THE EFFECT OF TUMOR MICROENVIRONMENT ON METASTASIS

摘要 转移是乳腺癌相关死亡的主要原因，是一个多步骤的过程，最终导致 在远处器官内形成肿瘤灶。然而，只有原发细胞内的一小部分癌细胞 肿瘤微环境能够完成整个转移级联反应，包括血管内注入， 在循环中存活、渗出和远处部位肿瘤生长。目前，还没有治愈的方法 转移性乳腺癌的治疗。了解促转移癌细胞的诱导因素 表型和癌细胞扩散机制是开发针对这种疾病的救命疗法的关键 致命的疾病。我们鉴定出一个高度侵袭性、非增殖性、非凋亡性、耐化疗的群体。 癌细胞能够向血管内扩散。这些细胞表达高水平的MenaINV，这是一种促进转移的亚型 肌动蛋白调节蛋白Mena，以及低水平的抗转移亚型Mena11a。我们发现 MenaINV表达(已发表)和干细胞计划(初步结果)是由Notch信号诱导的 肿瘤细胞通过与肿瘤相关的巨噬细胞直接接触。MenaINV-High/Mena11aLow的出现 干细胞可能是转移的关键步骤之一，因为这些细胞不仅存在于血管内- 有能力但也有引发肿瘤的能力。在原发乳腺肿瘤中，癌细胞表达MenaINV- 高/低能通过肿瘤转移微环境(TMEM)进入血管 门口。我们小组首先描述了毛细管壁中这些严格控制的瞬时开口，并 是由巨噬细胞、内皮细胞和表达膜蛋白的肿瘤细胞直接物理接触而成。 在肺转移瘤中也观察到了类似的显微解剖结构，但其扩散机制 来自此辅助站点的数据目前未知。有趣的是，我们发现化疗会导致联合- 巨噬细胞依赖性肿瘤细胞中MenaINV和干细胞转录因子Sox9的表达 机制。重要的是，我们和其他人发现化疗也会增加TMEM的密度 门口。因此，我们假设肿瘤相关的巨噬细胞诱导了一个促转移的癌细胞。 原发肿瘤和转移灶的表型，使它们能够通过TMEM门口传播，并且 化疗加强了这一过程。我们的目标是阐明核因子-kB和Notch在共同的- 体内原发肿瘤和肺转移瘤中侵袭性(MenaINV-High)和干细胞表型的诱导 评价癌细胞在肺转移瘤中的扩散机制及化疗效果 肺转移的癌细胞再扩散和干细胞和MenaINV-High表型的共激活。 我们的发现将为肿瘤微环境在诱发肿瘤中的作用提供机制方面的见解。 转移和癌细胞从转移灶再扩散。这将使我们能够识别分子 未来可与化疗相结合的治疗目标，以改善慢性粒细胞白血病患者的预后 转移性疾病，这将是抗击乳腺癌斗争的重大进步。

ABSTRACT Metastasis, the primary cause of breast cancer-related mortality, is a multistep process culminating with the formation of tumor foci within distant organs. However, only a subpopulation of cancer cells within the primary tumor microenvironment is capable of completing the entire metastatic cascade, which includes intravasation, survival in circulation, extravasation, and tumor growth at distant sites. Currently, there are no curative treatments for metastatic breast cancer. Understanding the factors that induce a pro-metastatic cancer cell phenotype and cancer cell dissemination mechanisms is key to developing life-saving therapies against this deadly disease. We identified a population of highly invasive, non-proliferating, non-apoptotic, chemo-resistant cancer cells capable of intravasation. These cells express high levels of MenaINV, a pro-metastatic isoform of the actin-regulatory protein Mena, and low levels of the anti-metastatic isoform, Mena11a. We found that MenaINV expression (published) and a stem cell program (preliminary results) are induced by Notch signaling in tumor cells by direct contact with tumor-associated macrophages. The emergence of MenaINV-High/Mena11aLow stem cells may be one of the crucial steps to metastasis because these cells are not only intravasation- competent but also have tumor-initiating capability. In primary breast tumors, cancer cells expressing MenaINV- High/Mena11aLow are able to enter blood vessels through Tumor Microenvironments of Metastasis (TMEM) doorways. These tightly controlled transient openings in capillary walls were first described by our group and are composed of macrophages, endothelial cells and Mena-expressing tumor cells in direct physical contact. Similar micro-anatomical structures are also observed in lung metastases, but the dissemination mechanism from this secondary site is currently unknown. Interestingly, we found that chemotherapy induces co- expression of MenaINV and stem cell transcription factor Sox9 in tumor cells through a macrophage-dependent mechanism. Importantly, we and others found that chemotherapy also increases the density of TMEM doorways. Thus, we hypothesize that tumor-associated macrophages induce a pro-metastatic cancer cell phenotype in primary tumors and metastatic foci, enabling them to disseminate via TMEM doorways, and that this process is potentiated by chemotherapy. We aim to delineate the involvement of NF-kB and Notch in co- induction of invasive (MenaINV-High) and stem phenotypes in both primary tumor and lung metastases in vivo, evaluate cancer cell dissemination mechanisms in lung metastases and evaluate the effect of chemotherapy on cancer cell re-dissemination from lung metastasis and co-activation of stem and MenaINV-High phenotype. Our findings will provide mechanistic insights into the effects of the tumor microenvironment on the induction of metastasis and cancer cell re-dissemination from metastatic foci. This will enable us to identify molecular targets for future therapies that could be combined with chemotherapy to improve outcomes for patients with metastatic disease which would be a major advance in the battle against breast cancer.