The Mechanisms of GM-CSF Inhibition of Breast Cancer Growth and Metastasis

描述（由申请方提供）：本提案重点在于了解GM-CSF诱导单核吞噬细胞产生sVEGFR-1的机制以及由此产生的抗肿瘤活性。我们的数据表明，当正常FVB/N雌性小鼠注射PyMT肿瘤细胞并形成肿瘤时，局部注射rmGM-CSF显著抑制肿瘤生长、肺转移、肿瘤内的氧，以及增加小鼠的总体存活。我们的假设是，GM-CSF将诱导驻留在乳腺肿瘤中的单核细胞和巨噬细胞产生并释放可溶性形式的VEGF受体-1（sVEGFR-1）。该诱饵受体是膜结合VEGFR-1的选择性剪接变体，其结合VEGF并使其丧失生物活性。随着肿瘤环境中VEGF的减少，其在维持内皮细胞存活和正常血管床中是必不可少的，肿瘤血管系统将分解并导致肿瘤内的图案化坏死和最终的肿瘤细胞死亡。我们已经发表了这些影响在体内基质胶塞测定，并显示减少血管生成这些栓。该提案中的初步数据表明，GM-CSF在乳腺癌的鼠模型中显著减少肿瘤生长和转移，部分是通过抑制肿瘤的可用氧。通过评估GM-CSF在人类肿瘤环境中的作用来进一步研究这些发现是至关重要的。我们将使用免疫缺陷的无胸腺裸鼠与MCF 10A、MCF 10AT 1 k、MCF 10 CA 1h和MCF 10 CA 1a人肿瘤细胞系联合观察这些效应。这些细胞系，当注射到裸鼠的乳腺脂肪垫中时致瘤性，是永生化的乳腺上皮细胞，并且在转移侵袭性方面各不相同。 因此，具体目标将解决以下问题：目标1。确定GM-CSF诱导的sVEGFR-1对乳腺肿瘤血管生成和转移的影响。目标2.确定负责响应GM-CSF产生sVEGFR-1的细胞。目标3. GM-CSF是否抑制裸鼠肿瘤生长、血管生成和转移？ 我们预计这些研究的结果将为肿瘤相关细胞的机制提供新的见解，在这种情况下，单核吞噬细胞，以及将其表型从肿瘤支持型改变为肿瘤抑制型的潜力。

DESCRIPTION (provided by applicant): This proposal focuses on understanding the mechanism of GM-CSF-induced sVEGFR-1 production from mononuclear phagocytes and the resulting anti-tumor activity therein. Our data indicates when normal FVB/N female mice are injected with PyMT tumor cells and form a tumor, local injection of rmGM-CSF significantly inhibits tumor growth, metastases to the lung, oxygen within the tumors, as well as increases overall survival of the mouse. Our hypothesis is that GM-CSF will induce the monocytes and macrophages, which reside in mammary tumors, to produce and release the soluble form of the VEGF receptor-1 (sVEGFR-1). This decoy receptor is an alternately-spliced variant of the membrane-bound VEGFR-1 that binds and sequesters VEGF from biological activity. With reduced VEGF in the tumor environment, which is essential in maintaining endothelial cell survival and normal blood vascular beds, the tumor vasculature will break down and result in patterned necrosis within the tumor and eventual tumor cell death. We have published these effects in vivo in a Matrigel plug assay and show reduced angiogenesis within these plugs. Preliminary data in this proposal suggest that GM-CSF significantly reduces tumor growth and metastases in a murine model of breast cancer, in part, by inhibiting the available oxygen to the tumor. It is essential to further these findings by evaluating the effects of GM-CSF in a human tumor environment. We will be using immunodeficient, athymic nude female mice in conjunction with MCF10A, MCF10AT1k, MCF10CA1h and MCF10CA1a human tumor cell lines to see these effects. These cell lines, tumorigenic when injected into the mammary fat pad of nude mice, are immortalized mammary epithelial cells and vary in metastatic aggressiveness. Thus the Specific Aims will address the following questions: Aim 1. To determine the effect of GM-CSF-induced sVEGFR-1 on angiogenesis and metastases in breast tumors. Aim 2. To determine the cells responsible for sVEGFR-1 production in response to GM-CSF. Aim 3. Does GM-CSF inhibit tumor growth, angiogenesis, and metastases of human tumors in nude mice? We anticipate the findings from these studies will provide novel insight in the mechanisms of tumorassociated cells, in this case mononuclear phagocytes, and the potential to change their phenotype from that of tumor-supporting to that of tumor-suppressive.