Sensitivity of a human oral carcinoma cell line to retinoic acid.

We have examined the effect of retinoic acid (RA) on proliferation of KB cells in both anchorage dependent and independent growth conditions. Our study shows that RA can cause a reduction in cell proliferation rate both in monolayer and in agar cultures. After 48 h of exposure to RA, the cells started to assume a flattened appearance and no longer formed multilayers. RA treatment also caused increase in generation time, reduction in saturation density and induced cell-to-substratum adhesiveness. These changes were reversed within 48 h after removal of RA from growth medium. The results show that this cell line is sensitive to RA-induced growth inhibition and morphologic alterations which are generally associated with reduced expression of the malignant phenotype.