The Molecular Mechanism Of MiR-572 Inhibiting The Malignant Biological Behavior Of Colorectal Cancer Cells And Enhancing Their Sensitivity To Chemotherapy

Objective:Colorectal cancer has a high incidence and malignancy,and the unclear molecular mechanism of colorectal cancer is one of the reasons limiting the development of molecular diagnosis and precision therapy,miRNA,the most intensively studied non-coding RNA,has been proved to be closely related to the occurrence and development of various tumors.There have been studies suggesting that many miRNA are abnormally expressed in colorectal cancer tissues,such as miR-17,miR-19a,miR-21,miR-125,etc.But there are still many miRNAs in colorectal cancer are not fully studied.In order to have a more comprehensive understanding of the occurrence and development mechanism of colorectal cancer,it is essential to further study these mirnas and explore their clinical significance.The purpose of this study was to investigate the expression characteristics of miR-572 in colorectal cancer,and to explore whether miR-572 might affect the biological function of colorectal cancer cells,and to elucidate its molecular mechanism.Methods:The expression differences of miR-572 in colorectal cancer tissues and corresponding adjacent tissues were detected,and the correlation between the expression of miR-572 and the clinical characteristics of patients was analyzed.Then,we transfected siRNA to overexpress or knock down miR-572 in colorectal cancer cell line by liposome method,and then evaluated the effect of miR-572 on the biological behavior of colorectal cancer cells by CCK8 experiment,plate cloning experiment,Transwell chamber migration experiment,wound healing assay experiment,cell apoptosis test and other experiments.Bioinformatics methods were used to predict the possible target genes of miR-572,which were further verified by double luciferase reporter genes and other experiments.Finally,Westernblot was used to investigate the possible signaling pathway.Results:qPCR results showed that the average expression level of miR-572 in colorectal cancer tissues and colorectal cancer cell lines was significantly lower than that in the control group,and the expression of miR-572 was related to tumor differentiation degree(P=0.049),invasion depth(P=0.041),lymph node metastasis(P<0.05),distant metastasis(P=0.017)and AJCC stage(P<0.05).CCK8 assay and plate cloning assay showed that miR-572 significantly inhibited the proliferation of colorectal cancer cells.Flow cytology showed that miR-572 induced G0-G1 phase arrested in colorectal cancer cells.Transwell chamber migration assay and cell wound healing assay showed that miR-572 inhibited the migration ability of colorectal cancer cells.miR-572 reduced the IC50 of 5-FU in colorectal cancer cells and significantly increased the apoptosis rate of miR-572.miR-572 inhibited subcutaneous tumorigenesis in nude mice.Overexpression of miR-572 inhibited SYT7 3’UTR double luciferase activity,and the fluorescence intensity did not decrease after the mutation of its binding site.Overexpression of miR-572 inhibited the expression of SYT7,which reversed the inhibitory effect of miR-572 on the proliferation of colorectal cancer cells and restored the promoting effect of miR-572 on the sensitivity of colorectal cancer cells to 5-fluorouracil chemotherapy.Westernblot showed that overexpression of miR-572 can cause changes in PI3K/AKT pathway related proteins,and overexpression of SYT7 can restore the above changes.Conclusion:miR-572 inhibited the malignant biological behavior of colorectal cancer cells and enhancing their sensitivity to chemotherapy by targeting SYT7 and inhibiting the PI3K/AKT signaling pathway.