Understanding Breast Cancer Metastasis to Lymph Node

 描述（申请人提供）：乳腺癌死亡的主要原因是癌症转移，而不是原发性肿瘤。为了转移，癌细胞必须离开原发肿瘤，在血液或淋巴循环中存活，侵入并定殖远处组织并建立转移灶。大多数癌被认为是通过血流和淋巴系统平行传播的。淋巴结转移被认为是由已经进入乳腺组织的自然淋巴引流以定殖下游前哨淋巴结的肿瘤细胞引起的。除了对淋巴转移的一般理解，还有一些关于淋巴转移的基本生物学问题尚未得到解答，例如：肿瘤细胞如何进入淋巴引流？体内淋巴转移的疗效如何？转移性和非转移性肿瘤是否都将细胞排入淋巴引流？进入淋巴引流的肿瘤细胞是亲代肿瘤细胞群的一个特化亚群吗？这些细胞通过什么样的分子机制进入淋巴，在淋巴液中生长，并在淋巴结中定植？为了回答这些问题，首先，我们的实验室开发了一种创新的显微外科技术，在免疫活性乳腺癌动物模型中收集淋巴液和其中含有的淋巴循环肿瘤细胞（LCTC）。随后，在与我们社区的外科医生以及印第安纳州大学医学院的外科医生的合作努力中，我们首次成功地应用了相同的技术来收集转移性乳腺癌女性淋巴引流中的LCTC。其次，我们提出Toll样受体（TLR）信号通路是肿瘤细胞进入淋巴引流的主要分子决定因素。已知TLR信号传导调节病原体感知和免疫细胞归巢。该途径还调节细胞因子和淋巴因子的释放，这些细胞因子和淋巴因子是感染早期淋巴结活化的一部分。在本提案中，我们将首次在乳腺癌大鼠模型以及乳腺癌女性中评估进入淋巴引流的乳腺癌细胞（LCTC）中TLR和与TLR细胞信号通路相关的关键蛋白的表达水平。我们将使用这些独特的细胞（LCTC）来评估在啮齿动物模型中激活或抑制TLR通路对淋巴结转移程度的功能作用。在患有乳腺癌的女性中，我们将LCTC中TLR和TLR信号通路相关蛋白的表达水平与前哨淋巴结的转移程度相关联。了解导致淋巴结转移第一步的因素可以导致一类抑制扩散的新疗法，基本上将恶性肿瘤转化为良性肿瘤。直接接触进入淋巴循环的肿瘤细胞为预后和个体化治疗提供了一个全新的范例。

 DESCRIPTION (provided by applicant): Cancer metastasis, not the primary tumor, is the main cause of death from breast cancer. To metastasize, a cancer cell must leave the primary tumor, survive in blood or lymphatic circulation, invade and colonize distant tissues and establish metastatic foci. Most carcinomas are thought to disseminate via the blood stream and the lymphatic system in parallel. Lymph node metastases are thought to arise from tumor cells that have entered the natural lymphatic drainage of the breast tissue to colonize the downstream sentinel nodes. Beyond this general level of understanding about lymphatic metastasis, there are fundamental biologic questions about lymphatic dissemination that remain unanswered such as: How do tumor cells enter the lymphatic drainage? What is the efficacy of lymphatic metastasis in vivo? Do metastatic and non-metastatic tumors both shed cells into the lymphatic drainage? Are the tumor cells that enter the lymphatic drainage a specialized subset of the parental tumor population? What specialized molecular mechanisms do these cells use to enter the lymph, thrive in the lymph fluid, and colonize the lymph node? To answer these questions, first, our laboratory has developed an innovative microsurgical technology to collect lymph, and the lymph circulating tumor cells (LCTC) contained therein, in an immunocompetent breast cancer animal model. Subsequently, in a collaborative effort with medical surgeons in our community, and those in Indiana University School of Medicine, we successfully applied this same technology to collect, for the first time, LCTC entering the lymph drainage in women with metastatic breast cancer. Second, we propose that the Toll-Like Receptor (TLR) signaling pathways is a major molecular determinant of tumor cell entry into the lymphatic drainage. TLR signaling is known to regulate pathogen sensing and homing of immune cells. This pathway also regulates cytokine and lymphokine release that are part of lymph node activation during the early stages of infection. In the present proposal we will evaluate expression levels of TLRs and key proteins associated with TLR cell signaling pathways for the first time in breast cancer cells (LCTC) entering the lymphatic drainage in the rat model of breast cancer as well as in women with breast cancer. We will use these unique cells (LCTC) to evaluate the functional role of activating or suppressing the TLR pathway on the extent of lymph node metastasis in the rodent model. In women with breast cancer we will correlate expression levels of TLRs and proteins associated with TLR signaling pathways in LCTC with the extent of metastasis in the sentinel node. Understanding the factors that contribute to the first step of lymph node metastasis can lead to a new class of therapies that suppress dissemination, essentially turning a malignant tumor into a benign tumor. Direct access to the tumor cells entering the lymph circulation provides a completely novel paradigm for prognosis and individualized therapy.