LEUKEMIA INHIBITORY FACTOR SUPPRESSES PROLIFERATION, ALKALINE-PHOSPHATASE ACTIVITY, AND TYPE-I COLLAGEN MESSENGER-RIBONUCLEIC-ACID LEVEL AND ENHANCES OSTEOPONTIN MESSENGER-RNA LEVEL IN MURINE OSTEOBLAST-LIKE (MC3T3E1) CELLS

The effect of leukemia inhibitory factor (LIF) on proliferation and phenotypic expression in murine osteoblastlike (MC3T3E1) cells was examined. LIF inhibited the proliferation of these cells by up to 20% and DNA synthesis was inhibited in a dose-dependent manner with an ED50 of about 0.2 ng/ml. The effect of LIF relative to matched controls increased with decreasing serum concentration, reaching 30% inhibition at 0.2% serum. LIF also reduced the stimulatory effects of platelet-derived growth factor and insulin-like growth factor I on DNA synthesis. The inhibition of the DNA synthesis by saturating concentration of transforming growth factor β was further enhanced by the addition of LIF, suggesting independent pathways for the action of the two growth inhibitors. In addition, LIF reduced alkaline phosphatase activity and the abundance of type I collagen messenger RNA, but increased the level of osteopontin messenger RNA. These findings suggest that LIF may play a role in regulating the function of osteoblasts. © 1990 by The Endocrine Society.