Expression of mitochondrial fusion protein-2 in melanoma tissues and its effect on the biological activity of tumor cells / 医学研究生学报

ABSTRACT

Objective　Melanoma is a malignant tumor with high clinical malignancy, rapid progression, poor prognosis and high mortality. It is of great clinical significance to explore the molecular mechanism of high metastasis of melanoma and find new tumor markers and therapeutic targets. The expression of mitochondrial fusion protein-2 (MFN2) in cutaneous melanoma tissues and peritumoral tissues was studied, and its correlation with clinical parameters was analyzed. The correlation between MFN2 and the biological behavior of melanoma was also discussed.　Methods　Immunohistochemistry was used to detect the expression of Med19 protein in cutaneous melanoma tissues and peritumoral tissues, and to analyze the correlation between MFN2 expression and clinical factors in patients. The lentiviral vector containing MFN2 coding sequence (Lenti-MFN2) infected with melanoma cell B16 was set up as the study group, and the lentivirus with green fluorescent protein gene (Lenti-GFP) as the control group. The mRNA and protein expressions of MFN2 and Ras-Raf1-ERK1/2 signaling pathways in transfected cells were detected by real-time quantitative PCR (qRT-PCR) and Western blot. Flow cytometry was used to detect changes in cell cycle and apoptosis. MTT assay and colony formation assay were used to detect changes in cell viability and proliferation capacity.　Results　The positive expression rate of MFN2 in peritumoral tissues was significantly higher than that in the skin melanoma tissues (83.9% vs 30.6%, P<0.05). MFN2 expression was associated with both lymph node metastasis and TNM staging (P<0.05). Compared with the control group, the proliferation activity and colony forming ability of B16 cells in the study group were significantly inhibited (P<0.05); the proportion of G0/G1 phase cells in B16 cells in the study group significantly increased [(46.3±10.3)% vs (67.9±12.6)%], and the apoptosis rate significantly increased [(12.5±1.6)% vs (57.4±12.6)%], with statistically significant differences (P<0.05). In comparison with the control group, the expression of Ras, Raf, ERK1/2 mRNA and protein in the study group significantly decreased (P<0.05).　Conclusion　MFN2 is down-regulated in melanoma tissues. Up-regulation of MFN2 expression can inhibit melanoma proliferation and promote cell apoptosis, which may be related to the inhibition of Ras-MAPK signaling pathway activity.