Vascular Biology in Cancer

1. IL-32在炎性疾病中的作用人类在解剖学、生理学和行为学的许多方面与其他动物不同；然而，大多数人类特有特征的基因型基础在很大程度上仍然未知。了解人类与其他物种的这些基因差异对我们的健康有重大意义。白细胞介素32 （Interleukin-32, IL-32）是一种新发现的细胞因子，在血管内皮中高表达，促炎细胞因子上调其表达。我们发现IL-32在内皮细胞粘附分子表达和白细胞粘附方面使内皮细胞对炎症细胞因子刺激的反应增敏。在疾病开始时，白细胞必须首先粘附在发炎的脉管系统上，然后通过血管壁迁移，然后在目标组织中积累。因此，白细胞与炎症内皮的相互作用是疾病发展的重要过程。与此一致的是，转基因小鼠内皮细胞中IL-32的表达升高了炎症，加重了败血症。由于炎症与肿瘤发生密切相关，我们观察到人类肿瘤样本中IL-32的显著升高，IL-32在体内的表达改变了肿瘤微环境，促进了肿瘤的进展，支持IL-32在炎症相关肿瘤发展中的积极作用。此外，在与CCR的Howard Young博士的合作中，我们发现IL-32在小鼠中的表达会导致狼疮表型。目前正在与范德比尔特大学的Tom Anue博士合作，致力于确定狼疮患者样本中IL-32表达的分子和细胞机制以及相关性。Vav和连环蛋白在血管形成和血管稳态中的相互作用。区分正常发育过程中的生理性血管生成与疾病条件下的病理性血管生成是一个非常重要的问题。这对治疗干预具有重要意义。我们报道了神经元连环蛋白delta-catenin也在血管内皮细胞中表达，并且在小鼠中仅缺失一个delta-catenin等位基因就足以在体外损害内皮细胞的运动和血管组装以及体内的病理性血管生成，从而抑制肿瘤生长。相反，delta-连环蛋白的一个或两个等位基因的缺失对激素诱导的子宫生理性血管生成没有影响。因为只有病理性血管生成对-连环蛋白水平的降低敏感，这可能为抗血管生成治疗提供一个很好的靶点。进一步分析表明，delta-catenin通过与鸟嘌呤核苷酸交换因子（GEF） Vav1相互作用调节RhoGTPase活性。Vav1在造血细胞中特异性表达并调节细胞分化。由于造血细胞和内皮细胞具有共同的祖细胞，因此在血管内皮中也检测到Vav1。然而，其在脉管系统中的功能目前尚不清楚。我们的初步分析表明，Vav1在血管生成和血管生成中具有相反的作用。与其GEF功能一致，内皮细胞中Vav1的中和会损害细胞运动和血管生成。出乎意料的是，小鼠Vav1基因缺失导致肿瘤血管形成和肿瘤生长显著增加。我们发现Vav1缺失小鼠的内皮祖细胞（EPCs）明显多于野生型小鼠。有趣的是，用野生型小鼠的骨髓替代Vav1缺失的骨髓完全消除了促进肿瘤血管形成和肿瘤生长的作用。这些数据表明Vav1负调控血管生成，这足以克服血管生成缺陷。此外，Vav1的缺失导致基底膜的减少和血管渗漏的增加。总之，这些发现说明了Vav1和连环蛋白相互作用在血管形成和完整性中的重要和复杂的功能。

1. IL-32 in inflammatory diseases. Humans differ from other animals in many aspects of anatomy, physiology and behavior; however, the genotypic basis of most human-specific traits remains largely unknown. Understanding these genetic differences of humans from other species has major implications to our health. Interleukin-32 (IL-32) is a newly discovered cytokine, which is highly expressed in vascular endothelium, and pro-inflammatory cytokines upregulate its expression. We found that IL-32 sensitizes endothelial response to inflammatory cytokine stimulation in cell adhesion molecule expression and leukocyte adhesion on endothelium. During disease initiation, leukocytes must first adhere to inflamed vasculature, then migrate through the vessel wall before accumulating in target tissues. Thus, the interaction of leukocytes with inflamed endothelium is a paramount process in disease development. Consistently, endothelial expression of IL-32 in transgenic mice elevated inflammation and worsened sepsis. Since inflammation closely links to tumorigenesis, we observed a significant elevation of IL-32 in human tumor samples, and expression of IL-32 in vivo changed the tumor microenvironment and enhanced tumor progression, supporting a positive role of IL-32 in inflammation associated tumor development. In addition, in collaboration with Dr Howard Young at the CCR, we found that expression of IL-32 in mice leads to a lupus phenotype. Current effort is engaged to determine the molecular and cellular mechanisms, as well as determine the correlation of IL-32 expression in lupus patient samples in collaboration with Dr Tom Anue at Vanderbilt University.2. Interaction of Vav and delta-catenin in vascular formation and vascular homeostasis. What distinguishes physiological angiogenesis during normal development from pathological angiogenesis in disease conditions is a very important question. It has significant implications for therapeutic interventions. We reported that delta-catenin, a neuronal catenin, is also expressed in vascular endothelial cells, and deletion of only one allele of delta-catenin in mice is sufficient to impair endothelial cell motility and vascular assembly in vitro and pathological angiogenesis in vivo, thereby inhibiting tumor growth. In contrast, deletion of one or both allele of delta-catenin had no effects on hormone-induced physiological angiogenesis in the uterus. Because only pathological angiogenesis is sensitive to decreased levels of delta-catenin, this may provide a good target for anti-angiogenic therapy. Further analysis suggests that delta-catenin regulates RhoGTPase activity via interacting with Vav1, a guanine nucleotide exchange factor (GEF). Vav1 is specifically expressed in hematopoietic cells and regulates cell differentiation. Since hematopoietic cells and endothelial cells share a common progenitor, Vav1 is also detected in vascular endothelium. However, its function in the vasculature is currently unknown. Our initial analysis indicates that Vav1 possesses opposite roles in angiogenesis and vasculogenesis. Consistent with its GEF function, neutralization of Vav1 in endothelial cells impaired cell motility and angiogenesis. Unexpectedly, genetic deletion of Vav1 in mice resulted in a significant increase of tumor vascular formation and tumor growth. We found significant more endothelial progenitor cells (EPCs) in Vav1 null mice than in wild type mice. Interestingly, replacement of Vav1 null bone marrow with bone marrow from wild type mice completely abolished the promotion of tumor vascular formation and tumor growth. These data imply that Vav1 negatively regulates vasculogenesis and this is sufficient to overcome angiogenic defects. Moreover, deletion of Vav1 caused a decrease of basement membrane and an increase of vascular leakiness. Together, these findings illustrate important and complex functions of Vav1 and delta catenin interaction in vascular formation and integrity.