Dietary Pterostilbene for MTA1-Targeted Interception in High-Risk Premalignant Prostate Cancer.

Prostate cancer remains one of the most prevalent cancers in aging men. Active surveillance subpopulation of patients with prostate cancer includes men with varying cancer risk categories of precancerous disease due to prostatic intraepithelial neoplasia (PIN) heterogeneity. Identifying molecular alterations associated with PIN can provide preventable measures through finding novel pharmacologic targets for cancer interception. Targeted nutritional interception may prove to be the most appropriate chemoprevention for intermediate- and high-risk active surveillance patients. Here, we have generated two prostate-specific transgenic mouse models, one overexpressing MTA1 (R26MTA1 ) and the other overexpressing MTA1 on the background of Pten heterozygosity (R26MTA1 ; Pten+/f ), in which we examined the potential chemopreventive efficacy of dietary pterostilbene. We show that MTA1 promotes neoplastic transformation of prostate epithelial cells by activating cell proliferation and survival, leading to PIN development. Moreover, MTA1 cooperates with PTEN deficiency to accelerate PIN development by increasing cell proliferation and MTA1-associated signaling. Further, we show that mice fed with a pterostilbene-supplemented diet exhibited more favorable histopathology with decreased severity and number of PIN foci accompanied by reduced proliferation, angiogenesis, and inflammation concomitant to reduction in MTA1 and MTA1-associated CyclinD1, Notch2, and oncogenic miR-34a and miR-22 levels. PREVENTION RELEVANCE: Developing novel interceptive strategies for prostate cancer chemoprevention is a paramount goal in clinical oncology. We offer preclinical evidence for the potential of pterostilbene as a promising natural agent for MTA1-targeted interceptive strategy in future cancer prevention trials towards protecting select patients with prostate cancer under active surveillance from developing cancer.

Evidence that EZH2 Deregulation is an Actionable Therapeutic Target for Prevention of Prostate Cancer.

Chemoprevention trials for prostate cancer by androgen receptor or androgen synthesis inhibition have proven ineffective. Recently, it has been demonstrated that the histone methlytransferase, EZH2 is deregulated in mouse and human high-grade prostatic intraepithelial neoplasia (HG-PIN). Using preclinical mouse and human models of prostate cancer, we demonstrate that genetic and chemical disruption of EZH2 expression and catalytic activity reversed the HG-PIN phenotype. Furthermore, inhibition of EZH2 function was associated with loss of cellular proliferation and induction of Tp53-dependent senescence. Together, these data provide provocative evidence for EZH2 as an actionable therapeutic target toward prevention of prostate cancer.

Grape Powder Supplementation Attenuates Prostate Neoplasia Associated with Pten Haploinsufficiency in Mice Fed High-Fat Diet.

SCOPE: Previous studies have identified potent anticancer activities of polyphenols in preventing prostate cancer. The aim of the current study is to evaluate the chemopreventive potential of grape powder (GP) supplemented diets in genetically predisposed and obesity-provoked prostate cancer. METHODS AND RESULTS: Prostate-specific Pten heterozygous (Pten+/f ) transgenic mice are fed low- and high-fat diet (LFD and HFD, respectively) supplemented with 10% GP for 33 weeks, ad libitum. Prostate tissues are characterized using immunohistochemistry and western blots, and sera are analyzed by ELISA and qRT-PCR. Pten+/f mice fed LFD and HFD supplemented with 10% GP show favorable histopathology, significant reduction of the proliferative rate of prostate epithelial cells (Ki67), and rescue of PTEN expression. The most potent protective effect of GP supplementation is detected against HFD-induced increase in inflammation (IL-1ß; TGF-ß1), activation of cell survival pathways (Akt, AR), and angiogenesis (CD31) in Pten+/f mice. Moreover, GP supplementation reduces circulating levels of oncogenic microRNAs (miR-34a; miR-22) in Pten+/f mice. There are no significant changes in body weight and food intake in GP supplemented diet groups. CONCLUSIONS: GP diet supplementation can be a beneficial chemopreventive strategy for obesity-related inflammation and prostate cancer progression. Monitoring serum miRNAs can facilitate the non-invasive evaluation of chemoprevention efficacy.

Green tea catechins for chemoprevention of prostate cancer in patients with histologically-proven HG-PIN or ASAP. Concise review and meta-analysis.

A focused, single outcome meta-analysis on the protective role of extracts of green tea catechins against prostate cancer. Randomized, placebo-controlled studies enrolling patients with a histologically confirmed diagnosis of high-grade Prostate Intraepithelial Neoplasia or Atypical Small Acinar proliferation but no prostate cancer were included. Meta-analysis for binary data was performed using Mantel-Haenszel statistics, using a random-effects model. Heterogeneity was investigated by calculating the I2. Four studies matched the inclusion criteria for the review. The pooled population was 223 patients; 114 and 109 patients were randomized to catechin and placebo groups, respectively. Nine cases of prstate cancer occurred in the catechin arm (7.9%), and 24 cases were reported in the placebo arm (22%). Pooled analysis resulted in a significant reduction of cancer risk in favor of the catechin arm (risk-ratio = 0.41; 95% CI: 0.19- 0.86; I2 = 0). In conclusion, our data suggest that the intake of concentrated green tea catechin preparations may confer a significant protective effect to carriers of early neoplastic lesions in the prostate. The quality of the evidence is moderate, and additional, largescale studies are warranted to substantiate these preliminary findings.

Prostate cancer chemoprevention by sulforaphane in a preclinical mouse model is associated with inhibition of fatty acid metabolism.

Increased de novo synthesis of fatty acids is a rather unique and targetable mechanism of human prostate cancer. We have shown previously that oral administration of sulforaphane (SFN) significantly inhibits the incidence and/or burden of prostatic intraepithelial neoplasia and well-differentiated adenocarcinoma in TRansgenic Adenocarcinoma of Mouse Prostate (TRAMP) mice. The present study used cellular models of prostate cancer and archived plasma/adenocarcinoma tissues and sections from the TRAMP study to demonstrate inhibition of fatty acid synthesis by SFN treatment in vitro and in vivo. Treatment of androgen-responsive (LNCaP) and castration-resistant (22Rv1) human prostate cancer cells with SFN (5 and 10 µM) resulted in downregulation of protein and mRNA levels of acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase (FASN), but not ATP citrate lyase. Protein and mRNA levels of carnitine palmitoyltransferase 1A (CPT1A), which facilitates fatty acid uptake by mitochondria for ß-oxidation, were also decreased following SFN treatment in both cell lines. Immunohistochemistry revealed a significant decrease in expression of FASN and ACC1 proteins in prostate adenocarcinoma sections of SFN-treated TRAMP mice when compared with controls. SFN administration to TRAMP mice resulted in a significant decrease in plasma and/or prostate adenocarcinoma levels of total free fatty acids, total phospholipids, acetyl-CoA and ATP. Consistent with these results, number of neutral lipid droplets was lower in the prostate adenocarcinoma sections of SFN-treated TRAMP mice than in control tumors. Collectively, these observations indicate that prostate cancer chemoprevention by SFN in TRAMP mice is associated with inhibition of fatty acid metabolism.

The impact of metformin use on the risk of prostate cancer after prostate biopsy in patients with high grade intraepithelial neoplasia

ABSTRACT Purpose We report our experience on metformin use in diabetic patients and its impact on prostate cancer (PCa) after a high-grade prostatic intraepithelial neoplasia (HGPIN) diagnosis. Materials and Methods We retrospectively analyzed 551 patients with a diagnosis of HGPIN without PCa in a first prostate biopsy. The cohort of the study consisted of 456 nondiabetic subjects, and 95 diabetic patients. Among the patients with diabetes 44 were treated with metformin, and 51 with other antidiabetic drugs. A transrectal ultrasound prostate biopsy scheme with 22 cores was carried out 4-6 months after the first diagnosis of HGPIN. Results Among 195 (35.4%) patients with cancer, there were statistically significant differences in terms of PCa detection (p<0.001), Gleason score distribution (p<0.001), and number of positive biopsy cores (p<0.002) between metformin users and non-users. Metformin use was associated with a decreased risk of PCa compared with neveruse (p<0.001). Moreover, increasing duration of metformin assumption (≥2 years) was associated with decreasing incidence of PCa and higher Gleason score ≥7 compared with assumption <2 years. Conclusions This preliminary experience suggests that metformin use may have some beneficial effects in patients with diabetes and HGPIN; metformin should not be overlooked in these patients because it is neither new nor expensive.

The impact of metformin use on the risk of prostate cancer after prostate biopsy in patients with high grade intraepithelial neoplasia.

PURPOSE: We report our experience on metformin use in diabetic patients and its impact on prostate cancer (PCa) after a high-grade prostatic intraepithelial neoplasia (HGPIN) diagnosis. MATERIALS AND METHODS: We retrospectively analyzed 551 patients with a diagnosis of HGPIN without PCa in a first prostate biopsy. The cohort of the study consisted of 456 nondiabetic subjects, and 95 diabetic patients. Among the patients with diabetes 44 were treated with metformin, and 51 with other antidiabetic drugs. A transrectal ultrasound prostate biopsy scheme with 22 cores was carried out 4-6 months after the first diagnosis of HGPIN. RESULTS: Among 195 (35.4%) patients with cancer, there were statistically significant differences in terms of PCa detection (p<0.001), Gleason score distribution (p<0.001), and number of positive biopsy cores (pv0.002) between metformin users and non-users. Metformin use was associated with a decreased risk of PCa compared with neveruse (p<0.001). Moreover, increasing duration of metformin assumption (≥2 years) was associated with decreasing incidence of PCa and higher Gleason score ≥7 compared with assumption <2 years. CONCLUSIONS: This preliminary experience suggests that metformin use may have some beneficial effects in patients with diabetes and HGPIN; metformin should not be overlooked in these patients because it is neither new nor expensive.

Preventive Effects of Fermented Brown Rice and Rice Bran against Prostate Carcinogenesis in TRAP Rats.

Fermented brown rice and rice bran with Aspergillus oryzae (FBRA) is considered to have the potential to prevent chemically-induced carcinogenesis in multiple organs of rodents. In the present study, we evaluated the possible chemopreventive effects of FBRA against prostate tumorigenesis. Six-week-old male rats of the transgenic rat for adenocarcinoma of prostate (TRAP) strain were fed diets containing 5% or 10% FBRA for 15 weeks. Animals were sacrificed at 21 weeks of age, and the ventral and lateral prostate were removed for histopathological evaluation and immunoblot analyses. FBRA decreased the incidence of adenocarcinoma in the lateral prostate and suppressed the progression of prostate carcinogenesis. Treatment with FBRA induced apoptosis and inhibited cell proliferation in histologically high-grade prostatic intraepithelial neoplasias. Phospho-AMP-activated kinase α (Thr172) was up-regulated in the prostate of rats fed the diet supplemented with FBRA. These results indicate that FBRA controls tumor growth by activating pathways responsive to energy deprivation and suggest that FBRA has translational potential for the prevention of human prostate cancer.

Randomized, placebo-controlled trial evaluating the safety of one-year administration of green tea catechins.

PURPOSE: Although preclinical, epidemiological and prior clinical trial data suggest that green tea catechins (GTCs) may reduce prostate cancer (PCa) risk, several preclinical studies and case reports have reported liver toxicities and acute gastrointestinal bleeding. Based on these observations, regulatory bodies have required stringent inclusion criteria with frequent, excessive toxicity monitoring and early stopping rules in clinical trials. These requirements have impeded recruitment and retention of subjects in chemoprevention trials and subsequent progress in agent development efforts. EXPERIMENTAL DESIGN: We conducted a placebo-controlled, randomized clinical trial of Polyphenon E® (PolyE®), a proprietary mixture of decaffeinated GTCs, containing 400 mg (-)-epigallocatechin-3-gallate (EGCG) per day, in 97 men with high-grade prostatic intraepithelial neoplasia (HGPIN) and/or atypical small acinar proliferation (ASAP). PolyE® containing 200 mg EGCG was administered with food, BID. A secondary study endpoint in this trial was a comparison of the overall one-year treatment related adverse events and grade 3 or higher adverse event on the two study arms. Monthly assessments of toxicity (CTCAE 4.0), concomitant medications and organ function, including hepatic panel, PT/PTT and LDH, were performed. RESULTS: Daily intake of a standardized, decaffeinated, catechin mixture containing 200 mg EGCG BID taken with food for 1 year accumulated in plasma and was well tolerated and did not produce treatment related adverse effects in men with baseline HGPIN or ASAP. CONCLUSION: The current data provides evidence of safety of decaffeinated, catechin mixture containing 200 mg EGCG BID to be further tested for prostate cancer prevention or other indications.

Dietary tocopherols inhibit PhIP-induced prostate carcinogenesis in CYP1A-humanized mice.

Tocopherols, the major forms of vitamin E, exist as alpha-tocopherol (α-T), ß-T, γ-T and δ-T. The cancer preventive activity of vitamin E is suggested by epidemiological studies, but recent large-scale cancer prevention trials with high dose of α-T yielded disappointing results. Our hypothesis that other forms of tocopherols have higher cancer preventive activities than α-T was tested, herein, in a novel prostate carcinogenesis model induced by 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP), a dietary carcinogen, in the CYP1A-humanized (hCYP1A) mice. Treatment of hCYP1A mice with PhIP (200 mg/kg b.w., i.g.) induced high percentages of mouse prostatic intraepithelial neoplasia (mPIN), mainly in the dorsolateral glands. Supplementation with a γ-T-rich mixture of tocopherols (γ-TmT, 0.3% in diet) significantly inhibited the development of mPIN lesions and reduced PhIP-induced elevation of 8-oxo-deoxyguanosine, COX-2, nitrotyrosine, Ki-67 and p-AKT, and the loss of PTEN and Nrf2. Further studies with purified δ-T, γ-T or α-T (0.2% in diet) showed that δ-T was more effective than γ-T or α-T in preventing mPIN formations and p-AKT elevation. These results indicate that γ-TmT and δ-T could be effective preventive agents of prostate cancer.

Metformin targets c-MYC oncogene to prevent prostate cancer.

UNLABELLED: Prostate cancer (PCa) is the second leading cause of cancer-related death in American men and many PCa patients develop skeletal metastasis. Current treatment modalities for metastatic PCa are mostly palliative with poor prognosis. Epidemiological studies indicated that patients receiving the diabetic drug metformin have lower PCa risk and better prognosis, suggesting that metformin may have antineoplastic effects. The mechanism by which metformin acts as chemopreventive agent to impede PCa initiation and progression is unknown. The amplification of c-MYC oncogene plays a key role in early prostate epithelia cell transformation and PCa growth. The purpose of this study is to investigate the effect of metformin on c-myc expression and PCa progression. Our results demonstrated that (i) in Hi-Myc mice that display murine prostate neoplasia and highly resemble the progression of human prostate tumors, metformin attenuated the development of prostate intraepithelial neoplasia (PIN, the precancerous lesion of prostate) and PCa lesions. (ii) Metformin reduced c-myc protein levels in vivo and in vitro. In Myc-CaP mouse PCa cells, metformin decreased c-myc protein levels by at least 50%. (iii) Metformin selectively inhibited the growth of PCa cells by stimulating cell cycle arrest and apoptosis without affecting the growth of normal prostatic epithelial cells (RWPE-1). (iv) Reduced PIN formation by metformin was associated with reduced levels of androgen receptor and proliferation marker Ki-67 in Hi-Myc mouse prostate glands. Our novel findings suggest that by downregulating c-myc, metformin can act as a chemopreventive agent to restrict prostatic neoplasia initiation and transformation. SUMMARY: Metformin, an old antidiabetes drug, may inhibit prostate intraepithelial neoplasia transforming to cancer lesion via reducing c-MYC, an 'old' overexpressed oncogene. This study explores chemopreventive efficacy of metformin in prostate cancer and its link to cMYC in vitro and in vivo.

Sixth joint meeting of J-CaP and CaPSURE--a multinational perspective on prostate cancer management and patient outcomes.

This report summarizes the presentations and discussions that took place at the Sixth Joint Meeting of J-CaP and CaPSURE held in San Francisco, USA, in August 2012. The J-CaP and CaPSURE Joint Initiative was established in 2007 with the objective of analyzing, reviewing, comparing and contrasting data for prostate cancer patients from Japan and the USA within the two important large-scale, longitudinal, observational databases-J-CaP and CaPSURE. Since this initial collaboration between teams in the USA and Japan, the initiative has now expanded to include representatives of other Asian countries, several of whom have either established or are planning their own national prostate cancer databases. Several key topics were considered at this Sixth Joint Meeting including the current status of the J-CaP and CaPSURE databases and opportunities for collaboration with the more recently developed Asian prostate cancer databases. The latest comparative data from J-CaP and CaPSURE regarding outcomes following androgen deprivation therapy and combined androgen blockade were also reviewed. The possibility of a global chemoprevention trial to investigate the influence of soy isoflavones on prostate cancer incidence was considered. In addition, the ongoing debate regarding the role of screening and the use of active surveillance as a treatment option in the USA was discussed. The collaborators agreed that sharing of data and treatment practices on a global scale would undoubtedly benefit the clinical management of prostate cancer patients worldwide.

The interactions of dietary tomato powder and soy germ on prostate carcinogenesis in the TRAMP model.

The interactions between bioactive-rich food components within a complex human diet for the inhibition of prostate carcinogenesis are largely unknown and difficult to quantify in humans. Tomato and soy products have each shown anti-prostate cancer (PCa) activity in laboratory studies. The objective of this study was to determine the efficacy of dietary tomato and soy germ, alone and in combination, for the inhibition of PCa in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. At 4 weeks of age, male C57BL/6 × FVB TRAMP mice (n = 119) were randomized to consume: AIN-93G control, 10% whole tomato powder (TP), 2% soy germ powder (SG), or 10% tomato powder with 2% soy germ powder (TP+SG) for 14 weeks. One hundred percent of mice fed the control diet had PCa, whereas PCa incidence was significantly lower in mice consuming TP (61%, P < 0.001), SG (66%, P < 0.001), and TP+SG (45%, P < 0.001). Although the protection offered by the combination of TP and SG was not synergistic, it was the most effective intervention. TP, SG, and TP+SG increased apoptotic index (AI) and modestly reduced the proliferative index (PI) in the prostate epithelium of TRAMP mice exhibiting primarily prostatic intraepithelial neoplasia. The dramatic reduction in the PI/AI ratio by the dietary interventions suggests that the control mice experience a stronger stimulus for malignant progression in the prostate microenvironment. Maximally effective and safe strategies for PCa prevention may result from optimizing combinations of nutrients and bioactives through an orchestration of dietary patterns.

Dietary resveratrol prevents development of high-grade prostatic intraepithelial neoplastic lesions: involvement of SIRT1/S6K axis.

SIRT1 (mammalian ortholog of the yeast silent information regulator 2) is a NAD-dependent histone deacetylase belonging to the multigene family of sirtuins. Anecdotal and epidemiologic observations provide evidence for beneficial effects of the calorie restriction mimetic resveratrol (RES), a SIRT1 activator in preventing cardiovascular diseases and cancer. Although SIRT1 possesses both tumorigenic and antitumorigenic potential, the molecular mechanisms underlying SIRT1-mediated tumor progression or inhibition are poorly understood. In this study, we investigated the role of SIRT1 in multiple human prostate cancer cell lines and prostate-specific PTEN knockout mouse model using resveratrol. Androgen-independent prostate cancer cell lines (C42B, PC3, and DU145) express higher levels of SIRT1 than androgen-responsive (LNCaP) and nontumorigenic prostate cells (RWPE-1). Resveratrol enhanced this expression without any significant effect on SIRT1 enzymatic activity. Inhibition of SIRT1 expression using shRNA enhanced cell proliferation and inhibited autophagy by repressing phosphorylation of S6K and 4E-BP1. These biologic correlates were reversed in the presence of resveratrol. Analysis of prostates from dietary intervention with resveratrol showed a significant reduction in prostate weight and reduction in the incidence of high-grade prostatic intraepithelial neoplastic (HGPIN) lesions by approximately 54% with no significant change in body weight. Consistent with the in vitro findings, resveratrol intervention in the PTEN knockout mouse model was associated with reduction in the prostatic levels of mTOR complex 1 (mTORC1) activity and increased expression of SIRT1. These data suggest that SIRT1/S6K-mediated inhibition of autophagy drives prostate tumorigenesis. Therefore, modulation of SIRT1/S6K signaling represents an effective strategy for prostate cancer prevention.

Opposing effects of androgen deprivation and targeted therapy on prostate cancer prevention.

UNLABELLED: Prostate cancer is an ideal target for chemoprevention. To date, chemoprevention clinical trials with 5α-reductase inhibitors have yielded encouraging yet ultimately confounding results. Using a preclinical mouse model of high-grade prostatic intraepithelial neoplasia (HG-PIN) induced by PTEN loss, we observed unprecedented deteriorating effects of androgen deprivation, in which surgical castration or MDV3100 treatment accelerated disease progression of the otherwise stable HG-PIN to invasive castration-resistant prostate cancer (CRPC). As an alternative, targeting the phosphoinositide 3-kinase (PI3K) signaling pathway via either genetic ablation of genes encoding PI3K components or pharmacologic inhibition of the PI3K pathway reversed the PTEN loss-induced HG-PIN phenotype. Finally, concurrent inhibition of the PI3K and mitogen-activated protein kinase (MAPK) pathways was effective in blocking the growth of PTEN-null CRPC. Together, these data have revealed the potential adverse effects of antiandrogen chemoprevention in certain genetic contexts (such as PTEN loss) while showing the promise of targeted therapy in the clinical management of this complex and prevalent disease. SIGNIFICANCE: Chemoprevention with antiandrogen therapies is attractive for prostate cancer, given its prevalence and established hormonally mediated pathogenesis. However, because PTEN loss has been found in 9% to 45% of HG-PIN in the clinic, the current findings suggest that patients with PTEN-deficient prostate tumors might be better treated with PI3K-targeted therapies.

[Influence of sodium selenite on carcinogenesis of the prostate and other organs induced by methylnitrosourea and testosterone in rats].

Influence of selenium on induced carcinogenesis of the prostate and other organs was studied in male Wistar rats. Carcinogenesis was induced (68) by using our modification of a combined double-stage model including surgical castration, single administration of N-methyl-N-nitrosourea (MNU) and long-term promotion by a mix of testosterone ethers (MTE). Seven days after MNU injection the rats were randomized to form 2 groups. Controls were fed drinking water while the study group - water containing sodium selenite 4mg/l, daily - till the end of the experiment. Controls (12) were not exposed to any treatment. They were followed up for 55 weeks until sacrificed. Apparent benign prostatic hyperplasia developed in rats subjected to castration, MNU and MTE. Also, such precancerous lesions as prostatic intraepithelial neoplasia (PIN) and prostate cancer including metastatic one were detected. Malignant lymphoma, other than in target tissues, was the most frequent. Prostate pathological changes and lymphomas were not registered in intact rats. Unlike rats treated with MNU and MTE and fed untreated drinking water, selenium did not influence significantly the development of prostate intraepithelial neoplasia but reduced multiplicity of prostate cancer by 44.6%. Simultaneously, the incidence of induced malignant lymphomas decreased by 26.4%.

Diet and prostate cancer - a holistic approach to management.

There is now increasing evidence from epidemiologic surveys and from laboratory, intervention, and case-control studies that diet and lifestyle plays a crucial role in prostate cancer biology and tumorigenesis. This applies to both the development and progression of prostate cancer, although in many cases the specific initiating factors in the diet are poorly understood. Conversely, many nutrients and herbs also show significant promise in helping to treat prostate cancer by slowing progression and reducing recurrence, ultimately reducing the risk of morbidity and mortality from the disease. Furthermore for all grades of prostate cancer, nutritional interventions complement conventional treatment to improve response and quality of life. Slowing or even reversing the progression of, high-grade prostate intraepithelial neoplasia [HGPIN]). with chemo-preventative agents could be the best primary defense against prostate cancer, preventing it from occurring in the first place. The information given in this review about prostate cancer chemoprevention summarizes the key evidence for the role of different dietary components and their effect on prostate cancer prevention and progression. Most nutritional chemoprevention agents also have the added benefit of being beneficial for the cardiovascular system, bone health and for the prevention of other cancers.

Phase III trial of selenium to prevent prostate cancer in men with high-grade prostatic intraepithelial neoplasia: SWOG S9917.

The threat of prostate cancer and the significant and often negative impact of its treatment underscore the importance of prevention. High-grade prostatic intraepithelial neoplasia (HGPIN) has been identified as a potential premalignant lesion marking an increased risk of prostate cancer and substantial evidence suggests that men with HGPIN are in need of prostate cancer prevention. In vitro, in vivo, epidemiologic, and clinical trial evidence that selenium supplementation protects against prostate cancer motivated the study we report here: a double-blind, randomized, placebo-controlled trial of selenium 200 (µg/d) as selenomethionine in men with HGPIN. The primary endpoint was progression of HGPIN to prostate cancer over a 3-year period. This National Cancer Institute Intergroup trial was coordinated by the Southwest Oncology Group (SWOG). Of 619 enrolled patients, 423 randomized men with HGPIN (212 selenium and 211 placebo) were eligible (by central pathology review) and included in the primary analysis. Three-year cancer rates were 36.6% (placebo) versus 35.6% (selenium; P = 0.73, adjusted). The majority of patients who developed cancer on trial (70.8%, selenium and 75.5%, placebo) had a Gleason score of 6 or less than 6; there were no differences in Gleason scores between the two arms. Subset analyses included the finding of a nonsignificantly reduced prostate cancer risk (relative risk = 0.82; 95% CI: 0.40-1.69) in selenium versus placebo patients in the lowest quartile of baseline plasma selenium level (<106 ng/mL). Overall, and in all other subsets defined by baseline blood selenium levels, selenium supplementation had no effect on prostate cancer risk. The 36% prostate cancer rate in men with HGPIN indicates the association of this lesion with an elevated prostate cancer risk. Future study in this setting should focus on selenium-deficient populations and selenium pharmacogenetics.

Bitter melon extract impairs prostate cancer cell-cycle progression and delays prostatic intraepithelial neoplasia in TRAMP model.

Prostate cancer remains the second leading cause of cancer deaths among American men. Earlier diagnosis increases survival rate in patients. However, treatments for advanced disease are limited to hormone ablation techniques and palliative care. Thus, new methods of treatment and prevention are necessary for inhibiting disease progression to a hormone refractory state. One of the approaches to control prostate cancer is prevention through diet, which inhibits one or more neoplastic events and reduces the cancer risk. For centuries, Ayurveda has recommended the use of bitter melon (Momordica charantia) as a functional food to prevent and treat human health related issues. In this study, we have initially used human prostate cancer cells, PC3 and LNCaP, as an in vitro model to assess the efficacy of bitter melon extract (BME) as an anticancer agent. We observed that prostate cancer cells treated with BME accumulate during the S phase of the cell cycle and modulate cyclin D1, cyclin E, and p21 expression. Treatment of prostate cancer cells with BME enhanced Bax expression and induced PARP cleavage. Oral gavage of BME, as a dietary compound, delayed the progression to high-grade prostatic intraepithelial neoplasia in TRAMP (transgenic adenocarcinoma of mouse prostate) mice (31%). Prostate tissue from BME-fed mice displayed approximately 51% reduction of proliferating cell nuclear antigen expression. Together, our results suggest for the first time that oral administration of BME inhibits prostate cancer progression in TRAMP mice by interfering cell-cycle progression and proliferation.

Targeted inhibition of mitochondrial Hsp90 suppresses localised and metastatic prostate cancer growth in a genetic mouse model of disease.

BACKGROUND: The molecular chaperone heat shock protein-90 (Hsp90) is a promising cancer drug target, but current Hsp90-based therapy has so far shown limited activity in the clinic. METHODS: We tested the efficacy of a novel mitochondrial-targeted, small-molecule Hsp90 inhibitor, Gamitrinib (GA mitochondrial matrix inhibitor), in the Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model. The TRAMP mice receiving 3-week or 5-week systemic treatment with Gamitrinib were evaluated for localised or metastatic prostate cancer, prostatic intraepithelial neoplasia (PIN) or localised inflammation using magnetic resonance imaging, histology and immunohistochemistry. Treatment safety was assessed histologically in organs collected at the end of treatment. The effect of Gamitrinib on mitochondrial dysfunction was studied in RM1 cells isolated from TRAMP tumours. RESULTS: Systemic administration of Gamitrinib to TRAMP mice inhibited the formation of localised prostate tumours of neuroendocrine or adenocarcinoma origin, as well as metastatic prostate cancer to abdominal lymph nodes and liver. The Gamitrinib treatment had no effect on PIN or prostatic inflammation, and caused no significant animal weight loss or organ toxicity. Mechanistically, Gamitrinib triggered acute mitochondrial dysfunction in RM1 cells, with loss of organelle inner membrane potential and release of cytochrome-c in the cytosol. CONCLUSIONS: The Gamitrinib has pre-clinical activity and favourable tolerability in a genetic model of localised and metastatic prostate cancer in immunocompetent mice. Selective targeting of mitochondrial Hsp90 could provide novel molecular therapy for patients with advanced prostate cancer.