ZIP7 Maintains Colon Cancer Radioresistance by Regulating Zinc-dependent Epithelial-mesenchymal Transition

Abstract Background: Irradiation-induced radioresistance often leads to the therapeutic failure of colon cancer. By regulating the redistribution of intracellular zinc, ZIP7 plays a dominating role in the activation of many critical signaling pathways in the progression of tumors. However, the relationship between ZIP7 and radioresistance is still unclear. Methods: ZIP7 expression of colon cancer was evaluated by analyzing public data from the GEPIA and CPTAC databases and validated based on immunohistochemistry (IHC) staining. Clonogenic survival assay was employed to examine the influence of intracellular zinc interference and ZIP7 knockdown on radioresistance of colon cancer, based on radioresistant colon cancer cells. At last, Western blot was performed to preliminarily explore the potential mechanisms. Results: ZIP7 was significantly upregulated in human colon cancers compared with adjacent normal tissues. ZIP7 knockdown could significantly reduce the radioresistance of colon cancer cells, while transmembrane ionophore of zinc could partially reverse this effect. In terms of mechanisms, ZIP7 knockdown significantly reversed the radiation-induced expression of elevated ZEB1 and down-regulated E-cadherin through regulating zinc. Conclusion: ZIP7 is crucial to maintain radioresistance of colon cancer cells through regulation of zinc distribution, and at least partially by maintenance of epithelial-mesenchymal transition (EMT).