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Fatty acid synthase (FAS) is a key enzyme of lipogenesis and its overexpression is found in proliferative cells. The extracts of pu-erh, black, oolong and green teas could reduce FAS expression at both the protein and mRNA levels in hepatocellular carcinoma HepG2 cells. FAS expression in HepG2 cells was strongly inhibited by PI3K inhibitor LY294002 and JNK inhibitor II and slightly inhibited by p38 inhibitor SB203580 and MEK1 inhibitor PD98059, separately. It suggested that the suppression of FAS by tea extracts may occur through down-regulation of the PI3K/AKt and JNK signaling pathways. Furthermore, the expression of FAS in the livers of rats fed pu-erh, black, oolong and green tea leaves were significantly suppressed. The gains in body weight, levels of triglyceride, total cholesterol, and LDL-cholesterol were also suppressed in the tea-fed rats. Although all 4 teas are active in suppressing the body weight gain, levels of lipids and FAS expression, pu-erh tea is the most active one.The major components of tea that have been demonstrated to be responsible for the anti-obesity and hypolipidemic effects are catechins, caffeine, and theanine. The composition of catechins, caffeine and theanine varied dramatically in pu-erh, black, oolong and green teas. The active principles and molecular mechanisms that exerted these biological effects in these teas deserve for further investigation.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA