Inhibition of Junctional Intercellular Communication as a Possible Short-Term Test to Detect Tumor-promoting Agents: Results with Nine Chemicals Tested by Dye Transfer Assay in Chinese Hamster V79 Cells1

In an attempt to establish an in vitro short-term test to detect tumorpromoting agents, we studied the effects of these agents on Junctional intercellular communication in cultured Chinese hamster V79 cells using a microinjection-dye transfer technique. When Lucifer Yellow CH solu tion is injected into a cell, the average number of cells that become fluorescent after 10 min is 11.6 ±7.8 (SD). When the phorbol ester 12O-tetradecanoylphorbol-13-acetate was used as a positive control, the extent of dye transfer was reduced to 2.9 ±2.1 cells within 2 h after incubation with 12-0-tetradecanoylphorbol-13-acetate(100 ng/ml). Nine chemicals that have been reported to have or suspected of having tumorpromoting activity in experimental animals were tested at different doses and after different incubation times. l,l,l-Trichloro-2,2-bisO?-chlorophenyl)ethane, lindane (1,2,3,4,5,6-hexachlorocyclohexane), phénobar bital, and butylated hydroxyanisole showed inhibitory properties in V79 cells, but with kinetics different from that of 12-O-tetradecanoylphorbol13-acetate. With l,l,l-trichloro-2,2-bis(/7-chlorophenyl)ethane and lin dane, exposure for 24 h resulted in full blockage of dye transfer; with phénobarbital,a treatment time of 96 h was necessary to achieve this effect, and butylated hydroxyanisole was more active after 48 h than after 24 or 72 h incubation. Five of the reported or suspected tumorpromoting agents, benzoyl peroxide, anthralin, deoxycholic acid, lithocholic acid, and butylated hydroxytoluene, had no effect on communica tion between V79 cells at noncytotoxic doses; deoxycholic acid, lithocholic acid, and butylated hydroxytoluene but not anthralin inhibited commu nication only at cytotoxic doses. Our results indicate that we can detect several, but not all, types of tumor-promoting agents, using microinjec tion-dye transfer assay of Junctional communication between Chinese hamster V79 cells.