Project 2

已在多种癌症中发现了10号染色体上缺失的磷酸酶和张力蛋白同源物(PTEN)的体细胞突变和缺失，在前列腺癌中，至少30%的原发癌和63%的转移性癌症发生PTEN改变。因为降低的PTEN活性增强了Pl-3依赖的激酶通路，从而促进了肿瘤的发生。明确Pl-3激酶信号下游的通路对于理解转化机制和确定新的治疗靶点是至关重要的。在转基因小鼠中激活的AKT的表达不足以导致前列腺癌中PTEN的表型缺失，因此前列腺癌的发展需要额外的Pl-3激酶信号的效应物。我们推测蛋白激酶C相关的蛋白激酶1(PRK1；在基因名称后称为PKN1)是一种Pl-3激酶效应因子，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，在人前列腺癌中过表达，在异种移植模型中促进增殖，并作为组蛋白H3激酶调节雄激素受体(AR)的活性。我们证明，在小鼠前列腺中有条件地表达具有结构性活性的PKN1足以在22周时产生小鼠PIN。在目标1中，我们使用转基因小鼠来表征由PKN1单独和与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。在目标2中，我们使用异种移植和细胞培养方法来确定PKN1是如何通过探索其作为裂解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来刺激肿瘤生长的。在目标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研究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。我们将生成新的前列腺癌临床前模型，这些模型概括了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