The biological effects of macrophage-colony-stimulating factor induced by progestin on growth and differentiation of endometrial adenocarcinoma cells.

Progestins have biological effects of regression and differentiation on human endometrial adenocarcinoma. We investigated the effects of progestin on the induction of macrophage-colony-stimulating factor (M-CSF) and its receptor messenger RNAs in the human endometrial adenocarcinoma cell line Ishikawa which has receptors for both estrogen and progesterone. Poly(A)+RNA extracted from Ishikawa cells cultured with or without synthetic progestin R5020 was subjected to Northern blot hybridization using M-CSF and c-fms cDNA probes. The expression of M-CSF mRNA in Ishikawa cells increased about 2.3 times following treatment with R5020 at 10(-7) M. Induction of M-CSF mRNA by R5020 was antagonized by anti-progestin RU486 in a dose-dependent manner. However, c-fms mRNA, coding the M-CSF receptor, was expressed constitutively in Ishikawa cells and its expression was not affected by hormonal treatment. We further examined the biological effects of M-CSF on endometrial cancer cells. Colony formation of Ishikawa cells in soft agar, which represents anchorage-independent cell growth, was inhibited by M-CSF treatment. On the other hand, accumulation of glycogen granules in cytoplasm detected by periodicacid-Schiff staining was observed in Ishikawa cells treated with M-CSF. These results indicate that M-CSF, whose gene expression was enhanced by progestin, suppressed growth and induced differentiation of endometrial adenocarcinoma cells. These effects of M-CSF on endometrial cancer cells are similar to those of progestins, so the effects of progestins on these cells are, at least in part, probably mediated by M-CSF in an autocrine or paracrine manner.