PDGF-BB and the metastatic brain microenvironment

项目总结 我的团队最近的研究强调了血小板衍生生长因子-B的临床相关性 恶性乳腺上皮细胞及其受体血小板衍生生长因子受体(PDGFB)的分泌 β(PDGFRβ)，表达于骨髓间充质系细胞(如成纤维细胞、周细胞、星形胶质细胞)。 促进乳腺癌脑转移(BCBM)。我们的研究表明：(1)PDGFB配体促进 原发和颅内乳腺肿瘤生长，(2)间充质细胞特异性PDGFRβ过度活动(FSP1- Cre；PdgfrbD849V/+)促进小鼠BCBM，(3)PDGFB配体在原发乳腺肿瘤中的表达 乳腺癌患者脑转移的预后，以及(4)小分子的抑制作用 选择性PDGFR抑制剂(Crenolanib)减少BCBM小鼠模型中的颅内肿瘤生长。这 已发表的工作发现PDGFB-to-PDGFRβ信号作为临床相关的信令节点用于预测， 和潜在的治疗，BCBM。我们继续调查乳腺癌来源的PDGFB是如何 机械调节大脑TME进一步揭示了先前未知的免疫调节和 血管效应。目前的应用将直接测试乳腺癌细胞的主要假设 表达PDGFB完全改变了脑转移的生态位，这两种方式都是通过创造一种促肿瘤形成 免疫微环境和引发血管变化。在目标1中，乳腺癌之间的相互作用 有/没有PDGFB的细胞和脑免疫微环境将在体外进行评估(小胶质细胞共同 培养和条件培养液实验)和体内(心内注射，然后脑注射 组织病理学评价和高复合光谱分析)。该目标还将评估PDGFB是否会导致 小胶质细胞吞噬反应的变化以及抗肿瘤/促肿瘤髓系细胞的转变 表型。这些研究将是第一次直接测试乳腺癌来源的PDGFB是否会驱动 脑转移微环境中的免疫逃避。在目标2中，乳腺癌之间的相互作用 有/没有PDGFB的细胞和脑微血管系统将在体外进行评估(血脑屏障球体， 微流体)和体内(心内注射，然后进行脑组织病理学评估)。这一目标将 还评估了PDGFB以自分泌方式发挥作用以上调蛋白水平的可能机制。 血管生成因子血管生成素-1及这些血管改变能否被小分子消融 PDGFRβ和/或TIE2(血管生成素受体)的抑制剂。这些研究将是第一个直接测试 乳腺癌来源的PDGFB通过自分泌间接改变脑微血管的假说 PDGFB-PDGFFRβ-Ang1轴。在建议的研究完成后，我们将会确定可能 PDGFB预调节允许转移的脑微环境的靶向机制(S) 到这个网站。

PROJECT SUMMARY Recent studies by my group have highlighted the clinical relevance of platelet-derived growth factor-B (PDGFB) secreted by malignant breast epithelial cells and its receptor, platelet-derived growth factor receptor beta (PDGFRβ), expressed on cells of the mesenchymal lineage (e.g., fibroblasts, pericytes, astrocytes) in the promotion of breast cancer metastasis to the brain (BCBM). Our studies revealed: (1) PDGFB ligand promotes primary and intracranial breast tumor growth, (2) mesenchymal-specific PDGFRβ hyperactivity (Fsp1- cre;PdgfrbD849V/+) promotes BCBM in mice, (3) PDGFB ligand expression in the primary breast tumor is prognostic of brain metastases in human breast cancer patients, and (4) inhibition with a small molecule selective PDGFR inhibitor (crenolanib) reduces intracranial tumor growth in mouse models of BCBM. This published work discovered PDGFB-to-PDGFRβ signaling as a clinically relevant signaling node for predicting, and potentially treating, BCBM. Our continued investigation into how breast cancer-derived PDGFB mechanistically modulates the brain TME has further revealed previously unknown immuno-modulatory and vascular effects. The current application will directly test the overarching hypothesis that breast cancer cells expressing PDGFB completely transform the brain metastatic niche, both by creating a pro-tumorigenic immune microenvironment and by invoking vascular changes. In Aim 1, the interaction between breast cancer cells with/without PDGFB and the brain immune microenvironment will be evaluated in vitro (microglial co- cultures and conditioned media experiments) and in vivo (intracardiac injections followed by brain histopathological evaluation and high-plex spectral cytometry). This aim will also evaluate if PDGFB causes changes in the microglial phagocytic response as well as shifts in anti-tumorigenic/pro-tumorigenic myeloid cell phenotypes. These studies will be the first to directly test whether breast cancer-derived PDGFB drives immune evasion in the brain metastatic microenvironment. In Aim 2, the interaction between breast cancer cells with/without PDGFB and the brain microvasculature will be evaluated in vitro (BBB spheroids, microfluidics) and in vivo (intracardiac injections followed by brain histopathological evaluation). This aim will also evaluate a putative mechanism by which PDGFB functions in an autocrine manner to upregulate the pro- angiogenic factor Angiopoietin-1, and whether these vascular changes can be ablated with small molecule inhibitors of PDGFRβ and/or Tie2 (angiopoietin receptor). These studies will be the first to directly test the hypothesis that breast cancer-derived PDGFB alters the brain microvasculature indirectly through an autocrine PDGFB-PDGFRβ-Ang1 axis. Upon completion of the proposed study, we will have determined potentially targetable mechanism(s) by which PDGFB pre-conditions the brain microenvironment allowing for metastasis to this site.