Project 2

已经在多种癌症中发现了10号染色体上磷酸酶和紧张素同源物缺失（PTEN）的体细胞突变和缺失，在前列腺癌中，至少30%的原发性癌症和63%的转移性癌症发生PTEN改变。因为PTEN活性的降低增强了促进肿瘤发生的Pl-3激酶依赖通路。确定Pl-3激酶信号传导下游的通路对于理解转化机制和确定新的治疗靶点至关重要。在转基因小鼠中，活化AKT的表达不足以引起前列腺PTEN的表型丧失，因此，前列腺癌发展到前列腺上皮内瘤变（PIN）之外，还需要其他的Pl-3激酶信号效应物。我们假设蛋白激酶c相关激酶1 （PRK1，根据基因名称命名为PKN1）是一种Pl-3激酶效应物，其特性表明它与AKT合作转化前列腺癌细胞。PKN1是PDK1的直接底物，在人前列腺癌中过度表达，促进异种移植模型中的增殖，并通过作为组蛋白H3激酶调节雄激素受体（AR）活性。我们发现，在小鼠前列腺中有条件地表达组成性活性PKN1足以在22周时产生小鼠PIN。在Aim 1中，我们使用转基因小鼠来表征PKN1单独或与AKT联合表达导致的前列腺癌表型。我们将确定PKN1在PTEN缺失引起的致瘤效应的转导中所起的作用。在Aim 2中，我们使用异种移植物和细胞培养方法，通过探索PKN1作为卵裂沟激酶的功能，以及作为调节细胞周期调节因子的表达和活性的因子，来确定PKN1如何刺激肿瘤生长。在Aim 3中，我们测试了PKN1激酶活性如何促进基因表达的模型。包括PKN1磷酸化的AR和PKN1产生的特异性表观遗传标记。这些目标的成功完成将为PTEN/PI-3激酶信号转导机制提供新的见解，包括PKN1如何促进前列腺细胞增殖以及PKN1如何调节AR。我们将建立新的前列腺癌临床前模型，概括PTEN缺失时发生的分子事件

: Somatic mutations and deletions in phosphatase and tensin homologue deleted on chromosome 10 (PTEN) have been identified in a variety of cancers, and in prostate cancer PTEN alterations occur in at least 30% of primary cancers and 63% of metastatic cancers. Since reduced PTEN activity enhances Pl-3 kinase-dependent pathways that promote tumorigenesis. defining the pathways that operate downstream of Pl-3 kinase signaling is essential for understanding transformation mechanisms and for identifying new therapeutic targets. Expression of activated AKT in transgenic mice is not sufficient to phenocopy PTEN loss in prostate, thus additional effectors of Pl-3 kinase signaling are required for prostate cancer to progress beyond prostate intra-epithelial neoplasia (PIN). We hypothesize that the Protein Kinase C-related kinase 1 (PRK1; termed PKN1 after the gene name) is a Pl-3 kinase effector whose properties suggest it cooperates with AKT to transform prostate cancer cells. PKN1 is a direct substrate of PDK1, is over-expressed in human prostate cancer and promotes proliferation in xenograft models, and it modulates androgen receptor (AR) activity by acting as a histone H3 kinase. We show that conditional expression of constitutively active PKN1 in mouse prostate is sufficient to generate murine PIN at 22 weeks. In Aim 1 we use transgenic mice to characterize prostate cancer phenotypes resulting from PKN1 expression, alone and in combination with AKT. We will determine the role PKN1 plays in transducing tumorigenic effects caused by loss of PTEN. In Aim 2 we use xenograft and cell culture approaches to determine how PKN1 stimulates tumor growth by exploring its function as a cleavage furrow kinase, and as a factor that modulates the expression and activity of cell cycle regulators. In Aim 3 we test models for how PKN1 kinase activity promotes gene expression. Including PKN1 phosphorylation of AR and PKN1 generation of specific epigenetic marks. Successful completion of these aims will provide new insights into PTEN/PI-3 kinase signal transduction mechanisms including how PKN1 promotes prostate cell proliferation and how PKN1 regulates AR. We will generate new pre-clinical models of prostate cancer that recapitulate molecular events that occur with loss of PTEN