摘要目的:探讨c-Myc调控的微小RNA(miRNA，miR)表达及其在三阴性乳腺癌(TNBC)转移中的作用机制。方法:采用慢病毒构建c-Myc低表达的人乳腺癌细胞系MDA-MB-231，分为c-Myc沉默组、阴性对照组和空白对照组，分别对不同MDA-MB-231细胞进行miRNA测序，实时定量反转录聚合酶链反应(RT-qPCR)验证具有显著差异的hsa-let-7a、hsa-let-7c、hsa-let-7d、hsa-miR-34c和hsa-miR-98在细胞中的表达，及20例三阴性乳腺癌组织和癌旁组织中c-Myc和hsa-let-7a的表达水平。采用方差分析、Sidak方法比较多组差异分析。结果:与对照组比较，c-Myc沉默组中有126个miRNA存在显著差异，其中84个显著上调，42个显著下调。RT-qPCR验证发现与对照组比较(1.007±0.128，1.003±0.084，1.008±0.138，1.013±0.184，1.009±0.148)，在c-Myc沉默组中，hsa-miR-34c(0.693±0.167， F＝6.825， P<0.05)、hsa-miR-98下调(0.737±0.145， F＝5.260， P<0.05)，hsa-let-7a(1.474±0.349， F＝7.081， P<0.05)、hsa-let-7c(1.630±0.485， F＝7.387， P<0.05)、hsa-let-7d上调(2.104±0.636， F＝11.370， P<0.05)。 结论:c-Myc调控let-7a、let-7c、let-7d、miR-34c和miR-98影响三阴性乳腺癌侵袭转移。

abstractsObjective:To investigate the expression of microRNA (miRNA, miR) regulated by c-myc and its mechanism in triple negative breast cancer (TNBC).Methods:Human breast cancer cell line MDA-MB-231 with c-myc knockdown was constructed by lentivirus and divided into c-myc knockdown group, negative control group and blank control group. MiRNA sequencing was performed on different MDA-MB-231 cells, respectively. The expression of hsa-let-7a, hsa-let-7c, hsa-let-7d, hsa-miR-34c and hsa-miR-98 with significant differences in cells was verified by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR), as well as the expression levels of c-Myc and hsa-let-7a in 20 triple-negative breast cancer tissues and paracancerous tissues. Variance analysis, Sidak method were used to compare the differences between the groups.Results:Compared with the control group, 126 miRNAs were significantly different in c-Myc knockdown cell lines, 84 of which were significantly up-regulated and 42 of which were significantly down-regulated. RT-qPCR confirmed that compared with control group (0.693±0.167, 1.003±0.084, 1.008±0.138, 1.013±0.184, 1.009±0.148), hsa-miR-34c (0.693±0.167, F=6.825, P<0.05), hsa-miR-98 (0.737±0.145, F=5.260, P<0.05) was significantly down-regulated, hsa-let-7a (1.474±0.349, F=7.081, P<0.05), hsa-let-7c (1.630±0.485, F=7.387, P<0.05), hsa-let-7d (2.104±0.636, F=11.370, P<0.05) was upregulated in c-Myc knockdown group. Conclusion:c-Myc may be regulates hsa-let-7a, hsa-let-7c, hsa-let-7d, hsa-miR-34c and hsa-miR-98 affect the invasion and metastasis of triple-negative breast cancer.