ABSTRACT
@#[Abstract] Objective: To investigate the effect of double oxidase 2 (DUOX2) on the sensitivity of colorectal cancer (CRC) cells to 5-fluorouracil (5-FU). Methods: CRC cell lines DLD-1, SW480, HCT116, SW620 and normal intestinal epithelial cell line NCM460 were selected, and the expression of DUOX2 in these cell lines were detected by qPCR. DUOX2 expression in HT-29 and HCT116 cells was stably knocked down by lentivirus infection technique. The knockdown efficiency was detected by qPCR and WB. Cells in sh-Control and sh-DUOX2 groups were treated with 5-FU at different concentrations (0, 5, 10, 20, 40, 80, 120 μg/ml). The effects of 5-FU on cell proliferation, apoptosis and cell cycle were detected by CCK-8 method and flow cytometry. HT29 cell transplanted xenograft model in nude mice was constructed to observe the effect of DUOX2 gene on the treatment efficacy of 5-FU. Results: the expression level of DUOX2 mRNA in CRC cells was significantly higher than that in NCM460 cells (P<0.05 or P<0.01). Compared with sh-Control group, the mRNA and protein expressions of DUOX2 in sh-DUOX2 group were significantly decreased (all P<0.01); the sensitivity of cells to 5-FU was enhanced, the apoptosis rate and the ratio of cells at G0/G1 phase were significantly increased (all P<0.01), and the ratio of cells at G2 and S phase was significantly decreased (all P<0.01). There was no significant difference in tumor volume and mass between sh-Control group and sh-DUOX2 group without 5-FU treatment (all P>0.05), but the volume and mass of transplanted tumor in sh-DUOX2+5-FU group after 5-FU treatment was significantly lower than that in sh-Control+5-FU group (all P<0.01). Conclusion: The sensitivity of CRC cells to 5-FU can be significantly enhanced by knocking down DUOX2 gene.