Effects of miR-638 on DNA repair capability by host cell reactivation (HCR) assay. Cells were transiently co-transfected by miR-638 mimic or inhibitor with pCMU-Luc vector pre-damaged by UVC, or anticancer drugs for the evaluation of DNA repair capacity. In (A) and (B), MDA-MB-231 and Hs578T exhibited significantly reduced luciferase activity, while MCF-7 cell lines showed increased luciferase activity in miR-638 mimic-transfected cells, but there were no changes in T47D and MCF-10A when co-transfected with either miR-638 mimic or inhibitor with pCMU-Luc vector pre-damaged by UVC or cisplatin. (C) Cells were co-transfected with miR-638 mimic or inhibitor with pCMU-Luc vector pre-treated with 5-FU. Reduced DNA repair capability was only observed in Hs578T cells but not in MDA-MB-231, MCF-7, T47D and MCF-10A cell lines. (D) Cells were co-transfected with miR-638 mimic or inhibitor and pCMU-Luc vector pre-treated with epirubicin. No significant DNA repair capability changes were observed in all cell lines. Results are displayed as mean data ± SE (*P <0.05, **P <0.01). 5-FU, 5-fluorouracil.