GREEN TEA CATECHINS (EGCG AND EGC) HAVE MODULATING EFFECTS ON THE ACTIVITY OF DOXORUBICIN IN DRUG-RESISTANT CELL-LINES

The chemopreventive effect of polyphenols from green tea [e.g. (-)-epi gallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC)] against c ancer has been demonstrated in several studies. The aim of this invest igation was to prove whether these compounds modulate the activity of antineoplastic drugs. Therefore, the influence of EGCG and EGC was tes ted on doxorubicin-resistant murine sarcoma (S180-dox) and human colon carcinoma (SW620-dox) cell lines. Both substances showed a sensitizin g effect on the cell lines if they had been treated with doxorubicin. These results suggest that protein kinase C may be inhibited by EGCG a nd EGG, and this may lead to a reduced expression of some drug resista nce related proteins.