Abstract: ObjectiveTo detect the changes of mitochondrialdynamicsproteins(Mfn2 and Drp1) in cell line SW579, and the effects of Mdivi-1 on cell proliferation,apoptosis and invasion of cell line SW579. Methods In SW579 and Nthy-ori 3-1, the expression levels of Mfn2 and Drp1 were determined by western blot, the Mfn2 and Drp1 mRNA expression levels were measured by RT- PCR .Then, SW579 cells were divided into control group(DMSO, 0.1%)and Mdivi-1 group (different concentrations of Mdivi-115，30 and 45 μmol/L). SW579 cells were treated with Mdivi-1 for 16 h。Then the ability of cell proliferation was detected using MTT assay,the mitochondrial membrane potential was detected by fluorescence spectrophotometer, the expression levels of cytochrome C and Caspase-3 were measured by Western blot, the Cyt C and Caspase-3 mRNA expression levels were determined by RT- PCR. the ability of invasion in each group was measured with Transwell assays. Results Compared with Nthy-ori 3-1,The mRNA and protein expression of the Mfn2 was remarkably decreased, whilethe mRNA and protein expression of the Drp1 was significantly increased in SW579 (P＜0.01). Compared with the control group, the cell survival rates and the mitochondrial membrane potential of SW579 weredecreased dramatically(P＜0.01),the mRNA and protein expression of the cytochrome C and Caspase-3 were increased dramatically (P＜0.01), the capability of invasion was markedly decreased in the Mdivi-1 group (P＜0.01) , which are all in a concentration-dependent manners (P＜0.01). Conclusion Abnormal mitochondrial dynamics may be involved in thyroid squamous cell carcinomaSW579 cells; Mdivi-1 can inhibit the cell proliferation as well as invasion, and also induce apoptosis.

Key words: thyroid neoplasms, carcinoma, squamous cell, cell proliferation, apoptosis, mitochondrial dynamics, Mdivi- 1, Mfn2, Drp1