Epigallocatechin-3-gallate and bicalutamide cause growth arrest and apoptosis in NRP-152 and NRP-154 prostate epithelial cells

Recent advances in dietary androgen receptor inhibitors

As a nuclear transcription factor, the androgen receptor (AR) plays a crucial role not only in normal male sexual differentiation and growth of the prostate, but also in benign prostatic hyperplasia, prostatitis, and prostate cancer. Multiple population-based epidemiological studies demonstrated that prostate cancer risk was inversely associated with increased dietary intakes of green tea, soy products, tomato, and so forth. Therefore, this review aimed to summarize the structure and function of AR, and further illustrate the structural basis for antagonistic mechanisms of the currently clinically available antiandrogens. Due to the limitations of these antiandrogens, a series of natural AR inhibitors have been identified from edible plants such as fruits and vegetables, as well as folk medicines, health foods, and nutritional supplements. Hence, this review mainly focused on recent experimental, epidemiological, and clinical studies about natural AR inhibitors, particularly the association between dietary intake of natural antiandrogens and reduced risk of prostatic diseases. Since natural products offer multiple advantages over synthetic antiandrogens, this review may provide a comprehensive and updated overview of dietary-derived AR inhibitors, as well as their potential for the nutritional intervention against prostatic disorders.

Dietary flavonoid patterns and prostate cancer: evidence from a Mexican population-based case-control study

Flavonoids are a broad group of bioactive compounds with anticarcinogenic effects on the prostate that have been scarcely evaluated in Latin American populations. Our objective was to evaluate the association between dietary patterns of flavonoid intake and prostate cancer (PC) in a population-based case-control study carried out in Mexico City. Based on a semi-quantitative FFQ with a frame reference of 3 years before diagnosis or interview, we used an updated database for estimating the daily intake (mg/d) of flavones, flavonols and flavanols for 395 confirmed incident PC cases and 797 population controls matched by age (± 5 years). Histological PC differentiation was evaluated using the Gleason score at diagnosis. Flavonoid dietary intake patterns (FDIP) were determined through principal component analysis, and their association with PC was estimated using logistic regression models. Three FDIP were identified: gallate pattern (GP) characterised by (-)-epicatechin-3-O-gallate, (-)-epigallocatechin-3-O-gallate and (+)-gallocatechin; luteolin pattern (LP) characterised by luteolin and (-)-epigallocatechin-3-O-gallate; and a mixed pattern (MP) that included (+)-catechin, (-)-epicatechin and quercetin. A higher GP (ORT3 v.T1 = 0·47; 95 % CI 0·33, 0·66) and LP intake (ORT3 v. T1 = 0·39; 95 % CI 0·27, 0·59) were associated with a decreased PC likelihood. In contrast, a higher MP intake (ORT3 v. T1 = 2·32; 95 % CI 1·67, 3·23) increased PC likelihood. The possible differential and synergistic anticarcinogenic role of flavonoid compounds in PC deserves further study.

Revisiting prostate cancer metabolism: From metabolites to disease and therapy

Prostate cancer (PCa), one of the most commonly diagnosed cancers worldwide, still presents important unmet clinical needs concerning treatment. In the last years, the metabolic reprogramming and the specificities of tumor cells emerged as an exciting field for cancer therapy. The unique features of PCa cells metabolism, and the activation of specific metabolic pathways, propelled the use of metabolic inhibitors for treatment. The present work revises the knowledge of PCa metabolism and the metabolic alterations that underlie the development and progression of the disease. A focus is given to the role of bioenergetic sources, namely, glucose, lipids, and glutamine sustaining PCa cell survival and growth. Moreover, it is described as the action of oncogenes/tumor suppressors and sex steroid hormones in the metabolic reprogramming of PCa. Finally, the status of PCa treatment based on the inhibition of metabolic pathways is presented. Globally, this review updates the landscape of PCa metabolism, highlighting the critical metabolic alterations that could have a clinical and therapeutic interest.

Bicalutamide causes heart failure in an elderly patient with prostate cancer

OBJECTIVE

To examine the molecular mechanisms by which bicalutamide may cause heart failure in an elderly patient.

METHODS

Retrospective analysis of bicalutamide as a cause of heart failure in Mr FD, an 82 years old with prostate cancer.

RESULTS

Following months of therapy, Mr FD was diagnosed with heart failure. Bicalutamide has been ceased, but 21 months later, Mr FD was still on heart failure medications, and passed away months later probably due to complications of prostate cancer. The Naranjo ADR probability scale gave this case a score of seven.

CONCLUSION

The Naranjo scale strongly suggests that bicalutamide was the cause of heart failure. Apoptosis seems to be one of the mechanisms mediating heart failure, with the involvement of many molecular actors, such as ET-1, Bcl-2 and cyclin-A. The author believes this to be the first analysis describing bicalutamide as a probable cause of heart failure.

New insights into the mechanisms of green tea catechins in the chemoprevention of prostate cancer

Prostate cancer is the most commonly diagnosed cancer and second most common cause of cancer deaths in American men. Its long latency, slow progression, and high incidence rate make prostate cancer ideal for targeted chemopreventative therapies. Therefore, chemoprevention studies and clinical trials are essential for reducing the burden of prostate cancer on society. Epidemiological studies suggest that tea consumption has protective effects against a variety of human cancers, including that of the prostate. Laboratory and clinical studies have demonstrated that green tea components, specifically the green tea catechin (GTC) epigallocatechin gallate, can induce apoptosis, suppress progression, and inhibit invasion and metastasis of prostate cancer. Multiple mechanisms are involved in the chemoprevention of prostate cancer with GTCs; understanding and refining models of fundamental molecular pathways by which GTCs modulate prostate carcinogenesis is essential to apply the utilization of green tea for the chemoprevention of prostate cancer in clinical settings. The objective of this article is to review and summarize the most current literature focusing on the major mechanisms of GTC chemopreventative action on prostate cancer from laboratory, in vitro, and in vivo studies, and clinical chemoprevention trials.

Green tea polyphenol EGCG blunts androgen receptor function in prostate cancer

Androgen deprivation therapy is the major treatment for advanced prostate cancer (PCa). However, it is a temporary remission, and the patients almost inevitably develop hormone refractory prostate cancer (HRPC). HRPC is almost incurable, although most HRPC cells still express androgen receptor (AR) and depend on the AR for growth, making AR a prime drug target. Here, we provide evidence that epigallocatechin-3-gallate (EGCG), the major polyphenol in green tea, is a direct antagonist of androgen action. In silico modeling and FRET-based competition assay showed that EGCG physically interacts with the ligand-binding domain of AR by replacing a high-affinity labeled ligand (IC(50) 0.4 μM). The functional consequence of this interaction was a decrease in AR-mediated transcriptional activation, which was due to EGCG mediated inhibition of interdomain N-C termini interaction of AR. Treatment with EGCG also repressed the transcriptional activation by a hotspot mutant AR (T877A) expressed ectopically as well as the endogenous AR mutant. As the physiological consequence of AR antagonism, EGCG repressed R1881-induced PCa cell growth. In a xenograft model, EGCG was found to inhibit AR nuclear translocation and protein expression. We also observed a significant down-regulation of androgen-regulated miRNA-21 and up-regulation of a tumor suppressor, miRNA-330, in tumors of mice treated with EGCG. Taken together, we provide evidence that EGCG functionally antagonizes androgen action at multiple levels, resulting in inhibition of PCa growth.

The effect of green tea on oxidative damage and tumour formation in Lobund-Wistar rats

A number of epidemiological studies suggest that the consumption of green tea reduces the incidence of prostate cancer. As the major catechins present in green tea are potent antioxidants, we hypothesized that genetic and cellular damage induced by oxygen free radicals could be significantly reduced by potent antioxidants in green tea, thus reducing the cumulative genetic and cellular damage with age, and slowing or preventing tumour formation. Long-term administration of a decaffeinated green tea extract to Lobund-Wistar rats for periods up to 26 months almost halved the incidence of primary tumours in the genitourinary tract when compared with an age-matched cohort receiving just water. We observed no inhibition of DNA adduct formation or lipid peroxidation in animals consuming green tea compared with animals consuming deionized water. The decrease in tumour formation was associated with an increase in 8-hydroxy-2'deoxyguanosine and 4-hydroxynonenal content (markers of DNA adduct formation and lipid peroxidation, respectively) in the epithelium of the ventral prostate in aging animals. In addition, there was an increase in 8-hydroxy-2'deoxyguanosine expression, but no change in 4-hydroxynonenal expression in the seminal vesicles of older animals. An age-associated increase in expression of the antioxidant enzymes manganese superoxide dismutase and catalase in the epithelium of the ventral prostate of aging animals was observed. Furthermore, there was also an increase in manganese superoxide dismutase expression, but no change in catalase expression in the seminal vesicles of older animals. These data demonstrate that consumption of green tea decreases the incidence of genitourinary tract tumours in the Lobund-Wistar rat, but has no effect on age-associated DNA adduct formation and lipid peroxidation in the ventral prostate and seminal vesicles of the aging rat.