IKKα-mediated biogenesis of miR-196a through interaction with Drosha regulates the sensitivity of cancer cells to radiotherapy.

Radioresistance is a major obstacle in successful clinical cancer radiotherapy, and the underlying mechanisms are not clear. Here we show that IKKα-mediated miR-196a biogenesis via interaction with Drosha regulates the sensitivity of nasopharyngeal carcinoma (NPC) cells to radiotherapy. Phosphorylation of IKKα at T23 site (p-IKKαT23) promotes the binding of IKKα to Drosha that accelerates the processing of miR-196a primary transcripts, leading to increased expressions of both precursor and mature miR-196a. Dephosphorylation of p-IKKαT23 downregulates miR-196a expression and promotes the resistance of NPC cells to radiation treatment. The miR-196a mimic suppresses while its inhibitor promotes the resistance of NPC to radiation treatment. Importantly, the expression of p-IKKαT23 is positively related to the expression of miR-196a in human NPC tissues, and expression of p-IKKαT23 and miR-196a is inversely correlated with NPC clinical radioresistance. Thus, our studies establish a novel mechanistic link between the inactivation of IKKαT23-Drosha-miR-196a pathway and NPC radioresistance, and de-inactivation of IKKαT23-Drosha-miR-196a pathway would be an efficient way to restore the sensitivity of radioresistant NPC to radiotherapy.