THE ROLE OF PTEN AND THE PI3K PATHWAY IN PROSTATE CANCER

该资助的三个项目高度集中于评估前列腺癌中的PTEN/MMAC 1肿瘤抑制基因和磷酸肌醇3-激酶（PI 3 K）信号通路。PI 3 K与前列腺癌有关，因为最近发现PTEN编码水解具有PTEN缺陷的癌症的脂质产物的磷酸酶。缺乏PTEN的前列腺癌细胞系具有PI 3 K下游酶的组成性激活，包括AKT蛋白- Ser/Thr激酶，并且重新引入PTEN（或添加PI 3 K抑制剂）阻断该途径并导致细胞生长降低和细胞凋亡增加。尽管细胞系的研究表明，抑制PI 3 K应该阻断由PTEN缺失引起的肿瘤的生长和存活，但没有证据表明这在体内是正确的。小鼠中PTEN的杂合丢失导致多种组织的增生，包括前列腺和前列腺癌。这些小鼠为人类前列腺癌提供了一个模型，该模型由PTEN缺失引起。拟议工作的目标是测试删除PI 3 K通路中酶的基因对小鼠前列腺癌发展的影响，并开发评估PI 3 K通路是否在人类前列腺癌中被激活的技术。拟议的工作涉及三个项目和三个核心之间的广泛合作，利用各个实验室的专业知识。在项目1中，Cantley实验室将产生小鼠，其中PI 3 K的调节亚基在前列腺中缺失。然后将这些小鼠与缺乏PTEN的小鼠杂交，以确定PI 3 k调节亚基的缺失是否阻断由PTEN缺失引起的前列腺癌的发展。在项目2中，Robert的实验室将产生小鼠，其中PI 3 K的催化亚基在前列腺中被删除用于样品目的。为了相同的目的，在前列腺中删除了PI 3 K的调节和催化亚基的多个基因。为了相同的目的，在前列腺中删除了PI 3 K的调节和催化亚基的多个基因。PI 3 K的调节和催化亚基的多个基因存在于小鼠和男性中，这些研究将表明其中哪一个对前列腺癌的发展最为关键。在项目3中，Sellers实验室将评估PI 3 K下游的其他蛋白质。 对于判断为对前列腺癌细胞系的PI 3 K依赖性生长或存活至关重要的下游靶标，将进行显性阴性形式的前列腺特异性表达或基因的靶向缺失。制药公司目前正在开发PI 3 K催化位点抑制剂、AKT抑制剂和PI 3 K调节亚基功能抑制剂。然而，迄今为止，可用的抑制剂不是足够特异性的，并且具有生物利用度和毒性的问题，这妨碍了评价。这些研究将表明这些蛋白质中的哪一种应该被靶向用于治疗前列腺癌。

The three projects of this grant are highly focused on evaluating the PTEN/MMAC1 tumor suppressor gene and the phosphoinositide 3-kinase (PI3K) signaling pathway in prostate cancer. PI3K has been implicated in prostate cancer because of the recent discovery that PTEN encodes a phosphatase that hydrolyzes the lipid products of cancers have defects in PTEN. Prostate cancer cell lines that lack PTEN have constitutive activation of enzymes down-stream of PI3K, including the AKT protein- Ser/Thr kinase and reintroduction of PTEN (or addition of PI3K inhibitors) blocks this pathway and leads to decreased cell growth and increased apoptosis. Although studies with cell lines suggest that inhibition of PI3K should block growth and survival of tumors that result from loss of PTEN, there is no evidence that this is true in vivo. Heterozygous loss of PTEN in mice results in hyperplasia in multiple tissues, including prostate and adenocarcinomas of the prostate. These mice provide a model for human prostate cancers that result from loss of PTEN. The goal of the proposed work is to test the effect of deleting genes of enzymes in the PI3K pathway on the development of prostate cancer in mice, and to develop techniques that will evaluate whether the PI3K pathway is activated in human prostate cancers. The proposed work involves extensive collaborations between the three projects and the three cores, taking advantage of the expertise of individual laboratories. In Project 1, the Cantley laboratory will generate mice in which the regulatory subunits of PI3K are deleted in the prostate. These mice will then be crossed with the mice that lack PTEN in order to determine whether loss of the PI3k regulatory subunit blocks the development of prostate cancers that result from loss of PTEN. In Project 2, the Robert's laboratory will generate mice in which the catalytic subunit of PI3K is deleted in the prostate for the sample purpose. Multiple genes for both the regulatory and catalytic subunits of PI3K is deleted in the prostate for the same purpose. Multiple genes for both the regulatory and catalytic subunit of PI3K is deleted in the prostate for the same purpose. Multiple genes for both the regulatory and catalytic subunits of PI3K exist in mice and men and these studies will indicate which of these is the most critical for prostate cancer development. In Project 3, the Sellers laboratory will evaluate additional proteins downstream of PI3K. For downstream targets judged to be critical for PI3K-dependent growth or survival of prostate cancer cell lines, prostate-specific expression of dominant- negative forms or targeted deletion of the genes will be performed. Pharmaceutical companies are currently developing PI3K catalytic site inhibitors, AKT inhibitors and inhibitors of the function of the regulatory subunit of PI3K. However, to date, the inhibitors available are not sufficiently specific and have problems with bioavailability and toxicity that preclude evaluation. These studies will suggest which of these proteins should be targeted for treatment of prostate cancer.