Alteration of intercellular communication in a human urothelial carcinoma cell-line by tumor-promoting agents.

BACKGROUND

Most of the findings that support a good association between inhibition of intercellular communication and tumor promotion have been demonstrated by studies of animal cells, while it has been accepted that most tumor-promoting agents are specific to species and organs. Therefore, the influence of tumor-promoting agents on intercellular communication was investigated using a human urothelial cell-line.

METHODS

The effects of six tumor-promoting agents, including dichlorodiphenyltrichloroethane (DDT), butylated hydroxyanisole (BHA), saccharin, cyclamic acid, phenobarbital, and DL-tryptophan, on intercellular communication in a human urothelial cell-line (JTC-30) were investigated by using a dye-transfer assay after 48- and 96-hour exposure to each agent. Cytotoxicity was determined using the colony-forming method after 48-hour and 7-day exposure to each agent.

RESULTS

DDT, BHA, saccharin, and cyclamic acid inhibited intercellular communication after either 48- or 96-hour exposure at concentrations that were nontoxic to the cells after 7-day exposure. Phenobarbital and DL-tryptophan inhibited intercellular communication only at toxic concentrations.

CONCLUSIONS

Since the former four agents are known to be direct tumor promoters, and the metabolites of the later two agents have been regarded as tumor promoters, the results suggest that current methodology using the JTC-30 cell-line may be applicable to the screening to detect direct tumor promoters of human urothelium.