Curcumin-Gene Expression Response in Hormone Dependent and Independent Metastatic Prostate Cancer Cells.

The androgen receptor is one of the key targets for prostate cancer treatment. Despite its less satisfactory effects, chemotherapy is the most common treatment option for metastatic and/or castration-resistant patients. There are constant needs for novel anti-prostate cancer therapeutic/prevention agents. Curcumin, a known chemo-preventive agent, was shown to inhibit prostate cancer cell growth. This study aimed to unravel the inhibitory effect of curcumin in prostate cancer through analyzing the alterations of expressions of curcumin targeting genes clusters in androgen-dependent LNCaP cells and androgen-independent metastatic C4-2B cells. Hierarchical clustering showed the highest number of differentially expressed genes at 12 h post treatment in both cells, suggesting that the androgen-dependent/independent manner of curcumin impacts on prostate cancer cells. Evaluation of significantly regulated top canonical pathways highlighted that Transforming growth factor beta (TGF-ß), Wingless-related integration site (Wnt), Phosphoinositide 3-kinase/Protein Kinase B/ mammalian target of rapamycin (PIK3/AKT(PKB)/mTOR), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) signaling were primarily inhibited, and Phosphatase and tensin homolog (PTEN) dependent cell cycle arrest and apoptosis pathways were elevated with curcumin treatment. The short term (3-24 h) and long term (48 h) effect of curcumin treatment revealed 31 and four genes modulated in both cell lines. TGF-ß signaling, including the androgen/TGF-ß inhibitor Prostate transmembrane protein androgen-induced 1 (PMEPA1), was the only pathway impacted by curcumin treatment after 48 h. Our findings also established that MYC Proto-Oncogene, basic helix-loop-helix (bHLH) Transcription Factor (MYC) signaling was down-regulated in curcumin-treated cell lines. This study established, for the first time, novel gene-networks and signaling pathways confirming the chemo-preventive and cancer-growth inhibitory nature of curcumin as a natural anti-prostate cancer compound.

Tsc2 disruption in mesenchymal progenitors results in tumors with vascular anomalies overexpressing Lgals3.

Increased mTORC1 signaling from TSC1/TSC2 inactivation is found in cancer and causes tuberous sclerosis complex (TSC). The role of mesenchymal-derived cells in TSC tumorigenesis was investigated through disruption of Tsc2 in craniofacial and limb bud mesenchymal progenitors. Tsc2cKOPrrx1-cre mice had shortened lifespans and extensive hamartomas containing abnormal tortuous, dilated vessels prominent in the forelimbs. Abnormalities were blocked by the mTORC1 inhibitor sirolimus. A Tsc2/mTORC1 expression signature identified in Tsc2-deficient fibroblasts was also increased in bladder cancers with TSC1/TSC2 mutations in the TCGA database. Signature component Lgals3 encoding galectin-3 was increased in Tsc2-deficient cells and serum of Tsc2cKOPrrx1-cre mice. Galectin-3 was increased in TSC-related skin tumors, angiomyolipomas, and lymphangioleiomyomatosis with serum levels in patients with lymphangioleiomyomatosis correlating with impaired lung function and angiomyolipoma presence. Our results demonstrate Tsc2-deficient mesenchymal progenitors cause aberrant morphogenic signals, and identify an expression signature including Lgals3 relevant for human disease of TSC1/TSC2 inactivation and mTORC1 hyperactivity.

Accelerated senescence in skin in a murine model of radiation-induced multi-organ injury.

Accidental high-dose radiation exposures can lead to multi-organ injuries, including radiation dermatitis. The types of cellular damage leading to radiation dermatitis are not completely understood. To identify the cellular mechanisms that underlie radiation-induced skin injury in vivo, we evaluated the time-course of cellular effects of radiation (14, 16 or 17 Gy X-rays; 0.5 Gy/min) in the skin of C57BL/6 mice. Irradiation of 14 Gy induced mild inflammation, observed histologically, but no visible hair loss or erythema. However, 16 or 17 Gy radiation induced dry desquamation, erythema and mild ulceration, detectable within 14 days post-irradiation. Histological evaluation revealed inflammation with mast cell infiltration within 14 days. Fibrosis occurred 80 days following 17 Gy irradiation, with collagen deposition, admixed with neutrophilic dermatitis, and necrotic debris. We found that in cultures of normal human keratinocytes, exposure to 17.9 Gy irradiation caused the upregulation of p21/waf1, a marker of senescence. Using western blot analysis of 17.9 Gy-irradiated mice skin samples, we also detected a marker of accelerated senescence (p21/waf1) 7 days post-irradiation, and a marker of cellular apoptosis (activated caspase-3) at 30 days, both preceding histological evidence of inflammatory infiltrates. Immunohistochemistry revealed reduced epithelial stem cells from hair follicles 14-30 days post-irradiation. Furthermore, p21/waf1 expression was increased in the region of the hair follicle stem cells at 14 days post 17 Gy irradiation. These data indicate that radiation induces accelerated cellular senescence in the region of the stem cell population of the skin.

Conditional reprogramming and long-term expansion of normal and tumor cells from human biospecimens.

Historically, it has been difficult to propagate cells in vitro that are derived directly from human tumors or healthy tissue. However, in vitro preclinical models are essential tools for both the study of basic cancer biology and the promotion of translational research, including drug discovery and drug target identification. This protocol describes conditional reprogramming (CR), which involves coculture of irradiated mouse fibroblast feeder cells with normal and tumor human epithelial cells in the presence of a Rho kinase inhibitor (Y-27632). CR cells can be used for various applications, including regenerative medicine, drug sensitivity testing, gene expression profiling and xenograft studies. The method requires a pathologist to differentiate healthy tissue from tumor tissue, and basic tissue culture skills. The protocol can be used with cells derived from both fresh and cryopreserved tissue samples. As approximately 1 million cells can be generated in 7 d, the technique is directly applicable to diagnostic and predictive medicine. Moreover, the epithelial cells can be propagated indefinitely in vitro, yet retain the capacity to become fully differentiated when placed into conditions that mimic their natural environment.

Phytochemicals in Wound Healing.

Significance: Traditional therapies, including the use of dietary components for wound healing and skin regeneration, are very common in Asian countries such as China and India. The increasing evidence of health-protective benefits of phytochemicals, components derived from plants is generating a lot of interest, warranting further scientific evaluation and mechanistic studies. Recent Advances: Phytochemicals are non-nutritive substances present in plants, and some of them have the potential to provide better tissue remodeling when applied on wounds and to also act as proangiogenic agents during wound healing. Critical Issues: In this review, we briefly discuss the current understanding, important molecular targets, and mechanism of action(s) of some of the phytochemicals such as curcumin, picroliv, and arnebin-1. We also broadly review the multiple pathways that these phytochemicals regulate to enhance wound repair and skin regeneration. Future Directions: Recent experimental data on the effects of phytochemicals on wound healing and skin regeneration establish the potential clinical utility of plant-based compounds. Additional research in order to better understand the exact mechanism and potential targets of phytochemicals in skin regeneration is needed. Human studies a2nd clinical trials are pivotal to fully understand the benefits of phytochemicals in wound healing and skin regeneration.

Alteration of skin properties with autologous dermal fibroblasts.

Dermal fibroblasts are mesenchymal cells found between the skin epidermis and subcutaneous tissue. They are primarily responsible for synthesizing collagen and glycosaminoglycans; components of extracellular matrix supporting the structural integrity of the skin. Dermal fibroblasts play a pivotal role in cutaneous wound healing and skin repair. Preclinical studies suggest wider applications of dermal fibroblasts ranging from skin based indications to non-skin tissue regeneration in tendon repair. One clinical application for autologous dermal fibroblasts has been approved by the Food and Drug Administration (FDA) while others are in preclinical development or various stages of regulatory approval. In this context, we outline the role of fibroblasts in wound healing and discuss recent advances and the current development pipeline for cellular therapies using autologous dermal fibroblasts. The microanatomic and phenotypic differences of fibroblasts occupying particular locations within the skin are reviewed, emphasizing the therapeutic relevance of attributes exhibited by subpopulations of fibroblasts. Special focus is provided to fibroblast characteristics that define regional differences in skin, including the thick and hairless skin of the palms and soles as compared to hair-bearing skin. This regional specificity and functional identity of fibroblasts provides another platform for developing regional skin applications such as the induction of hair follicles in bald scalp or alteration of the phenotype of stump skin in amputees to better support their prosthetic devices.

A model system to analyse the ability of human keratinocytes to form hair follicles.

Earlier studies showed that dermal cells lose trichogenic capacity with passage, but studies on the effect of keratinocyte passage on human hair follicle neogenesis and graft quality have been hampered by the lack of a suitable model system. We recently documented human hair follicle neogenesis in grafted dermal-epidermal composites, and in the present study, we determined the effects of keratinocyte passage on hair follicle neogenesis. Dermal equivalents were made with cultured human dermal papilla cells and were overlaid with either primary or passaged human keratinocytes to form dermal-epidermal composites; these were then grafted onto immunodeficient mice. Superior hair follicle neogenesis was observed using early keratinocyte cultures. Characteristics such as formation of hair shafts and sebaceous glands, presence of hair follicles with features of anagen or telogen follicles, and reproducible hair and skin function parameters make this model a tool to study human hair follicle neogenesis and development.

Loss of the NKX3.1 tumorsuppressor promotes the TMPRSS2-ERG fusion gene expression in prostate cancer.

BACKGROUND: In normal prostate epithelium the TMPRSS2 gene encoding a type II serine protease is directly regulated by male hormones through the androgen receptor. In prostate cancer ERG protooncogene frequently gains hormonal control by seizing gene regulatory elements of TMPRSS2 through genomic fusion events. Although, the androgenic activation of TMPRSS2 gene has been established, little is known about other elements that may interact with TMPRSS2 promoter sequences to modulate ERG expression in TMPRSS2-ERG gene fusion context. METHODS: Comparative genomic analyses of the TMPRSS2 promoter upstream sequences and pathway analyses were performed by the Genomatix Software. NKX3.1 and ERG genes expressions were evaluated by immunoblot or by quantitative Real-Time PCR (qRT-PCR) assays in response to siRNA knockdown or heterologous expression. QRT-PCR assay was used for monitoring the gene expression levels of NKX3.1-regulated genes. Transcriptional regulatory function of NKX3.1 was assessed by luciferase assay. Recruitment of NKX3.1 to its cognate elements was monitored by Chromatin Immunoprecipitation assay. RESULTS: Comparative analysis of the TMPRSS2 promoter upstream sequences among different species revealed the conservation of binding sites for the androgen inducible NKX3.1 tumor suppressor. Defects of NKX3.1, such as, allelic loss, haploinsufficiency, attenuated expression or decreased protein stability represent established pathways in prostate tumorigenesis. We found that NKX3.1 directly binds to TMPRSS2 upstream sequences and negatively regulates the expression of the ERG protooncogene through the TMPRSS2-ERG gene fusion. CONCLUSIONS: These observations imply that the frequently noted loss-of-function of NKX3.1 cooperates with the activation of TMPRSS2-ERG fusions in prostate tumorigenesis.

Sun exposure causes somatic second-hit mutations and angiofibroma development in tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is characterized by the formation of tumors in multiple organs and is caused by germline mutation in one of two tumor suppressor genes, TSC1 and TSC2. As for other tumor suppressor gene syndromes, the mechanism of somatic second-hit events in TSC tumors is unknown. We grew fibroblast-like cells from 29 TSC skin tumors from 22 TSC subjects and identified germline and second-hit mutations in TSC1/TSC2 using next-generation sequencing. Eighteen of 22 (82%) subjects had a mutation identified, and 8 of the 18 (44%) subjects were mosaic with mutant allele frequencies of 0 to 19% in normal tissue DNA. Multiple tumors were available from four patients, and in each case, second-hit mutations in TSC2 were distinct indicating they arose independently. Most remarkably, 7 (50%) of the 14 somatic point mutations were CC>TT ultraviolet 'signature' mutations, never seen as a TSC germline mutation. These occurred exclusively in facial angiofibroma tumors from sun-exposed sites. These results implicate UV-induced DNA damage as a cause of second-hit mutations and development of TSC facial angiofibromas and suggest that measures to limit UV exposure in TSC children and adults should reduce the frequency and severity of these lesions.

Skin regenerative potentials of curcumin.

Curcumin, an active constituent of the spice turmeric, is well known for its chemopreventive properties and is found to be beneficial in treating various disorders including skin diseases. Curcumin protects skin by quenching free radicals and reducing inflammation through the inhibition of nuclear factor-kappa B. Curcumin also affects other signaling pathways including transforming growth factor-ß and mitogen-activated protein kinase pathway. Curcumin also modulates the phase II detoxification enzymes which are crucial in detoxification reactions and for protection against oxidative stress. In the present review, the biological mechanisms of the chemopreventive potential of curcumin in various skin diseases like psoriasis, vitiligo, and melanoma is discussed. The application of curcumin in skin regeneration and wound healing is also elucidated. We also explored the recent innovations and advances involved in the development of transdermal delivery systems to enhance the bioavailability of curcumin, particularly in the skin. Recent clinical trials pertaining to the use of curcumin in skin diseases establishes its benefits and also the need for additional clinical trials in other diseases are discussed.

Human TSC2-null fibroblast-like cells induce hair follicle neogenesis and hamartoma morphogenesis.

Hamartomas are composed of cells native to an organ but abnormal in number, arrangement or maturity. In the tuberous sclerosis complex (TSC), hamartomas develop in multiple organs because of mutations in TSC1 or TSC2. Here we show that TSC2-null fibroblast-like cells grown from human TSC skin hamartomas induced normal human keratinocytes to form hair follicles and stimulated hamartomatous changes. Follicles were complete with sebaceous glands, hair shafts and inner and outer root sheaths. TSC2-null cells surrounding the hair bulb expressed markers of the dermal sheath and dermal papilla. Tumour xenografts recapitulated characteristics of TSC skin hamartomas with increased mammalian target of the rapamycin complex 1 (mTORC1) activity, angiogenesis, mononuclear phagocytes and epidermal proliferation. Treatment with an mTORC1 inhibitor normalized these parameters and reduced the number of tumour cells. These studies indicate that TSC2-null cells are the inciting cells for TSC skin hamartomas, and suggest that studies on hamartomas will provide insights into tissue morphogenesis and regeneration.

Androgen responsive and refractory prostate cancer cells exhibit distinct curcumin regulated transcriptome.

Curcumin (diferuloylmethane) is the major active component of turmeric and is being actively investigated for its anti-cancer properties. To better understand the biological mechanisms of the chemopreventive potential of curcumin in prostate cancer, we have evaluated curcumin regulated transcriptome in prostate cancer cells. Hierarchical clustering methods and functional classification of the Curcumin-Gene Expression Response (Cu-GER) showed temporal co-regulation of genes involved in oxidative stress response and growth signaling pathways. Interestingly, C4-2B, androgen independent metastatic prostate cancer cells exhibited attenuated Cu-GER response in comparison to parental androgen dependent and less aggressive LNCaP cells. Androgen Receptor (AR) regulated genes which play critical roles in normal growth and differentiation of the prostate gland, as well as in prostate cancer, were also a part of the Cu-GER. Of note, curcumin downregulated transcript encoded by the potentially causal TMPRSS2-ERG gene fusion, a common oncogenic alteration noted in 50-70% of prostate cancer patients. Further more, expression of EGFR and ERBB2 receptor were found to be downregulated in curcumin treated LNCaP and C4-2B cells. This report for the first time establishes novel features of Cu-GER in prostate cancer cells of varying tumorigenic phenotypes and provides potentially novel read-outs for assessing effectiveness of curcumin in prostate cancer and likely in other cancers. Importantly, new gene-networks identified here further delineate molecular mechanism(s) of action of curcumin in prostate cancer cells.

Delineation of TMPRSS2-ERG splice variants in prostate cancer.

PURPOSE: The expression of the ETS-related gene (ERG) is low or undetectable in benign prostate epithelial cells. High prevalence of ERG overexpression in prostate cancer cells due to TMPRSS2-ERG fusions suggest for causal roles of ERG protein in the neoplastic process. TMPRSS2-ERG fusion junctions have been extensively studied in prostate cancer. However, virtually nothing is known about the nature of full-length transcripts and encoded proteins. This study focuses on qualitative and quantitative features of full-length TMPRSS2-ERG transcripts in prostate cancer. EXPERIMENTAL DESIGN: Full-length TMPRSS2-ERG transcripts were cloned and sequenced from a cDNA library generated from pooled RNA of six TMPRSS2-ERG fusion-positive prostate tumors. The encoded ERG proteins were analyzed in HEK293 cells. Copy numbers of TMPRSS2-ERG splice variants were determined by quantitative reverse transcription-PCR in laser capture microdissected prostate cancer cells. RESULTS: Two types of TMPRSS2-ERG cDNAs were identified: type I, which encodes full-length prototypical ERG protein (ERG1, ERG2, ERG3), and type II, encoding truncated ERG proteins lacking the ETS domain (ERG8 and a new variant, TEPC). In microdissected prostate tumor cells from 122 patients, relative abundance of these variants was in the following order: ERG8 > TEPC > ERG 3 > ERG1/2 with combined overexpression rate of 62.3% in prostate cancer. Increased ratio of type I over type II splice forms showed a trend of correlation with less favorable pathology and outcome. CONCLUSIONS: Qualitative and quantitative features of specific ERG splice variants defined here promise to enhance the utility of ERG as a biomarker and therapeutic target in prostate cancer.

Evaluation of a nanotechnology-based carrier for delivery of curcumin in prostate cancer cells.

We have initiated studies to enhance targeted delivery of an anticancer agent, curcumin, for prostate cancer treatment by incorporating this agent into the liposomes (nanodelivery vehicles primarily composed of phospholipids) coated with prostate membrane specific antigen specific antibodies. We prepared curcumin-loaded liposomes of various lipid compositions by sonication at an average size of 100-150 nm. Un-entrapped curcumin was removed by size exclusion chromatography. Data show that curcumin preferentially partitioned into liposomes prepared from dimyristoyl phosphatidyl choline (DMPC) and cholesterol among the various compositions tested. The anti-proliferative activity of liposomal curcumin was studied using two human prostate cancer cell lines (LNCaP and C4-2B) by a tetrazolium dye-based (MTT) assay. Treatment of cells with liposomal curcumin (5-10 microM) for 24-48 h at 37 degrees C resulted in at least 70-80% inhibition of cellular proliferation without affecting their viability. On the other hand, free curcumin exhibited similar inhibition only at 10-fold higher doses (>50 microM). We also observed that LNCaP cells were relatively more sensitive to liposomal curcumin mediated block of cellular proliferation than C4-2B cells. We are currently developing liposome formulations with targeting ability to further improve the efficacy of curcumin in vivo.

Shikonin analogue (SA) 93/637 induces apoptosis by activation of caspase-3 in U937 cells.

Beta,beta-dimethyl acryl shikonin is an extract from the root of plant Arnebia nobilis which has been shown to possess anti-cancer activity. However, its toxicity limited further development of shikonin as a therapeutic agent. Subsequently, several analogues of beta,beta-dimethyl acryl shikonin were synthesized. One of these analogues, shikonin 93/637 was found to be significantly less toxic compared to shikonin. This study is aimed to determine the cell cycle associated differences in the susceptibility of U937 cells to apoptosis induced by shikonin analogue 93/637 (SA). Lower concentrations of SA (approximately 100 nM) showed no significant changes in cell growth. However, higher concentrations (approximately 500 nM) resulted in growth inhibition of U937 cells after 48 h of treatment with SA as measured by MTT assay. Flow cytometric analysis showed that SA treatment resulted in blocking of cell cycle progression in G1 phase. Decreased expression of Cyclin D, CDK 4 and PCNA was observed with SA treatment corroborating the G1 block. DNA gel electrophoresis showed an oligonucleotide ladder pattern, a distinct characteristic of DNA fragmentation associated with programmed cell death. Ribonuclease protection assay revealed inhibition of bcl2 expression at transcriptional level. SA treatment also resulted in induction of caspase-3 activity. The results suggest the involvement of bcl2 and Caspase-3 in SA induced apoptosis of human U937 cells.

Green tea polyphenol and epigallocatechin gallate induce apoptosis and inhibit invasion in human breast cancer cells.

Currently, there is no effective therapy for estrogen independent breast cancer. MDA-MB-231 is an estrogen receptor negative highly invasive human breast cancer cell line and has been used as a relevant model system to evaluate drugs with chemopreventive potential against highly invasive breast cancer phenotypes. Epidemiological studies though inconclusive have shown that consumption of Green Tea Polyphenols (GTP) reduces the incidence and progression of breast cancer. Green tea is an important source of antioxidants that may be useful for chemoprevention of cancer. Recently published preclinical study from our lab suggested that GTP and EGCG treatment inhibit proliferation and induce apoptosis of MDA-MB-231. In this study, we have evaluated apoptotic and anti-invasive activity of green tea polyphenols (GTP) and its principal constituent Epigallocatechin gallate (EGCG) in MDA-MB-231 human breast cancer cell line. In in vitro human breast cancer model, EGCG and GTP induced apoptosis and significantly decreased invasion of breast cancer cells. Western blotting of MDA-MB-231 cell lysates from EGCG and GTP treated and untreated control revealed an increase in bax, reduction in bcl2 and PARP cleavage. Quantitative fluorescence labeling resulted in a 24-28% reduction in invasion through matrigel by EGCG and 15-23% reduction by GTP in a dose dependent manner. Focussed microarray analysis and reverse transcriptase polymerase chain reaction and zymogram analysis revealed inhibition of MMP-9 expression by polyphenol treatment. Furthermore, AKT was found to be inhibited both at the RNA and protein level by polyphenol treatment. Moreover EGCG and GTP decreased AKT phosphorylation as found out by Western blotting for Phospho-AKT (Ser-473). beta-catenin level was found to be decreased both in cytoplasm and nucleus. For the first time we report the connection of beta-catenin and AKT modulation by GTP and EGCG as a possible mechanism for the induction of apoptosis in human breast cancer cells and also inhibition in their invasive capacity.

Beneficial role of curcumin in skin diseases.

In recent years, considerable interest has been focused on curcumin a compound, isolated from turmeric. Curcumin is used as a coloring, flavoring agent and has been traditionally used in medicine and cuisine in India. The varied biological properties of curcumin and lack of toxicity even when administered at higher doses makes it attractive to explore its use in various disorders like tumors of skin, colon, duodenum, pancreas, breast and other skin diseases. This chapter reviews the data on the use of curcumin for the chemoprevention and treatment of various skin diseases like scleroderma, psoriasis and skin cancer. Curcumin protects skin by quenching free radicals and reducing inflammation through nuclear factor-KB inhibition. Curcumin treatment also reduced wound-healing time, improved collagen deposition and increased fibroblast and vascular density in wounds thereby enhancing both normal and impaired wound-healing. Curcumin has also been shown to have beneficial effect as a proangiogenic agent in wound-healing by inducing transforming growth factor-beta, which induces both angiogenesis and accumulation of extracellular matrix, which continues through the remodeling phase of wound repair. These studies suggest the beneficial effects of curcumin and the potential of this compound to be developed as a potent nontoxic agent for treating skin diseases.

Picroliv accelerates epithelialization and angiogenesis in rat wounds.

Tissue repair and wound healing are complex processes that involve inflammation, granulation and tissue remodeling. Angiogenesis plays a central role in wound healing. Earlier, we have shown that picroliv, a natural product obtained from the roots of Picrorhiza kurrooa, up-regulates the expression of vascular endothelial growth factor in human umbilical vein endothelial cells and of insulin-like growth factor in rats during hypoxia. In the present study, we have investigated the effect of picroliv in an ex vivo rat aorta ring model of angiogenesis. Picroliv enhanced the sprouting and migration of endothelial cells. We also investigated punch wound healing on days 4 and 7 after wounding by histology, morphometry and collagenization. The data showed improved re-epithelialization, neovascularization and migration of various cells such as endothelial, dermal myofibroblasts and fibroblasts into the wound bed after picroliv treatment. Immunohistochemical localization showed increased VEGF and alpha smooth muscle actin staining consistent with an increased number of microvessels in granulation tissue. These findings suggest that picroliv could be developed as a therapeutic angiogenic agent for the restoration of the blood supply in diseases involving inadequate blood supply such as limb ischemia, ischemic myocardium and wound healing.

Green tea polyphenols and its constituent epigallocatechin gallate inhibits proliferation of human breast cancer cells in vitro and in vivo.

Tea [Camellia sinensis (Theaceae)] intake is second only to water in terms of worldwide popularity as a beverage. The Green tea polyphenols have been shown to have a protective effect in prostate cancer in various pre-clinical animal models and has been reported to be effective in several other cancer types as well. An inverse association between the risk of breast cancer and the intake of green tea has also been reported in Asian Americans. Several epidemiological studies have shown that breast cancer progression is delayed in the Asian population that consumes green tea on regular basis. In this study, we report the effectiveness of green tea polyphenols (GTP) and its constituent Epigallocatechin Gallate (EGCG) in tumor regression using both in-vitro cell culture models and in vivo athymic nude mice models of breast cancer. The anti-proliferative effect of GTP and EGCG on the growth of human breast cancer MDA-MB-231 cell was studied using a tetrazolium dye-based (MTT) assay. Both GTP and EGCG treatment had the ability to arrest the cell cycle at G1 phase as assessed by flow cytometry. The expression of Cyclin D, Cyclin E, CDK 4, CDK 1 and PCNA were down regulated over the time in GTP and EGCG treated experimental group, compared to the untreated control group as evaluated by western blot analysis for cell cycle proteins, which corroborated the G1 block. Nude mice inoculated with human breast cancer MDA-MB-231 cells and treated with GTP and EGCG were effective in delaying the tumor incidence as well as reducing the tumor burden when compared to the water fed and similarly handled control. GTP and EGCG treatment were also found to induce apoptosis and inhibit the proliferation when the tumor tissue sections were examined by immunohistochemistry. Our results suggest that GTP and EGCG treatment inhibits proliferation and induce apoptosis of MDA-MB-231 cells in-vitro and in-vivo. All together, these data sustain our contention that GTP and EGCG have anti-tumor properties.