Affiliations: Laboratory for Cancer Research, College of Pharmacy,
Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8020,
USA
Note: [] Laboratory for Cancer Research, College of Pharmacy, Rutgers,
The State University of New Jersey, 164 Frelinghuysen Road, Piscataway, NJ
08854-8020, USA. Tel.: +1 732 445 5361; Fax: +1 732 445 0687; E-mail:
[email protected]
Abstract: Tea {\it (Camellia sinensis)} preparations have been shown to
inhibit tumorigenesis at the initiation, promotion, and progression stages in
different animal models. The anti-proliferative effects of tea polyphenols may
be a key mechanism, especially in the NNK-induced lung tumorigenesis model with
mice. Studies with cell lines have demonstrated that tea polyphenols inhibit
cell proliferation and induce apoptosis. The effective concentrations used in
these studies (20--100 \muM) are usually higher than those
observed in blood and tissues of humans and animals, which are in the low
micromolar range. Glucuronide and sulfate conjugated and methylated catechins
as well as ring fission products (due to intestinal microflora) have been
observed in human plasma and urine. Purified green and black tea polyphenols
inhibited the H-{\it ras} induced mitogen-activated protein kinases, AP-1
activities, and the growth of 30.7b Ras 12 and BES21 cells. Among the
catechins, both the galloyl structure on the B ring and the gallate moiety are
important for the inhibition. Both
(-)-epigallocatechin-3-gallate and
theaflavin-3,3'-digallate inhibited the phosphorylation of
c-jun and p44/42 (ERK 1/2). More mechanistic and human studies in these areas
will help us to understand the possible inhibitory action of tea against
carcinogenesis in humans. Abbreviations: EGCG,
(-)-epigallocatechin-3-gallate; EGC,
(-)-epigallocatechin; ECG,
(-)-epicatechin-3-gallate; EC,
(-)-epicatechin; NNK,
4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone; DGT, decaffeinated green tea;
MAP kinase, mitogen activating protein kinase; AP-1, activator protein-1;
NF\kappaB, nucleoprotein factor
\kappaB.
Journal: BioFactors, vol. 13, no. 1-4, pp. 73-79, 2000
