Biochemical and Biophysical Research Communications, Vol.524, No.4, 929-935, 2020
The role of autonomously secreted PGE2 and its autocrine/paracrine effect on bone matrix mineralization at the different stages of differentiating MC3T3-E1 cells
Bone is consisted of osteoblast-linage cells, bone-forming cells in various differentiation stages. However, it is not fully understood how communicate and interact these cells immigrated from bone marrow. In this study, we showed that prostaglandin E2 (PGE(2)) had a role in autonomous modification of matrix mineralization in osteoblastic cell line, MC3T3-E1, and interactions across the cells in different differentiation stages. Analysis using LC-MS/MS and inhibitors showed the autonomous secretion of PGE(2) among the prostanoids in differentiation stages and that depend on COX-2, a key enzyme for production of PGE(2). Treatment with inhibitors of PGE(2) receptors and COX-2 indicated that secreted PGE(2) regulates matrix mineralization in an autocrine/paracrine manner. In addition, we showed that the expression profile of PGE(2) receptors (EP1-EP4) and PGE(2) effects on matrix mineralization derived from it changed during cell differentiation. Treatment with inhibitors of PGE(2) signaling in the early differentiation stage of MC3T3-E1 cells induced significant changes in matrix mineralization several days after. Stimulation with the extracts from culture medium of the matured cells including PGE(2) and co-culture with the matured cells secreting PGE(2) significantly promoted matrix mineralization of the early stage cells, in contrast, treatment with inhibitor of COX-2 and PGE(2) receptors failed to do so. These results support that PGE(2) plays important roles in the interaction system of osteoblast-linage cells in bone tissue to regulate matrix mineralization reflecting condition of bone-forming cells, that is, population and maturation. (C) 2020 Elsevier Inc. All rights reserved.