Zhou Suna, Ye Wenguang, Zhang Yanjun, Yu Dequan, Shao Qiuju, Liang Jun, Zhang Mingxin
Department of Radiotherapy, Tangdu Hospital, Fourth Military Medical University Xi'an, Shaanxi, China.
Department of Gastroenterology, Tangdu Hospital, Fourth Military Medical University Xi'an, Shaanxi, China.
Am J Transl Res. 2016 Jul 15;8(7):2992-3002. eCollection 2016.
Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Chemoresistance occurrence is a major cause of treatment failure in HCC. Currently, extensive research has revealed diverse mechanisms for chemoresistance, but the molecular mechanisms underlying the role of miRNAs in resistance to 5-FU are not confirmed in HCC cells. By quantitative real-time polymerase chain reaction (qRT-PCR) analysis, we found that miR-144 was significantly decreased in HCC cell lines. It has been further demonstrated that miR-144 were significantly down-regulated in Bel-7402/5-FU cells compared with parental Bel-7402 cells by qRT-PCR and western blot. The expression of Nrf2 was reversely correlated to that of miR-144 in HCC cells. Moreover, Enhancement of 5-FU-induced cytotoxicity and apoptosis are resulted from the transfection with miR-144 mimics in Bel-7402/5-FU cells. Mechanically, miR-144 promoted nuclear factor erythroid-2-related factor-2 (Nrf2) mRNA degradation by directly targeting the Nrf2 3'untranslated region (3'UTR). In addition, ectopic expression of miR-144 in Bel-7402/5-FU cells reduced the levels of Nrf2 and inhibited the transcription of Nrf2-dependent HO-1 gene, thus contributing to 5-FU sensibilization. Conversely, re-expression of Nrf2 partly attenuated the chemosensibilization of miR-144. Our study showed that miR-144 serves as a potential chemoresistance-reversal agent in hepatocellular carcinoma cells, which is at least partly due to the down-regulation of Nrf2-dependent antioxidant pathway.
肝细胞癌（HCC）是全球最常见的恶性肿瘤之一。化疗耐药的发生是HCC治疗失败的主要原因。目前，广泛的研究已经揭示了多种化疗耐药机制，但miRNA在5-氟尿嘧啶（5-FU）耐药中作用的分子机制在HCC细胞中尚未得到证实。通过定量实时聚合酶链反应（qRT-PCR）分析，我们发现miR-144在HCC细胞系中显著降低。通过qRT-PCR和蛋白质印迹进一步证明，与亲本Bel-7402细胞相比，miR-144在Bel-7402/5-FU细胞中显著下调。在HCC细胞中，Nrf2的表达与miR-144的表达呈负相关。此外，在Bel-7402/5-FU细胞中转染miR-144模拟物可增强5-FU诱导的细胞毒性和细胞凋亡。机制上，miR-144通过直接靶向Nrf2的3'非翻译区（3'UTR）促进核因子红细胞2相关因子2（Nrf2）mRNA的降解。此外，在Bel-7402/5-FU细胞中异位表达miR-144可降低Nrf2的水平并抑制Nrf2依赖性HO-1基因的转录，从而促进5-FU增敏。相反，重新表达Nrf2部分减弱了miR-144的化学增敏作用。我们的研究表明，miR-144在肝癌细胞中作为一种潜在的化疗耐药逆转剂，这至少部分是由于Nrf2依赖性抗氧化途径的下调。
