questionnaire was used to assess the quality of images and sound.Results Of 713 questionnnaires distributed, 418 were collected. The quality of image and voice was ranked very good or good by 95 and 92 of the audience, respectively. The quality of live surgery was considered high by 94 of the audience.Conclusion Digital video images can be transformed directly to an Internet protocol without compression of the motion images using DVTS. Live surgery via teleconference using DVTS can help surgeons learn the skills of endoscopic surgery. [ABSTRACT FROM AUTHOR]

Purpose To review the outcomes associated with holmium laser enucleation of the prostate (HoLEP) to identify the efficacy and safety in relation to the prostate size in subjects with symptomatic benign prostatic hyperplasia (BPH).Patients and Methods A retrospective review was conducted of the data from 97 patients who had undergone HoLEP combined with mechanical morcellation. All patients completed both the preoperative and the 6-month postoperative assessment. The morbidity and improvement in the outcome variables were compared in groups classified according to the baseline prostate volume <50 cm3(group 1), ≥50 cm3–<100 cm3(group 2), and ≥100 cm3(group 3).Results The peak urinary flow rate (Qmax), postvoiding residual urine volume (PVR), International Prostate Symptom Score (IPSS) and quality of life (QoL) score all improved significantly after HoLEP, and no significant differences were observed among the groups. The mean total operation times were 70.3, 99.1, and 155.5 minutes for groups 1, 2, and 3, respectively (P< 0.0001 group 1 vgroup 2 vgroup 3). The mean times required to complete the enucleation and morcellation were 44.7 v66.5 v107.3 minutes (P< 0.0001) and 8.6 v10.9 v23.8 minutes (P< 0.0001), respectively. The efficacy for tissue enucleation and morcellation was 0.44 v0.57 v0.75 gmin (P< 0.0001) and 2.5 v3.3 gmin (P 0.016) v3.2 gmin (P 0.035). The mean hemoglobin loss after HoLEP was greater in group 3 than in group 1 (P 0.036), but it was still low (1.8 gdL). Major complications included bladder-muscle injury in one patient in group 2 and one in group 3 and long-lasting urinary incontinence in one patient in group 1 and one in group 2 (2.1). No blood transfusion or transurethral resection syndrome was observed in any of the groups.Conclusions Holmium laser enucleation is an effective treatment for symptomatic BPH independent of prostate size. [ABSTRACT FROM AUTHOR]

Phorbol 12-myristate 13-acetate (PMA) induces cellular apoptosis in prostate cancer cells, the growth of which is governed by androgen/androgen receptor (AR) signaling, but the mechanism by which PMA exerts this effect remains unknown. Therefore, in this study, we investigated the mechanistic action of PMA in prostate cancer cells with regard to AR. We showed that PMA decreased E2F1 as well as AR expression in androgen-dependent prostate cancer LNCaP cells. Furthermore, PMA activated JNK and p53 signaling, resulting in the induction of cellular apoptosis. In LNCaP cells, androgen deprivation and a novel anti-androgen enzalutamide (MDV3100) augmented cellular apoptosis induced by PMA. Moreover, castration-resistant prostate cancer (CRPC) C4-2 cells were more sensitive to PMA compared with LNCaP cells and were sensitized to PMA by enzalutamide. Finally, the expression of PKC, E2F1, and AR was diminished in PMA-resistant cells, indicating that the gain of independence from PKC, E2F1, and AR functions leads to PMA resistance. In conclusion, PMA exerted its anti-cancer effects via the activation of pro-apoptotic JNK/p53 and inhibition of pro-proliferative E2F1/AR in prostate cancer cells including CRPC cells. The therapeutic effects of PMA were augmented by androgen deletion and enzalutamide in androgen-dependent prostate cancer cells, as well as by enzalutamide in castration-resistant cells. Taken together, PMA derivatives may be promising therapeutic agents for treating prostate cancer patients including CRPC patients. [ABSTRACT FROM AUTHOR]

Androgen receptor (AR) signaling is critical for the tumorigenesis and development of prostate cancer, as well as the progression to castration-resistant prostate cancer. We previously showed that the heterochromatin protein 1 (HP1) β isoform plays a critical role in transactivation of AR signaling as an AR coactivator that promotes prostate cancer cell proliferation. However, the roles of other HP1 isoforms, HP1α and HP1γ, in AR expression and prostate cancer remain unclear. Here, we found that knockdown of HP1γ, but not HP1α, reduced AR expression and cell proliferation by inducing cell cycle arrest at G1 phase in LNCaP cells. Conversely, overexpression of full-length HP1α and its C-terminal deletion mutant increased AR expression and cell growth, whereas overexpression of HP1γ had no effect. Similarly, HP1α overexpression promoted 22Rv1 cell growth, whereas HP1γ knockdown reduced the proliferation of CxR cells, a castration-resistant LNCaP derivative. Taken together, HP1 isoforms distinctly augment AR signaling and cell growth in prostate cancer. Therefore, silencing of HP1β and HP1γ may be a promising therapeutic strategy for treatment of prostate cancer [ABSTRACT FROM AUTHOR]