LXR activation potentiates sorafenib sensitivity in HCC by activating microRNA-378a transcription
LXR activation potentiates sorafenib sensitivity in HCC by activating microRNA-378a transcription
复制标题
LXR 激活通过激活 microRNA-378a 转录增强 HCC 中索拉非尼的敏感性
DOI：
10.7150/thno.45158
复制
发表时间：
2020-01-01
期刊：
影响因子：
12.4
通讯作者：
Cai, Xiujun
中科院分区：
文献类型：
--
作者：
Lin, Zhongjie;Xia, Shunjie;Cai, Xiujun
索拉非尼耐药是中晚期肝细胞癌治疗的主要障碍。MicroRNAs(MiRNAs)是一种多功能的基因表达调控因子，对人类疾病有着深远的影响。因此，更好地了解异常表达的miRNAs的生物学机制对于发现新的、有希望的肝癌治疗靶点至关重要。本研究旨在探讨miR-378a-3p在肝癌细胞对索拉非尼耐药中的作用，并阐明其分子机制。方法：基于miRNA芯片和生物信息学分析，对新的HUB基因miR-378a-3p进行鉴定。MiR-378-3p的异常表达在不同的肝癌患者队列和索拉非尼耐药(SR)的肝癌细胞系中得到证实。通过体内外功能获得和功能丧失实验研究miR-378a-3p及其下游和上游调控机制的功能作用。通过一系列分子生物学实验研究了miR-378a-3p、LxR、α和IGF1R之间的相互作用。然后，评价miR-378a-3p与其靶点在肝癌组织中的临床相关性。采用人肝癌患者来源异种移植模型评价LXRα及其下游基因miR-378a-3p的治疗价值。结果：在已建立的索拉非尼耐药的肝癌细胞系中，miR-378a-3p的表达经常下调。MiR-378a-3p水平降低与索拉非尼治疗后肝细胞癌患者总体存活率较低有关。MiR-378a-3p过表达诱导SR肝癌细胞凋亡，而miR-378a-3p沉默则起相反作用。IGF1R被确定为miR-378a-3p的一个新靶点。此外，在SR肝癌细胞中，miR-378的原代表达水平与其前体miRNA的表达水平不一致，这是由于出口蛋白5(XPO5)的下调，从而减少了前体miR-378的核输出，抑制了miR-378-3p的成熟。在此背景下，我们结合了肝脏X受体α(LXRα)的激动剂GW3965，它作为miRNA-378a的转录激活剂，及其激活使索拉非尼耐药细胞在体外和体内对索拉非尼治疗再次增敏。结论：XPO5的表达减少阻碍了miR-378a-3p的成熟，从而导致IGF-1R的过度表达，并抵消了索拉非尼诱导的细胞凋亡的作用。LXRα能够激活肝癌细胞中miRNA-378a-3p的转录，可能成为索拉非尼联合应用抑制肝癌进展的潜在治疗策略。
Sorafenib resistance is a major obstacle to the treatment of advanced hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) are multifunctional regulators of gene expression with profound impact for human disease. Therefore, better understanding of the biological mechanisms of abnormally expressed miRNAs is critical to discovering novel, promising therapeutic targets for HCC treatment. This study aimed to investigate the role of miR-378a-3p in the sorafenib resistance of HCC and elucidate the underlying molecular mechanisms. Methods: A novel hub miR-378a-3p was identified based on miRNA microarray and bioinformatics analysis. The abnormal expression of miR-378-3p was validated in different HCC patient cohorts and sorafenib-resistant (SR) HCC cell lines. The functional role of miR-378a-3p and its downstream and upstream regulatory machinery were investigated by gain-of-function and loss-of-function assays in vitro and in vivo. Interactions among miR-378a-3p, LXRα, and IGF1R were examined by a series of molecular biology experiments. Then, the clinical relevance of miR-378a-3p and its targets were evaluated in HCC samples. HCC patient-derived xenograft (PDX) model was used to assess the therapeutic value of LXRα and its downstream miR-378a-3p. Results: miR-378a-3p expression was frequently reduced in established sorafenib-resistant HCC cell lines. The decreased miR-378a-3p levels correlated with poor overall survival of HCC patients following sorafenib treatment. miR-378a-3p overexpression induced apoptosis in SR HCC cells, whereas miR-378a-3p silencing exerted the opposite effects. IGF1R was identified as a novel target of miR-378a-3p. Furthermore, the primary miR-378 level was not consistent with its precursor miRNA level in SR HCC cells, which was attributed to the downregulation of exportin5 (XPO5) and subsequently reduced nuclear export of precursor miR-378 and restrained maturation of miR-378-3p. In this context, we combined an agonist GW3965 of liver X receptor alpha (LXRα), which functioned as a transcription activator of miRNA-378a, and its activation re-sensitized sorafenib-resistant cells to sorafenib treatment in vitro and in vivo. Conclusions: Our finding suggested decreased expression of XPO5 prevents maturation of miR-378a-3p, which leaded to the overexpression of IGF-1R and counteracted the effects of sorafenib-induced apoptosis. LXRα was able to activate miRNA-378a-3p transcription in HCC cells and could be a potential combinable treatment strategy with sorafenib to suppress HCC progression.