AIM:To explore the effects of miR-21 on biological behavior of colon cancer cells and their sensi-tivity to epidermal growth factor receptor monoclonal antibody cetuximab .METHODS:Lentiviral vectors were constructed to generate up-and down-regulations of miR-21 lentiviruses (LV-miR-21 and LV-anti-miR-21, respectively), and the cor-responding negative control viruses (LV-miR-21 NC and LV-anti-miR-21 NC, respectively) were also constructed.The vi-ruses were used to infect human colon cancer RKO cells .The changes of the miR-21 expression level , the cell prolifera-tion, the colony-forming ability, the cell apoptosis and the sensitivity of the cells to cetuximab were detected by real -time PCR, MTT assay, soft agar colony assay , flow cytometry and CCK-8 assay.RESULTS: The lentivirus titers of LV-miR-21, LV-miR-2 NC, LV-anti-miR-21 and LV-anti-miR-21 NC were 3.0 ×1012 TU/L, 6.0 ×1011 TU/L, 2.0 ×1012 TU/L and 8.0 ×1011 TU/L, respectively.The infection efficiency was over 80% by the observation of green fluorescence .The miR-21 expression level , the cell proliferation , and the colony-forming ability in LV-miR-21 group were significantly higher than those in LV-anti-miR-21 group.The early apoptotic rate and the inhibitory rate of cetuximab for the cells in LV-anti-miR-21 group were higher than those in LV-miR-21 group.CONCLUSION: miR-21 promotes the proliferation of colon cancer cells.Down-regulation of miR-21 enhances the sensitivity of the colon cancer cells to the targeted therapy drug cetuximab.%目的：探讨miR-21在结肠癌细胞中的生物学功能及对EGFR单抗西妥昔敏感性的影响。方法：通过慢病毒载体的构建及包装生成上调/下调miR-21的慢病毒LV-miR-21和LV-anti-miR-21并感染人结肠癌RKO细胞，采用qRT-PCR、MTT、非锚定依赖性细胞生长、流式细胞术、CCK-8等技术检测上调/下调miR-21后细胞的miR-21表达水平、细胞增殖、克隆形成能力、细胞凋亡能力及对西妥昔单抗药物敏感性的变化。结果： LV-miR-21与LV-anti-miR-21慢病毒的滴度分别为3．0×1012 TU/L和2．0×1012 TU/L，将病毒颗粒分别感染人结肠癌RKO细胞，观察绿色荧光，感染效率在80％以上。 LV-miR-21组的miR-21表达水平、细胞增殖能力和克隆形成能力均高于LV-anti-miR-21组，差异有统计学意义（P＜0．05）。而LV-anti-miR-21组的细胞早期凋亡率及西妥昔单抗对细胞的抑制率均高于LV-miR-21组（P＜0．05）。结论：miR-21可促进结肠肿瘤细胞的增殖。下调miR-21可以增加结肠癌细胞对靶向治疗药物西妥昔单抗的敏感性。
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