Mechanisms of Induction and Suppression of Viral and Tumor-derived Oncogene-depe

我们一直在研究通过丝裂原活化蛋白激酶(MAPK)信号通路发挥作用的癌基因的转化机制。DRM(D OWN-R由Mos调节)/Gremlin是本实验室首次发现的一种骨形态发生蛋白(BMP)拮抗剂，在体内以组织特异性方式表达。除原代成纤维细胞和少数细胞株外，大多数转化细胞都不表达DRM/Gremlin，我们观察到癌基因转化可以通过MAPK途径抑制其表达。我们推测，这种表达缺失可能对特定肿瘤的发生或发展很重要。我们最近的工作集中在表征DRM的特性，并分析其在转化细胞中的功能和作用机制。利用体细胞和辐射杂交分析，我们将DRM/Gremlin定位于人类15号染色体(q13-q15)，该区域的缺失与乳腺癌、间皮和前列腺癌有关。我们还将小鼠的基因定位到小鼠2号染色体上的一个区域，该区域包含在人类15号染色体上发现的标记。RNA分析表明，该基因主要在人的卵巢、小肠、结肠、脑和骨骼肌中表达。对大脑不同区域的RNA分析表明，大脑特定区域的RNA水平增加，我们在培养的正常星形胶质细胞和神经元中检测到了表达。在被测试的10个脑肿瘤来源的系中只有1个被检测到表达。当逆转录病毒和表达DRM/Gremlin的质粒克隆重新导入这些细胞时，其中一些表现出与生长转化相关的表型特征的变化。我们正在分析这些反应，并使用针对纯化的细菌表达的人DRM/Gremlin的RNA探针和抗血清，进行原位和免疫组织化学分析，以确定阳性人体组织中DRM/Gremlin表达的特定位置。

We have been studying the transformation mechanisms of oncogenes that act through the Mitogen Activated Protein Kinase (MAPK) signaling pathway. DRM ( D own- R egulated by M os)/Gremlin is a Bone Morphogenetic Protein (BMP) antagonist, initially identified by our lab, which is expressed in a tissue-specific fashion in vivo. With the exception of primary fibroblasts and a few cell lines, most transformed cells in culture fail to express DRM/Gremlin, and we observed that its expression can be suppressed by oncogene transformation, via the MAPK pathway. We hypothesized this loss of expression may be important for the initiation or progression of specific tumors. Our recent work has focused on characterizing the properties DRM and analyzing its function and mechanism of action in transformed cells. Using somatic cell and radiation hybrid analysis we mapped DRM/Gremlin to human chromosome 15(q13-q15), a region whose deletion has been linked to breast, mesothelial and prostate malignancies. We also mapped the murine gene to a region of mouse chromosome 2 that contains markers found on human chromosome 15. RNA analysis indicated the gene was expressed primarily in human ovary, small intestine, colon, brain, and skeletal muscle. Analysis of RNA from different regions of the brain indicated increased levels in specific areas of the brain, and we detected expression in normal astrocytes and neurons in culture. Expression was detected in only one of ten brain tumor-derived lines tested. When retroviral and plasmid clones expressing DRM/Gremlin were reintroduced into these cells, some showed alterations in growth transformation-associated phenotypic characteristics. We are analyzing these responses, and, using RNA probes and antisera developed against purified bacterially expressed human DRM/Gremlin, we are performing in situ and immunohistochemical analysis to identify specific sites of DRM/Gremlin expression within positive human tissues.