von Willebrand Factor在胃肠道恶性肿瘤血源性播散中的作用及机制研究

The interplay between cancer cells and platelets has been recognized as a "deadly ally" in cancer metastasis. The two types of cells interact through surface receptor and active molecules secreted from platelets. Among molecules critical for platelet interaction with cancer cells is von Willebrand factor (VWF), which can facilitate interplays among cancer cells, platelets, and vascular endothelial cells to promote cancer metastasis. However, the underlying mechanisms for the interplay remain poorly understood. Our preliminary data show that cells from gastric, collon and lung cancers express VWF, which promotes cancer cell adhere to the subendothelial matrix and transmigration through the endothelium. These preliminary data have led us to propose to define novel roles of VWF in cancer pathogenesis, especially metastasis using complementory technologies. We will first detect surface-bound VWF on cancer cells by flow cytometry and in a hydrodynamic chamber system that mimics blood flow.We will then use siRNA, tissue array, and assays for cell adhesion to study how manuipulating VWF expression and activity will alter the courses of cancer cell growth, migration and metastasis. These in vitro experiments will be complemented with studying animal models to determine the in vivo significance of VWF in facilitating interactions between cancer cells and platelets. Finally, we will associate levels of VWF expression with the degree of malignacy and ability to metastasis in the three type of cancers in samples from patients. Results from these studies could provide new mechanistic insights into the metastasis of cancer cells and role of VWF and platelets in the process. New therapeutics and their targets could potential be developed from these studies.

肿瘤转移过程中瘤细胞与血小板之间的相互作用被认为是一种"致死同盟"，两者通过表面受体和自分泌因子相互作用致瘤栓形成促进转移，其中 VWF（von Willebrand factor, VWF）可能在瘤细胞与血小板、内皮细胞间相互作用中起关键作用，但其作用及机制目前尚不清楚。我们前期工作发现部分胃癌、结肠癌和肺癌细胞株表达VWF，VWF能够促进癌细胞的粘附与迁移能力。据此我们将运用微流体技术模拟血道环境，并应用RNA干扰、组织芯片、细胞粘附实验及动物实验等技术，进一步研究胃癌、结肠癌细胞产生VWF的组织差异性、VWF介导血小板-瘤细胞粘附反应的机制、及对胃肠道肿瘤血源播散的影响及机制，阐明VWF在肿瘤转移中的作用及机制，为恶性肿瘤转移机制研究提出新的理论假说，并为恶性肿瘤转移防治提供新思路和新靶点。

VWF（von Willebrand factor, VWF）可能在瘤细胞与血小板、内皮细胞间相互作用中起关键作用，但其对恶性肿瘤血道转移的影响及机制目前尚不清楚。本项目对胃癌、结肠癌患者血浆及肿瘤组织内VWF水平的差异性研究表明人类胃、结肠癌组织表达VWF，表达水平与癌组织的分化程度、远处转移具有相关性，胃肠道癌患者的血浆VWF水平较正常人群显著增高。对细胞系的研究显示多种胃、结肠癌细胞系均表达VWF，表达水平较低，癌细胞进行三维培养后VWF的表达水平增高，Thrombin能刺激癌细胞VWF mRNA及蛋白表达水平的增高。在多种癌细胞系中，胃癌细胞系BGC823在培养过程中VWF表达的水平较高。应用Anti-VWF抗体及VWFsiRAN处理能降低BGC823细胞对血小板界面、Matrigel界面、内皮细胞界面及癌细胞界面的粘附能力。PI3K抑制剂LY294002能抑制VWF的表达，降低Integrin表达，降低癌细胞对血小板界面、Matrigel界面、内皮细胞界面及癌细胞界面的粘附能力。项目经过一年的研究，已基本完成实验内容，达到预期研究目标；根据前期对VWF表达水平的研究结果，我们在实验过程中对实验方法进行了优化，建立了稳定转染VWF的BGC823-pEGFP-N1-VWF细胞系用于动物实验及微流体实验，目前动物实验和微流体实验尚未完成。

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