FLAVONOIDS (APIGENIN, TANGERETIN) COUNTERACT TUMOR PROMOTER-INDUCED INHIBITION OF INTERCELLULAR COMMUNICATION OF RAT-LIVER EPITHELIAL-CELLS

We have shown previously that two flavonoids, apigenin and tangeretin, enhance gap junctional intercellular communication (GJIC) in rat live r epithelial cells, named REL cells. Here, we show that these two flav ones also antagonize the inhibition of GJIC induced by tumor promoters like 12-O-tetradecanoyl-phorbol acetate (TPA) and 3,5,di-tertio-butyl -4-hydroxytoluene (BHT). Their preventive effect is rapid. It does not seem to involve any change of the amount of the connexin expressed in REL cells, connexin 43 (Cx 43), and in its phosphorylation state. Oth er flavonoids tested including naringenin, myricetin, catechin and chr ysin did not enhance GJIC nor counteract TPA-induced inhibition of GJI C. (C) 1997 Elsevier Science Ireland Ltd.