Proproliferative function of adaptor protein GRB10 in prostate carcinoma.

Growth factor receptor-binding protein 10 (GRB10) is a well-known adaptor protein and a recently identified substrate of the mammalian target of rapamycin (mTOR). Depletion of GRB10 increases insulin sensitivity and overexpression suppresses PI3K/Akt signaling. Because the major reason for the limited efficacy of PI3K/Akt-targeted therapies in prostate cancer (PCa) is loss of mTOR-regulated feedback suppression, it is therefore important to assess the functional importance and regulation of GRB10 under these conditions. On the basis of these background observations, we explored the status and functional impact of GRB10 in PCa and found maximum expression in phosphatase and tensin homolog (PTEN)-deficient PCa. In human PCa samples, GRB10 inversely correlated with PTEN and positively correlated with pAKT levels. Knockdown of GRB10 in nontumorigenic PTEN null mouse embryonic fibroblasts and tumorigenic PCa cell lines reduced Akt phosphorylation and selectively activated a panel of receptor tyrosine kinases. Similarly, overexpression of GRB10 in PTEN wild-type PCa cell lines accelerated tumorigenesis and induced Akt phosphorylation. In PTEN wild-type PCa, GRB10 overexpression promoted mediated PTEN interaction and degradation. PI3K (but not mTOR) inhibitors reduced GRB10 expression, suggesting primarily PI3K-driven regulation of GRB10. In summary, our results suggest that GRB10 acts as a major downstream effector of PI3K and has tumor-promoting effects in prostate cancer.-Khan, M. I., Al Johani, A., Hamid, A., Ateeq, B., Manzar, N., Adhami, V. M., Lall, R. K., Rath, S., Sechi, M., Siddiqui, I. A., Choudhry, H., Zamzami, M. A., Havighurst, T. C., Huang, W., Ntambi, J. M., Mukhtar, H. Proproliferatve function of adaptor protein GRB10 in prostate carcinoma.

Fisetin Enhances Chemotherapeutic Effect of Cabazitaxel against Human Prostate Cancer Cells.

Although treatment of prostate cancer has improved over the past several years, taxanes, such as cabazitaxel, remain the only form of effective chemotherapy that improves survival in patients with metastatic castration-resistant prostate cancer. However, the effectiveness of this class of drugs has been associated with various side effects and drug resistance. We previously reported that fisetin, a hydroxyflavone, is a microtubule-stabilizing agent and inhibits prostate cancer cell proliferation, migration, and invasion and suggested its use as an adjuvant for treatment of prostate and other cancer types. In this study, we investigated the effect of fisetin in combination with cabazitaxel with the objective to achieve maximum therapeutic benefit, reduce dose and toxicity, and minimize or delay the induction of drug resistance and metastasis. Our data show for the first time that a combination of fisetin (20 µmol/L) enhances cabazitaxel (5 nmol/L) and synergistically reduces 22Rν1, PC-3M-luc-6, and C4-2 cell viability and metastatic properties with minimal adverse effects on normal prostate epithelial cells. In addition, the combination of fisetin with cabazitaxel was associated with inhibition of proliferation and enhancement of apoptosis. Furthermore, combination treatment resulted in the inhibition of tumor growth, invasion, and metastasis when assessed in two in vivo xenograft mouse models. These results provide evidence that fisetin may have therapeutic benefit for patients with advanced prostate cancer through enhancing the efficacy of cabazitaxel under both androgen-dependent and androgen-independent conditions. This study underscores the benefit of the combination of fisetin with cabazitaxel for the treatment of advanced and resistant prostate cancer and possibly other cancer types. Mol Cancer Ther; 15(12); 2863-74. ©2016 AACR.

Nanoencapsulation of natural triterpenoid celastrol for prostate cancer treatment.

Celastrol (CL), a triterpenoid extracted from the Chinese herb Tripterygium wilfordii, has recently attracted interest for its potential antitumor effects. However, unfavorable physicochemical and pharmacokinetics properties such as low solubility, poor bioavailability, and systemic toxicity, are limiting its therapeutic application. In this context, the development of innovative nanocarriers can be useful to overcome these issues, and nanoencapsulation would represent a powerful strategy. In this study, we developed novel CL-loaded poly(ε-caprolactone) nanoparticles (NPs), and investigated their antiproliferative efficacy on prostate cancer cells. CL-NPs were prepared using a nanoprecipitation method and fully characterized by physicochemical techniques. The antiproliferative effects on LNCaP, DU-145, and PC3 cell lines of CL-NPs, compared to those of free CL at different concentrations (0.5, 1.0, and 2.0 µM), were investigated. Moreover, fluorescence microscopy was utilized to examine the cellular uptake of the nanosystems. Furthermore, to elucidate impact of nanoencapsulation on the mechanism of action, Western analyses were conducted to explore apoptosis, migration, proliferation, and angiogenesis alteration of prostate cancer cells. The results confirmed that CL-NPs inhibit proliferation dose dependently in all prostate cancer cells, with inhibitory concentration50 less than 2 µM. In particular, the NPs significantly increased cytotoxicity at lower/medium dose (0.5 and 1.0 µM) on DU145 and PC3 cell lines with respect to free CL, with modulation of apoptotic and cell cycle machinery proteins. To date, this represents the first report on the development of biocompatible polymeric NPs encapsulating CL. Our findings offer new perspectives for the exploitation of developed CL-NPs as suitable prototypes for prostate cancer treatment.

YB-1 expression promotes epithelial-to-mesenchymal transition in prostate cancer that is inhibited by a small molecule fisetin.

Epithelial-to-mesenchymal transition (EMT) plays an important role in prostate cancer (PCa) metastasis. The transcription/translation regulatory Y-box binding protein-1 (YB-1) is known to be associated with cancer metastasis. We observed that YB-1 expression increased with tumor grade and showed an inverse relationship with E-cadherin in a human PCa tissue array. Forced YB-1 expression induced a mesenchymal morphology that was associated with down regulation of epithelial markers. Silencing of YB-1 reversed mesenchymal features and decreased cell proliferation, migration and invasion in PCa cells. YB-1 is activated directly via Akt mediated phosphorylation at Ser102 within the cold shock domain (CSD). We next identified fisetin as an inhibitor of YB-1 activation. Computational docking and molecular dynamics suggested that fisetin binds on the residues from ß1 - ß4 strands of CSD, hindering Akt's interaction with YB-1. Calculated free binding energy ranged from -11.9845 to -9.6273 kcal/mol. Plasmon Surface Resonance studies showed that fisetin binds to YB-1 with an affinity of approximately 35 µM, with both slow association and dissociation. Fisetin also inhibited EGF induced YB-1 phosphorylation and markers of EMT both in vitro and in vivo. Collectively our data suggest that YB-1 induces EMT in PCa and identify fisetin as an inhibitor of its activation.

Resveratrol-loaded nanoparticles based on poly(epsilon-caprolactone) and poly(D,L-lactic-co-glycolic acid)-poly(ethylene glycol) blend for prostate cancer treatment.

Nanoencapsulation of antiproliferative and chemopreventive phytoalexin trans-resveratrol (RSV) is likely to provide protection against degradation, enhancement of bioavailability, improvement in intracellular penetration and control delivery. In this study, polymeric nanoparticles (NPs) encapsulating RSV (nano-RSV) as novel prototypes for prostate cancer (PCa) treatment were designed, characterized and evaluated using human PCa cells. Nanosystems, composed of a biocompatible blend of poly(epsilon-caprolactone) (PCL) and poly(d,l-lactic-co-glycolic acid)-poly(ethylene glycol) conjugate (PLGA-PEG-COOH), were prepared by a nanoprecipitation method, and characterized in terms of morphology, particle size and zeta potential, encapsulation efficiency, thermal analyses, and in vitro release studies. Cellular uptake of NPs was then evaluated in PCa cell lines DU-145, PC-3, and LNCaP using confocal fluorescence microscopy, and antiproliferative efficacy was assessed using MTT assay. With encapsulation efficiencies ranging from 74% to 98%, RSV was successfully loaded in PCL:PLGA-PEG-COOH NPs, which showed an average diameter of 150 nm. NPs were able to control the RSV release at pH 6.5 and 7.4, mimicking the acidic tumoral microenvironment and physiological conditions, respectively, with only 55% of RSV released within 7 h. In gastrointestinal simulated fluids, NPs released about 55% of RSV in the first 2 h in acidic medium, and their total RSV content within the subsequent 5 h at pH 7.4. Confocal fluorescence microscopy observations revealed that NPs were efficiently taken up by PCa cell lines. Furthermore, nano-RSV significantly improved the cytotoxicity compared to that of free RSV toward all three cell lines, at all tested concentrations (from 10 µM to 40 µM), proving a consistent sensitivity toward both the androgen-independent DU-145 and hormone-sensitive LNCaP cells. Our findings support the potential use of developed nanoprototypes for the controlled delivery of bioactive RSV for PCa chemoprevention/chemotherapy.

Oral infusion of pomegranate fruit extract inhibits prostate carcinogenesis in the TRAMP model.

We earlier provided evidence that oral consumption of pomegranate fruit extract (PFE) inhibits prostate cancer (PCa) cell growth in nude mice. To ascertain convincing evidence of chemopreventive effects of PFE against PCa, its efficacy requires to be evaluated in animal models that closely emulate human disease. Here, we provide evidence of remarkable tumor growth inhibitory effects of PFE using the TRAMP model. Mice received 0.1 and 0.2% PFE, equivalent to 250 and 500 ml of pomegranate juice, in drinking water, starting at 6 weeks and examined at 12, 20 and 34 weeks of age. In water-fed group, 100% mice developed palpable tumors by 20 weeks compared with only 30 and 20% in the 0.1 and 0.2% PFE-supplemented groups, respectively. At 34 weeks, palpable tumors were observed in 70 of 0.1% and only 50 of 0.2% PFE-supplemented mice. Compared with median survival of 43 weeks in water-fed mice, 0.1 and 0.2% PFE-supplemented mice exhibited median life expectancy of 73 and 92 weeks, respectively. Compared with respective water-fed groups, none of the mice in PFE-supplemented groups exhibited metastases to any of the distant organs at 20 weeks and only 20% mice exhibited metastasis at 34 weeks of age. Many of the PFE-supplemented animals had multiple foci of well-differentiated carcinoma but no evidence of poorly differentiated carcinoma. PFE supplementation resulted in simultaneous and significant inhibition of IGF-I/Akt/mTOR pathways in the prostate tissues and tumors. We suggest that pomegranate juice be evaluated in clinical trials in patients at high risk for developing PCa.

Ligand-dependent corepressor acts as a novel androgen receptor corepressor, inhibits prostate cancer growth, and is functionally inactivated by the Src protein kinase.

The activated androgen receptor (AR) promotes prostate cancer (PCa) growth. AR antagonists repress the AR by recruitment of corepressors. Not much is known about the inactivation of AR by corepressors in the presence of agonists (androgens). Here we show that the corepressor LCoR acts as an androgen-dependent corepressor that represses human PCa growth in vivo. In line with this, progressive decrease of ligand-dependent corepressor expression was observed in the PCa TRAMP mouse model with increasing age. LCoR interacts with AR and is recruited to chromatin in an androgen-induced manner. Unexpectedly, the LXXLL motif of LCoR is dispensable for interaction with the AR. Rather, the data indicate that LCoR interacts with the AR DNA binding domain on DNA. Interestingly, the interaction of LCoR with AR is inhibited by signaling pathways that are associated with androgen-independent PCa. Here we also show that the Src kinase inactivates the corepressive function of LCoR. Interfering with endogenous Src function by a dominant negative Src mutant, the growth inhibitory activity of LCoR is enhanced in vivo in a xenograft mouse model system. Thus, our studies indicate a role of LCoR as an AR corepressor and a tumor suppressor. Further, the decreased expression or inactivation of LCoR is as an important step toward PCa carcinogenesis in vivo.

Effective prostate cancer chemopreventive intervention with green tea polyphenols in the TRAMP model depends on the stage of the disease.

PURPOSE: We have shown previously that oral feeding of green tea polyphenols (GTP) to transgenic adenocarcinoma of the mouse prostate mice in a purely chemopreventive setting significantly inhibits prostate cancer development. To translate this to a human situation, the present study was designed to identify the stage of prostate cancer that is most vulnerable to chemopreventive intervention by GTP. EXPERIMENTAL DESIGN: GTP infusion (0.1% in drinking water) to transgenic adenocarcinoma of the mouse prostate was initiated at ages representing different stage of the disease: (a) 6 weeks (group 1, normal prostate), (b) 12 weeks (group 2, prostatic intraepithelial neoplasia), (c) 18 weeks (group 3, well-differentiated adenocarcinoma), and (b) 28 weeks (group 4, moderately differentiated adenocarcinoma). At age 32 weeks, subsets of animals were evaluated by magnetic resonance imaging, ultrasound, and prostate weight and for serum insulin-like growth factor (IGF)-I/IGF binding protein-3 and IGF signaling. RESULTS: Tumor-free survival was extended to 38 weeks (P < 0.001) in group 1, 31 weeks (P < 0.01) in group 2, and 24 weeks (P < 0.05) in group 3 compared with 19 weeks in water-fed controls. Median life expectancy was 68 weeks in group 1, 63 weeks in group 2, 56 weeks in group 3, and 51 weeks in group 4 compared with 42 weeks in the control mice. IGF-I and its downstream targets including phosphatidylinositol 3-kinase, pAkt, and phosphorylated extracellular signal-regulated kinase were significantly inhibited only when intervention was initiated early when prostatic intraepithelial neoplasia lesions were common. CONCLUSIONS: Our studies indicate that chemopreventive potential of GTP decreases with advancing stage of the disease and underscore the need to design appropriate chemoprevention clinical trails.

Lupeol inhibits proliferation of human prostate cancer cells by targeting beta-catenin signaling.

Lupeol, a dietary triterpene, was shown to decrease serum prostate-specific antigen levels and inhibit the tumorigenicity of prostate cancer (CaP) cells in vivo. Here, we show that Lupeol inhibits the proliferative potential of CaP cells and delineated its mechanism of action. Employing a focused microarray of human CaP-associated genes, we found that Lupeol significantly modulates the expression level of genes such as ERBB2, tissue inhibitor of metalloproteinases-3, cyclin D1 and matrix metalloproteinase (MMP)-2 that are known to be associated with proliferation and survival. A common feature of these genes is that all of them are known to either regulate or act as downstream target of beta-catenin signaling that is highly aberrant in CaP patients. Lupeol treatment significantly (1) reduced levels of beta-catenin in the cytoplasmic and nuclear fractions, (2) modulated expression levels of glycogen synthase kinase 3 beta (GSK3beta)-axin complex (regulator of beta-catenin stability), (3) decreased the expression level and enzymatic activity of MMP-2 (downstream target of beta-catenin), (4) reduced the transcriptional activation of T Cell Factor (TCF) responsive element (marker for beta-catenin signaling) in pTK-TCF-Luc-transfected cells and (5) decreased the transcriptional activation of MMP-2 gene in pGL2-MMP-2-Luc-transfected cells. Effects of Lupeol treatment on beta-catenin degradation were significantly reduced in CaP cells where axin is knocked down through small interfering RNA transfection and GSK3beta activity is blocked. Collectively, these data suggest the multitarget efficacy of Lupeol on beta-catenin-signaling network thus resulting in the inhibition CaP cell proliferation. We suggest that Lupeol could be developed as an agent for chemoprevention as well as chemotherapy of human CaP.

Delphinidin, a dietary anthocyanidin in pigmented fruits and vegetables: a new weapon to blunt prostate cancer growth.

In a recent publication, we have shown that delphinidin, an anthocyanidin induces apoptosis and cell cycle arrest in highly metastatic human prostate cancer (PCa) PC3 cells. Extending these studies, we provide additional evidence that delphinidin induces apoptosis and cell cycle arrest in androgen refractory human PCa 22Rnu1 cells and that these effects are concomitant with inhibition of NFkappaB. We observed that delphinidin treatment to 22Rnu1 cells resulted in a dose-dependent (i) G(2)/M phase cell cycle arrest, (ii) induction of apoptosis (iii) and inhibition of NFkappaB signaling. The induction of apoptosis by delphinidin was mediated via activation of caspases since a general caspase inhibitor Z-VAD-FMK significantly reversed this effect. Delphinidin treatment to cells resulted in a dose-dependent decrease in (i) phosphorylation of IKKgamma (NEMO), (ii) phosphorylation of NFkappaB inhibitory protein IkappaBalpha, (iii) phosphorylation of NFkappaB/p65 at Ser(536) and NFkappaB/p50 at Ser529, (iv) NFkappaB/p65 nuclear translocation, and (v) NFkappaB DNA binding activity. Taken together, our data show that delphinidin induces apoptosis of both androgen independent and androgen refractory human PCa cells via activation of caspases and in addition, this effect might be due to inhibition of NFkappaB signaling. We suggest that delphinidin could be developed as a novel agent against PCa.

A dietary anthocyanidin delphinidin induces apoptosis of human prostate cancer PC3 cells in vitro and in vivo: involvement of nuclear factor-kappaB signaling.

Delphinidin, a major anthocyanidin present in many pigmented fruits and vegetables, possesses antioxidant, anti-inflammatory, and antiangiogenic properties. In this study, we provide evidence that it could be developed as a novel agent against human prostate cancer (PCa). We observed that delphinidin treatment to human PCa LNCaP, C4-2, 22Rnu1, and PC3 cells resulted in a dose-dependent inhibition of cell growth without having any substantial effect on normal human prostate epithelial cells. We selected PC3 cells as a test model system because of their highly aggressive proliferative nature. Delphinidin treatment of cells resulted in a dose-dependent induction of apoptosis and arrest of cells in G(2)-M phase. This induction of apoptosis seems to be mediated via activation of caspases because N-benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluromethylketone significantly reduced apoptosis induced by delphinidin. We also observed that delphinidin treatment of cells resulted in a dose-dependent decrease in (a) phosphorylation of IkappaB kinase gamma (NEMO), (b) phosphorylation of nuclear factor-kappaB (NF-kappaB) inhibitory protein IkappaBalpha, (c) phosphorylation of NF-kappaB/p65 at Ser(536) and NF-kappaB/p50 at Ser(529), (d) NF-kappaB/p65 nuclear translocation, and (e) NF-kappaB DNA binding activity. Delphinidin administration (2 mg, i.p. thrice weekly) to athymic nude mice implanted with PC3 cells resulted in a significant inhibition of tumor growth. Analysis of tumors from delphinidin-treated mice showed significant decrease in the expression of NF-kappaB/p65, Bcl2, Ki67, and PCNA. Taken together, our data suggest that delphinidin could be developed as an agent against human PCa.

Combined inhibitory effects of green tea polyphenols and selective cyclooxygenase-2 inhibitors on the growth of human prostate cancer cells both in vitro and in vivo.

PURPOSE: Cyclooxygenase-2 (COX-2) inhibitors hold promise for cancer chemoprevention; however, recent toxicity concerns suggest that new strategies are needed. One approach to overcome this limitation is to use lower doses of COX-2 inhibitors in combination with other established agents with complementary mechanisms. In this study, the effect of (-)epigallocatechin-3-gallate (EGCG), a promising chemopreventive agent from green tea, was tested alone and in combination with specific COX-2 inhibitors on the growth of human prostate cancer cells both in vitro and in vivo. EXPERIMENTAL DESIGN: Human prostate cancer cells LNCaP, PC-3, and CWR22Rnu1 were treated with EGCG and NS398 alone and in combination, and their effect on growth and apoptosis was evaluated. In vivo, athymic nude mice implanted with androgen-sensitive CWR22Rnu1 cells were given green tea polyphenols (0.1% in drinking water) and celecoxib (5 mg/kg, i.p., daily, 5 days per week), alone and in combination, and their effect on tumor growth was evaluated. RESULTS: Combination of EGCG (10-40 micromol/L) and NS-398 (10 micromol/L) resulted in enhanced (a) cell growth inhibition; (b) apoptosis induction; (c) expression of Bax, pro-caspase-6, and pro-caspase-9, and poly(ADP)ribose polymerase cleavage; (d) inhibition of peroxisome proliferator activated receptor gamma; and (e) inhibition of nuclear factor-kappaB compared with the additive effects of the two agents alone, suggesting a possible synergism. In vivo, combination treatment with green tea polyphenols and celecoxib resulted in enhanced (a) tumor growth inhibition, (b) lowering of prostate-specific antigen levels, (c) lowering of insulin-like growth factor-I levels, and (d) circulating levels of serum insulin-like growth factor binding protein-3 compared with results of single-agent treatment. CONCLUSIONS: These data suggest synergistic and/or additive effects of combinatorial chemopreventive agents and underscore the need for rational design of human clinical trials.

Oral consumption of green tea polyphenols inhibits insulin-like growth factor-I-induced signaling in an autochthonous mouse model of prostate cancer.

We earlier demonstrated that oral infusion of green tea polyphenols inhibits development and progression of prostate cancer in transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Evidence indicates that elevated levels of IGF-I with concomitant lowering of IGF binding protein (IGFBP)-3 are associated with increased risk for prostate cancer development and progression. In this study, we examined the role of IGF/IGFBP-3 signaling and its downstream and other associated events during chemoprevention of prostate cancer by green tea polyphenols in TRAMP mice. Our data demonstrated an increase in the levels of IGF-I, phosphatidylinositol 3'-kinase, phosphorylated Akt (Thr-308), and extracellular signal-regulated kinase 1/2 with concomitant decrease in IGFBP-3 in dorso-lateral prostate of TRAMP mice during the course of cancer progression, i.e., as a function of age. Continuous green tea polyphenol infusion for 24 weeks to these mice resulted in substantial reduction in the levels of IGF-I and significant increase in the levels of IGFBP-3 in the dorso-lateral prostate. This modulation of IGF/IGFBP-3 was found to be associated with an inhibition of protein expression of phosphatidylinositol 3'-kinase, phosphorylated forms of Akt (Thr-308) and extracellular signal-regulated kinase 1/2. Furthermore, green tea polyphenol infusion resulted in marked inhibition of markers of angiogenesis and metastasis most notably vascular endothelial growth factor, urokinase plasminogen activator, and matrix metalloproteinases 2 and 9. Based on our data, we suggest that IGF-I/IGFBP-3 signaling pathway is a prime pathway for green tea polyphenol-mediated inhibition of prostate cancer that limits the progression of cancer through inhibition of angiogenesis and metastasis.

Modulation of phosphatidylinositol-3-kinase/protein kinase B- and mitogen-activated protein kinase-pathways by tea polyphenols in human prostate cancer cells.

We have earlier shown that oral infusion of a polyphenolic fraction isolated from green tea, at a human achievable dose (equivalent to six cups of green tea per day), significantly inhibits prostate cancer (PCA) development and metastasis in transgenic adenocarcinoma of mouse prostate (TRAMP) model that closely mimics progressive form of human prostatic disease (Gupta et al. [2001]: Proc. Natl. Acad. Sci. U.S.A. 98:10350-10355.). A complete understanding of the mechanism(s) and molecular targets of PCA chemopreventive effects of tea polyphenols may be useful in developing novel approaches for its prevention. In this study, we employed two distinct human PCA cell lines viz. DU145 (androgen-unresponsive prostate carcinoma cells) and LNCaP (androgen-responsive prostate carcinoma cells) and, employing immunoblot analysis, we evaluated the effect of epigallocatechin-3-gallate (EGCG), the major polyphenol present in green tea and theaflavins (TF), the major polyphenol present in black tea on phosphatidylinositol-3-kinase (PI3K)/protein kinase B (PKB) and mitogen-activated protein kinase (MAPK) pathways. Both EGCG and TF treatment were found to (i) decrease the levels of PI3K and phospho-Akt and (ii) increase Erk1/2 in both DU145 and LNCaP cells. Our data showing the inhibition of the constitutive levels of PI3K and the phosphorylation of Akt could be important because the treatment approaches should be aimed at the inhibition of the constitutive levels of PI3K and Akt. Our data also suggest that Erk1/2 could be involved in the anti-cancer effects of EGCG and TF. Taken together, our study, for the first time demonstrated the modulation of the constitutive activation of PI3K/Akt and Erk1/2 pathways by EGCG as well as TF. We suggest that detailed studies in appropriate tumor model system are needed to establish the relevance of the cell culture work to in vivo models.

Tea beverage in chemoprevention of prostate cancer: a mini-review.

Because prostate cancer has a long latency period and is typically diagnosed in elderly men, it represents an ideal candidate disease for chemoprevention. Therefore, even a modest delay achieved through intervention could have a significant impact on the outcome of this disease. Epidemiological and laboratory studies have provided convincing evidence that diet, genetic factors, and lifestyle are major causes of prostate cancer. Although surgery, radiotherapy, and hormone therapy are the most widely accepted curative options for a selected group of patients suffering from prostate cancer, the side effects of these treatments are many. In recent years, many dietary agents have been being described that show a wide range of chemopreventive effects in cell culture and selected animal model systems of prostate carcinogenesis. One such agent is the beverage tea, which, next to water, is the most popularly consumed beverage in the world. The epidemiological studies and recent data, amassed from various laboratories around the world, provide evidence that tea polyphenols such as epigallocatechin-3-gallate, epigallocatechin, and epicatechin-3-gallate may have the potential to lower the risk of prostate cancer in the human population. Recently, it has been shown that green tea polyphenols, when given to TRAMP, a transgenic mouse model that mimics progressive forms of human prostate cancer, exert remarkable preventive effects against prostate cancer development. Chemoprevention of prostate cancer by tea polyphenols appears to occur through the modulation of various molecular targets. This article attempts to address the issue of the possible use of tea, especially green tea, for the chemoprevention of prostate cancer.