MOUSE MODELS OF OVARIAN CANCER

我们提出了制造可遗传的卵巢癌小鼠模型的策略。这样的模型将有助于理解疾病的病因，并提供更现实的系统来评估诊断、预防和治疗方法。考虑到这种疾病是导致美国女性实体肿瘤死亡的第四大原因，以及目前存在的三种更常见的致命实体肿瘤的转基因模型，建立转基因卵巢癌模型是一个特别合理的目标。当人们考虑到与乳腺癌相比，卵巢癌的死亡风险时，这种模型的必要性进一步得到强调。在美国，卵巢癌的发病率约为每10万名妇女中有3.3例。这每年产生大约20,000个新病例，但它们导致的死亡频率非常高，即每年有近15,000名美国妇女死于这种疾病。相比之下，乳腺癌每年的发病率约为18万例，每年约有4.6万人死亡。因此，乳腺癌的发病率是卵巢癌的9倍，但导致的死亡人数是卵巢癌的3倍。在这个应用中，我们证明了有足够的资源开始开发卵巢癌的可遗传模型，并描述了获得创建第二代模型所需的资源和信息的方法。为了实现这些目标，我们提出了以下具体目标：特定目标1：确定当过度表达、异常表达或失活时可能导致卵巢癌风险增加的基因：有足够的信息开始生产具有几个主要作用基因/癌基因的转基因动物。一个更大的问题存在于隐性作用基因的选择上，即那些功能丧失导致卵巢肿瘤发生的基因。在转基因动物中识别这样的基因以进行操作是这一目标的重点。具体目标2：培育出罹患卵巢癌风险增加的转基因小鼠。我们已经在大鼠基因组中发现了一种逆转录病毒样元件，该元件在大鼠卵巢中特异表达。我们已经克隆了它负责卵巢特异性表达的部分，并证明了它驱动报告基因的表达。这个启动子将作为我们最初努力开发卵巢癌小鼠模型的骨干。为了达到这个目的，我们建议使用这个启动子来建立转基因小鼠，这些转基因小鼠在卵巢癌中表达正常和突变的重要基因。对于隐性基因，即肿瘤/生长抑制基因，我们有能力产生胚系“敲除”，但更令人感兴趣的是利用这种启动子驱动卵巢特异性体内生产的可能性，作为一种手段，以卵巢特有的方式对肿瘤/生长抑制基因进行功能性“敲除”。特异性目的3：鉴定在MOSE细胞中特异表达的启动子。启动子目前在多种卵巢细胞类型中发挥作用，包括表面上皮细胞。因此，在该启动子控制下的基因操作产生的卵巢肿瘤可能来自多种细胞类型。这样的肿瘤模型将会引起一定的兴趣，尽管卵膜和颗粒细胞肿瘤在女性中并不像那些来自表面上皮的肿瘤那样常见。在此，我们建议鉴定一种小鼠卵巢表面上皮细胞特异性启动子。特定目的4：提高癌的频率和特异性，缩短潜伏期。在这里，我们将根据需要检查各种遗传和生理策略，以提高小鼠卵巢癌的频率、特异性和缩短潜伏期。

We propose strategies to produce inheritable mouse models of ovarian cancer. Such models will aid in understanding the disease's etiology and provide more realistic systems in which to evaluate diagnostic, prevention, and treatment methods. Creation of transgenic ovarian cancer models is a particularly rational goal considering this disease is the fourth leading cause of deaths from solid tumors in American women and transgenic models of the three more commonly lethal solid tumors currently exist. The need for such models is further underscored when one considers the risk of death from ovarian cancer compared to for example breast cancer. The incidence of ovarian cancer is approximately 3.3 per 100,000 women in the United Sates. This yields approximately 20,000 new cases annually but they result in a remarkably high frequency of death, i.e. nearly 15,000 American women die from the disease each year. In contrast, breast cancer has a frequency of approximately 180,000 cases per year and accounts for approximately 46,000 annual deaths. Thus, breast cancer has a frequency 9 times as high as ovarian cancer but results in 3-times as many deaths. In this application, we demonstrate that sufficient resources exist to begin to develop inheritable models of ovarian cancer and describe approaches to obtain the resources and information needed to create second generation models. To accomplish these goals, we propose the following Specific Aims: SPECIFIC AIM number 1: Identify the genes which when overexpressed, expressed in aberrant form, or inactivated will likely lead to an increased risk of ovarian cancer: Sufficient information is available to start producing transgenic animals with several dominantly acting genes/oncogenes. A much larger problem exists with regard to selection of recessively acting genes, i.e. those genes whose lost function contributes to ovarian oncogenesis. Identification of such genes for manipulation in transgenic animals is the focus of this Aim. SPECIFIC AIM number 2: Creation of genetically engineered mice at increased risk of developing ovarian cancer. We have identified a retrovirus-like element in the rat genome which is specifically expressed in rat ovaries. We have cloned the portion of it responsible for ovarian specific expression and demonstrated that it drives reporter gene expression. This promoter will serve as the backbone of our initial efforts to develop mouse models of ovarian cancer. In this Aim, we propose to use this promoter to create transgenic mice constitutively expressing normal and mutated genes of importance in ovarian cancer. In the case of recessive genes, i.e. tumor/growth suppresser genes, we have the capability to produce germline "knockouts", but of greater interest is the possibility of using this promoter to drive ovarian specific intrabody production as a means to functionally "knockout" tumor/growth suppresser genes in an ovarian specific manner. SPECIFIC AIM number 3: Identify a promoter that is specifically expressed in MOSE cells. The promoter currently available functions in multiple ovarian cell types including the surface epithelium. Therefore, the ovarian tumors produced when genes are manipulated under control of this promoter may derive from multiple cell types. Such tumor models will be of certain interest although theca and granulosa cell tumors are not as common in women as those derived from the surface epithelium. Here, we propose to identify a mouse ovarian surface epithelial cell specific promoter. SPECIFIC AIM number 4: Increase carcinoma frequency and specificity and decrease latency. Here, we will examine various genetic and physiological strategies as needed to increase frequency, specificity, and decrease latency of ovarian cancer in mice.