TGF-β-CTGF轴在肝脏祖细胞的恶性转化中的作用和机制研究

发布时间：2018-06-12 23:23

本文选题：二乙基亚硝胺 + 前列环素　；参考：《华中科技大学》2016年博士论文

【摘要】：肝细胞癌世界上排名第六的最常见癌症,由于预后不良而成为癌症死因中排名第三位的恶性肿瘤。由于缺乏可行的有效治疗措施,对高危病人的预防已经被作为一个可选的策略。肝癌可以发源于肿瘤起始细胞即肿瘤干细胞。肝癌的的主要风险因子是肝硬化,而且一系列的证据表明转化生长因子和结缔组织生长因子在肝硬化和肝癌的进展中发挥重要作用,并且TGF-β在肝脏祖细胞恶化成为肿瘤起始细胞中也发挥至关重要的作用。本文中,我们发现在二乙基亚硝胺诱导的大鼠肝癌模型中肝脏祖细胞的激活大量增加,并且肝脏祖细胞中CTGF的表达也有明显升高。但是当我们同时给予DEN和CTGF合成抑制剂Iloprost后发现肝脏祖细胞的激活减少,其中CTGF的表达也同步降低。更重要的是,肝癌的发生率也出现明显的下降。此外,DEN注射引起TGF-β和肿瘤起始细胞标记物的表达增加,并且两者之间呈正相关性。而给予CTGF合成抑制剂同样可以降低TGF-β1和肿瘤起始细胞标记物的表达。这也进一步预示CTGF和TGF-β可能参与肿瘤起始细胞的产生进而在肝癌的发生中发挥作用。为了模拟大鼠体内的长期的TGF-β存在的环境,我们在体外用长期(18周)低剂量TGF-β1(0.25ng/ml)处理大鼠肝脏祖细胞系WB-F344而建立WB-F344-TβLT细胞系。我们发现长期低剂量TGF-β处理可以损害肝脏祖细胞的分化能力而促进肝脏祖细胞的恶性转化,这与之前的一些研究结果具有一致性。进而,我们准备探讨CTGF在这种长期的低剂量TGF-β1诱导的肝脏祖细胞的恶性转化中的作用。所以,我们利用慢病毒构建了敲减CTGF的大鼠肝脏祖细胞并研究了其在肝脏祖细胞中的生物学功能,结果显示敲减CTGF后可以在一定程度上恢复肝脏祖细胞的分化能力,并且肝脏祖细胞的恶性程度明显降低。我们前期的研究结果证实TGF-β1可以在肝脏祖细胞中诱导CTGF的表达。本文中,我们进一步探讨CTGF对TGF-β信号通路的影响,以及通过什么机制发挥作用。我们发现CTGF可以通过促进TGF-β1-Smad3通路的激活,抑制TGF-β1-Smad1/5通路的激活水平介导促进肝脏祖细胞的恶性转化的作用。综上所述,我们证实了大鼠肝癌发生过程中有肝脏祖细胞的参与,CTGF合成抑制剂可以起到保护肝脏,减少肝癌发生的作用。在TGF-β1所诱导的肝脏祖细胞的恶性转化过程中,CTGF在其中也发挥促进作用。另外,我们初步证明了TGF-β-CTGF的恶性循环可以增加肝癌的发生,促进肝脏祖细胞的恶性转化,并且通过调控肝脏祖细胞中不同TGF-β/Smad通路的激活水平来发挥作用。我们的研究首次确认TGF-β-CTGF轴通过调节不同Smad的激活水平来促进肝脏祖细胞的恶性转化和肝癌的发生。
[Abstract]:Hepatocellular carcinoma (HCC), the sixth most common cancer in the world, is the third leading cause of cancer death due to poor prognosis. Prevention of high-risk patients has been an optional strategy due to the lack of feasible and effective treatment measures. Liver cancer can originate from tumor initiation cells, or tumor stem cells. The main risk factor for liver cancer is cirrhosis, and a series of evidence suggests that transforming growth factor and connective tissue growth factor play an important role in the progression of liver cirrhosis and liver cancer. TGF- 尾 also plays a crucial role in the progression of liver progenitor cells into tumor initiation cells. In this paper, we found that the activation of liver progenitor cells and the expression of CTGF in liver progenitor cells were significantly increased in the rat liver cancer model induced by diethylnitrosamine. However, when we were given both den and Iloprost, we found that the activation of liver progenitor cells was decreased, and the expression of CTGF was also decreased. More importantly, the incidence of liver cancer also showed a significant decline. In addition, the expression of TGF- 尾 and tumor initiation cell markers was increased after injection of den, and there was a positive correlation between the expression of TGF- 尾 and TGF- 尾. CTGF synthesis inhibitor also decreased the expression of TGF- 尾 1 and tumor initiation cell markers. This further indicates that CTGF and TGF- 尾 may be involved in the production of tumor initiation cells and thus play a role in the development of liver cancer. In order to simulate the long-term existence of TGF- 尾 in rats, we established WB-F344-T 尾 LT cell line by treating rat liver progenitor cell line WB-F344 with low-dose TGF- 尾 _ 1 0.25ng / ml for 18 weeks in vitro. We found that long-term low-dose TGF- 尾 treatment can damage the differentiation ability of liver progenitor cells and promote the malignant transformation of liver progenitor cells, which is consistent with some previous studies. Furthermore, we intend to explore the role of CTGF in the malignant transformation of liver progenitor cells induced by low dose TGF- 尾 1. Therefore, we used lentivirus to construct rat liver progenitor cells with CTGF knockout and to study its biological function in liver progenitor cells. The results showed that CTGF knockout could restore the differentiation ability of liver progenitor cells to some extent. The malignancy of liver progenitor cells was significantly decreased. Our previous study confirmed that TGF- 尾 1 could induce CTGF expression in liver progenitor cells. In this paper, we further investigate the effect of CTGF on TGF- 尾 signaling pathway and its mechanism. We found that CTGF can promote the malignant transformation of liver progenitor cells by promoting the activation of TGF- 尾 1-Smad3 pathway and inhibiting the activation level of TGF- 尾 1-Smad1 / 5 pathway. In conclusion, we confirmed that CTGF synthesis inhibitor can protect the liver and reduce the occurrence of liver cancer in rats. CTGF also plays a promoting role in the malignant transformation of liver progenitor cells induced by TGF- 尾 1. In addition, we preliminarily proved that the vicious cycle of TGF- 尾 -CTGF can increase the occurrence of liver cancer, promote the malignant transformation of liver progenitor cells, and play a role by regulating the activation level of different TGF- 尾 / Smad pathway in liver progenitor cells. Our study confirmed for the first time that the TGF- 尾 -CTGF axis promotes the malignant transformation of liver progenitor cells and the occurrence of liver cancer by regulating the activation levels of different Smad.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R735.7

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