The long-term goal of this revised application is to design effective prevention strategies for reducing the incidence of liver cancer in high-risk populations. Primary liver cancer, mainly hepatocellular carcinoma (HCC), is one of the most common cancers in Asia and Africa. The poor prognosis of this malignancy results in it being the third most common cause of cancer deaths in the world. Chronic infection with hepatitis B viruses (HBV) and dietary aflatoxin exposure are two major etiologic risk factors for HCC in high-risk areas. The great challenge in cancer prevention and control is how to manage those who have already been exposed to carcinogens, such as individuals who are HBsAg carriers and have long-term aflatoxin exposure. Chemoprevention has been proposed as the good tool to target these high-risk populations. Among various identified chemopreventive agents, green tea polyphenols (GTP) have been shown to be safe and high effective in inhibition of carcinogen-induced mutagenesis and tumorigenesis in bioassays and animal models for different target organ sites, including aflatoxin-induced liver tumors.
The specific aims for this study are (1) to incorporate molecular biomarkers analysis for aflatoxin exposure, HBV infection, and oxidative DNA damage into an on-going randomized, double blinded, and placebo-controlled intervention trial of GTP in 1,800 residents who are double seropositive of HBsAg and aflatoxin-albumin adduct in Fusui County, Guangxi Zhuang Autonomous Region, People's Republic of China; efficacy of the chemopreventive trial will be determined by monitoring changes of levels of risk-factor specific molecular biomarkers and the actual incidence of HCC in the studied population. (2) to examine and assess the efficacy of GTP in reducing aflatoxin biomarkers by measuring aflatoxin-albumin adducts in serum and various aflatoxin biomarkers in urine collected from 300 participants in different time of the study. Difference in metabolic phenotypes/genotypes as they related to aflatoxin biomarker levels will be determined. (3) to evaluate the inhibitory effect of GTP on HBV-associated markers including HBV-DNA replication and HBV-induced immunologic changes in serum samples. (4) to determine antioxidative role of GTP in inhibition of the level of 8-hydroxy-2'-deoxyguanosine in urine samples collected from the study participants and (5) to determine and assess long-term bioavailability and biotransformation of GTP and the long-term toxicological effect of GTP on study participants. The results of this study would help to evaluate the chemoprotective effect of GTP against human HCC and to understand the molecular mechanisms of GTP in chemoprevention of human HCC caused by well-defined major risk factors.
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