Res. Chem. Intermed.
, Vol. 30, No. 6, pp. 627–636 (2004)
Also available online - www.vsppub.com
Redifferentiation of human hepatoma cells induced
by green tea polyphenols
, FANG DAI
, CHENYANG ZHAO
, QINGYI WEI
, LI YANG
, RONGLIANG ZHENG
and ZHONGLI LIU
National Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou,
Gansu 730000, China
School of life science, Lanzhou University, Lanzhou, Gansu 730000, China
Tianjin Medical University, Tianjin, 300070, China
Gansu Provincial People’s Hospital, Lanzhou, Gansu 730000, China
Received 12 March 2004; accepted 20 April 2004
Abstract—A novel approach for the treatment of cancer is the differentiation therapy in which cancer
cells are induced to attain a mature phenotype when exposed to differentiation inducers. To examine
the effects of polyphenols extracted from green tea, i.e. (−)-epicatechin (EC), (−)-epigallocatechin
(EGC), (−)-epicatechin gallate (ECG) and (−)-epigallocatechin gallate (EGCG), on the proliferation
and redifferentiation of human hepatoma cell line SMMC-7721, we measured the changes of cell
growth, cell surface charge and cell morphography after treament with green tea polyphenols. It was
found that the growth curve of treated cells was decreased remarkably, cell surface charge of treated
cells was decreased and the microvilli on the surface of treated cells were reduced obviously. It
conﬁrmed that green tea polyphenols could reverse malignant phenotypic characteristics and induced
redifferentiation of SMMC-7721 cells. The ability of green tea polyphenols to inhibit reactive
oxygen species (ROS)-mediated oxidative damage of DNA was also assessed in vitro by measuring
the conversion of supercoiled pBR322 plasmid DNA to the open circular and linear forms. It was
found that green tea polyphenols could signiﬁcantly inhibit the oxidative damage of DNA induced by
a water-soluble azo initiator 2,2
-azobis(2-amidinopropane hydrochloride) (AAPH). However, they
could promote the oxidative damage of DNA induced by H
at high concentrations.
The relationship between the anti-cancer activity and antioxidation-prooxidation activity of green tea
polyphenols is discussed.
Keywords: Green tea polyphenols; redifferentiation; anti-cancer; antioxidation; DNA damage.
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