An expanding body of preclinical evidence suggests EGCG, the major catechin found
in green tea (Camellia sinensis), has the potential to impact a variety of human diseases.
Apparently, EGCG functions as a powerful antioxidant, preventing oxidative damage
in healthy cells, but also as an antiangiogenic and antitumor agent and as a modulator
of tumor cell response to chemotherapy. Much of the cancer chemopreventive properties
of green tea are mediated by EGCG that induces apoptosis and promotes cell growth
arrest by altering the expression of cell cycle regulatory proteins, activating killer
caspases, and suppressing oncogenic transcription factors and pluripotency maintain
factors. In vitro studies have demonstrated that EGCG blocks carcinogenesis by affecting
a wide array of signal transduction pathways including JAK/STAT, MAPK, PI3K/AKT, Wnt
and Notch. EGCG stimulates telomere fragmentation through inhibiting telomerase activity.
Various clinical studies have revealed that treatment by EGCG inhibits tumor incidence
and multiplicity in different organ sites such as liver, stomach, skin, lung, mammary
gland and colon. Recent work demonstrated that EGCG reduced DNMTs, proteases, and
DHFR activities, which would affect transcription of TSGs and protein synthesis. EGCG
has great potential in cancer prevention because of its safety, low cost and bioavailability.
In this review, we discuss its cancer preventive properties and its mechanism of action
at numerous points regulating cancer cell growth, survival, angiogenesis and metastasis.
Therefore, non-toxic natural agent could be useful either alone or in combination
with conventional therapeutics for the prevention of tumor progression and/or treatment
of human malignancies.
Copyright © 2011 Elsevier Inc. All rights reserved.