Epigallocatechin-3-gallate in Melanoma Management

University Of Wisconsin Madison, Madison WI

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Abstract

DESCRIPTION (provided by applicant): Cutaneous melanoma is the most lethal form of skin cancer. Because melanoma is typically refractor to available therapies, exploration of new treatment and prevention strategies is a high priority. In recent years, chemoprevention has emerged as a novel strategy for the management of neoplasia. In a recent study (Nihal et ah, Intl J Cancer; In Press), we demonstrated that epigallocatechin-3-gallate (EGCG), the major antioxidant present in green tea resulted in a significant chemopreventive effects in human melanoma Hs-294T and A-375 cells. The anti-proliferative response of EGCG was accompanied by i) induction of apoptosis, ii) down-modulation of Bcl-2, iii) up-regulation of Bax, iv) activation of caspases -3, -7, and -9, v) decrease in cyclin Dl and cdk2, and vi) induction of cyclin kinase inhibitors (ckis) p6INK4a, p21 WAF1/CIP1 and p27KPl. Our recent preliminary data demonstrated that i) EGCG inhibits the constitutive activation of NF-kappaB pathway, and ii) EGCG, in combination with interferon (IFN)-2b (a drug widely used for the treatment of melanoma), imparts synergistic anti-proliferative and pro-apoptotic effects in human melanoma cells. Based on these novel published and preliminary observation, in this application, we propose to investigate the hypothesis that the cancer chemopreventive properties of EGCG against melanoma in vivo are based on its pro-apoptotic and/or cell cycle blocking potential, which is mediated via modulations and interactions of the NF-kappaB-pathway and cki-cyclin-cdk network. We further hypothesize that EGCG will provide synergistic anti-proliferative effects against melanoma as an adjuvant in combination with standard interferon therapy. We will first assess the anti-melanoma effects of EGCG under in vivo conditions in athymic nude mice implanted with melanoma xenografts. We will then determine the specific effects of EGCG on melanoma xenografts in vivo in regard to: a) apoptosis, b) NF-kappaB-pathway, c) cki-cdk-cyclin network, and d) their interactions. Finally, we will determine if EGCG imparts synergistic anti-melanoma effects in combination with IFNalpha-2b in vivo in athymic nude mice implanted with human melanoma xenografts. We believe that the outcome of this study will establish the chemopreventive potential of EGCG against melanoma development in vivo. Further, this study will provide a basis for clinical studies involving: 1) EGCG monotherapy for the chemoprevention of recurrence in high risk primary melanoma patients following surgery and 2) EGCG/IFN combination to enhance the efficacy to allow IFN dose reduction and amelioration of IFN-toxicity in patients.