ACY-1215, a HDAC6 inhibitor, decreases the dexamethasone-induced suppression of osteogenesis in MC3T3-E1 cells

Glucocorticoid-induced osteoporosis is the commonest form of drug-induced osteoporosis. Histone deacetylase 6 (HDAC6) is involved in the differentiation from mesenchymal stem cells to osteoblasts. However, the role of ricolinostat (ACY-1215, HDAC6 inhibitor) in the dexamethasone (Dex)-induced proliferation and differentiation of preosteoblasts remains to be elucidated. The protein expression and mRNA expression levels of HDAC6, osteopontin (OPN), runt-related transcription factor 2 (Runx2), osterix (Osx), collagen I (COL1A1) and glucocorticoid receptor (GR) in MC3T3-E1 cells were analyzed by western blot analysis and reverse transcription-quantitative PCR analysis. The cell viability was detected by CCK-8 assay. The alkaline phosphatase (ALP) activity and capacity of mineralization was determined by ALP assay kit and alizarin red staining. HDAC6 expression was increased in patient serum and Dex-induced MC3T3-E1 cells at a certain concentration range; 1 µM Dex was selected for further experimentation. Cell viability was decreased after Dex induction and restored following ACY-1215 treatment. The ALP activity and capability for mineralization was decreased when MC3T3-E1 cells were induced by 1 µM Dex and was gradually improved by the treatment of ACY-1215 at 1, 5 and 10 mM. The expression of OPN, Runx2, Osx and COL1A1 was similar, with the changes of capability for mineralization. Furthermore, GR expression was increased in Dex-induced MC3T3-E1 cells. ACY-1215 promoted the GR expression in MC3T3-E1 cells from 1–5 mM while GR receptor expression was increased with 10 mM ACY-1215 treatment. In conclusion, ACY-1215 reversed the Dex-induced suppression of proliferation and differentiation of MC3T3-E1 cells.