Tumor-suppressive miR-34a induces senescence-like growth arrest through modulation of the E2F pathway in human colon cancer cells
Tumor-suppressive miR-34a induces senescence-like growth arrest through modulation of the E2F pathway in human colon cancer cells
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DOI：
10.1073/pnas.0707351104
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发表时间：
2007-09-25
影响因子：
11.1
通讯作者：
Nakagama, Hitoshi
中科院分区：
文献类型：
--
作者：
Tazawa, Hiroshi;Tsuchiya, Naoto;Nakagama, Hitoshi
越来越多的证据表明 microRNA 作为新型肿瘤抑制基因或癌基因在人类致癌过程中发挥着重要作用。然而，它们确切的生物学作用仍然很大程度上难以捉摸。在本研究中，我们旨在鉴定参与细胞增殖调节的 microRNA 种类。通过定量 RT-PCR 分析，我们证明在用 DNA 损伤剂阿霉素处理的人结肠癌细胞系 HCT 116 中，miR-34a 高度上调。将 miR-34a 瞬时引入两种人结肠癌细胞系 HCT 116 和 RKO 中，导致细胞增殖完全抑制并诱导衰老样表型。此外，当与去端肽胶原复合并施用以进行药物递送时，miR-34a还抑制小鼠肿瘤中HCT 116和RKO细胞的体内生长。基因表达微阵列和免疫印迹分析揭示了 miR-34a 的引入下调了 E2F 通路。还观察到 p53 通路的上调。此外，与对应的正常组织相比，25 例人类结肠癌中有 9 例 (36%) 的 miR-34a 表达降低。我们的结果证明 miR-34a 通过调节 E2F 信号通路发挥细胞增殖的有效抑制剂的作用。 miR-34a 功能的废除可能导致异常细胞增殖，导致结肠癌的发展。
Accumulating evidence suggests a role for microRNAs in human carcinogenesis as novel types of tumor suppressors or oncogenes. However, their precise biological role remains largely elusive. In the present study, we aimed to identify microRNA species involved in the regulation of cell proliferation. Using quantitative RT-PCR analysis, we demonstrated that miR-34a was highly up-regulated in a human colon cancer cell line, HCT 116, treated with a DNA-damaging agent, adriamycin. Transient introduction of miR-34a into two human colon cancer cell lines, HCT 116 and RKO, caused complete suppression of cell proliferation and induced senescence-like phenotypes. Moreover, miR-34a also suppressed in vivo growth of HCT 116 and RKO cells in tumors in mice when complexed and administered with atelocollagen for drug delivery. Gene-expression microarray and immunoblot analyses revealed down-regulation of the E2F pathway by miR-34a introduction. Up-regulation of the p53 pathway was also observed. Furthermore, 9 of 25 human colon cancers (36%) showed decreased expression of miR-34a compared with counterpart normal tissues. Our results provide evidence that miR-34a functions as a potent suppressor of cell proliferation through modulation of the E2F signaling pathway. Abrogation of miR-34a function could contribute to aberrant cell proliferation, leading to colon cancer development.