The role of p52 in prostate cancer

描述（由申请人提供）： 雄激素剥夺治疗是前列腺癌患者的标准治疗。不幸的是，这种治疗只是姑息性的，最终患者会复发，产生去势抵抗性肿瘤，导致死亡。越来越多的证据表明，雄激素受体（AR）的异常激活和凋亡抵抗细胞的发展有助于去势抵抗性前列腺癌（CRPC）的生长。CRPC中的AR活化可能通过改变AR的敏感性或特异性的多种机制发生。我们发表的和初步的数据表明，NF-κ B2/p52（p52）在前列腺癌中过表达，p52的过表达通过激活AR信号传导和保护细胞免受雄激素剥夺治疗诱导的凋亡而促进CRPC进展。p52在雄激素剥夺条件下与AR相互作用并激活AR，并增加许多雄激素调节基因（包括前列腺特异性抗原（PSA））的表达。p52激活的AR结合PSA启动子的远端区域，但不结合近端区域，而DHT激活的AR结合PSA启动子的近端和远端增强子，表明p52激活的AR与DHT激活的AR在构象上不同。我们进一步证明，p52降低了microRNA let-7的表达，并增加了Lin28的表达，Lin28是let-7的主要负调节因子。基于这些发现，我们假设NF-κ B2/p52在前列腺癌的发生和发展中起着关键作用。这项建议有三个具体目标。1.确定p52在前列腺癌中的功能作用。该目标的重点是使用在生理范围内表达野生型AR和p52的雄激素敏感性前列腺癌细胞模型来定义p52在AR激活和前列腺癌进展中的作用。p52将在雄激素响应性p52阴性LNCaP和LAPC-4（表达野生型AR）人前列腺癌细胞中诱导表达，以进一步测试p52对雄激素介导的前列腺癌细胞体外和体内生长的影响。此外，我们将在建立的转基因小鼠模型中确定p52在前列腺癌发展和进展中的因果作用。2.表征p52激活的AR转录复合物。ChIP-Seq分析将用于对p52激活的AR基因组募集位点进行全面、高分辨率的定位，并将所得图谱与经典的类固醇激活受体图谱进行比较。3.描述前列腺癌中p52介导的信号通路。我们将确定p52是否通过直接转录抑制其启动子或间接通过其对Lin28（let-7c加工的主要调节因子）的作用来调节let-7c的表达。然后我们将确定let-7c是否通过c-myc介导p52诱导AR激活。我们将在体外和体内研究Lin28/let-7c对p52介导的前列腺癌细胞生长和进展的影响。这些研究的完成将提供p52信号网络在前列腺癌中的重要作用，并可能为前列腺癌提供良好的诊断和/或预后指标和潜在的治疗靶点。

DESCRIPTION (provided by applicant): Androgen deprivation therapy is the standard treatment for patients with prostate cancer. Unfortunately this treatment is only palliative and eventually patients will relapse with castratio resistant tumors, which cause death. Accumulating evidence suggests that abnormal activation of androgen receptor (AR) and development of apoptotic resistant cells contribute to castration-resistant prostate cancer (CRPC) growth. AR activation in CRPC may occur by a variety of mechanisms that alter the sensitivity or specificity of AR. Our published and preliminary data demonstrate that NF-¿B2/p52 (p52) is overexpressed in prostate cancer and overexpression of p52 facilitates CRPC progression through activating AR signaling and protecting cells from apoptotic death induced by androgen deprivation therapy. p52 interacts with and activates the AR under androgen deprived conditions and increases expression of many androgen regulated genes including prostate-specific antigen (PSA). p52-activated AR binds to the distal region, but not the proximal regions of the PSA promoter, whereas, DHT-activated AR binds to both the proximal and distal enhancers of the PSA promoter, suggesting that p52-activated AR is conformationally different from DHT-activated AR. We further demonstrate that p52 decreases the expression of microRNA let-7 and increases the expression of Lin28, a master negative regulator of let-7. Based on these findings, we hypothesize that NF-¿B2/p52 plays a critical role in the development and progression of prostate cancer. There are three specific aims of this proposal. 1. Determine the functional roles of p52 in prostate cancer. This aim focuses on defining the role of p52 in AR activation and prostate cancer progression using androgen-sensitive prostate cancer cell models that expresses a wild-type AR and p52 in a physiological range. p52 will be inducibly expressed in the androgen-responsive, p52-negative LNCaP and LAPC-4 (expressing wild type AR) human prostate cancer cells to further test the effect of p52 on androgen-mediated prostate cancer cell growth in vitro and in vivo. In addition, we will determine the causal role of p52 in prostate cancer development and progression in the established transgenic mouse model. 2. Characterize the p52-activated AR transcriptional com-plexes. ChIP-Seq analysis will be used to perform comprehensive, high-resolution mapping of p52-activated AR genomic recruitment sites and to compare the resulting profile with that of the classical, steroid-activated receptor. 3. Characterize the p52-mediated signaling pathway in prostate cancer. We will determine whether p52 regulates let-7c expression by direct transcriptional repression of its promoter or indirectly via its effect on Lin28, the master regulaor of let-7c processing. We will then determine whether let-7c mediates p52-induction of AR activation through c-myc. We will examine the effects of Lin28/let-7c on p52- mediated prostate cancer cell growth and progression in vitro and in vivo. Completion of these studies will provide the vital role of p52 signaling network in prostate cancer, and will likely present excellent diagnostic and/or prognostic indicators and potential therapeutic targets for prostate cancer.