目的：探讨双氧化酶 2（dual oxidase 2，DUOX2）对结直肠癌（colorectal cancer，CRC）细胞5-氟尿嘧啶（5-fluorouracil，5-FU）药物敏感性的影响。方法：选用CRC细胞系DLD-1、SW480、HCT116、SW620与正常肠上皮细胞株NCM460，用qPCR法检测细胞中DUOX2的表达水平。利用慢病毒感染技术，稳定敲降HT-29与HCT116细胞中DUOX2表达，qPCR法和WB法检测敲降效率。用不同浓度（0、5、10、20、40、80、120 μg/ml）5-FU处理sh-Control组与sh-DUOX2组细胞 ，用 CCK-8 法、流式细胞术分别检测5-FU对细胞增殖、细胞凋亡和细胞周期的影响。构建裸鼠 HT29 细胞移植瘤模型，观察DUOX2基因对5-FU疗效的影响。结果：DUOX2 mRNA 在 CRC 细胞中的表达水平显著高于 NCM460 细胞（P<0.05 或 P<0.01）。 敲 降 DUOX2 基 因后，与sh-Control 组 相 比 ，sh-DUOX2 组 HT29和HCT116细胞中DUOX2 mRNA和蛋白表达水平明显下降（均P<0.01）；细胞对5-FU的敏感性增强，细胞凋亡率明显升高（均 P<0.01），G0/G1 期比例显著升高、G2 期与 S 期比例显著下降（均P<0.01）。未经5-FU治疗的sh-Control组与sh-DUOX2组裸鼠移植瘤体积及质量比较差异均无统计学意义（均P>0.05），经5-FU治疗的sh-DUOX2+5-FU组移植瘤体积及质量明显低于sh-Control+5-FU组（均P<0.01）。结论：敲降DUOX2基因可显著增强CRC细胞对5-FU的敏感性。

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.

国家癌症中心肿瘤科研专项课题（No. NCC2017A23）