Differentiative and proliferative effects of (But)2cAMP, n-butyric acid and prednisolone on the malignant melanoma cell line (TM-1) in vitro and in vivo.

Both (But)2cAMP and n-butyric acid suppressed the proliferation of TM-1 cells and induced the formation and elongation of the cellular processes in vitro. Prednisolone stimulated the proliferation of TM-1 cells and increased the number of polygonal cells in vitro. These results indicated that (But)2cAMP and n-butyric acid induce the differentiation of TM 1 cells, whereas prednisolone brings the cells in an undifferentiated state. The growth of TM-1 cell tumor transplanted into nude mice was suppressed by 5 mg of (But)2cAMP and 1 mg of theophylline. Remarkable histological changes were seen in the tumors treated with these agents as compared with untreated tumors. This suggests that (But)2cAMP suppresses the proliferation of TM-1 cells in vivo.