The lymph node microenvionment in tumor metastasis

描述（由申请人提供）：淋巴结是大多数实体肿瘤的初始转移部位，包括乳腺癌和黑色素瘤。临床记录表明，从淋巴结转移到远处转移的进展是切除肿瘤，引流淋巴结可以改善许多肿瘤类型的临床预后。令人惊讶的是，我们对淋巴结微环境中可能导致肿瘤转移的因素知之甚少。我们的初步数据表明，原发肿瘤的引流和远端淋巴结的转移是通过诱导整合素来实现的。1和vegf - r3介导的淋巴管生成，而不是淋巴结的血管生成。肿瘤转移到淋巴结需要淋巴管生成。选择性抑制整合素？淋巴结中的1或VEGF-R3阻断淋巴结淋巴管生成，阻止肿瘤转移到淋巴结。相反，注射VEGF-C刺激淋巴结淋巴管生成会加速淋巴结转移。即使在没有原发肿瘤的情况下，当肿瘤细胞直接注入淋巴系统时，刺激正常小鼠的淋巴结淋巴管生成也能促进肿瘤细胞归巢和外渗到受刺激的淋巴结。这种归巢可以通过整合素拮抗剂抑制淋巴管生成来阻断。1或VEGF-R3。这些研究表明，淋巴结淋巴管生成通过增强肿瘤细胞粘附和外渗到淋巴结，直接促进淋巴结转移。为了进一步了解淋巴结微环境在肿瘤转移中的作用，我们将验证整合素4？通过paxillin介导的1介导的信号传导促进淋巴内皮细胞迁移和整合素？1介导的蛋白激酶A、Raf和caspase 8信号通路在淋巴管生成和肿瘤转移过程中促进淋巴内皮细胞存活；淋巴结淋巴内皮通过表达关键肿瘤细胞趋化剂如CCL21和肿瘤细胞粘附配体/受体如整合素，促进肿瘤细胞的归巢、粘附和外渗。1、VCAM和E-Selectin；淋巴结内的炎症介质和骨髓源性细胞在促进肿瘤转移中起作用。本提案的目的是：1)确定整合素的作用？淋巴内皮细胞迁移过程中1-paxillin相互作用的研究2)确定蛋白激酶A、Raf和caspase 8在整合素4？1介导淋巴内皮细胞在淋巴管生成过程中的存活；3)探讨肿瘤转移过程中特异性趋化因子和粘附受体在促进肿瘤细胞吸引和淋巴内皮粘附中的作用；4)确定炎症介质和细胞在淋巴结淋巴管生成和转移中的作用。重要的是，我们关于淋巴结淋巴管生成在肿瘤转移中的作用的初步发现表明，淋巴结淋巴管生成的检测可以通过帮助预测尚未形成的转移灶的位置来促进癌症的诊断。这些结果也表明，淋巴结淋巴管生成抑制剂可能在癌症治疗中发挥重要作用。在本应用中提出的研究可能会导致开发和测试新的药物来诊断和预防或治疗转移性癌症。

DESCRIPTION (provided by applicant): Lymph nodes are the initial sites of metastasis for most solid tumors, including breast carcinoma and melanoma. Progression from lymph node metastases to distant metastases is suggested by the clinical record as excision of tumor-bearing, draining lymph nodes can improve clinical outcome for many tumor types. Surprisingly, little is known about the factors in the lymph node microenvironment that may contribute to tumor metastasis. Our preliminary data show that primary tumors precondition draining as well as distal lymph nodes for tumor metastasis by inducing integrin ?4?1 and VEGF-R3-mediated lymphangiogenesis but not hemangiogenesis in lymph nodes. Lymph node lymphangiogenesis is then required for tumor metastasis to lymph nodes. Selective inhibition of integrin ?4?1 or VEGF-R3 in lymph nodes blocks lymph node lymphangiogenesis and prevents tumor metastasis to lymph nodes. In contrast, stimulation of lymph node lymphangiogenesis by injections of VEGF-C accelerates metastasis to stimulated lymph nodes. Stimulation of lymph node lymphangiogenesis in normal mice also promoted tumor cell homing to and extravasation into stimulated lymph nodes even in the absence of a primary tumor when tumor cells were injected directly into the lymphatic system. This homing could be blocked by suppressing lymphangiogenesis with antagonists of integrin ?4?1 or VEGF-R3. These studies suggest that lymph node lymphangiogenesis directly promotes lymph node metastasis by enhancing tumor cell adhesion and extravasation into the node. To further our understanding of the role of the lymph node microenvironment in tumor metastasis, we will test the hypotheses that integrin ?4?1 mediated signaling via paxillin promotes lymphatic endothelial cell migration and that integrin ?4?1 mediated signaling via Protein Kinase A, Raf and caspase 8 promote lymphatic endothelial cell survival during lymphangiogenesis and subsequent tumor metastasis; that lymph node lymphatic endothelium promotes the homing, adhesion and extravasation of tumor cells by expressing key tumor cell chemoattractants such as CCL21 as well as tumor cell adhesion ligands/receptors, such as integrin ?4?1, VCAM and E-Selectin; and that inflammatory mediators and bone marrow derived cells within the lymph node play roles in promoting tumor metastasis. The aims of this proposal are: 1) To determine the role of integrin ?4?1-paxillin interaction during lymphatic endothelial cell migration; 2) To determine the roles of protein kinase A, Raf and caspase 8 in integrin ?4?1 mediated lymphatic endothelial cell survival during lymphangiogenesis; 3) To evaluate the roles of specific chemokine and adhesion receptors in promoting tumor cell attraction and adhesion to lymphatic endothelium during tumor metastases; 4) To determine the contributions of inflammatory mediators and cells in lymph node lymphangiogenesis and metastasis. Importantly, our preliminary findings on the role of lymph node lymphangiogenesis in tumor metastasis indicate that detection of lymph node lymphangiogenesis may facilitate cancer diagnosis by helping to predict the sites of metastatic lesions yet to form. These results also suggest that inhibitors of lymph node lymphangiogenesis may play important roles in cancer therapeutics. The studies proposed in this application are likely to lead to the development and testing of new agents to diagnose and prevent or treat metastatic cancer.