| Objective To investigate the function and mechanism of small integrated membrane protein 22 (SMIM22) in malignant progression of lung cancer. Methods First, TCGA database was used to obtain the expression level of SMIM22 in lung cancer tissue. Then the effects of SMIM22 on the proliferation, apoptosis and cycle of lung cancer cells were observed in H1299 and H1975 cells. The effect of interference was observed by qPCR and the effect on lung cancer cell proliferation was assessed by CCK 8, and that on lung cancer cell apoptosis and cycle was evaluated by flow cytometry. The effect of interfering SMIM22 on the levels of p-MEK, MEK and c-myc protein in H1299 cells was detected by Western blot. The effect of interfering SMIM22 on the mRNA expression of c-myc downstream genes Cyclin D2, Cyclin E1, CDK 2 and CDK 4 was determined by qPCR. Results Compared with the adjacent tissues, the expression of SMIM22 was higher in lung cancer tissue (P＜0.05) and was related to the poor prognosis of patients. The decreased expression of SMIM22 inhibited lung cancer cell proliferation, promoted cell apoptosis and blocked the cell cycle at G0/G1 phase. After knocking down SMIM22, the expression level of proteins related to MEK-MYC pathway (such as p-MEK, c-MYC) decreased, and the expression level of related genes (such as Cyclin D2, Cyclin E1, CDK2, CDK4) also decreased significantly (P＜0.01).Conclusion SMIM22 ws highly expressed in lung cancer tissue and participates in the malignant development of lung cancer by regulating the MEK-MYC pathway, which may become a new potential diagnostic index and therapeutic target for lung cancer. |
