目的：探讨上调miRNA-34a表达对人结肠癌细胞株体外生长的影响。方法：分别用人工合成的miRNA-34a模拟物与阴性对照序列转染人结肠癌HT-29细胞，培养一定时间后，用MTT法检测细胞增殖情况；流式细胞技术检测细胞的凋亡；qRT-PCR、Western blot法检测SIRT1的mRNA和蛋白的表达。结果：与转染阴性序列的HT-29细胞比较，转染miRNA-34a模拟物的HT-29细胞48 h后增殖能力明显降低；72 h后细胞凋亡率明显增加，miRNA-34a靶基因SIRT1的mRNA与蛋白表达均明显降低，差异均有统计学意义（均P<0.05）。结论：miRNA-34a可能通过调节其靶基因SIRT1的表达影响结肠癌细胞的生物学行为，上调miRNA-34a的表达能抑制结肠癌细胞的生长。
Effect of miRNA-34a up-regulation on growth of human colon cancer cells in vitro
Objective: To investigate the effect of up-regulating miRNA-34a expression on growth of human colon cancer cells in vitro. Methods: Human colon cancer HT-29 cells were transfected with artificially synthesized miRNA-34a mimics and negative control sequences respectively. After culture for various times, the cell proliferation was measured by MTT assay, the apoptosis was detected by flow cytometry, and the expression of SIRT1 mRNA and protein was detected by qRT-PCR and Western blot analysis, respectively. Results: Compared with HT-29 cells transfected with negative control sequences, the proliferation of HT-29 cells transfected with miRNA-34a mimics was significantly decreased after 48-h culture; the apoptosis rate was significantly increased, and both expressions of SIRT1 mRNA and protein were significantly down-regulated after 72-h culture, and all differences had statistical significance (all P<0.05). Conclusion: MiRNA-34a can influence the biological behaviors of colon cancer cells probably through regulating expression of its target gene SIRT1, and up-regulating miRNA-34a expression can inhibit the growth of colon cancer cells.