酰基辅酶A硫酯酶12调控胆固醇代谢抑制肝癌侵袭转移的功能机制研究

Hepatocellular carcinoma (HCC) has a high rate of metastasis and recurrence after surgery and extremely poor prognosis. Until recently, there has not been effective target for HCC metastasis. In our previous studies, HCC metastases were separated by laser capture microdissection, and were subjected to microarray analysis by comparing with their corresponding non-metastatic cancer tissues. The results showed that acyl-coenzyme A thioesterase 12 (ACOT12) was closely correlated to HCC metastasis. Further studies confirmed that ACOT12 was significantly down-regulated in HCC metastasis, and that overexpression of ACOT12 obviously reduced in vitro migration and invasion of HCC cell line. ACOT12 regulates the intracellular acyl-coenzyme A level, and is a key enzyme in cholesterol metabolism, and cholesterol metabolism is closely related to cancer metastasis. Based on these studies, we hypothesized that ACOT12 suppresses hepatocellular carcinoma metastasis by regulating cholesterol metabolism. This project focuses on three aspects as follows: 1) The correlation between the expression level of ACOT12 gene and HCC metastasis, 2) The role of ACOT12 in HCC metastasis and cholesterol metabolism of HCC cells, 3) The mechanism for suppressing HCC metastasis by ACOT12 mediated-cholesterol metabolic changes. The results from this project will help us to demonstrate the functional mechanism of cholesterol metabolism in HCC metastasis, and to provide vital basis for identifying ACOT12 as target gene or protein for HCC metastasis.

肝癌术后转移复发率高、预后差。目前，对肝癌转移缺少有效干预靶标。我们前期通过显微切割分离肝癌转移灶进行基因表达芯片分析发现，酰基辅酶A硫酯酶12（ACOT12）与肝癌转移有密切联系。进一步研究证实，ACOT12在肝癌转移过程中显著下调，过表达ACOT12可显著抑制肝癌细胞株的迁移和侵袭能力。依据ACOT12是调控细胞内乙酰辅酶A水平并影响胆固醇代谢的关键酶，而胆固醇代谢与癌症的侵袭转移密切相关，我们推测ACOT12可能通过调控胆固醇代谢影响肝癌的侵袭转移。本项目拟在前期研究基础开展以下研究：①分析验证ACOT12的表达与肝癌转移的相关性，②ACOT12在肝癌侵袭转移和肝癌胆固醇代谢中的功能作用，③ACOT12通过调控胆固醇代谢影响肝癌侵袭转移的分子机制。本项目研究获得结果，可深入揭示胆固醇代谢在肝癌侵袭转移中的功能及作用机制，为确定ACOT12作为肝癌转移潜在干预靶点提供重要基础。

肝癌术后转移复发率高、预后差。目前，对肝癌转移缺少有效的预测和干预靶标。我们前期通过显微切割分离肝癌转移灶进行基因表达芯片分析发现，酰基辅酶A硫酯酶12（ACOT12）与肝癌转移有密切联系。项目的主要研究内容包括：1）分析验证ACOT12 的低表达与肝癌转移和不良预后的相关性；2）ACOT12在肝癌侵袭转移中的功能作用；3）ACOT12 在肝癌细胞乙酰辅酶A代谢和胆固醇代谢中的功能作用；4）揭示ACOT12通过调控乙酰辅酶A代谢和胆固醇代谢途径抑制肝癌转移的分子机制。项目取得的重要结果、关键数据及其科学意义如下：1）通过大样本临床标本的验证，确认了ACOT12基因的低表达与肝癌转移及肝癌患者不良预后的相关性；2）证实ACOT12是肝癌转移的关键抑制因子；3）证实ACOT12是调控细胞乙酰辅酶A代谢和胆固醇代谢的关键酶；4）揭示了ACOT12的下调导致肝癌细胞乙酰辅酶A水平、组蛋白乙酰化水平和胆固醇水平的提高，进而通过表观激活TWIST2基因的表达和促进上皮间质转化（EMT）过程从而驱动肝癌转移的分子机制。这些研究结果表明，ACOT12基因的表达水平可作为肝癌转移的预测指标，并为将乙酰辅酶A代谢关键酶ACOT12作为肝癌转移的干预靶标提供了理论基础；同时这些研究结果也提示，代谢物乙酰辅酶A水平的累积可能是肝癌转移的重要驱动因素，为肿瘤细胞的代谢重编程是肿瘤转移起始性因素的理论提供了实验证据。