Pleiotrophin Promotes a Pro-Tumor and Pro-Metastatic Phenotype - Resubmission - 1

 描述(申请人提供)：肿瘤相关巨噬细胞促进乳腺癌和胰腺癌的恶性进展、转移和化疗耐药。此外，患者肿瘤中巨噬细胞的水平与乳腺癌预后较差有关。肿瘤相关巨噬细胞的表型受到过多输入的影响，包括肿瘤内的细胞因子环境。在乳腺癌和胰腺癌的遗传模型中，我们发现了一组表达血管内皮生长因子受体2(VEGFR2)的巨噬细胞。使用流式细胞术和免疫组织化学分析，我们发现这一群体富含与促进血管生成、免疫抑制和转移的巨噬细胞相关的标记。在体外，我们发现肝素结合多肽(PTN)是一种诱导巨噬细胞表达VEGFR2和抗炎细胞因子的候选细胞因子。此外，我们发现PTN刺激的巨噬细胞在体外极大地增加了癌细胞的迁移。在MMTV-PyMT转基因小鼠乳腺癌模型中，我们观察到肿瘤PTN的表达与VEGFR2巨噬细胞的水平和恶性进展有关。Crizotinib，一种多营养素受体，间变性淋巴瘤激酶的抑制剂，减少了体内的抗炎和VEGFR2巨噬细胞。这一下降伴随着肿瘤血管生成和肺转移的显著减少。根据我们的初步数据，我们假设VEGFR2巨噬细胞促进恶性进展和转移。这项工作的具体目标集中在确定PTN刺激的巨噬细胞在肿瘤微环境中的功能，评估靶向抗PTN治疗在乳腺癌临床前模型中的疗效，以及确定巨噬细胞VEGFR2的表达是否与肿瘤的进展和转移有关。这项工作的潜在影响包括识别一种新的癌前巨噬细胞生物标记物，针对它们的治疗策略，以及加深对巨噬细胞在转移中的功能的理解。

 DESCRIPTION (provided by applicant): Tumor-associated macrophages promote progression to malignancy, metastasis, and resistance to chemotherapy in breast and pancreatic cancer. Furthermore, the level of macrophages in patient tumors correlates with a worse prognosis in breast cancer. The phenotype of tumor associated macrophages is influenced by a plethora of inputs, including the cytokine milieu within the tumor. We have identified a population of macrophages in genetic models of breast and pancreatic adenocarcinoma that express Vascular Endothelial Growth Factor Receptor 2 (Vegfr2). Using flow cytometry and immunohistochemical analyses, we found that this population is enriched for markers associated with macrophages that promote angiogenesis, immune suppression, and metastasis. In vitro, we identified the heparin-binding peptide, pleiotrophin (PTN), as a candidate cytokine that induces Vegfr2 and anti-inflammatory cytokine expression by macrophages. Additionally, we found that PTN-stimulated macrophages greatly increase cancer cell migration in vitro. In the MMTV-PyMT transgenic murine model of breast cancer, we observed that tumor PTN expression correlates with levels of Vegfr2+ macrophages and progression to malignancy. Crizotinib, an inhibitor of the pleiotrophin receptor, Anaplastic Lymphoma Kinase, reduced anti-inflammatory and Vegfr2+ macrophages in vivo. This decrease was concomitant with a significant reduction in tumor angiogenesis and pulmonary metastasis. From our preliminary data, we hypothesize that Vegfr2+ macrophages promote progression to malignancy and metastasis. Specific aims of this work are focused on identifying the function of PTN-stimulated macrophages in the tumor microenvironment, evaluating the efficacy of targeted anti-PTN therapy in preclinical models of breast cancer, and determining if macrophage Vegfr2 expression is required for tumor progression and metastasis. The potential impact of this work includes identifying a novel biomarker of pro-malignant macrophages, a therapeutic strategy to target them, and developing a deeper understanding of the function of macrophages in metastasis.