ANGPTL4在肺癌转移中的作用及分子机制研究

Angiopoietin-like protein 4 (ANGPTL4) plays complex and often contradictory roles in vascular biology and tumor metastasis, but little is known about its function in lung cancer metastasis. In our previous study, we found that ANGPTL4 mRNA expression was very low in human lung tissue and was significantly increased in metastatic lung cancer cell lines(A549, NCI-H1755 and NCI-H1299). We also found serum ANGPTL4 is higher in lung cancer patients, compared to healthy control. In addtion, ANGPTL4 levels were higher in lung cancer patients with metastasis than in those without metastasis. To evaluate the function of ANGPTL4 in lung cancer metastasis, conditioned medium (CM) was collected from COS7-lenti-ANGPTL4 or COS7-lenti-control cells, which were established by transduction with a lentiviral vector expressing ANGPTL4 or an empty lentiviral vector and transwell assays were performed, the results showed that treatment with CM-ANGPTL4 could promote the migration of lung cancer cells.Consistent with these results, overexpression of ANGPTL4 also promote the migration of lung cancer cells..All the results from our lab indicate that ANGPTL4 might correlate with lung cancer metastasis. However, the function and mechanism of ANGPTL4 affecting lung cancer metastasis remain unclear. In this project, we plan to evaluate the function of ANGPTL4 in lung cancer metastasis using more cell lines, especially in vivo experiments. Further, with bioinformatics analysis, we want to find the target gene using cDNA array and protein array and to analysis the mechanism of ANGPTL4 affecting lung cancer metastasis. In addtion, we will detect and compare serum ANGPTL4 protein levels in more lung cancer patients. Then we will analysis the relationship of ANGPTL4 levels and clinicopathologic features. Finaly, we will expound the function and mechanism of ANGPTL4 in lung cancer metastasis and provide molecular markers of lung cancer metastasis.

ANGPTL4与肿瘤转移和血管新生密切相关，目前国内外研究表明在不同的肿瘤中ANGPTL4的功能不同，甚至相反，但其作用机理尚未阐明。我们在前期工作发现，ANGPTL4在正常肺组织中不表达，而在具有高转移潜能的肺癌细胞系中高表达；用分泌性ANGPTL4处理肺癌细胞系或在肺癌细胞系中过表达ANGPTL4，均能促进肺癌细胞的体外迁移能力，反之亦然；我们还发现肺癌患者血清中ANGPTL4浓度高于正常人，而且伴发转移的患者明显高于早期未发生转移的患者。上述结果提示ANGPTL4与肺癌转移密切相关，但是其影响肺癌转移的分子机制并不明确。本研究拟结合肺癌患者临床标本，进一步确定ANGPTL4在肺癌转移中的功能，并从cDNA芯片和蛋白质组学入手，结合生物信息学分析，深入探讨ANGPTL4影响肺癌转移的分子机制，为阐明肺癌转移机理提供实验依据，同时也为肺癌转移或预后判断提供分子标志。

肺癌是严重威胁人类健康的恶性肿瘤之一，其死亡率在世界范围内均为肿瘤相关死亡的首位。由于缺乏病变的早期诊断技术，而晚期病变又没有有效的治疗手段，因此肺癌的预后非常差。对于大部分肺癌患者来说，出现远端器官的转移是死亡的主要原因，尽管关于肺癌的转移相关机制已经进行了大量研究，但晚期病变和出现转移的肺癌患者的预后仍不容乐观，5年生存率低于15%。本项目探讨了ANGPTL4在肺癌转移的功能及其机制，为肺癌的预后判断和治疗提供了理论依据。. 本项目研究发现与配对癌旁组织相比，ANGPTL4在81.91% 的肺癌组织中高表达；TCGA数据表明ANGPTL4的表达高低与肺癌患者病理学分级有关，而生存期分析发现，ANGPTL4表达高意味着肺癌患者总生存期及无复发生存期均较短。在肺癌细胞系NCI-H358和NCI-H460中过表达ANGPTL4，能够明显促进肺癌细胞的体外迁移与侵袭，在动物体内促进肺癌细胞的转移潜能；反之，在肺癌细胞系A549和SPC-A-1中干扰ANGPTL4，能够明显抑制肺癌细胞的体外迁移与侵袭及动物体内的转移。我们进一步检测了肺癌患者血清中ANGPTL4的水平，结果表明肺癌患者血清中ANGPTL4的浓度（154.07±136.65 ng/ml）明显高于其他肺病患者（50.14±17.14 ng/ml）及健康志愿者（58.73±34.85 ng/ml）。若将肺癌患者血清ANGPTL4诊断的cut-off值设为93.50 ng/mL，其敏感性64.1%，特异性为84.4%，具有一定的诊断价值。进一步分析发现，发生转移的肺癌患者血清中ANGPTL4的浓度（185.62±173.54 ng/ml）高于未发生转移的肺癌患者（113.76±58.56 ng/ml）；Ⅰ期患者血清中ANGPTL4的浓度（88.66±29.19 ng/ml）低于Ⅱ期-Ⅲ期（129.10±67.01 ng/ml）及Ⅳ期患者（185.62±173.54 ng/ml）。以上数据表明肺癌患者血清中ANGPTL4的浓度与肺癌转移和恶性进展相关，提示血清ANGPTL4可以作为肺癌患者预后诊断的标志物。. 本项目的研究结果表明ANGPTL4能够促进肺癌的转移，与肺癌的恶性进展密切相关。本研究为肺癌患者的诊断及预后判断提供了候选标志物，也为肺癌的治疗提供了候选分子靶点。