The Role of Endothelial ACKR1 in Triple-Negative Breast Cancer Metastasis

转移是导致乳腺癌死亡的最常见原因。在乳腺癌亚型中，三倍于 阴性乳腺癌(TNBC)是最致命的，因为它增加了转移的可能性。肿瘤细胞 外渗是肿瘤转移的关键步骤，允许循环中的肿瘤细胞离开血管系统和种子。 远处的组织。清楚了解肿瘤细胞外溢的主要调节因素将有助于深入了解 TNBC转移的进展。 ACKR1是一种潜在的TNBC细胞外渗调节因子。在许多情况下，ACKR1表达式是 内皮细胞(EC)中白细胞外渗所必需的。内皮细胞ACKR1结合CXCL2，一种前迁移分子 趋化因子，并将其定位于EC连接，引导中性粒细胞通过白细胞外渗。CXCL2 在TNBC细胞中的表达也是肿瘤细胞从肺微血管渗出和肿瘤发生所必需的 转移。我们的初步数据显示，至少一种类型的TNBC基质细胞需要ACKR1 从原发肿瘤转移到肺部。这些数据表明，内皮细胞ACKR1-CXCL2相互作用 可能在TNBC转移中介导肿瘤细胞外渗。因此，我们假设内皮细胞ACKR1 通过在EC连接处保留CXCL2促进TNBC细胞外渗，导致增加 TNBC的转移性扩散。 为了解决这一假设，我们将检查内皮细胞ACKR1表达的体内意义 使用我们验证的ACKR1内皮细胞特异性基因敲除小鼠模型。我们将测试以下要求 内皮细胞ACKR1对原位种植的TNBC肿瘤向肺内远处转移的作用 循环中的肿瘤细胞渗入肺组织。我们将确定外渗的哪些步骤需要 通过使用IDIDI FLOW共培养系统评估ACKR1低表达和ACKR1高表达的内皮细胞 概述了肺微血管的剪应力状态。我们将研究这些步骤是否 通过将CXCL2中和抗体引入IDIDI FLOW系统并观察到 它们对每一步外渗的影响。 我们建议的研究将确定内皮细胞ACKR1在TNBC转移进展和 确定内皮细胞ACKR1和CXCL2在肿瘤细胞外渗中发挥作用的具体步骤。 了解这些过程可能会指导ACKR1作为转移和转移的预后标志的发展 可以提供对正在评估的候选趋化因子和趋化因子受体抑制剂的机械性洞察 用于治疗乳腺癌。

Metastasis is the most common cause of breast cancer mortality. Of the breast cancer subtypes, triple- negative breast cancer (TNBC) is the deadliest due to its increased likelihood to metastasize. Tumor cell extravasation is a critical step of metastasis and allows circulating tumor cells to exit the vasculature and seed distant tissues. Clear understanding of the major regulators of tumor cell extravasation will provide insights into the progression of TNBC metastasis. One potential regulator of TNBC cell extravasation is ACKR1. In many contexts, ACKR1 expression is required in endothelial cells (EC) for leukocyte extravasation. Endothelial ACKR1 binds CXCL2, a promigratory chemokine, and localizes it to EC junctions to guide neutrophils through leukocyte extravasation. CXCL2 expression in TNBC cells is also necessary for tumor cell extravasation from lung microvasculature and for tumor metastasis. Our preliminary data show that ACKR1 is required in at least one stromal cell type for TNBC metastasis from the primary tumor to the lung. These data suggest that endothelial ACKR1-CXCL2 interactions may mediate tumor cell extravasation in TNBC metastasis. Therefore, we hypothesize that endothelial ACKR1 promotes TNBC cell extravasation by retaining CXCL2 at EC junctions, resulting in the increased metastatic spread of TNBC. To address this hypothesis, we will examine the in vivo significance of endothelial ACKR1 expression using our validated ACKR1 endothelial cell-specific knockout mouse model. We will test the requirement for endothelial ACKR1 for metastasis of orthotopically implanted TNBC tumors to distant sites in the lung and for extravasation of circulating tumor cells into lung tissue. We will determine which steps of extravasation require ACKR1 by evaluating ACKR1-low and ACKR1-overexpressing ECs using an Ibidi flow co-culture system that recapitulates the shear stress conditions of pulmonary microvasculature. We will examine whether these steps are dependent on CXCL2 by introducing CXCL2-neutralizing antibodies to the Ibidi flow system and observing their effects on each extravasation step. Our proposed studies will establish the role of endothelial ACKR1 in TNBC metastatic progression and determine the specific steps of tumor cell extravasation in which endothelial ACKR1 and CXCL2 function. Understanding these processes may guide development of ACKR1 as a prognostic marker for metastasis and can provide mechanistic insight into candidate chemokine and chemokine receptor inhibitors under evaluation for treatment of breast cancer.