Inhibiting effect of microRNA-187-3p on osteogenic differentiation of osteoblast precursor cells by suppressing cannabinoid receptor type 2.

Induction of osteoblast differentiation is an effective approach in promoting osteoblastogenesis and bone formation. MicroRNA (miR) is a kind of small regulatory RNA molecules that control both physiological and pathological processes. The purpose of this research was to explore the function of miR-187-3p in proliferation and osteogenic differentiation in human osteoblastic precursor cells (hFOB 1.19). Our results showed a significant promotion of cell proliferation by miR-187-3p in hFOB 1.19 cell accompanied by increased proliferating cell nuclear antigen (PCNA) and Ki67 expression, whereas miR-187-3p knockdown led to an inhibition of cell proliferation. Moreover, our data revealed that miR-187-3p was decreased in hFOB 1.19 cells undergoing osteoblastic differentiation. Silencing of miR-187-3p dramatically accelerated hFOB 1.19 osteoblastic differentiation, as evidenced by the increase of alkaline phosphatase (ALP) activity and calcium deposition, as well as elevated osteopontin (OPN), collagen type I alpha 1 (COL1A1), and bone sialoprotein (BSP) gene expression, whereas overexpression of miR-187-3p suppressed osteoblastic differentiation. Furthermore, we demonstrated that miR-187-3p could inhibit cannabinoid receptor type 2 (CNR2) expression by targeting its 3' untranslated region (UTR). Upregulation of CNR2 inversed the inhibiting influence of miR-187-3p on hFOB 1.19 osteogenic differentiation. Collectively, our results showed a pivotal role of miR-187-3p/CNR2 axis in osteoblastic differentiation, indicating that miR-187-3p may serve as a promising target in the therapy of osteoporosis.