[Icariin promotes alcohol-inhibited osteogenic differentiation of MC3T3-1-E1 cells by regulating LAP autophagy]

This study investigated the mechanism of autophagy in the differentiation processes of MC3T3-E1 cells under osteogenic induction(physiological) and alcohol(AL) intervention(pathological), as well as the mechanism by which icariin(ICA) affected osteogenic differentiation of MC3T3-E1 cells under the pathological condition of AL intervention. Osteogenic mineralized nodule staining confirmed that the cells could differentiate into osteoblasts. After determining the appropriate concentrations of AL and ICA using the CCK-8 assay, seven groups were set up in this study: complete medium(CM) group, osteogenic induction medium(OIM) group, OIM+0.25 mol·L~(-1) AL group, OIM+0.25 mol·L~(-1) AL+1×10~(-8) mol·L~(-1) ICA group, OIM+0.25 mol·L~(-1) AL+1×10~(-7) mol·L~(-1) ICA group, OIM+0.25 mol·L~(-1) AL+1×10~(-6) mol·L~(-1) ICA group, and OIM+0.25 mol·L~(-1) AL+1×10~(-5) mol·L~(-1) ICA group, with a culture period of 7 days. Alkaline phosphatase(ALP) staining was used to detect the relative ALP area. Western blot and RT-qPCR were employed to analyze the expression of osteogenesis-and autophagy-related proteins and mRNAs. Reactive oxygen species(ROS) staining was used to detect ROS levels, and apoptosis was assessed through mitochondrial membrane potential assays. The results showed that ICA increased the relative ALP area that had been reduced by AL intervention. AL down-regulated the expression levels of Wnt family member 1(Wnt1), along with the osteogenesis-related mRNAs Wnt1, β-catenin, Runt-related transcription factor 2(Runx2), osteoprotegerin(OPG), and ALP, thereby inhibiting osteogenic differentiation. ICA up-regulated the expression levels of the osteogenesis-related proteins and mRNAs that had been inhibited by AL, promoting osteogenic differentiation. AL inhibited typical autophagy, while ICA regulated Rubicon to suppress LC3-associated phagocytosis(LAP) and promote typical autophagy. ICA also reduced the ROS levels that were elevated by AL and decreased the apoptosis of osteoblasts induced by AL intervention. In conclusion, ICA can regulate Rubicon to inhibit LAP, promote typical autophagy, eliminate ROS, reduce apoptosis, and ultimately enhance the osteogenic differentiation of MC3T3-E1 cells under the pathological condition of AL intervention by modulating the Wnt/β-catenin signaling pathway.