TELOMERASE INHIBITION, TELOMERASE SHORTENING, AND SENESCENCE OF CANCER-CELLS BY TEA CATECHINS

Animal in vivo studies and human epidemiological observations indicate d potent anticancer effects for tea. Here we demonstrate that epigallo catechin gallate (EGCG), a major tea catechin, strongly and directly i nhibits telomerase, an enzyme essential for unlocking the proliferativ e capacity of cancer cells by maintaining the tips of their chromosome s. Telomerase inhibition was elaborated in a cell-free system (cell ex tract) as well as in living cells. In addition, the continued growth o f two representative human cancer cell lines, U937 monoblastoid leukem ia cells and HT29 colon adenocarcinoma cells, in the presence of nonto xic concentrations of EGCG showed life span limitations accompanied wi th telomere shortening, chromosomal abnormalities, and expression of t he senescence-associated beta-galactosidase. It is suggested that telo merase inhibition could be one of the major mechanisms underlying the anticancer effects of tea. (C) 1998 Academic Press.