NEW PROTOONCOGENE, INT 5, IN BREAST NEOPLASIA

乳腺癌是人类最有问题的癌症类型之一。这个 乳腺癌的病因学涉及一种复杂的遗传、 荷尔蒙和饮食因素。试图对…有一个清楚的了解 这些因素如何参与乳腺肿瘤的发生一直受到阻碍， 部分原因是缺乏关于特定遗传损伤的信息 有助于肿瘤发展的启动和/或进化。我们的 最近的研究导致鉴定和克隆int-5基因组DNA， 一种独特的高度保守的小鼠乳腺肿瘤病毒(MMTV) BALB/c癌前病变D2细胞的整合位点基因 肺泡结节(HAN)。Int-5与其他int基因不同：它一直是 在癌前病变中发现，而不是在癌变肿瘤中发现 在化学诱导的肿瘤中，而不是病毒诱导的肿瘤中； 在包括乳腺在内的各种正常组织中。INT-5也是 与其他与乳腺癌有关的癌基因(c-myc， C-Ha-ras、c-erbB和HER-2/neu)，因为它们可能在早期 癌前病变。INT-5在乳腺和乳腺中的过表达 肿瘤和乳腺癌细胞株也表明它参与了 乳腺癌的发生。因此，int-5基因是一个很好的候选基因。 研究该基因在乳腺癌中的作用。我们的目标是 直接检测INT-5基因的转化能力以建立其 体外细胞培养和体内转基因在乳腺癌中的作用 动物模型。我们的具体目标是：克隆人和老鼠 使用小鼠基因组探针获得INT-5cDNA，并通过以下方法鉴定这些克隆 确定其核苷酸序列；2)确定其核苷酸序列 和Int-5基因组克隆的结构组织；3)建立 MMTV-INT-5表达载体转化INT-5基因的能力 细胞培养和转基因动物模型系统；改造正常人 携带MMTV-int-5融合基因的乳腺上皮细胞(MCF-10)的建立及检测 该基因在转化细胞中的过度表达是否会导致肿瘤 在裸鼠体内形成。此外，我们还将产生INT-5转基因动物， 在乳腺发育的不同阶段检查这些动物 和妊娠/哺乳形成汉族人及其演变为 乳腺肿瘤，以及检查任何增加的乳房发病率 这些动物中的癌症；4)建立INT-5的预后意义 分析原发乳腺肿瘤中INT-5的过度表达 并将这些数据与其他临床因素进行比较。这些研究将 提供基本知识并帮助您了解 INT-5基因及其编码蛋白，以及转化能力 Int-5基因及其在乳腺癌中的作用。转基因动物也提供了 一个研究乳腺癌发病率的模型，以确定如何 可以通过各种干预措施减少发病率，并研究 其他癌基因在激活该基因中的协同作用(如果有) 乳腺肿瘤中的基因。

Breast cancer is one of the most problematic types of human cancer. The etiology of breast cancer involves a complex interplay of genetic, hormonal, and dietary factors. Attempts to gain a clear understanding of how these factors participate in mammary tumorigenesis have been hampered, in part, by a lack of information on the specific genetic lesions that contribute to the initiation and/or evolution of tumor development. Our recent studies have resulted in identifying and cloning int-5 genomic DNA, a unique and highly conserved novel mouse mammary tumor virus (MMTV) integration locus gene from the BALB/c precancerous D2 hyperplastic alveolar nodule(HAN). Int-5 is different from other int genes: it has been found in precancerous, rather than cancerous neoplasms; it has been found in chemically-, rather than virus-induced neoplasms; and it is expressed in a variety of normal tissues, including the mammary gland. Int-5 is also different from other oncogenes implicated in breast cancer (c-myc, c-Ha-ras, c-erbB and HER-2/neu) because of its possible role in early preneoplastic changes. Overexpression of int-5 in mammary and breast tumors and also in breast cancer cell lines suggests its involvement in mammary carcinogenesis. Therefore, int-5 gene is a good candidate for investigating the role of this gene in mammary cancer. Our objective is to test the transforming ability of int-5 gene directly to establish its role in breast cancer using in vitro cell culture and in vivo transgenic animal models. Our specific aims are: We will 1) clone mouse and human int-5 cDNAs using mouse genomic probe and characterize these clones by determining their nucleotide sequence; 2) determine the nucleotide sequence and structural organization of int-5 genomic clone; 3) establish the transforming ability of int-5 gene using MMTV-int-5 expression vector in cell culture and transgenic animal model systems; transform normal human breast epithelial cells (MCF-10) with MMTV-int-5 fusion gene and examine whether overexpression of this gene in transformed cells leads to tumor formation in nude mice. Also, we will generate int-5 transgenic animals, examine these animals during different stages of mammary gland development and pregnancy/lactation for formation of HAN and their progression to mammary tumors, as well as examine any increased incidence of mammary cancer in these animals; 4) establish the prognostic significance of int-5 overexpression by analyzing primary breast tumors for int-5 overexpression and comparing these data with other clinical factors. These studies will provide basic knowledge and help in understanding the characteristics of int-5 gene and its encoded protein, as well as the transforming ability of int-5 gene and its role in breast cancer. Transgenic animals also provide a model to study the incidence of breast cancer, to determine how this incidence can be reduced by various interventions, and to study the synergistic effect of other oncogenes, if any, in the activation of this gene in mammary neoplasms.