Inhibitory effect of testosterone on gap junctional intercellular communication of human transitional cell carcinoma cell lines.

A dye transfer method was applied to investigate the effect of testosterone on gap junctional intercellular communication (IC) of two kinds of human transitional cell carcinoma cell lines, JTC-30 and JTC-32. When JTC-30 cells were cultured with testosterone at nontoxic concentrations (17-69 microM), a dose and time dependent inhibition of dye transfer was observed. More than 90% inhibition occurred after exposure to 69 microM testosterone for 96 h. The inhibition was reversed rapidly after testosterone deprivation. Similar results were obtained with JTC-32 cells. 17 beta-Estradiol showed no inhibitory effect on IC of both transitional cell carcinoma cell lines even at toxic levels. Testosterone exhibited no inhibitory effect on IC of human fibroblasts. The inhibitory effect of 5 alpha-dihydrotestosterone was almost similar to that of testosterone. At concentrations examined, cyproterone acetate influenced neither dye transfer nor the inhibitory effect of testosterone, suggesting a mechanism of testosterone action different from that of the known receptor system. Since blockage of IC has been indicated as one reliable evidence for tumor promotion, current results suggest that testosterone is a possible endogenous promoter of the bladder carcinoma and may therefore possibly play a role on the sexually different incidence of bladder carcinoma.