Low-level shRNA Cytotoxicity Can Contribute to MYC-induced Hepatocellular Carcinoma in Adult Mice
Low-level shRNA Cytotoxicity Can Contribute to MYC-induced Hepatocellular Carcinoma in Adult Mice
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DOI：
10.1038/mt.2009.222
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发表时间：
2010-01-01
影响因子：
12.4
通讯作者：
Grimm, Dirk
中科院分区：
文献类型：
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作者：
Beer, Shelly;Bellovin, David I.;Grimm, Dirk
短发夹rna （shRNAs）已成为一种新的治疗方式，但其在体内的非特异性作用越来越受到关注。在这里，我们使用病毒载体在条件myc转基因小鼠的肝脏中表达针对内源性p53的shrna。正如预期的那样，当MYC同时表达时，shrna沉默肝脏p53并加速肝脏肿瘤发生。令人惊讶的是，各种不相关的对照shrna同样诱导了肿瘤发生的快速发生，类似于四氯化碳（CCl4），一种强致癌物。我们发现，即使是边际shRNA剂量也可以触发组织学上可检测的肝毒性和增加的肝细胞凋亡。此外，我们注意到shRNA的表达在全局上失调了肝脏microRNA （miRNA）的表达，并且在MYC的存在下shRNA的水平和活性进一步增加。在表达MYC的转基因小鼠中，边缘shrna诱导的肝损伤足以进一步刺激肝细胞分裂，这反过来又与有丝分裂周期蛋白B1的表达显著增加相关。因此，即使在低剂量下，shrna也能引起低水平的肝毒性，从而促进MYC癌基因诱导肝脏肿瘤发生的能力。我们的数据表明，shrna作为临床药物使用时可能存在致癌潜力，特别是在组织遗传上倾向于细胞转化和增殖的情况下。
Short hairpin RNAs (shRNAs) have emerged as a novel therapeutic modality, but there is increasing concern over nonspecific effects in vivo. Here, we used viral vectors to express shRNAs against endogenous p53 in livers of conditional MYC-transgenic mice. As expected, the shRNAs silenced hepatic p53 and accelerated liver tumorigenesis when MYC was concurrently expressed. Surprisingly, various irrelevant control shRNAs similarly induced a rapid onset of tumorigenesis, comparable to carbon tetrachloride (CCl4), a potent carcinogen. We found that even marginal shRNA doses can already trigger histologically detectable hepatoxicity and increased hepatocyte apoptosis. Moreover, we noted that shRNA expression globally dysregulated hepatic microRNA (miRNA) expression, and that shRNA levels and activity further increased in the presence of MYC. In MYC expressing transgenic mice, the marginal shRNA-induced liver injury sufficed to further stimulate hepatocellular division that was in turn associated with markedly increased expression of the mitotic cyclin B1. Hence, even at low doses, shRNAs can cause low-level hepatoxicity that can facilitate the ability of the MYC oncogene to induce liver tumorigenesis. Our data warrant caution regarding the possible carcinogenic potential of shRNAs when used as clinical agent, particularly in circumstances where tissues are genetically predisposed to cellular transformation and proliferation.