The correlation between PAK5 (P21-activated kinase 5) and Ezrin gene expression and chemotherapy resistance of osteosarcoma patients was investigated. The cisplatin (CDDP)-resistance model of osteosarcoma cells SOSP-9607/CDDP was established to detect the cell growth curve. Methyl thiazolyl tetrazolium (MTT) assay was used to detect the drug resistance of cells to chemotherapy drugs. Transwell assay was used to detect the invasive capacity of cells. Semi-quantitative PCR (qPCR) was used to detect the mRNA expression levels in the drug resistance-related genes PAK5 and Ezrin. Western blot analysis was used to detect the protein expression levels in PAK5 and Ezrin. Tumor tissues were taken from the osteosarcoma patients with chemotherapy resistance to detect the expression levels of PAK5 and Ezrin via immunohistochemical detection, and the correlation between PAK5 and Ezrin expressions was studied. The results of MTT assay showed that the growth rate of SOSP-9607 was similar to that of SOSP-9607/CDDP, and the difference was not statistically significant (P>0.05). The sensitivity of SOSP-9607 to CDDP was significantly higher than that of SOSP-9607/CDDP, and the difference was statistically significant (P<0.01). Transwell assay showed that the migration capacity of SOSP-9607/CDDP was significantly better than that of SOSP-9607 (P<0.01), indicating that the drug resistance cell lines of osteosarcoma were constructed successfully. Semi-qPCR and western blot analysis showed that the protein expression levels in PAK5 and Ezrin in SOSP-9607/CDDP were significantly higher than those in SOSP-9607 (P<0.01). The results of immunohistochemistry showed that the expression quantities of PAK5 and Ezrin in osteosarcoma tissues were significantly higher than those in para-tumor tissues (P<0.01). Pearson's correlation analysis showed that expression of PAK5 and Ezrin was positively correlated (r=0.197, P=0.023). The osteosarcoma resistance is closely related to the expression levels of PAK5 and Ezrin genes. Thus, PAK5 and Ezrin genes may affect the tolerance of osteosarcoma patients to chemotherapy drugs during treatment via the synergistic effect.

The effects of mesenchymal stem cells (MSCs) from three different sources in the treatment of bone defect with stem cells, and the differences of curative effects were studied. The umbilical cord, adipose and bone marrow mesen-chymal stem cells (BMSCs) of Sprague-Dawley (SD) rats were isolated and extracted, and the phenotype was identified for the 4th generation. The SD rat model of bone defect was established. The rats were randomly divided into: Normal saline group, umbilical cord mesenchymal stem cell (UMSC) group, adipose mesenchymal stem cell (AMSC) group and BMSC group. Rats were treated with tail intravenous injection, followed by radiological examination. The relative expression levels of factors bone morphogenetic protein-2 (BMP-2), osteocalcin (OCN), alkaline phosphatase (ALP), sclerostin (SOST), collagen carboxy-terminal telopeptide (CTX) and tartrated resistant acid phosphatase (TRACP) were measured via fluorescence quantitative PCR and western blotting. Among the three different kinds of stem cell supernatant, the detection using bicinchoninic acid (BCA) method showed that the content of P4-generation new cytokines was the highest. Wound healing in the three stem cell supernatant groups was significant at 3 weeks after operation, which was faster than that in DF12 control group; the expression levels of BMP-2, OCN and ALP in the bone samples treated with three kinds of MSC supernatants after 5 weeks were significantly increased compared with those in control group. The expression levels of SOST, CTX and TRACP were significantly decreased compared with those in control group. Three kinds of MSC supernatants can promote the bone regeneration through promoting the secretion of relatively more osteoblast factors, and inhibit the bone loss. The concentration of cytokines in UMSC supernatant was the highest under the same culture condition, and BMSC supernatant has a better effect in improving the bone defect repair of rats under the same concentration of cytokines.

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