NF-kB mediated induction of VEGFR-3 and new lymphatic vessels in breast cancer

描述(申请人提供)：长期以来，与肿瘤相关的慢性炎症一直与血液和淋巴转移有关，这两者都与癌症患者存活率的降低直接相关。除了这种相关性，人们对炎症相关转移的分子基础知之甚少。旨在询问这一问题的研究可能会促进有效治疗方法的开发，以改善患者的结果。这项拟议的研究将提供对促进转移的炎症中心机制的分子洞察。核因子-κB是控制炎症反应的主要途径，在上皮性肿瘤中由于肿瘤细胞和肿瘤微环境中的宿主细胞过度产生炎性细胞因子而经常过度活跃。我们的初步研究表明，激活NF-κB通路会增加血管内皮生长因子受体-3的表达，血管内皮生长因子受体-3是驱动淋巴管生成和淋巴转移的主要受体。也有证据表明，在淋巴管内皮细胞(LEC)中，VEGFR-3的表达可能受NF-κB的p50亚单位和淋巴管特异性转录因子Prox1的调节。与高活性的NF-κB信号一致，我们发现，在促淋巴管生成的乳腺肿瘤系中，NF-κB诱导因子IL-1β、MIF和KC/CXCL1过表达，并与VEGFR-3的特异性配体VEGFR-C156S协同作用，协同诱导LEC增殖。总之，我们的研究结果表明，NF-κB和Prox1激活VEGFR-3启动子，可能导致VEGFR-3表达增加和晶状体上皮细胞表面受体密度增加。由于VEGFR-3受体的密度在淋巴管生成过程中可能是一个限速步骤，我们推测，NF-κB和Prox1介导的VEGFR-3转录增加在诱导肿瘤淋巴管生成中起关键作用。为了验证这一假设，我们提出了以下具体目标：(1)描绘依赖于NF-κB的炎症介质的作用 目的：(1)探讨IL-1β、MIF和KC/CXCL1在体外对VEGFR-3表达、VEGFR-3信号的激活和细胞内皮细胞刺激的影响；(2)阐明Prox1在NF-κB介导的VEGFR-3表达调控中的作用；(3)明确宿主和肿瘤来源的IL-1β、MIF和KC/CXCL1细胞因子在体内诱导乳腺癌相关淋巴管生成和淋巴转移中的作用。这些目标的成功完成有望为专门针对肿瘤淋巴管生成和转移的治疗方法的设计提供必要的分子基础，从而推进我们改善癌症患者生存的总体目标。

DESCRIPTION (provided by applicant): Tumor-associated chronic inflammation has long been linked to both hematogenous and lymphatic metastases, both of which directly correlated with reduced cancer patient survival. Beyond this correlation, little is known about the molecular basis of inflammation-associated metastasis. Studies designed to interrogate this question could advance development of effective therapies to improve patient outcomes. The proposed investigation will provide molecular insight into central mechanisms of inflammation that promote metastasis. The main pathway controlling inflammatory responses, Nuclear Factor kappa B (NF-κB), is frequently hyperactive in epithelial tumors due to over-production of inflammatory cytokines by neoplastic cells as well as by host cells within the tumor microenvironment. Our preliminary studies demonstrate that activation of the NF-κB pathway increases expression of vascular endothelial growth factor receptor-3 (VEGFR-3), the main receptor driving lymphangiogenesis and lymphatic metastasis. Evidence is also presented that in lymphatic endothelial cells (LECs) VEGFR-3 expression might be regulated by both the p50 subunit of NF-κB and the lymphatic-specific transcription factor, Prox1. Consistent with hyperactive NF-κB signaling, we found that NF-κB-inducing factors IL-1β, MIF and KC/CXCL1 are overexpressed in pro-lymphangiogenic breast tumor lines and act in concert with a VEGFR-3 specific ligand, VEGF-C156S, to synergistically induce LECs proliferation. Collectively, our findings imply that NF-κB and Prox1 activate the VEGFR-3 promoter, likely leading to increased VEGFR-3 expression and higher receptor density on the surface of LECs. Because the density of VEGFR-3 receptors is a likely rate-limiting step during lymphangiogenesis, we hypothesize that NF-κB and Prox1 mediated increase of VEGFR-3 transcription is crucial for induction of tumor lymphangiogenesis. To test this hypothesis, we propose the following Specific Aims: (1) Delineate the effects of NF-κB dependent inflammatory mediators IL-1β, MIF and KC/CXCL1 on VEGFR-3 expression, activation of VEGFR-3 signaling and LEC stimulation in vitro; (2) Delineate the role of Prox1 in NF-κB-mediated regulation of VEGFR-3 expression; (3) Define the role of host and tumor-derived IL-1β, MIF and KC/CXCL1 cytokines in induction of breast cancer-associated lymphangiogenesis and lymphatic metastasis in vivo. Successful completion of these aims is anticipated to provide the molecular basis imperative for the design of therapies specifically targeting tumor lymphangiogenesis and metastasis, thus advancing our overall goal of improving cancer patient survival.