Neoplastic transformation of melanocytes by Grm1

描述(申请人提供)：本建议的目的是研究G蛋白偶联的七个跨膜区受体Grm1异位表达引起黑素细胞转化的分子机制，并研究在这些细胞中持续表达Grm1介导其致癌潜力的必要性。我们的目标是基于我们最初的假设和在我们最近的出版物中对该假设的确认。此前，我们建议使用一种转基因小鼠，TG-3，具有自发黑色素瘤的易感性，作为研究这种疾病的模型系统。我们鉴定了由于转基因整合而改变的宿主序列为Grm1。我们发现Grm1在肿瘤组织中有异常表达，而在对照样本中未见表达。我们假设Grm1在TG-3中与黑色素瘤的发生有关。然后，我们通过建立一个新的转基因株来验证这一假设，该转基因系仅针对黑素细胞表达Grm1，将Grm1的cDNA置于黑素细胞特异性启动子DOPAChrome互换酶(DCT)的调控下。这个新的DCT-Grm1转基因品系(E系)表现出与TG-3类似的黑色素瘤发生的易感性。此外，我们还证明了GRM1在一些人黑色素瘤细胞系和活检样本中的表达，但在正常黑素细胞或良性痣中未见表达。因此，我们已经明确地证明了Grm1的异常表达和黑色素瘤的发展在我们的系统中的病因作用。基于这些结果，我们建议启动一系列实验，使用来自黑素细胞肿瘤的细胞来开始解开使用我们的模型系统的复杂但协调良好的细胞转化网络。我们的具体目标是：1.研究和鉴定在保持转化表型过程中对Grm1持续表达的要求。2.扩大并验证Grm1在人黑色素瘤中的致癌作用。3.探讨GRM1在TG-3小鼠肿瘤发生发展过程中持续表达的必要性。4.探讨MAPK信号在我们的小鼠模型系统中的作用。

DESCRIPTION (provided by applicant): The Aims of this proposal are to study the molecular mechanisms of transformation of melanocytic cells elicited by the ectopic expression of the G-protein-coupled seven transmembrane-domain receptor, Grm1, and to examine the requirement of continuing expression of Grm1in mediating its oncogenic potential in these cells. Our Aims are based on our initial hypothesis and confirmation of the hypothesis in our recent publication. Previously we proposed to use a line of transgenic mice, TG-3, with a predisposition to spontaneous melanoma development as a model system to study this disease. We identified the altered host sequences due to the integration of the transgene to be Grm1. We showed the aberrant expression of Grm1 in tumor but not control samples. We hypothesized that Grm1 is responsible for the genesis of melanoma in TG- 3. We then tested this hypothesis by generating a new transgenic line with expression of Grm1l targeted only to melanocytes, by placing the cDNA of Grm1 under the regulation of the melanocyte specific promoter, dopachrome tautomerase (Dct). This new Dct-Grm1 transgenic line (the E line) showed predisposition to melanoma development similar to that of TG-3. Furthermore, we also demonstrated the expression of GRM1 in some human melanoma cell lines and biopsy samples but not in normal melanocytes or benign nevi. Thus, we have demonstrated unequivocally the etiological role of aberrant Grm1 expression and melanoma development in our system. Based on these results, we propose to initial a set of experiments using cells derived from melanocytic tumors to begin to unravel the complicated yet well coordinated network of cellular transformation using our model system. Our specific aims are: 1. To investigate and characterize the requirement for continuing expression of Grm1l in the maintenance of the transformed phenotypes. 2. To extend and validate the oncogenic role of Grm1 in human melanoma. 3. To examine the requirement for continuous Grm1 expression in onset and progression of tumor in TG-3 mice. 4. To explore MAPK signaling in our mouse model system.