[The effects of etretinate and anticancer drugs on the cell line of a squamous cell carcinoma of human skin (HSC-1)].

The purpose of this study is to examine the effects on the HSC-1 cell cycle of etretinate and anticancer drugs (BLM, 5-FU, MMC, PSK), using flow cytometry, and those of combined treatment on cell counts in HSC-1 cell culture. In the DNA histogram, when HSC-1 cells in the stationary period were exposed to etretinate, the S phase cells increased as a proportion of the cell population, mainly because of accelerated development from the G1 + 0 phase into the S phase. Combine treatment with etretinate, BLM and 5-FU decreased the number of HSC-1 cells to a greater extent than combined treatment with BLM and 5-FU. These results suggest that the stimulation of the G1 + 0 phase by etretinate enhanced the cytotoxicity of the anticancer drugs, and that a combination of etretinate with these drugs was effective in treating malignant epithelial tumors.