REGULATION OF GROWTH BY ALPHA V INTEGRINS

α v β 6整联蛋白在人口腔鳞状细胞癌（SCC）中经常新表达，并且是SCC细胞系体外增殖和迁移所需的。已知的与α v β 6相互作用的细胞外基质配体是纤连蛋白和腱生蛋白，它们在SCC的基质基质中丰富。此外，最近显示α v β 6结合并激活潜伏的TGF β。敲除小鼠研究强烈表明，α v β 6是肺中TGF β 1激活所必需的。还已知TGF β调节许多类型癌的增殖和侵袭，并对癌生长发挥抑制或刺激作用。因此，alphavbeta 6可能通过激活TGF β间接影响SCC进展，或通过其细胞质结构域传递信号直接影响SCC进展。我们的初步数据表明，两种不同的口腔鳞状细胞癌细胞系的增殖强烈依赖于α v β 6，α v β 6的中和抗体干扰了高度侵袭性口腔鳞状细胞癌细胞系（HSC-3）在裸鼠中的生长。为了更详细和更严格的条件下表征α v整合素在SCC生长中的作用，我们将采用几种模型系统，包括人SCC细胞系和小鼠中化学或遗传诱导的SCC。几种不同的实验方法将用于评估α v整合素在肿瘤细胞生长中的功能。首先，我们将使用中和抗体或配体类似物破坏α v β 6功能或所有α v整联蛋白的功能。我们还将开发具有更高体内效力的中和抗体，并在不同的体内模型中测试它们对SCC生长的影响。其次，我们将操纵alphavbeta 6在SCC细胞系中的表达，并研究这些细胞系在体内的生长。第三，我们将产生转基因小鼠，在Tet-On系统的控制下，在舌上皮中有条件地过表达β 6。在这些小鼠中，将研究在不同进展阶段存在或不存在α v β 6的化学致癌作用。此外，我们将研究alphavbeta 6对SCC生长的影响是否通过激活TGF β或通过直接alphavbeta 6信号传导介导。这些研究的长期目标是详细了解α v整合素参与调节口腔SCC生长、侵袭和进展的途径。此外，我们正在研究使用α v整合素的中和抗体用于口腔癌免疫治疗的可能性。

The alphavbeta6 integrin is frequently neo-expressed in human oral squamous cell carcinoma (SCCs), and is required for proliferation and migration and migration of SCC cell lines in vitro. The known extracellular matrix ligands that interact with alphavbeta6 are fibronectin and tenascin, which are abundant in the stromal matrix of SCCs. In addition, alphavbeta6 was recently shown to bind and activate latent TGFbeta. Knockout mouse studies strongly suggest that alphavbeta6 is required for activation of TGFbeta1 in the lung. TGFbeta is also known to regulate proliferation and invasion of many types of carcinomas, and to exert either inhibitory or stimulatory effects on carcinoma growth. Thus, alphavbeta6 may influence SCC progression either indirectly via activation of TGFbeta, or directly by transmitting signals through its cytoplasmic domain. Our preliminary data show that the proliferation of two different oral SCC lines strongly depends on alphavbeta6, and that a neutralizing antibody to alphavbeta6 interferes with the growth in nude mice of a highly aggressive oral SCC line, termed HSC-3. To characterize the role of alphav integrins in SCC growth in more detail and under more stringent conditions, we will employ several model systems, including panels of human SCC cell lines and chemically or genetically induced SCCs in mice. Several different experimental approaches will be used to assess alphav integrin function in tumor cell growth. First, we will disrupt alphavbeta6 function, or the function of all alphav integrins, using neutralizing antibodies or ligand analogs. We will also develop neutralizing antibodies with higher in vivo potency, and test their effects on SCC growth in different in vivo models. Second, we will manipulate alphavbeta6 expression in SCC cell lines and study growth of these cell lines in vivo. Third, we will generate transgenic mice that conditionally over-express beta6 in the tongue epithelium, under control of the Tet-On system. In these mice, chemical carcinogenesis in the presence or absence of alphavbeta6 at different stages of progression will be studied. In addition, we will investigate whether alphavbeta6 effects on SCC growth are mediated through activation of TGFbeta or through direct alphavbeta6 signaling.. The long-term goal of these studies is to provide a detailed understanding of the involvement of alphav integrins in the pathways that regulate oral SCC growth, invasion and progression. In addition, we are investigating the possibility of using neutralizing antibodies to alphav integrins for immunotherapy of oral cancer.