Mechanism of chemopreventive synergism from the combination of EGCG and Erlotinib

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DESCRIPTION (provided by applicant): Squamous cell carcinoma of the head and neck (SCCHN), a serious healthcare problem in the United States and worldwide, is one of the deadliest of all cancers with more than 48,000 new cases diagnosed and 15,000 deaths each year in the United States. SCCHN is significantly associated with exposure to tobacco carcinogens. Both former and active smokers remain at high risk of developing invasive cancer in tobacco carcinogen-exposed fields - especially the oral cavity and larynx. These cancers generally begin as small, often unnoticed, lesions inside the mouth and more than one third of untreated precancerous oral lesions undergo malignant transformation into squamous cell cancer. Despite advances in conventional surgical procedures, radiotherapy, and chemotherapy, the overall survival rate for SCCHN has not been significantly improved in past few decades. Moreover, a large fraction of these precancerous lesions recur despite complete surgical removal. An effective prevention method which can be implemented before invasive cancer develops is highly desirable in reducing the incidence of SCCHN and other tobacco carcinogen-related malignancies. The current proposal is designed for the prevention of premalignant lesions of the head and neck using a combinatorial approach. The overexpression of epidermal growth factor receptor (EGFR) has been found in 80-90% of SCCHN, in dysplastic lesions and histologically normal mucosa from SCCHN patients, indicating that EGFR upregulation represents an early event in carcinogenesis and may serve as an important target for intervention in developing preventive strategies. However, EGFR inhibitors showed only modest response rates as single agents. The combination of erlotinib with other chemopreventive agents might improve efficacy through synergistic growth inhibitory properties. However, the critical challenge is to identify an effective combination which can offer synergistic growth inhibition. We hypothesize that using the combination of erlotinib, an EGFR inhibitor, with EGCG, a multi targeted natural compound, may reduce cancer incidence and greatly benefit patients at high risk for developing cancer. Specific Aim 1 focuses on the mechanism of synergy between these two compounds with special emphasis on FOXO-p21/p27/Bim and mTOR-pS6 signaling and their regulation by AKT and ERK. Specific Aim 2 seeks to determine whether the expression levels of selected biomarkers in biopsied tissue samples are favorably modulated by the combined treatment. PUBLIC HEALTH RELEVANCE: Both active and former smokers remain at high risk of developing invasive cancer in tobacco carcinogen- exposed fields - especially the oral cavity and larynx and a chemopreventive approach is highly desirable to reduce the number of tobacco carcinogen-related malignancies including head and neck. This project focuses on the identification of molecular targets which are critical for the synergistic chemopreventive potentia of a combination of EGFR TKI erlotinib and green tea polyphenol EGCG. This combined chemoprevention treatment is a novel approach to blocking carcinogenesis and may further impact and reduce cancer incidence and help to design Phase II trial.