It was planned to synthesize miR-let-7 overexpression (mimics) and interference expression (inhibitor) and transiently transfect colon cancer cell HCT116, detect the expression levels of miR-let-7 and HMGA2 in the cells after transfection and the targeted regulation effect of miR-let-7 on HMGA2, then detect the effect of upregulation/downregulation of miR-let-7 on HMGA2, and detect the proliferation, migration, and invasion of HCT116 cells. The gene discussed is HMGA2; the disease is malignant colon neoplasm.