Ron Receptor Tyrosine Kinase Signaling in Breast Cancer

 描述（由申请人提供）： 乳腺癌（BC）是女性中最常见的癌症，大约有250万有乳腺癌个人病史的美国女性今天仍然活着。晚期癌症具有高死亡风险，使BC成为美国女性癌症相关死亡的第二大原因。尽管在筛查和检测方面取得了重大进展，但BC仍然是妇女的主要杀手，迫切需要确定新的途径来对抗BC。罗恩受体在约50%的人类BC中过表达，并且是患有这种疾病的女性中转移和预后不良的独立预测因子。虽然罗恩过表达是人类BC和转移的重要因素，但我们对罗恩促进侵袭性疾病发展的机制的认识存在重大差距。为了进一步检查罗恩，产生产生乳腺特异性罗恩过表达的转基因小鼠。这些小鼠被称为MMTV-Ron小鼠，模仿在人类患者中观察到的侵袭性疾病模式，所有雌性小鼠都发展出高度转移性乳腺肿瘤。在这个临床相关的模型中，我们发现乳腺肿瘤上调了罗恩配体，肝细胞生长因子样蛋白（HGFL），尽管这种生长因子存在于循环中。利用HGFL缺陷的MMTV-罗恩小鼠，我们的初步研究显示了HGFL对致癌罗恩激活和乳腺肿瘤生长和进展的重要性。利用HGFL缺陷的乳腺肿瘤细胞，我们发现HGFL的重建促进肿瘤细胞的自主存活、迁移和侵袭。此外，我们表明，全球HGFL损失也通过调节免疫细胞募集，巨噬细胞极化，乳腺癌干细胞样细胞/肿瘤起始细胞（BCSC）数量和血管生成显着影响肿瘤微环境。对骨髓来源的巨噬细胞的分析显示，HGFL增强Stat 3活化并促进替代性巨噬细胞活化的标志物的表达，支持HGFL诱导的罗恩信号传导在抑制抗肿瘤免疫应答中的作用。这些研究得到了最近报告的进一步支持，该报告表明骨髓细胞（特别是巨噬细胞）中的罗恩信号传导对于抑制细胞毒性T细胞反应和促进肿瘤生长至关重要。综合起来，这些数据支持肿瘤细胞内在和外在的功能HGFL诱导的罗恩激活促进乳腺肿瘤的生长和转移。在此修订的更新申请中，我们将直接定义乳腺肿瘤发生过程中巨噬细胞和上皮细胞中罗恩信号传导途径的功能，并将检查肿瘤细胞产生的HGFL通过自分泌和旁分泌信号传导指导肿瘤生长和免疫抑制的意义。我们将检验肿瘤细胞产生的HGFL通过协同激活肿瘤微环境中的髓样和上皮罗恩信号传导促进侵袭性BC的假设。为了验证这一假设，提出了三个具体目标：（i）阐明髓样罗恩信号传导增强乳腺肿瘤生长的机制;（ii）确定HGFL支持BC生长和转移的来源和机制;（iii）确定肿瘤细胞特异性罗恩表达在促进乳腺肿瘤发生中的功能。总的来说，我们希望了解HGFL-Ron信号轴在BC发展和传播中的作用，并为新的诊断或治疗方式提供理论基础，这些新的诊断或治疗方式针对肿瘤本身和免疫反应，以降低BC死亡率。

 DESCRIPTION (provided by applicant): Breast cancer (BC) is the most commonly diagnosed cancers in women, and approximately 2.5 million American women with a personal history of breast cancer are alive today. Late stage cancer comes with a high risk of mortality, making BC the second leading cause of cancer-related deaths in women in the US. Despite major advances in screening and detection, BC is still a major killer of women and the identification of novel pathways to combat BC is urgently needed. The Ron receptor is overexpressed in ~50% of human BC and is an independent predictor of metastases and poor prognosis in women with this disease. While Ron overexpression is an important factor in human BC and metastasis, a significant gap exists in our knowledge about the mechanisms by which Ron promotes the development of aggressive disease. To examine Ron further, transgenic mice were generated that produce mammary-specific Ron overexpression. These mice, referred to as the MMTV-Ron mice, mimic the aggressive disease pattern observed in human patients with all female mice developing highly metastatic breast tumors. In this clinically relevant model, we discovered that mammary tumors upregulate the Ron ligand, hepatocyte growth factor-like protein (HGFL), despite the presence of this growth factor in the circulation. Utilizing MMTV-Ron mice deficient in HGFL, our preliminary studies show the importance of HGFL for oncogenic Ron activation and mammary tumor growth and progression. Utilizing HGFL deficient mammary tumor cells, we show that reconstitution of HGFL promoted tumor cell autonomous survival, migration and invasion. Further, we show that global HGFL loss also dramatically affected the tumor microenvironment by regulating immune cell recruitment, macrophage polarization, breast cancer stem-like cell/tumor initiating cell (BCSC) numbers, and angiogenesis. Analysis of bone marrow derived macrophages shows that HGFL augments Stat3 activation and promotes the expression of markers of alternative macrophage activation, supporting a role for HGFL-induced Ron signaling in suppressing anti-tumor immune responses. These studies are further supported by recent reports showing that Ron signaling in myeloid cells, and specifically in macrophages, is critical for suppressing cytotoxic T-cell responses and promoting tumor growth. Combined, these data support both tumor cell intrinsic and extrinsic functions for HGFL-induced Ron activation in promoting mammary tumor growth and metastasis. In this revised renewal application, we will directly define the functions of the Ron signaling pathway in macrophages and epithelial cells during breast tumorigenesis and will examine the significance of tumor cell produced HGFL in directing tumor growth and immunosuppression through autocrine and paracrine signaling. We will test the hypothesis that tumor cell produced HGFL promotes aggressive BC through the cooperative activation of myeloid and epithelial Ron signaling within the tumor microenvironment. To test this hypothesis, three Specific Aims are proposed: (i) to elucidate the mechanism(s) by which myeloid Ron signaling augments breast tumor growth; (ii) to determine the source and mechanism by which HGFL supports BC growth and metastasis, and (iii) to define the function of tumor cell-specific Ron expression in promoting breast tumorigenesis. In total, we hope to understand the role of the HGFL-Ron signaling axis in the development and spread of BC and provide a rationale for new diagnostic or treatment modalities that target both the tumor proper and immune response to mitigate BC mortality.