Warburg效应和组蛋白修饰在砷诱导的肝细胞恶性转化过程中的cross-talk

Endemic arsenism is one of the key prevention and control endemic disease in China. Arsenic has been classified as a definitive human carcinogen, but the mechanisms by which arsenic induces carcinogenesis are not fully elucidated. It has been reported that aerobic glycolysis, a phenomenon termed the Warburg effect, is a metabolic hallmark of most cancer cells，and abnormal alteration of histone modification plays roles in carcinogenesis. Moreover, the cross-talk between Warburg effect and histone modification contributes the development of cancer. We noticed the change of histone modification pattern and the mRNA of glycolysis enzymes, such as PKM2, in a malignantly transformed variant of L-O2, that emerged from long-term exposure to arsenic. Thus, we proposed a hypothesis that the cross-talk between Warburg effect and histone modification might be involved in arsenic induced hepatocellular malignant transformation. So, in this proposal, we will first investigate the association of arsenic exposure with histone modification and expression of glycolysis enzymes; and then use human liver L-O2 cells and L-O2-As cells as study model, analyze the alteration of glycolysis enzymes, its regulator and histone modification pattern, and explore their cross-talk during the malignant transformation induced by arsenic. This study will provide theory basis and experiment data for elucidating the molecular mechanism of arsenic carcinogenesis and prevention and cure of arsenism.

地方性砷中毒是我国重点防控的地方病之一。砷已被列为确定致癌物，但其作用机制尚未完全阐明。研究表明，癌细胞的代谢特点是有氧糖酵解即Warburg效应，而组蛋白修饰异常在癌症发生过程中发挥重要作用，且二者的cross-talk促进了肿瘤的发展。申请者发现，在砷诱导的恶性转化肝细胞株L-O2-As中，组蛋白修饰模式发生改变，且PKM2等糖酵解酶mRNA表达显著增加。因此，我们推测Warburg效应和组蛋白修饰的cross-talk促进了砷诱导肝细胞恶性转化过程。故我们首先通过分子流行病学研究人群外周血白细胞组蛋白修饰、糖酵解酶表达与砷暴露的关系，然后利用正常肝细胞株L-O2及恶性转化肝细胞株L-O2-As作为研究模型，分析糖酵解酶及其调节因子和组蛋白修饰模式在砷诱导肝细胞恶性转化过程中的变化，并探讨二者之间的cross-talk，为深入理解砷致癌作用分子机制和慢性砷中毒的防治提供理论和实验依据。

地方性砷中毒是我国重点防控的地方病之一。砷已被列为确定致癌物，但其作用机制尚未完全阐明。在本研究中，我们首先通过分子流行病学研究人群外周血白细胞组蛋白修饰、糖酵解酶表达与砷暴露的关系，然后利用正常肝细胞株L-O2及恶性转化肝细胞株L-O2-As作为研究模型，探讨了砷是如何诱导Warburg效应的、Warburg效应在砷诱导肝细胞增殖和恶性转化中的作用以及USP22等组蛋白修饰相关酶等在此过程中的作用。H2AK119Ub、H2BK120Ac、H2BK120Ub、H3K4Me3、H3K79Me3和H4Ac这六种组蛋白修饰的组合可用来预测或评估人群中砷暴露的水平；砷暴露人群外周血白细胞中MT-ND1 mRNA、NDUFB8 mRNA和NDUFA9 mRNA含量降低。在低剂量砷作用下，p53 表达降低、核因子NF-κB和AKT通路活化、c-Myc表达量增加，促进了HK2等糖酵解关键酶表达，进而诱导Warburg效应；USP22等组蛋白修饰相关酶也通过调节HK2、PDK1和LDHA等糖酵解关键酶的表达，进一步诱导Warburg效应，进而促进增殖，最终诱导肝细胞发生恶性转化。此外，低剂量砷通过诱导ROS促进AKT活化，从而诱导Warburg效应，且ROS通过活化AKT信号通路来维持恶性转化细胞L-02-As的恶性表型。该研究为深入理解砷致癌作用机制以及慢性砷中毒的防治提供了理论和实验依据。