miR-424-5p通过下调BCL-2的表达抑制人肺癌A549细胞增殖

microRNAs(miRNAs)是一类在真核生物中广泛存在的长度约为20～22个核苷酸的单链非编码小RNA，通过与其靶基因mRNA的3′非翻译区（3′UTR）结合发挥转录后抑制作用，参与调节细胞生长增殖、细胞代谢、细胞凋亡以及肿瘤的发生发展等过程。为研究microRNA-424-5p（miR-424-5p）在肺癌细胞中的作用及机理，利用lipo2000转染试剂将miR-424-5p mimics转染入人的非小细胞型肺癌细胞(NSCLC)A549中，流式细胞术检测A549细胞的周期变化及凋亡情况，发现细胞生长阻滞于G1/G0期且凋亡率显著上升。利用克隆形成实验和CCK-8法分别检测，发现miR-424-5p导致A549细胞增殖能力及活力降低。用在线数据库预测出抗凋亡基因BCL-2可能是miR-424-5p的靶基因，随后扩增BCL-2 mRNA 的3′UTR，采用双荧光素酶报告实验及Western印迹检测证明BCL-2确为miR-424-5p的靶基因。构建BCL-2的真核表达载体pCMV-HA-BCL-2，与空载分别转染A549细胞后发现过表达BCL-2可抵消miR-424-5p引起的细胞周期阻滞及细胞凋亡。以上结果提示，miR-424-5p可以通过下调BCL-2的表达来抑制肺癌细胞增殖。

miR-424-5p Suppresses the Proliferation of Human Lung Cancer A549 Cells through Targeting BCL-2

microRNAs (miRNAs) are small non-coding single-stranded RNAs with 20-22 nucleotides in length, which play significant roles in the regulation of tumor pathogenesis and progression. In order to explore the effects of miR-424-5p on the proliferation of lung cancer cells, miR-424-5p mimics were transfected into the human lung cancer cell line A549, then cell cycle and apoptosis were evaluated by flow cytometry. The results showed that cell cycle was arrested at the G0/G1 phase, and the percentage of apoptotic cells was significantly increased in A549 cells that transfected with miR-424-5p mimics. Furthermore, the results of CCK-8 and clone formation revealed that the proliferation of A549 cells was notably decreased following upregulation of miR-424-5p. By using online databases, luciferase reporter system and Western blot, we confirmed that BCL-2 was a direct target gene of miR-424-5p. Over-expression of BCL-2 can neutralize the effects of miR-424-5p. In conclusion, we identified BCL-2 as a direct target of miR-424-5p and over-expression of miR-424-5p was able to inhibit growth and promote apoptosis in lung cancer A549 cells by down-regulating BCL-2.