ObjectiveTo explore the key molecules regulated by norcantharidin (NCTD) in colon cancer treatment.MethodsWe used cell counting kit-8 and 5-ethnyl-2′-deoxyuridine/Hoechst staining assays to study the effects of NCTD on cell proliferation in colon cancer. Annexin V-fluorescein isothiocyanate/propidium iodide staining was used to evaluate apoptosis, whereas Transwell assays were conducted to evaluate migration and invasion. We performed RNA sequencing to analyze the changes in gene expression after treatment. Differential analysis was performed using differential expression sequencing 2 (Deseq2) in R. Cytoscape was used to construct a competing endogenous RNA (ceRNA) network and Gene Expression Omnibus (GEO) datasets were used to validate sine oculis homeobox homolog 4 (SIX4) expression in colon cancer tissues. Furthermore, the prognostic potential of SIX4 was evaluated using receiver-operating characteristic curves. We conducted an immune infiltration analysis to explore the SIX4 relationship with the immune microenvironment in colon cancer. Finally, SIX4 expression, pan-cancer prognosis, tumor mutation burden (TMB) correlations, microsatellite instability (MSI), and mismatch repair (MMR) were analyzed.ResultsNCTD inhibited colon cancer cell proliferation (P .0001), induced apoptosis (P = .0007), and suppressed the migration and invasion of colon cancer cells. The H19/miR-193b-3p/SIX4 axis was identified as the key ceRNA network involved in the anticancer activity of NCTD. SIX4 is highly expressed in colon cancer tissues, shortening patient survival and affecting immune infiltration. A pan-cancer analysis showed that SIX4 overexpression affects the survival of various cancers. Finally, we correlated SIX4 expression with TMB, MSI, and MMR expression.ConclusionNCTD inhibits the malignant behaviour of colon cancer cells. SIX4 is abnormally expressed in multiple tumor types, significantly affecting the overall survival of patients with cancer, and is a core regulatory target of NCTD in the treatment of colon cancer.