THE EFFECT OF TUMOR MICROENVIRONMENT ON METASTASIS

摘要 转移是乳腺癌相关死亡率的主要原因，是一个多步骤的过程， 在远处器官内形成肿瘤病灶。然而，在原发灶中只有癌细胞亚群 肿瘤微环境能够完成整个转移级联，包括内渗， 循环中的存活、外渗和远处肿瘤生长。目前，没有治疗方法 转移性乳腺癌的治疗了解诱导促转移癌细胞的因素 表型和癌细胞传播机制是开发救生疗法的关键 致命的疾病我们发现了一群高度侵袭性、非增殖性、非凋亡性、化疗耐药的 能够渗透的癌细胞。这些细胞表达高水平的MenaINV，MenaINV是一种促转移同种型。 肌动蛋白调节蛋白Mena和低水平的抗转移亚型Mena 11 a。我们发现 MenaINV表达（已发表）和干细胞程序（初步结果）由Notch信号传导诱导。 通过与肿瘤相关的巨噬细胞直接接触来抑制肿瘤细胞。MenaINV-High/Mena 11 aLow的出现 干细胞可能是转移的关键步骤之一，因为这些细胞不仅是内渗的， 但也有引发肿瘤的能力。在原发性乳腺肿瘤中，表达MenaINV的癌细胞- High/Mena 11 aLow能够通过肿瘤转移微环境（TMEM）进入血管 门口这些在毛细血管壁中受到严格控制的瞬时开口首先由我们的小组描述， 由直接物理接触的巨噬细胞、内皮细胞和表达Mena的肿瘤细胞组成。 在肺转移瘤中也观察到类似的显微解剖结构，但播散机制 目前还不清楚这个二级网站的信息有趣的是，我们发现化疗会诱导共- MenaINV和干细胞转录因子Sox 9在肿瘤细胞中通过巨噬细胞依赖性 机制重要的是，我们和其他人发现化疗也增加了TMEM的密度， 门口因此，我们假设肿瘤相关巨噬细胞诱导促转移癌细胞 在原发肿瘤和转移灶中的表型，使它们能够通过TMEM门口传播， 这个过程通过化学疗法得到加强。我们的目标是描述NF-kB和Notch在共同的 在体内原发性肿瘤和肺转移中诱导侵袭性（MenaINV-高）和干细胞表型， 评估肺转移癌细胞播散机制和评估化疗效果 对来自肺转移的癌细胞再传播以及干细胞和MenaINV-High表型的共活化的影响。 我们的研究结果将为肿瘤微环境对诱导肿瘤细胞凋亡的影响提供机制上的见解。 转移和癌细胞从转移灶再扩散。这将使我们能够识别分子 未来治疗的目标，可以与化疗相结合，以改善患者的结果， 转移性疾病，这将是对抗乳腺癌的一个重大进展。

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.