Downregulation of NAD(P)H:quinone oxidoreductase 1 inhibits proliferation, cell cycle and migration of cholangiocarcinoma cells.

We previously reported that upregulation of NAD(P)H:quinone oxidoreductase 1 (NQO1) in cholangiocarcinoma (CCA; a fatal bile duct cancer) was associated with poor prognosis. It was also demonstrated that the suppression of NQO1 was able to enhance the chemosensitivity of CCA cells. In the present study, in order to elucidate the biological role of NQO1 in CCA, the effects of small interfering RNA (siRNA)-mediated knockdown of NQO1 on cell proliferation, cell cycle and migration were determined in KKU-100 CCA cells, which notably expressed NQO1. The cell proliferation ability and cell cycle distribution were identified by clonogenic cell survival assay and flow cytometric analysis, respectively. Wound healing and Transwell migration assays were performed to evaluate cell migration. The molecules involved in cell proliferation and migration were determined by western blot analysis and reverse transcription-quantitative polymerase chain reaction analysis. The results demonstrated that NQO1 siRNA-mediated knockdown effectively impaired colony formation capacity, induced cell cycle arrest at the G phase and suppressed migration of KKU-100 cells. CCA cells transfected with NQO1 siRNA exhibited increased expression levels of p21 and decreased cyclin D1 protein expression levels. Furthermore, the ratio of matrix metalloproteinase 9/tissue inhibitors of metalloproteinases 1 (TIMP1) mRNA expression level was decreased in the NQO1-knockdown cells. Therefore, the present study provided evidence supporting the biological role of NQO1 in the regulation of cell proliferation, cell cycle and migration of CCA cells. Therefore, NQO1 may prove to be a potential molecular target to enhance CCA treatment.