Green tea polyphenols for prostate cancer chemoprevention: a translational perspective
(Johnson, Bailey et al. 2010) Download
Every year nearly 200,000 men in the United States are diagnosed with prostate cancer (PCa), and another 29,000 men succumb to the disease. Within certain regions of the world population based studies have identified a possible role for green tea in the prevention of certain cancers, especially PCa. One constituent in particular, epigallocatechin-3-gallate also known as EGCG has been shown in cell culture models to decrease cell viability and promote apoptosis in multiple cancer cell lines including PCa with no effect on non-cancerous cell lines. In addition, animal models have consistently shown that standardized green tea polyphenols when administered in drinking water delay the development and progression of PCa. Altogether, three clinical trials have been performed in PCa patients and suggest that green tea may have a distinct role as a chemopreventive agent. This review will present the available data for standardized green tea polyphenols in regard to PCa chemoprevention that will include epidemiological, mechanism based studies, safety, pharmacokinetics, and applicable clinical trials. The data that has been collected so far suggests that green tea may be a promising agent for PCa chemoprevention and further clinical trials of participants at risk of PCa or early stage PCa are warranted.
Nutraceuticals and prostate cancer prevention: a current review
(Trottier, Bostrom et al. 2010) Download
Nutraceuticals are 'natural' substances isolated or purified from food substances and used in a medicinal fashion. Several naturally derived food substances have been studied in prostate cancer in an attempt to identify natural preventative therapies for this disease. Vitamin E, selenium, vitamin D, green tea, soy, and lycopene have all been examined in human studies. Other potential nutraceuticals that lack human data, most notably pomegranate, might also have a preventative role in this disease. Unfortunately, most of the literature involving nutraceuticals in prostate cancer is epidemiological and retrospective. The paucity of randomized control trial evidence for the majority of these substances creates difficulty in making clinical recommendations particularly when most of the compounds have no evidence of toxicity and occur naturally. Despite these shortcomings, this area of prostate cancer prevention is still under intense investigation. We believe many of these 'natural' compounds have therapeutic potential and anticipate future studies will consist of well-designed clinical trials assessing combinations of compounds concurrently.
beta-carboline alkaloid-enriched extract from the amazonian rain forest tree pao pereira suppresses prostate cancer cells
(Bemis, Capodice et al. 2009) Download
Bark extracts from the Amazonian rain forest tree Geissospermum vellosii (pao pereira), enriched in alpha-carboline alkaloids have significant anticancer activities in certain preclinical models. Because of the predominance of prostate cancer as a cause of cancer-related morbidity and mortality for men of Western countries, we preclinically tested the in vitro and in vivo effects of a pao pereira extract against a prototypical human prostate cancer cell line, LNCaP. When added to cultured LNCaP cells, pao pereira extract significantly suppressed cell growth in a dose-dependent fashion and induced apoptosis. Immunodeficient mice heterotopically xenografted with LNCaP cells were gavaged daily with pao pereira extract or vehicle control over 6 weeks. Tumor growth was suppressed by up to 80% in some groups compared with tumors in vehicle-treated mice. However, we observed a striking U-shaped dose-response curve in which the highest dose tested (50 mg/kg/d) was much less effective in inducing tumor cell apoptosis and in reducing tumor cell proliferation and xenograft growth compared with lower doses (10 or 20 mg/kg/d). Although this study supports the idea that a pao pereira bark extract has activity against human prostate cancer, our in vivo results suggest that its potential effectiveness in prostate cancer treatment may be limited to a narrow dose range.
Pharmacological values of medicinal mushrooms for prostate cancer therapy: the case of Ganoderma lucidum
(Mahajna, Dotan et al. 2009) Download
Prostate cancer (PCa) is the most common male malignancy in many Western countries. Primary PCa is hormone dependent and is manageable by hormonal therapy. However, it rapidly develops to hormone-refractory tumors due to the accumulation of mutations in the androgen receptor and/or the acquisition of alternative cellular pathways that support proliferation and inhibit apoptosis of prostate cancer. To date, no effective therapy is available for clinically hormone-insensitive or hormone-refractory stages of prostate cancer.
Milk intake and the risk of type 2 diabetes mellitus, hypertension and prostate cancer
(Martini and Wood 2009) Download
Milk intake is widely recommended for a healthy diet. Recent evidences suggest that milk/dairy products are associated with a lower risk of type 2 diabetes and hypertension. On the other hand, high calcium intake has been associated with a higher risk of prostate cancer. The calcium and vitamin D content in dairy foods could have beneficial effects on glucose metabolism and renin/angiotensin system as well regulates body weight. The association between high dairy/calcium consumption and prostate cancer risk are related to the presence of estrogens and insulin like growth factor (IGF-I) in milk. Based on the current evidence, it is possible that milk/dairy products, when consumed in adequate amounts and mainly with reduced fat content, has a beneficial effect on the prevention of hypertension and diabetes. Its potential role in the pathogenesis of prostate cancer is not well supported and requires additional study.
Review: green tea polyphenols in chemoprevention of prostate cancer: preclinical and clinical studies
(Khan, Adhami et al. 2009) Download
The prevention of prostate cancer (PCa) is a crucial medical challenge in developed countries. PCa remains surrounded by puzzles in spite of the considerable progress in research, diagnosis, and treatment. It is an ideal target for chemoprevention, as clinically significant PCa usually requires more than two decades for development. Green tea and its major constituent epigallocatechin gallate (EGCG) have been extensively studied as a potential treatment for a variety of diseases including cancer. In this review, we highlight the evidences of green tea polyphenols from preclinical and clinical studies in the chemoprevention/chemotherapy of PCa.
Nutritional prevention of cancer: new directions for an increasingly complex challenge
(Kristal and Lippman 2009) Download
A Phase II randomized, placebo-controlled clinical trial of purified isoflavones in modulating steroid hormones in men diagnosed with localized prostate cancer
(Kumar, Krischer et al. 2007) Download
Our purpose was to evaluate the safety and effectiveness of purified isoflavones in producing an increase in plasma isoflavones and a corresponding change in serum sex hormone binding globulin (SHBG) and steroid hormone levels in men diagnosed with early stage prostate cancer. In this Phase II randomized, double-blinded, placebo-controlled trial, 53 prostate cancer patients with a Gleason score of 6 or below were supplemented with 80 mg purified isoflavones or placebo for 12 weeks. Changes in plasma isoflavones, serum steroid hormones, and safety markers were analyzed from baseline to 12 wk. A total of 50 subjects completed the study. Although significant increases in plasma isoflavones (P < 0.001) was observed with no clinical toxicity, the corresponding modulation of serum SHBG, total estradiol, and testosterone in the isoflavone-treated group compared to men receiving placebo was nonsignificant. Increasing plasma isoflavones failed to produce a corresponding modulation of serum steroid hormone levels in men with localized prostate cancer. The study establishes the need to explore other potential mechanisms by which prolonged and consistent purified isoflavone consumption may modulate prostate cancer risk.
Bemis, D. L., J. L. Capodice, et al. (2009). "beta-carboline alkaloid-enriched extract from the amazonian rain forest tree pao pereira suppresses prostate cancer cells." J Soc Integr Oncol 7(2): 59-65.
Johnson, J. J., H. H. Bailey, et al. (2010). "Green tea polyphenols for prostate cancer chemoprevention: a translational perspective." Phytomedicine 17(1): 3-13.
Khan, N., V. M. Adhami, et al. (2009). "Review: green tea polyphenols in chemoprevention of prostate cancer: preclinical and clinical studies." Nutr Cancer 61(6): 836-41.
Kristal, A. R. and S. M. Lippman (2009). "Nutritional prevention of cancer: new directions for an increasingly complex challenge." J Natl Cancer Inst 101(6): 363-5.
Kumar, N. B., J. P. Krischer, et al. (2007). "A Phase II randomized, placebo-controlled clinical trial of purified isoflavones in modulating steroid hormones in men diagnosed with localized prostate cancer." Nutr Cancer 59(2): 163-8.
Mahajna, J., N. Dotan, et al. (2009). "Pharmacological values of medicinal mushrooms for prostate cancer therapy: the case of Ganoderma lucidum." Nutr Cancer 61(1): 16-26.
Martini, L. A. and R. J. Wood (2009). "Milk intake and the risk of type 2 diabetes mellitus, hypertension and prostate cancer." Arq Bras Endocrinol Metabol 53(5): 688-94.
Trottier, G., P. J. Bostrom, et al. (2010). "Nutraceuticals and prostate cancer prevention: a current review." Nat Rev Urol 7(1): 21-30.