MicroRNA-552 Promotes Tumor Cell Proliferation And Migration By Directly Targeting DACH1 Via Wnt/β-catenin Signaling Pathway In Colorectal Cancer

Objective The aim is to investigate the effect of microRNA-552(miR-552)on proliferation and migration of colorectal cancer cells,and to explore the target genes of miR-552 downstream and the target regulation relationship.Thus elucidating the specific molecular regulation mechanism of mi R-552 on the biological function of colorectal cancer.Methods1.Detect expression of miR-552 in colorectal cancer tissues and cell lines by RT-qPCR.2.MiR-552-inhibitor(miR-552-in)was transfected into colorectal cancer LOVO and SW620 cells.The transfection efficiency was observed and the stable expression cell lines were selected.3.The effect of miR-552 level on the proliferation ability of tumor cells was detected by MTT and plate colony formation assays.4.The effect of miR-552 on the migration ability of tumor cells was detected by transwell and wound-healing assays.5.Verify the downstream target of miR-552 through Luciferase reporter assay.6.The expression of DACH mRNA and protein level were detected by RT-qPCR and Western blotting,respectively.7.Expression of core protein in Wnt/β-catenin signaling pathway were tested by Western blotting.Results1.The average expression level of miR-552 in colorectal cancer tissues and cell lines: we detected 20 pairs of colorectal cancer tissues and adjacent normal tissues,the result indicated that the expression of miR-552 in cancer tissues was significantly higher than that in normal tissues.Furthermore,compared with normal colorectal cell line NCM460,the expression of miR-552 was significantly increased in colorectal cancer cell lines,such as LOVO,SW620 and HCT116.2.The cell growth rate slowed down,the number of flat clone formation decreased and the cell migration ability descended after transfection of miR-552-in,compared with control group(transfected with mi R-552-NC).3.Luciferase reporter assay showed that DACH1 was confirmed to be the downstream target of miR-552.4.The results of RT-qPCR and western blotting showed that the expression of DACH1 mRNA and protein level were both increased when the expression of miR-552 was downregulated.5.The changes of core protein of Wnt/β-catenin signaling pathway were detected by western blotting.The results showed that compared with the negative control group,the protein expression of c-Myc,cyclinD1,DACH1,β-catenin and GSK3β decreased after transfected with miR-552-in.Conclusions Through this experiment research proves that miR-552 is highly expressed in colorectal cancer tissues and cell lines,it can promote the proliferation and migration of tumor cells as a cancer gene.Inhibiting the expression of miR-552 can decrease the proliferation and migration ability of tumor cells.DACH1 is the downstream target gene of miR-552.MiR-552 inhibits the expression of DACH1 through the Wnt/β-catenin signaling pathway,thereby promoting the proliferation and migration of colorectal tumor cells.