·Primary cultured MSCs were isolated from the bone marrow of C57BL/6J mice and humans. After the mouse MSCs were given different concentrations (0?12.50 μmol/L) of etoposide for 12, 24, 36, 48 and 60 h, the cell proliferation ability was detected by CCK-8 kit assay. The apoptosis detection kit was performed to detect apoptosis of osteoblast/osteosarcoma cell line UMR-106 treated by etoposide (0, 0.001, 0.01, 0.1, 1 μmol/L). The mouse and human MSCs (simultaneously inducing osteogenic differentiation), and UMR-106 cells were treated with etoposide (0, 0.001, 0.01, 0.1, 1 μmol/L), whose osteogenic differentiation was analyzed by alkaline phosphatase (ALP) staining and alizarin red staining. The mRNA levels of osteogenic differentiation markers i.e., Alp, osteocalcin, and collagen type Ⅰ α 1 chain were analyzed by real-time quantitative PCR. After the UMR-106 cells were treated with etoposide (0.001 μmol/L), Illumina Xten′s high-throughput transcriptome sequencing and bioinformatics analysis were used to find the target gene related with osteogenic differentiation, which was then verified by PCR. Western blotting was used to detect the expression of osterix (OSX), runt-related transcription factor 2 (RUNX2) and DNA binding inhibitor 1 (ID1) in the etoposide (0, 0.001, 0.01, 0.1, 1 μmol/L) treated mouse MSCs.

·The effect of etoposide on the proliferation of mouse MSCs was concentration-dependent. When the concentration was ≥0.20 μmol/L, etoposide inhibited the proliferation of MSCs. The half-maximal inhibitory concentrations (IC₅₀) for 48 h and 60 h were 2.192 μmol/L and 1.399 μmol/L, respectively. Apoptosis detection results showed that the apoptotic rates of UMR-106 cells treated with 0.001?1 μmol/L etoposide were 16.137%?28.300%. The results of ALP staining, alizarin red staining and PCR showed that etoposide at 0.001?0.1 μmol/L significantly promoted the osteogenic differentiation of mouse and human MSCs and UMR-106 cells. RNA sequencing analysis showed that etoposide up-regulated connective tissue growth factor expression in the UMR-106 cells. Western blotting results showed that 0.001 and 0.01 μmol/L etoposide significantly increased the protein expression of OSX, RUNX2 and ID1 in the mouse MSCs.

·The anti-tumor drug etoposide can promote the osteogenic differentiation of MSCs, which may be related to the up-regulation of ID1, RUNX2 and OSX expressions.