肝素结合蛋白Midkine通过调控糖代谢促进肿瘤发生发展的分子机制研究

Growth factor Midkine (MK) is a heparin-binding protein of low molecular weight, which belongs to pleiotrophin family. Midkine participates in many physiological phenomena such as neuro development, immune reaction and inflammation. Previous studies have shown that the expression of Midkine is upregulated in different types of malignant tumor, and the overexpressed Midkine is able to promote tumor progression by regulating cell proliferation and migration. Although some evidences suggest that Midkine is a potent target for cancer diagnosis and treatment, the utilization of Midkine has been postponed, because the detailed working mechanism of Midkine is still ambiguous.. Aberrant metabolism is one of the main characters in the tumor cells. The relationship between Midkine and tumor cell metabolism has not been reported yet. In this project, we will synthetically combine metabolomics, molecular cell biology and biochemistry methods to figure out the detailed function of Midkine in tumor progression. The different metabolites in hepatocarcinoma cells transduced with Midkine shRNAs will be uncovered by metabolomics. Based on these information, we will find the metabolic pathways regulated by Midkine in cancer cells. Next, we will study whether and how the Midkine related metabolites contribute to tumor progression by coordinating certain signaling pathways in tumor cell, animal model and clinical samples. Finally, we will illustrate the mechanism of Midkine promoting tumor progression by modulating cancer cell metabolism. This project will bring some new clues for the translational application of Midkine in cancer diagnosis and treatment.

肝素结合蛋白Midkine（MK）是一种可分泌的小分子量蛋白，属于多效生长因子家族。研究发现，Midkine在多种恶性肿瘤中表达上调，并且对肿瘤的发生发展具有促进作用。虽然Midkine具有成为诊断标志物和治疗靶点的潜力，但目前的研究不足以全面揭示Midkine在肝肿瘤发生发展中的作用，严重制约了Midkine临床转化应用。. 代谢异常是肿瘤细胞的重要特征之一，而Midkine对肿瘤代谢的影响尚未有过报道。为更全面地揭示Midkine的功能，本研究拟将代谢组分析与生物学研究相结合，深入系统地阐明Midkine在肝肿瘤发生发展中的功能和作用机制。本研究将通过代谢组学分析确定Midkine调控的代谢途径，揭示受Midkine调控的代谢物所影响的信号通路，阐明Midkine通过影响代谢促进肿瘤发生发展的分子机制，为更好地将Midkine转化应用到临床诊断和治疗提供理论依据。

多效生长因子家族成员Midkine是一种小分子量分泌蛋白，具有多种生理调节功能。研究显示，Midkine在多种肿瘤中呈现表达上调趋势，并对肿瘤发生发展具有促进作用，但机制尚不明确。.AMPK蛋白不仅是细胞代谢的核心感受和调控因子，也对肿瘤的发生发展具有重要的调控作用。我们发现Midkine与AMPK具有相关性。因此，本项目集中于研究Midkine通过调控AMPK促进肿瘤发生发展的分子机制，主要包括以下研究内容：确认Midkine在肿瘤中的表达模式以及对肿瘤细胞恶性生物学行为的影响，明确Midkine对于AMPK活性的影响，揭示Midkine调控AMPK活性的分子机制，阐明Midkine通过AMPK通路调控肿瘤发生发展的方式，在临床肿瘤组织中验证MDK与AMPK的相关性。.通过研究，我们确认了Midkine促进肿瘤细胞增殖的功能，并首次揭示了Midkine促进细胞增殖需要依赖于AMPK通路的现象；阐明了Midkine抑制AMPK通路的分子机制，即Midkine通过结合LKB1，阻止LKB1与STRAD和Mo25形成蛋白复合体，从而抑制LKB1的自激活，削弱作为上游激酶的LKB1对于AMPKα亚基磷酸化作用，从而抑制AMPK的活性；证明了Midkine必需进入细胞才能完成对AMPK的抑制功能；在肿瘤临床样本中证明了Midkine与AMPK的相关性。.本项目具有重要的理论和实践意义。首先，LKB1-AMPK通路与糖尿病，恶性肿瘤等疾病密切相关，我们的研究发现了Midkine通过抑制LKB1-AMPK的激活促进肿瘤细胞的增殖，为LKB1-AMPK相关重大疾病的治疗提供了更多理论依据；其次，我们的研究揭示了生长因子Midkine需要从细胞外转移到细胞内部，并通过蛋白-蛋白相互作用的方式调控LKB1-AMPK通路的全新机制，为进一步研究Midkine及其它生长因子的功能提供给了新的思路。