GENES FOR ORAL CARCINOGENESIS

该研究项目的总体目标是确定基因， 负责正常人口腔角化细胞的体外转化 致瘤细胞，并在这样做，以测试假设，人类 口腔癌的发生是由于多个癌细胞的相继激活或失活， 基因，例如，生长因子，生长因子受体，肿瘤抑制因子 基因和致癌基因。 我们之前已经建立了体外口服 癌发生模型;我们永生化正常人口腔角质形成细胞， 用克隆的“高危”人乳头瘤病毒（HPV）DNA对它们进行免疫 如HPV-16和HPV-18 DNA，并随后将永生化的 通过将细胞暴露于烟草相关化学物质， 致癌物质。 当正常细胞暴露于化学致癌物时， 不能转化为癌细胞，并且总是发生凋亡。 尽管已知正常人口腔角质形成细胞的永生化 由病毒癌蛋白如E6和E7诱导， Rb肿瘤抑制因子，化学致癌物诱导的机制， 永生化细胞向致瘤细胞的转化仍然是未知的。 在目前的建议中，我们计划寻找已经确定或 未鉴定的基因，可能是负责转换的 通过mRNA差异显示将永生化细胞转化为肿瘤细胞， 克隆了与永生化细胞差异表达的cDNA， 肿瘤细胞，构建表达克隆的cDNA的表达载体，和 确定用所述细胞转染的细胞的表型的改变， 向量。 至少6个未识别（未知）基因的全长将 及其生物学活性对细胞增殖、 体外锚定不依赖于体内致瘤性，以及 细胞的分化潜能将在永生化和 致瘤细胞 类似的研究将通过使用已知的 基因的cDNA，其在上述两种细胞系中的表达模式是 明显不同。

The overall goal of this research project is to identify genes which are responsible for the in vitro conversion of normal human oral keratinocytes to tumorigenic cells, and in doing so to test the hypothesis that human oral cancer arises by sequential activation or inactivation of multiple genes, e.g., growth factors, growth factor receptors, tumor suppressor genes, and oncogenes. We have previously established an in vitro oral carcinogenesis model; We immortalized normal human oral keratinocytes by transfecting them with cloned "high risk" human papillomavirus (HPV) DNA such as HPV-16 and HPV-18 DNA, and subsequently converted the immortalized cells to tumorigenic cells by exposing them to tobacco-related chemical carcinogens. When normal cells were exposed to chemical carcinogens they failed to convert to cancer cells and always underwent to apoptosis. Though the immortalization of normal human oral keratinocytes is known to be induced by viral oncoproteins such as E6 and E7 which inactivate p53 and Rb tumor suppressors, the mechanisms of the chemical carcinogen-induced conversion of the immortalized cells to tumorigenic cells remain unknown. In the present proposal we plan to search for already identified or unidentified genes which may be responsible for the conversion of the immortalized cells to tumor cells by conducting mRNA differential display, cloning of cDNAs which differently expressed from the immortalized and tumor cells, constructing expression vectors that express cloned cDNAs, and determining the alterations in the phenotypes of cells transfected with the vectors. The full-length of at least 6 unidentified (unknown) genes will be cloned and their biological activities on the cell proliferation, on the in vitro anchorage independency on the in vivo tumorigenicity, and on the differentiation potential of cells will be tested in the immortalized and tumorigenic cells. Similar studies will be performed by using known genes'cDNAs whose expression patterns in the above two cell lines are clearly different.