MCT4促进肝癌增殖、侵袭转移的分子机制及临床意义的研究

Monocarboxylate transporter 4 (MCT4) is an efficient exporter of lactic acid and is a critical component in glycolytic metabolism of cancer cell. Recent studies show that high expression of MCT4 is associated with poor survival in various human malignancies. Expression and biological function(such as HCC proliferation, invasion and metastasis)of MCT4 in hepatocellular carcinoma (HCC) has so far not been investigated. In our previous research, we found that high MCT4 expression is indicative of elevated alpha fetoprotein (AFP) levels and larger tumor size, which leads to poorer disease free survival (DFS) and overall survival (OS). The high expression of MCT4 can promote HCC proliferation, invasion and metastasis. We also found that MCT4 can activate the PI3K-Akt signal pathway. We intend to figure out the effect and the mechanism of MCT4 in HCC proliferation, invasion and metastasis. In future, we want:(1)to observe the phenotypic changes in cell proliferation, invasion and metastasis by using high or low-MCT4 expression cells and figure out the effect of MCT4 in HCC proliferation, invasion and metastasis by.animal experiments; (2)to explore the molecule mechanism of activating PI3K-Akt signal pathway and HIF-1α by MCT4, and also to find a group which can work as a guidline of therapy included MCT4 and other prognostic molecules which will be found in this study; (3)to figure out MCT4 as a prognostic biomarker in HCC and provide potential individualized therapy based on MCT4 expression by a prospective clinical study. The project will take full advantage of translational medicine research strategy, through multiple levels of “cells - animals - patients” to.demonstrate the mechanism of the MCT4 in the HCC proliferation, invasion and metastasis process. Its completion will provide new candidate markers for HCC treatment, and new potential drug targets for treatment of HCC.

MCT4是一种转运细胞内外乳酸、丙酮酸及酮体等的膜转运蛋白，在肿瘤糖代谢过程中发挥了重要作用，有研究显示其表达与肿瘤预后相关，但其在肝癌增殖、侵袭转移中的作用及分子机制尚不清楚。我们前期研究发现其在高侵袭性及高转移性的肝癌组织中高表达，与肝癌病人的预后显著相关；MCT4在体外可促进肝癌细胞增殖、诱导肝癌细胞上皮间质转化、血管生成及细胞外基质降解，并增强肝癌细胞的侵袭能力；并且MCT4可激活PI3K-Akt信号通路和HIF-1α转录调节因子。本项目拟从细胞水平、动物模型及临床病例多层次中进一步分析MCT4在肝癌增殖、侵袭复发转移中的作用，深入探讨其在肝癌中的作用方式和分子调控机制，解析MCT4调节HIF-1α表达的方式和作用靶点，明确其介导的信号通路，并确认其复合物在发挥功能的效应分子途径中的作用。

MCT4作为介导乳酸跨膜转运蛋白，维持细胞周围环境的酸碱平衡，实现对糖酵解的调控，而糖酵解是肿瘤细胞获取能量的重要途径。细胞中乳酸的转出由 MCT4 介导，这是糖酵解必要条件，从而使细胞糖酵解产生的大量乳酸可以顺利转出细胞。本课题回顾性检测肝癌病人MCT4 蛋白的表达水平，确定了MCT4作为预测肝癌治疗预后影响因素。.进一步以MCT4作为研究靶点，在肝癌细胞系中通过高通量测序，筛选出MCT4基因下游的功能基因。确定TRAPPC5作为下游实验分子。研究了TRAPPC5在肝癌细胞中的表达情况及在肝癌增殖转移中的作用，详细阐明TRAPPC5的在肝癌发生发展过程中的作用机制。确定了在肝癌中，TRAPPC5基因的表达通过影响MCT4表达，促进了肝癌细胞的增殖及转移侵袭能力，并且促进了肝癌EMT过程。.分析了基质金属蛋白酶12 (MMP-12)在肝癌侵袭转移中作用及对临床预后的关系，结果表明MMP-12表达水平越高，肿瘤体积越大，肿瘤细胞分化越差，TNM分期越高，预后越差。MMP-12表达与PD-L1表达呈正相关。进一步分析表明，MMP-12可能通过IL-6信号通路调控PD-L1的表达。我们确定了MMP-12在肝癌患者中的表达与肿瘤细胞分化、预后、PD-L1表达有着密切关系。.检测了GLUT3在肝癌组织中的表达情况，并结合临床参数，生存曲线分析GLUT3对肝癌病人OS和DFS的意义，并通过验证组病例进一步确定其预测价值。在实验组中，GLUT3表达与肿瘤数目、AFP水平、TNM分期、组织分化程度有关，高表达GLUT3提示高水平AFP、多肿瘤结节、组织分化差及较晚的TNM分期。在验证组中，GLUT3表达与肿瘤大小、AFP水平、血管侵犯、组织分化程度有关，高表达GLUT3提示高水平AFP、大肝癌、组织分化差及血管侵犯。在实验组中，GLUT3表达水平与患者DFS、OS均有关。高表达GLUT3预示了较差的DFS和OS.。为了验证上述结论，我们进一步选取了同时期的另一中心的肝癌病人，并验证了GLUT3预测肝癌病人生存预后的预测价值。高表达GLUT3预示了较差的DFS和OS。通过COX回归分析模型结果显示GLUT3表达是肝癌患者生存的独立预后因素。