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

 描述（由申请方提供）：肿瘤相关巨噬细胞促进乳腺癌和胰腺癌进展为恶性肿瘤、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的预后较差相关。 肿瘤相关巨噬细胞的表型受到大量输入的影响，包括肿瘤内的细胞因子环境。我们已经在乳腺癌和胰腺癌的遗传模型中鉴定了一群表达血管内皮生长因子受体2（Vegfr 2）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，这个人口是丰富的标志物与巨噬细胞，促进血管生成，免疫抑制和转移。在体外，我们确定了肝素结合肽，多效生长因子（PTN），作为一个候选细胞因子，诱导Vegfr 2和抗炎细胞因子表达的巨噬细胞。此外，我们发现PTN刺激的巨噬细胞在体外大大增加了癌细胞的迁移。在乳腺癌的MMTV-PyMT转基因鼠模型中，我们观察到肿瘤PTN表达与Vegfr 2+巨噬细胞的水平和恶性进展相关。克唑替尼是一种多效生长因子受体（间变性淋巴瘤激酶）的抑制剂，可减少体内抗炎和Vegfr 2+巨噬细胞。这种减少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Vegfr 2+巨噬细胞促进恶性肿瘤和转移的进展。这项工作的具体目标是确定肿瘤微环境中PTN刺激的巨噬细胞的功能，评估乳腺癌临床前模型中靶向抗PTN治疗的疗效，并确定巨噬细胞Vegfr 2表达是否是肿瘤进展和转移所必需的。这项工作的潜在影响包括确定促恶性巨噬细胞的新生物标志物，靶向它们的治疗策略，以及更深入地了解巨噬细胞在转移中的功能。

 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.