By downregulating Ku80, hsa-miR-526b suppresses non-small cell lung cancer

Ku80 is involved in DNA double-strand breaks (DSBs) repair. Ku80 is overexpressed in lung cancer tissues, yet, molecular mechanisms have not been examined. We identified that miRNA, hsa-miR-526b, is bound to the 3′-UTR of Ku80 mRNA, thus decreasing Ku80 expression in NSCLC cells. Hsa-miR-526b was downregulated in NSCLC tissues compared with corresponding non-tumorous tissues, and its expression was inversely correlated with Ku80 upregulation. Overexpression of Ku80 and downregulation of hsa-miR-526b were associated with poor clinical outcomes of NSCLC patients. Hsa-miR-526b suppressed NSCLC cell proliferation, clonogenicity, and induced cell cycle arrest and apoptosis. Hsa-miR-526b inhibited xenografts and orthotopic lung tumor growth. Further, Ku80 knockdown in NSCLC cells suppressed tumor properties in vitro and in vivo similar to hsa-miR-526b overexpression. In agreement, Ku80 restoration partially reversed cell cycle arrest and apoptosis induced by hsa-miR-526b in NSCLC cells in vitro and in vivo. In addition, hsa-miR-526b overexpression or Ku80 knockdown increased p53 and p21(CIP1/WAF1) expression. These findings reveal that hsa-miR-526b is a potential target in cancer therapy.