The Six1/Eya Transcriptional complex as a mediator of lymphangiogenesis and lymph

描述（由申请人提供）：乳腺癌是女性癌症相关死亡的第二大原因，死亡是由于肿瘤细胞转移扩散到远处器官。 癌细胞通过血管扩散，或者通过淋巴系统扩散，对于乳腺癌尤其重要。 虽然肿瘤通过血液传播已被广泛研究，但导致淋巴传播的机制知之甚少。 该提案的重点是了解淋巴管生成和乳腺肿瘤转移扩散的新机制，通过Six 1/Eya 2转录复合物控制VEGF-C水平。 待检验的假设是乳腺癌中Six 1过表达导致VEGF-C上调，导致淋巴管生成增加并增强转移的早期阶段，包括肿瘤细胞的淋巴播散。 Six 1激活VEGF-C并刺激淋巴转移的能力取决于其与Eya 2磷酸酶辅因子的相互作用以及Eya 2的酶活性。 如果这一假设是正确的，它将提供重要的见解乳腺癌转移的机制，并提供了一个新的战略，通过干扰Six 1/Eya 2功能，通过抑制Six 1/Eya相互作用和/或Eya 2磷酸酶活性的“药物”的方法治疗靶向淋巴转移的基本原理。 为了解决这一假设，我们将：1）检验VEGF-C是Six 1/Eya 2的直接转录靶点的假设，以及Six 1和Eya 2与VEGF-C和人乳腺癌中的淋巴管生成相关的假设; 2）使用体内小鼠转移模型检验VEGF-C是Six 1诱导的淋巴管生成和转移的关键介质的假设;和3）检验Eya 2是Six 1诱导的淋巴管生成和体内转移所必需的假设，特别强调Six 1和Eya 2之间的相互作用，以及Eya 2磷酸酶活性的作用。 靶向Six 1/Eya 2有可能在疾病的早期（在本提案中研究）和晚期抑制乳腺癌。 由于Six 1/Eya 2发育调节因子在大多数正常成人组织中表达不足，以及它们在癌症中的再表达，靶向该复合物的治疗剂应该抑制淋巴管生成和转移，副作用有限。 因此，Six 1/Eya 2复合物是一个理想的乳腺癌治疗靶点，该提案中的工作将为最终靶向该复合物奠定基础。

DESCRIPTION (provided by applicant): Breast cancer is the second leading cause of cancer-related deaths among women, with deaths occurring due to the metastatic spread of tumor cells to distant organs. Spread of cancer cells occurs via blood vessels or, particularly important for breast cancer, via the lymphatic system. Although tumor dissemination via the blood has been extensively studied, the mechanisms that lead to lymphatic dissemination are poorly understood. This proposal focuses on understanding a new mechanism of lymphangiogenesis and breast tumor metastatic spread, via control of VEGF-C levels by the Six1/Eya2 transcriptional complex. The hypothesis to be tested is that Six1 overexpression in breast cancers leads to upregulation of VEGF-C, resulting in increased lymphangiogenesis and enhancing the early stages of metastasis including lymphatic dissemination of tumor cells. The ability of Six1 to activate VEGF-C and stimulate lymphatic metastasis is dependent on its interaction with the Eya2 phosphatase co-factor, and on the enzymatic activity of Eya2. If this hypothesis is correct, it will provide important insights into the mechanism of breast cancer metastasis and provide a rationale for a new strategy to therapeutically target lymphatic metastasis by interfering with Six1/Eya2 function through the "druggable" approaches of inhibiting Six1/Eya interaction and/or Eya2 phosphatase activity. To address this hypothesis, we will: 1) Test the hypothesis that VEGF-C is a direct transcriptional target of Six1/Eya2, and that Six1 and Eya2 correlate with VEGF-C and lymphangiogenesis in human breast cancer; 2) Test the hypothesis that VEGF-C is a critical mediator of Six1-induced lymphangiogenesis and metastasis using in vivo mouse metastasis models; and 3) Test the hypothesis that Eya2 is required for Six1-induced lymphangiogenesis and metastasis in vivo, with a specific emphasis on the interaction between Six1 and Eya2, as well as the role of the Eya2 phosphatase activity. Targeting Six1/Eya2 has the potential to inhibit breast cancer both at early (studied in this proposal) and later stages of the disease. Due to the paucity of expression of the Six1/Eya2 developmental regulators in most normal adult tissues, and their re-expression in cancers, therapeutic agents targeting this complex should inhibit lymphangiogenesis and metastasis with limited side effects. Thus the Six1/Eya2 complex is an ideal breast cancer therapeutic target, and work within this proposal will lay the foundation for eventual targeting of the complex.