低氧对口腔癌细胞可溶性ephrin-A1表达的分子调控及其在促血管生成中的作用

Angiogenesis is rate-limiting step in tumor growth, invasion and metastasis. Ephrin-A1 and its primary receptor, EphA2, play a vital role in tumor angiogenesis. In our previous studies, we found a significant up-regulation of both membrane-bound ephrin-A1 and soluble ephrin-A1 in SCC-9 cells under hypoxia stimulation. However, the molecular mechanisms underlying this process and its roles in tumor angiogenesis are still not clarified. In the present study, we hypothesize that expression of both membrane-bound ephrin-A1 and soluble ephrin-A1 are modulated by HIF-1α under hypoxia condition and play essential roles in angiogenesis in OSCC in a juxacrine and/or paracrine manner, during which some new proteolytic enzymes may be involved in soluble ephrin-A1 production. The current study will focus on these hypothesizes both in vitro and in vivo. Our results may shade light on a new mechanism in ephrinA1-induced angiogenesis in tumor hypoxic microenvironment and may also provide us new targets for tumor anti-angiogenic treatment.

血管生成是肿瘤生长、侵袭、转移等病理过程的关键限速步骤。Ephrin-A1/EphA2是重要的促肿瘤血管生成因子。前期研究中，我们发现低氧可显著上调口腔癌细胞膜偶联型及可溶性ephrin-A1的表达。为深入探讨其潜在的分子调控机制及功能，本项目首次提出“HIF-1α参与调控了低氧状态下口腔癌细胞膜偶联型及可溶性ephrin-A1的表达，并通过某种蛋白酶切机制增加了后者的胞外释放，二者进一步通过邻分泌和/或旁分泌途径在口腔癌血管生成中发挥关键作用”。拟开展的研究内容有：Ephrin-A1/EphA2、HIF-1α、MMP在口腔癌组织中的表达及与血管生成的关系；HIF-1α调控口腔癌细胞膜偶联型及可溶性ephrin-A1表达的分子机制；Ephrin-A1信号通路对低氧口腔癌裸鼠模型血管生成的影响。本课题有望揭示ephrin-A1激活低氧条件下肿瘤血管生成的新机制，为肿瘤抗血管治疗提供新靶点。

血管生成是肿瘤生长、侵袭、转移等病理过程的关键限速步骤。Ephrin-A1是重要的促肿瘤血管生成因子。前期研究中，我们发现低氧可显著上调口腔癌细胞膜偶联型及可溶性ephrin-A1的表达。为深入探讨其潜在的分子调控机制及功能，本项目首次提出“HIF-1α参与调控了低氧状态下口腔癌细胞膜偶联型及可溶性ephrin-A1的表达，并通过某种蛋白酶切机制增加了后者的胞外释放，二者进一步通过邻分泌和/或旁分泌途径在口腔癌血管生成中发挥关键作用”。开展的研究内容有：Ephrin-A1/EphA2、HIF-1α、MMP在口腔癌组织中的表达及与血管生成的关系；HIF-1α调控口腔癌细胞膜偶联型及可溶性ephrin-A1表达的分子机制；Ephrin-A1信号通路对低氧口腔癌裸鼠模型血管生成的影响。研究发现：a、口腔癌组织中ephrin-A1、MMP-2、HIF-1α表达与MVD显著相关（P＜0.01），而MMP-9表达与MVD相关性无统计学意义；b、口腔癌患者术前血清可溶性ephrin-A1浓度为（0.681±0.062）ng/ml，术后为（0.545±0.058）ng/ml，术后较术前显著下降（P=0.005），证实在体内ephrin-A1可被肿瘤细胞分泌到肿瘤微环境中；c、细胞学实验，低氧可显著增加SCC细胞可溶性ephrin-A1的分泌，MMP特异性阻断剂GM6001可抑制可溶性ephrin-A1的胞外释放；d、低氧组SCC细胞MMP-2表达明显上调，其变化趋势与HIF-1α表达趋势基本一致，而MMP-9表达无动态变化，说明口腔癌细胞可溶性ephrin-A1释放增加由MMP-2介导；e、动物实验证实，低氧组MMP-2、ephrin-A1表达明显上调，而MMP-9表达变化不明显，HIF-1α干扰后可溶性ephrin-A1血清含量明显降低。本研究揭示了低氧/HIF-1α/MMP-2/可溶性ephrin-A1信号轴促口腔癌血管生成的新机制，对深入认识肿瘤血管生成和筛选新的抗肿瘤血管生成治疗靶点具有重要的科学意义。