The Role of VILIP-1 in Development of Skin Tumors

描述(申请人提供)：使用差异显示和其他分子技术，我们发现在选定的高级别小鼠鳞状细胞癌(SCC)和肿瘤细胞系中，缺乏与人粘蛋白样蛋白1(VILIP-1)同源的基因表达。VILIP-1在SCC细胞系中的异位表达导致cAMP水平升高、细胞增殖减少和RhoA活性降低，从而导致侵袭性降低。需要在体内验证的中心假说是，VILIP-1表达的缺失通过下调环核苷酸依赖的途径来增强SCC细胞的恶性表型，其中包括特定的肿瘤进展相关靶点，如小GTP酶，从而构成导致恶性表型的事件链中的重要因素。相反，VILIP-1的表达应该通过减少肿瘤细胞的生长和/或抑制肿瘤的进展来增加对皮肤癌的抵抗力。为此，我们设计了三个特定的目标：1)检测VILIP-1表达缺失可能导致恶性程度增加的生物学和生化机制。在本实验中，我们将在环核苷酸调控的背景下，研究VILIP-1转基因细胞和被击倒的SCC细胞的细胞增殖、分化、黏附、迁移和侵袭能力。我们将侧重于cAMP和cGMP所起的相对层级作用，以及它们作为小GTP酶可能的效应因子的作用。2)评价K5-VILIP-1转基因小鼠体内致癌的敏感性。这些小鼠对皮肤化学致癌的敏感性较低，将被用来在体内评估VILIP-1的作用机制。3)以SHK-1为背景，采用紫外线致癌方法研究K5-VILEP-1转基因小鼠的体内皮肤癌易感性。

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.