The Role of VILIP-1 in Development of Skin Tumors

描述（由申请人提供）：使用差异显示和其他分子技术，我们在选定的高级别小鼠鳞状细胞癌（SCC）和肿瘤细胞系中发现了与人类视蛋白样蛋白1 （VILIP-1）同源的基因表达缺失。在SCC细胞系中，VILIP-1的异位表达导致与cAMP水平升高、细胞增殖降低和RhoA激活降低相关的侵袭性表型降低。在体内测试的中心假设是，VILIP-1表达的缺失通过下调环核苷酸依赖通路（包括特定的肿瘤进展相关靶点，如小gtpase）来增强SCC细胞的恶性表型，从而构成导致恶性表型的事件链中的重要因素。相反，VILIP-1的表达应该通过降低肿瘤细胞生长和/或抑制肿瘤进展来增加对皮肤癌的抵抗力。为此，我们设计了三个具体目标：1)研究VILIP-1表达缺失可能导致恶性肿瘤增加的生物学和生化机制。在本实验中，我们将研究VILIP-1转染物和敲低SCC细胞在环核苷酸调控下的细胞增殖、分化、粘附、迁移和侵袭性。我们将重点关注cAMP和cGMP的相对分级作用，它们都是由VILIP-1调节的，以及它们作为小GTPases的可能效应器的参与。2)我们将评估K5-VILIP-1转基因小鼠的体内癌变易感性。这些小鼠对皮肤化学致癌的易感性较低，并将用于评估VILIP-1的体内作用机制。3)利用回交至SHK-1基因背景的K5-VILEP-1转基因小鼠体内紫外线致癌机制研究皮肤癌变易感性。

DESCRIPTION (provided by applicant): Using differential display and other molecular techniques we identified the absence of expression of a gene homologous to the human Visinin-like Protein 1 (VILIP-1) in selected high grade murine squamous cell carcinoma (SCC) and in tumor cell lines. Ectopic expression of VILIP-1 in SCC cell lines resulted in a less aggressive phenotype associated with increased levels of cAMP, decreased cell proliferation and decreased RhoA activation. The central hypothesis to be tested in vivo is that the loss of VILIP-1 expression enhances the malignant phenotype of SCC cells by down-regulating cyclic nucleotide-dependent pathways that include specific tumor-progression-related targets, such as small GTPases, thus constituting an important element in the chain of events leading to the malignant phenotype. Conversely, VILIP-1 expression should increase resistance to skin carcinogenesis by decreasing tumor cell growth and/or inhibiting tumor progression. For this purpose we have designed three specific aims: 1) Examine biological and biochemical mechanisms whereby loss of VILIP-1 expression may lead to increased malignancy. In this experiment, we will study cell proliferation, differentiation, adhesiveness, migration and invasiveness of VILIP-1 transfectants and knocked-down SCC cells in the context of cyclic nucleotide regulation. We will focus on the relative hierarchical role played by cAMP and cGMP, both known to be regulated by VILIP-1, and their participation as possible effectors of small GTPases. 2) We will evaluate the in vivo susceptibility to carcinogenesis in K5-VILIP-1 transgenic mice. These mice should be less susceptible to skin chemical carcinogenesis and will be utilized to evaluate in vivo the mechanism of action of VILIP-1. 3) Investigate the in vivo susceptibility to skin carcinogenesis using a protocol of ultraviolet carcinogenesis in K5-VILEP-1 transgenic mice backcrossed to a SHK-1 background.