Keratinization of transformed epithelial cells of the rat urinary bladder: its quantification and effect of various drugs.

In vitro and in vivo transformed epithelial cells of the rat urinary bladder keratinized well on a coverslip culture. Keratinization proceeded more rapidly in in vitro-transformed cells than in in vivo-induced bladder cancer cells. The grade of keratinization was estimated from the absorption spectrum of a papanicolaou-stained specimen which afforded two peaks derived from keratinized cells and viable cells. Using this semiquantitative method, effect of various drugs on keratinization was studied on 3 lines of in vitro-transformed epithelial cells. Vitamin A and its analogs prevented the keratinization in 2 out of 3 lines at dosage over 1 micrograms/ml, but other drugs such as vitamin C, E, and K, steroid hormones, cyclic AMP, polyamines, polyanions, and dimethyl sulfoxide were ineffective for preventing keratinization. Amino acid compositions of keratinized cells and viable cells were not fundamentally different.