Hypoxia‐induced factor‐1α promotes radioresistance of esophageal cancer cells by transcriptionally activating LINC01116 and suppressing miR‐3612 under hypoxia

Abstract

Esophageal cancer (EC) is a challenging tumor to treat with radiotherapy, often exhibiting resistance to this treatment modality. To explore the factors influencing radioresistance, we focused on the role of hypoxia‐induced factor‐1α (HIF‐1α), and its interaction with the long noncoding RNA long intergenic nonprotein coding RNA 1116 (LINC01116). We analyzed the LINC01116 expression in EC and EC cell lines/human normal esophageal epithelial cell line (Het‐1A). LINC01116 was silenced/overexpressed in EC109/KYSE30 cells under hypoxia, followed by radioresistance assessment. We measured HIF‐1α levels in hypoxic EC cells and further validated the binding of HIF‐1α with LINC01116, analyzing their interaction in EC cells. We then performed experiments in EC109 cells by transfection them with sh‐HIF‐1α/oe‐LINC01116 to verify the effects. Additonally, we analyzed the localization of LINC01116 and its binding with miR‐3612, followed by a combined experiment performed to validate the results. Our findings indicated that LINC01116 was highly expressed in EC and further elevated in hypoxic EC cells. LINC01116 was expressed at a high level in EC, which was further elevated in EC cells under hypoxic conditions. Knockdown of LINC01116 triggered EC cell apoptosis, thus suppressing radioresistance. Further investigation revealed that HIF‐1α transcriptionally activated LINC01116 expression under hypoxia, and silencing HIF‐1α lowered EC cell radioresistance by downregulating LINC01116. Under hypoxic conditions, LINC01116 could function as a sponge for miR‐3612 and inhibit its expression. This interaction between LINC01116 and miR‐3612 played a crucial role in mediating radioresistance in EC cells. Briefly, under hypoxic conditions, HIF‐1α facilitates radioresistance of EC cells by transcriptionally activating LINC01116 expression and downregulating miR‐3612.