Estradiol via estrogen receptor beta inhibits chondrogenesis of mouse vertebral growth plate in vitro.

PURPOSE: Abnormal growth of vertebral growth plate (VGP) was considered as one of the etiologic factors in adolescent idiopathic scoliosis (AIS). Previous studies described that estrogen played an important role in the pathogenesis of AIS. The present study was aimed to investigate the effect of estrogen/estrogen receptor axis on mouse VGP chondrocytes in vitro. METHODS: Chondrocytes were isolated from mouse VGP and treated with or without 17ß-estradiol (E2). Cell proliferation was measured by the cell growth rate assay. Gene expression of collagen type II and aggrecan were evaluated by real-time PCR. Expression of the proliferating cell nuclear antigen (PCNA), Sox9, and Smad4 were detected by Western blotting. RESULTS: Estradiol inhibited the proliferation of VGP chondrocytes and the gene expression of collagen type II and aggrecan and downregulated the protein expression of PCNA, Sox9, and Smad4. In addition, the inhibitory effect of estradiol was reversed by ERß small interfering RNA (siRNA) or PHTPP, an ERß antagonist. CONCLUSIONS: Estradiol via estrogen/estrogen receptor ß axis inhibits the proliferation and differentiation of VGP chondrocytes, which might give some new insight into the regulatory mechanism of bone development.