CircIFNGR2 enhances proliferation and migration of CRC and induces cetuximab resistance by indirectly targeting KRAS via sponging to MiR-30b

Currently the clinical efficacy of colorectal cancer (CRC) which is the most common malignant tumors over the world has not reached an ideal level. Cetuximab, the monoclonal antibody targeting the extracellular domain of EGFR, has shown its great efficacy in the promotion of apoptosis and the inhibition of tumor cells-like characteristics in numerous cancers. However certain KRAS wild-type CRC patients unexpectedly show cetuximab resistance and the specific mechanism remains unclear. Circular RNAs (circRNAs) as the promising novel type of biomarkers in the cancer diagnosis and therapy, have been reported to be related with the drug resistance. In this study, with wondering the mechanism of cetuximab resistance in KRAS wild-type CRC patients, we evaluate the impact of circIFNGR2 on CRC and detect the association among circIFNGR2, miR-30b and KRAS via various experiments such as RT-qPCR, immunohistochemistry, luciferase assays, cell functional experiments and xenograft model. We conclude that circIFNGR2 induces cetuximab resistance in colorectal cancer cells by indirectly regulating target gene KRAS by sponging miR-30b at the post-transcriptional level. It is thus suggested that inhibition of circIFNGR2 can be a promising therapeutic strategy for malignant CRC patients with cetuximab resistance.