Induction of heat labile alkaline phosphatase by butyrate in differentiating endometrial cells

The addition of 2 mM sodium butyrate to monolayers enhances differentiation of Ishikawa endometrial cells. Cells from this cell line have been shown to enlarge and lift off the dish into dome structures over a period of 24-48 h in response to a factor in fetal bovine serum (FBS) [Fleming, 1995 J Cell Biochem in press]. When butyrate is added to monolayers, together with FBS, three- to fourfold higher numbers of differentiated structures, domes and predomes, can be counted. It had previously been shown [Holinka et al., 1986b] that estradiol induces heat stable placental alkaline phosphatase in Ishikawa cells. The addition of butyrate, on the other hand, results in a significant increase in levels of a heat labile alkaline phosphatase isozyme. The heat labile isozyme is also increased to some extent in cells stimulated to differentiate in response to FBS in the absence of butyrate. Differential inhibition by homoarginine and phenylalanine indicates that butyrate is inducing the liver-bone kidney isozyme that is found in endometrial glands in vivo.