IN-VITRO INHIBITION OF GAP JUNCTIONAL INTERCELLULAR COMMUNICATION BY CHEMICAL CARCINOGENS

This study was conducted to assess the effects of chemical carcinogens on the gap junction-mediated intercellular communication in cultured mammalian cells. The method of scrape-loading dye transfer of lucifer yellow was adapted as a measure of gap junctional communication. Clone 9 cells derived from rat liver were treated with a model chemical car cinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and the gap junct ional communication was assessed by measuring the transfer of scrape-l oaded lucifer yellow dye. When cells were treated with the carcinogen at 0.3 mg/ml, the fluorescent dye transfer was inhibited by 90% in 60 min. Other chemical agents, which include direct or indirect carcinoge ns and antitumor drugs, were also examined for their effects on the ga p junctional communication. Direct carcinogens, such as MNNG, hydroxyl amine and ethidium bromide, exhibited strong inhibition of intercellul ar communication, while indirect carcinogens, such as aflatoxin B-1 an d ethionine, exerted minor effects. Effects of test chemicals on the c ell communication through gap junctions were readily quantitated by co unting the number of cells stained with the fluorescent dye.