c-Src促进肿瘤发生的新机理

It is well known that aerobic glycolysis (Warburg effect) plays crucial roles in the formation and maintenance of tumor microenvironment, and in the proliferation, anti-apoptosis and metastasis of cancer cells. c-src is one of the most important proto-oncogenes in cells. Over-activation of c-Src tyrosine kinase activity is related to the initiation and malignant transformation of several kinds of tumors. It was reported that c-Src could indirectly increase Warburg effect by promoting HIF-1 alpha expression. However, it remains unclear whether c-Src shows direct regulatory effect on glycolysis. We have screened all the enzymes involved in glycolysis for their interaction with c-Src and found that c-Src could interact exclusively with and phosphorylate HK1 (hexokinase 1) among all the examined enzymes. Moreover, knocking-down of HK1 significantly decreased tumor cells’ proliferation. Our data thus indicate that c-Src may directly regulate Warburg effect via phosphorylating and stimulating enzymatic activity of HK1, and eventually promote tumorigenesis. In this project we intend to determine the sites on HK1 phosphorylated by c-Src, further reveal the molecular mechanisms by which c-Src regulates enzymatic activity of HK1 and promote tumorigenesis.

肿瘤细胞的有氧糖酵解（Warburg effect）在肿瘤微环境的形成和维持，肿瘤细胞的增殖、抗凋亡和转移过程中起重要作用。c-src是细胞中最重要的原癌基因之一，其蛋白产物c-Src酪氨酸激酶的过渡激活与多种肿瘤的发生与恶性转化密切相关。研究表明c-Src能够通过促进HIF-1alpha的表达间接提高Warburg 效应。但c-Src是否对糖酵解有直接的调节作用目前仍不清楚。我们在前期工作中用免疫共沉淀的方法筛选发现c-Src只与己糖激酶1（HK1）相互作用，而不与糖酵解中的其它酶结合；c-Src能磷酸化HK1，且敲低HK1能显著降低肿瘤细胞的增殖速度。提示c-Src可能通过磷酸化HK1激活其酶活性，从而直接调控Warburg效应，促进肿瘤发生。在该项目中我们拟进一步鉴定HK1的磷酸化位点，揭示c-Src调节HK1酶活性的分子机理及其在肿瘤发生中的作用。

良好地完成了本项目所计划的研究内容，并取得了如下成果。.本研究发现c-Src在激活的情况下能够和己糖激酶（Hexokinase: HK）相互结合，并且磷酸化Ⅰ型己糖激酶（HK1）的732位酪氨酸。通过检测HK1的催化活性，我们发现c-Src介导的酪氨酸磷酸化修饰使得HK1的酶活性显著增加，能够更快速的将葡萄糖转化为6-磷酸葡萄糖。突变HK1的c-Src酪氨酸磷酸化位点会显著削弱c-Src促进的糖酵解、细胞增殖和肿瘤发生。.总之，我们对c-Src调节HK促进糖酵解的分子机理和功能进行了深入的研究，不仅为肿瘤细胞依赖于糖酵解提供了新的证据，还为c-Src促进肿瘤的发生提供了新的视角，对开发新的肿瘤治疗药物提供了有益的理论依据。.同时，通过本项目的资助与研究，我们已经在《Cell Reports》和《Nature Communications》杂志上各发表1篇SCI论文，总影响因子达到20.4，同时培养了两名博士研究生和一名硕士研究生，使其获得了良好的专业素养。