Abstract
OBJECTIVES: Human papillomavirus (HPV) infection is closely associated with the development of more than 95% of cervical cancer. Clinical trials using several chemopreventive agents are underway, but results are inconclusive. Most agents used in trials inhibited the growth of cancer cells in vitro, and about half of patients had some degree of clinical responses; however, the therapeutic effect was confounded by high rates of spontaneous regression and relapse. The selection of nontoxic agents especially food, beverage, and natural products that suppress oncogenic HPV, inhibit malignant transformation, and can additionally be used long term may be important for cervical cancer prevention. METHODS: We evaluated green tea compound (epigallocatechin gallate and polyphenols E) effects on immortalized cervical epithelial and cervical cancer cells. HPV-immortalized cervical epithelial cells, TCL1, and HPV-positive cervical cancer cells, Me180 and HeLa, were used in the study. The effects of green tea compounds on cell growth, apoptosis, cell cycle, and gene expression were examined and characterized. RESULTS: Both epigallocatechin gallate and polyphenols E inhibited immortalized cervical epithelial and cancer cell growth. Apoptosis induction and cell cycle changes were observed in a dose-dependent manner. Western blot analysis of apoptosis-related proteins, p53 and p21, showed dose-dependent increase, whereas p27 was not affected. HPV-E7 protein expression was decreased by green tea compounds. CONCLUSIONS: This study provides information on the potential mechanisms of action of green tea compounds in suppression of HPV-related cervical cells, and it will enable us to assess the feasibility of using these agents.