TISSUE SPECIFIC AND NEOPLASTIC GENE EXPRESSION

高等真核生物的基本发育过程之一是 每个组织中特定的一组基因的激活和 所有其他基因的抑制。在癌症的病理状态下， 组织的表型发生了戏剧性的变化，表明 基因表达的特定模式的错位。这个 这项研究的长期目标是找出组织的机制 特定的基因表达及其在癌症中的影响。 研究这些过程的一个很好的模型是人类 碱性磷酸酶(AP)基因系统。胎盘同工酶 (PLAP)由PLAP-1基因编码，肠道 同工酶(IAP)按亲缘关系(90%同源) IAP基因。第三个基因plap-2有95%的同源性。 与PLAP-1基因结合，并可能编码类似于 在睾丸癌中过度生产。表达基因的细胞系 具体来说，plap-1基因或iap基因将是 研究以找出差异表达式是否 由转录或转录后机制控制的。 类似的研究也将在似乎表达基因的细胞系中进行。 Plap-2基因。负责的核苷酸序列 通过对细胞的转染会发现差异表达 带有合适的启动子融合基因，然后是定点 诱变。最终，这项工作将导致孤立的 与AP基因调控序列相互作用的细胞因子 (或通过AP转录本)介导组织特异性基因 表情。 一些人类肿瘤异常表达碱性磷酸酶 活动。这在睾丸癌中最为明显。 (精原细胞瘤)，90%以上的患者有 血清PLAP样酶水平升高。像拍子一样的 酶可能是plap-2基因的产物，也可能是 来自PLAP-1转录本的转录后修饰。 为了测试这些可能性，从睾丸、精原细胞瘤和细胞中提取的mrna 产生PLAP样酶的品系将用cdna进行分析。 用基因特异性探针进行克隆和Northern杂交。这些 研究最终将导致对组织如何 在癌症中，特定的基因表达会发生变化。

One of the basic developmental processes in higher eukaryotes is the activation of specific sets of genes in each tissue and the repression of all other genes. In the pathological state of cancer, dramatic alterations occur in the phenotypes of tissues, suggesting a derangement in the specified pattern of gene expression. The long term goals of this study are to find the mechanisms of tissue specific gene expression and how it is affected in cancer. An excellent model for studying these processes is the human alkaline phosphatase (AP) gene system. The placental isoenzyme (PLAP) is encoded by the PLAP-1 gene, and the intestinal isoenzyme (IAP) by the closely related (90 percent homologous) IAP gene. A third gene, the PLAP-2, is 95 percent homologous with the PLAP-1 gene and may encode the 'PLAP'Like' AP that is overproduced in testicular carcinomas. Cell lines that express specifically either the PLAP-1 gene or the IAP gene will be studied to find out whether the differential expression is controlled by transcriptional or posttranscriptional mechanisms. Similar studies will be done with cell lines that appear to express the PLAP-2 gene. Nucleotide sequences that are responsible for differential expression will be found by transfection of the cells with suitable promoter fusion genes followed by site-directed mutagenesis. Ultimately, this work will lead to the isolation of cellular factors that interact with AP gene regulatory sequences (or with AP transcripts) to mediate tissue-specific gene expression. Some human tumors aberrantly express alkaline phosphatase activity. This is most evident in testicular carcinomas (seminomas), where greater than 90 percent of patients have elevated levels of serum PLAP-like enzyme. The PLAP-like enzyme may be the product of the PLAP-2 gene, or perhaps arises from posttranscriptional modification of the PLAP-1 transcript. To test these possibilities, mRNA from testes, seminoma and cell lines producing the PLAP-like enzyme will be analyzed by cDNA cloning and Northern blotting with gene-specific probes. These studies will ultimately lead to an understanding of how tissue specific gene expression is altered in cancer.