INHIBITORY-ACTION OF (-)-EPIGALLOCATECHIN GALLATE ON RADIATION-INDUCED MOUSE ONCOGENIC TRANSFORMATION

The anticarcinogenic activity of a major component of green tea, (-) e pigallocatechin gallate (EGCg) was examined by using the radiation-ind uced oncogenic transformation in C3H10T1/2 cells. EGCg substantially s uppressed the radiation-induced transformation so that the transformat ion frequency with 15 mu M of ECCg was reduced nearly to spontaneous l evels. This effect of EGCg was in a dose-dependent manner and signific ant suppression of transformation was observed even in treatment of ce lls with 5 mu M of EGCg concentration where the cytotoxicity was mild, The inhibitory effect of EGCg was maximal when it was present during the entire incubation period. However, neither treatment Drier to nor concurrent with radiation was effective, suggesting that EGCg action i s mainly involved in the promotional stage of C3H10T1/2 cell transform ation. (C) 1997 Elsevier Science Ireland Ltd.