CALCITONIN DIRECTLY ACTS ON MOUSE OSTEOBLASTIC MC3T3-E1 CELLS TO STIMULATE MESSENGER-RNA EXPRESSION OF C-FOS, INSULIN-LIKE GROWTH-FACTOR-I AND OSTEOBLASTIC PHENOTYPES (TYPE-1 COLLAGEN AND OSTEOCALCIN)

The present study was performed to examine whether calcitonin directly acted on mouse osteoblastic MC3T3-E1 cells to stimulate the mRNA expression of insulin-like growth factor-1 (IGF-1) and c-fos, followed by an increase in their proliferation and differentiation. Eel calcitonin increased [H-3]thymidine incorporation and alkaline phosphatase activity as well as the mRNA expression of type 1 collagen and osteocalcin which were characteristic of osteoblasts. Eel calcitonin (10(-8)M) induced c-fos mRNA transiently after its addition, followed by gene expression of IGF-1, an important autocrine/paracrine growth factor in the regulation of osteoblastic proliferation. We first demonstrated that calcitonin directly acted on osteoblasts to stimulate transcription of c-fos and IGF-1 genes as well as functional phenotypes including type 1 collagen and osteocalcin. (C) 1994 Academic Press, Inc.