The role of macrophages in triple-negative breast cancer invasion and metastasis

 描述(由申请人提供)：患有三阴性乳腺癌(TNBC)的妇女，是乳腺癌中最具侵袭性的亚型，生存时间最短，复发率最高。这些患者目前没有可用的靶向治疗形式，大多数(~77%)在5年内死于转移。然而，转移是如何依赖于来自肿瘤微环境的信号的本质还不是很清楚。巨噬细胞也与人类乳腺癌的侵袭和转移以及耐药性有关，最近还被认为与TNBC有关。M1样促炎巨噬细胞被认为抑制肿瘤的生长和转移，而肿瘤相关巨噬细胞(TAM)则被认为是M2样促转移巨噬细胞。然而，最近的蛋白质组学和RNA研究表明，巨噬细胞群体由比以前认识到的更多的表型亚型组成。因此，TNBC TAMs的表型以及它们与TNBCs相互作用的机制还不是很清楚，需要进一步描述。在最近的研究中，我一直在验证一种假设，即TNBC通过CCL5招募一种独特的TAMS亚型，从而推动侵袭和转移。使用基因匹配的转移性和非转移性TNBC肿瘤，只有转移抑制因子Raf Kinase抑制蛋白(RKIP)的表达不同，我发现RKIP不仅改变了招募的TAM的数量，还改变了它们的表型。我进一步证明，转移性肿瘤中表达的CCL5招募TAM，分泌促转移因子，促进TNBC细胞的侵袭，在人类TNBC患者中高表达，并有助于患者生存的预后标志。综上所述，这些发现表明，TNBC招募的TAM在表型和功能上都不同于其他TAM以及M1或M2巨噬细胞。我现在建议检验这样一个假设，即这些TAMs可以通过调节促转移因子的表达和分泌的独特表面受体来区分。我进一步提出，CCL5招募的TAMs通过GRN和其他相关因子的表达来驱动转移。具体地说，我将：1)确定TNBC中TAMS的表型；2)确定TAMS和分泌的因子在TNBC转移中的功能作用。本研究具有创新性，因为它试图了解在TNBC中发现的一个新的亚型的表型，以及在TNBC中驱动侵袭的体内机制。总之，这些结果可以产生新的诊断标记物和预后标志，并确定潜在的治疗靶点，以耗尽或重新编程TNBC患者的前转移TAMs。这项工作还应该有助于更好地理解TAMS在TNBC患者不良结局中的作用。

 DESCRIPTION (provided by applicant): Women with triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer, have the shortest survival times and the highest rate of relapse. These patients have no currently available forms of targeted therapy and most (~77%) succumb to metastases within 5 years. However, the nature of how metastasis relies on signaling from the tumor microenvironment is not well understood. Macrophages have also been linked to human breast cancer invasion and metastasis as well as drug resistance, and recently have been implicated in TNBC. M1-like pro-inflammatory macrophages are thought suppress tumor growth and metastasis, whereas the tumor-associated macrophages (TAMs) are characterized as M2-like pro-metastatic macrophages. However, recent proteomic and RNA studies indicate that macrophage populations are composed of more phenotypic subtypes than previously recognized. Thus, the phenotype of TNBC TAMs and the mechanisms by which they interact with TNBCs are not well understood and require further characterization. In recent studies I have been testing the hypothesis that TNBC recruits a unique subtype of TAMs via CCL5 that drives invasion and metastasis. Using genetically matched metastatic and non-metastatic TNBC tumors that differ only by expression of the metastasis suppressor Raf Kinase Inhibitory Protein (RKIP), I show that RKIP alters not only the number of recruited TAMs but also their phenotype. I further demonstrate that CCL5 expressed by metastatic tumors recruits TAMs that secrete pro-metastatic factors, promote invasion of TNBC cells, are highly expressed in human TNBC patients, and contribute to a prognostic signature for patient survival. Taken together, these findings suggest that TNBC recruited TAMs are both phenotypically and functionally distinct from other TAMs, and M1 or M2 macrophages. I now propose to test the hypothesis that these TAMs can be distinguished by unique surface receptors that regulate expression and secretion of pro-metastatic factors. I further propose that TAMs recruited by CCL5 to metastatic TNBCs drive metastasis through expression of GRN along with other associated factors. Specifically, I will: 1) Characterize the phenotype of pro-metastatic TAMs in TNBC; and 2) Determine the functional role of TAMs & TAM secreted factors in TNBC metastasis. This study is innovative because it seeks to understand the phenotype of a novel TAM subtype identified in TNBC, as well as the in vivo mechanism of TAM driven invasion in TNBC. Together, these results could generate new diagnostic markers and prognostic signatures as well as identify potential therapeutic targets to deplete or reprogram pro-metastatic TAMs in TNBC patients. This work should also lead to a better understanding of the role of TAMs in the poor outcomes of TNBC patients.