The let-7a microRNA protects from growth of lung carcinoma by suppression of k-Ras and c-Myc in nude mice
The let-7a microRNA protects from growth of lung carcinoma by suppression of k-Ras and c-Myc in nude mice
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let-7a microRNA 通过抑制裸鼠中的 k-Ras 和 c-Myc 来防止肺癌生长
DOI：
10.1007/s00432-009-0747-5
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发表时间：
2010-07-01
影响因子：
3.6
通讯作者：
Peng, Hui-min
中科院分区：
文献类型：
--
作者：
He, Xiao-yan;Chen, Jun-xia;Peng, Hui-min
Let-7microRNA(MiRNA)表达下调在肺癌的发病机制中起重要作用。K-RAS和c-Myc是肺癌中的两个关键癌基因，已被发现在体外被LET-7靶向。然而，这些发现在体内的相关性尚不清楚。本研究旨在探讨let-7家族成员let-7a在体内对肺癌生长的影响，并探讨let-7对k-ras和c-Myc的抑制作用是否参与肺癌的发生。将A549、A549-对照和A549-let-7a细胞分别接种于裸鼠皮下。30天后，处死小鼠；切除移植瘤并称重。用实时定量逆转录-聚合酶链式反应(RT-PCR)检测LET-7a在肿瘤移植瘤中的表达。免疫印迹和免疫组织化学方法检测移植瘤中k-RAS和c-Myc的表达。实时定量RT-PCR结果显示，A549-let-7a细胞注射组let-7a的表达明显高于A549对照细胞组和A549细胞注射组(P<0.01)。在A549-let-7a细胞移植瘤中，与A549细胞注射组和A549对照细胞注射组相比，瘤重显著降低(P<；0.05)，k-RAS和c-Myc蛋白表达显著降低(P<；0.01)，LET-7a过表达可通过抑制k-RAS和c-Myc抑制肺癌裸鼠皮下移植瘤生长。
Down-regulation of let-7 microRNA (miRNA) plays an important role in the pathogenesis of lung cancer. k-Ras and c-Myc, two key oncogenes in lung cancer, have been found to be targeted by let-7 in vitro. However, the in vivo relevance of these findings is unknown. The aim of the present study is to determine the effect of let-7a, a member of let-7 family, on the growth of lung cancer in vivo and to investigate whether let-7-induced suppression of k-Ras and c-Myc is involved in lung cancer.A549-let-7a cell line and A549-control cell line, two stable transfected cell lines over-expressing let-7a and the control miRNA, were established and preserved in our lab. A549, A549-control, and A549-let-7a cells were injected subcutaneously into nude mice, respectively. After 30 days, the mice were killed; the xenografts were excised and weighed. The expression of let-7a in tumor xenografts was assessed by real-time reverse transcription-PCR (RT-PCR). The expression of k-Ras and c-Myc in xenografts were determined by western blot and immunohistochemistry detection.Real-time RT-PCR showed the expression of let-7a was increased significantly in A549-let-7a cells-injected group, compared with A549-control cells-injected group and A549 cells-injected group (P < 0.01). In the xenografts of A549-let-7a cells-injected group, a significant depression in tumor weight (P < 0.05) and significant decrease of k-Ras and c-Myc protein were observed (P < 0.01), compared to A549 cells-injected group and A549-control cells-injected group.Overexpression of let-7a can inhibit the growth of lung cancer transplanted subcutaneously in nude mice by suppression of k-Ras and c-Myc.