Expression of MYH9 in human osteosarcoma tissues and its effects on epithelial-mesenchymal transition and invasion of osteosarcoma cells / 医学研究生学报

ABSTRACT

Objective Non-muscle myosin heavy chain 9 (MYH9) plays an important regulatory role in the development of tumor.This study aimed to explore the expression of MYH9 in osteosarcoma tissues and its effects on epithelial-mesenchymal transition and invasion of osteosarcoma cells.Methods We collected 52 cases of osteosarcoma tissues and para-carcinoma tissues at 5 cm form the edge of the tumor.RT-PCR and immunohistochemistry were used to analyze the expression level of MYH9 mRNA and protein in the osteosarcoma tissues and para-carcinoma tissues.MYH9 shRNA plasmid was transfected into U2-OS cells to silenced the expression of MYH9, after transfected, the cells were divided into three groups the normal U2-OS cells were the control group, the U2-OS cells transfected with empty plasmid were the empty group and U2-OS cells transfected with MYH9 shRNA were interference group.RT-PCR was used to detect the changes of MYH9 mRNA levels in the U2-OS cells, the protein level of MYH9, EMT related protein E-cadherin and Vimentin were detected by Western blot, and the ability of cell invasion was evaluated by Transwell assay.Results The results of RT-PCR showed that the relative expression MYH9 mRNA in para-carcinoma tissues(1.526±0.148) was significantly lower than that in cancer tissues (3.547±0.195) (P<0.05).The results of immunohistochemistry showed that MYH9 protein was mainly expressed in cytoplasm, and the expression in cancer tissues was significantly higher than that in para-carcinoma tissues, the positive expression rate were 59.6%(31/52) and 26.9%(14/52) respectively, the difference was statistically significant(P<0.05).The results of Western blot showed that the relative expression of MYH9 mRNA in interference group was significantly lower than that in control group and empty group (P<0.05) after silenced MYH9 gene, and compared with the control group, the E-cadherin in U2-OS cells was significantly up-regulated but the Vimentin was down-regulated.After 48h, all of the groups had cells through the microfiltration membrane, the numbers of cells through the microfiltration membrane in interference group(41.2±15.1) was significantly lower than that in control group(117.3±12.4) and empty group(193.5±14.7) (P<0.05).Conclusion The expression of MYH9 protein in osteosarcoma tissues was significantly higher than that in para-carcinoma t tissues, silenced MYH9 gene can reduce the invasive ability of osteosarcoma by reducing the epithelial interstitial transition.