IL-8 is involved in radiation therapy resistance of esophageal squamous cell carcinoma via regulation of PCNA.

Esophageal squamous cell carcinoma (ESCC) is one of the prevalent and deadly cancers worldwide, especially in Eastern Asia. Our present study revealed that the expression of IL-8 was increased in radiation therapy resistance of ESCC cells. Targeted inhibition of IL-8 by its neutralization antibody (anti-IL-8) can re-sensitize ESCC cells to radiation therapy and suppress the expression of proliferating cell nuclear antigen (PCNA). IL-8 can regulate the expression of PCNA via modulating its mRNA stability and promoter activity. Mechanistically, IL-8 can regulate the expression of miR-27b-5p, which can directly bind with 3′UTR of PCNA to decrease its mRNA stability. Further, anti-IL-8 can decrease the expression of transcription factor YY1, which can bind with the promoter of PCNA to increase its transcription. Taken together, our data revealed that IL8 can regulate the radiation resistance of ESCC cells and expression of PCNA. It suggested that targeted inhibition of IL-8 may improve the clinical treatment efficiency of radio therapy.