The role of p52 in prostate cancer

描述(由申请人提供)： 雄激素剥夺疗法是前列腺癌患者的标准治疗方法。不幸的是，这种治疗只是姑息性的，最终患者会复发，出现CASTRO耐药肿瘤，从而导致死亡。越来越多的证据表明雄激素受体(AR)的异常激活和抗凋亡细胞的发育促进了去势耐受前列腺癌(CRPC)的生长。CRPC中AR的激活可能通过多种机制发生，从而改变AR的敏感性或特异性。我们已发表的和初步的数据表明，核因子-B2/p52(P52)在前列腺癌中过表达，p52的过表达通过激活AR信号和保护细胞免受雄激素剥夺治疗诱导的细胞凋亡而促进CRPC的进展。在雄激素缺乏的情况下，P52与AR相互作用并激活AR，并增加包括前列腺特异性抗原(PSA)在内的许多雄激素调节基因的表达。P52激活的AR与PSA启动子的远端区域结合，但不与PSA启动子的近端区域结合，而DHT激活的AR与PSA启动子的近端和远端增强子结合，提示P52激活的AR与DHT激活的AR在构象上是不同的。我们进一步证明，p52降低了microRNA let-7的表达，增加了let-7的主要负调控因子Lin28的表达。基于这些发现，我们假设核因子-B2/p52在前列腺癌的发生和发展中起关键作用。这项提议有三个具体目标。1.确定p52在前列腺癌中的功能作用。本研究的目的是利用雄激素敏感的前列腺癌细胞模型，在生理范围内表达野生型AR和P52，以确定P52在AR激活和前列腺癌进展中的作用。P52将在雄激素敏感、p52阴性的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在体外和体内对雄激素介导的前列腺癌细胞生长的影响。此外，我们还将在已建立的转基因小鼠模型中确定p52在前列腺癌发生和发展中的因果作用。2.鉴定p52激活的AR转录复合体。ChIP-Seq分析将用于对p52激活的AR基因组招募位点进行全面、高分辨率的绘制，并将结果与经典的类固醇激活受体的图谱进行比较。3.研究前列腺癌中p52介导的信号转导途径。我们将确定p52是通过直接转录抑制其启动子来调节let-7c的表达，还是间接通过其对let-7c加工的主要调节因子Lin28的影响来调节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。我们将检测Lin28/let-7c在体外和体内对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.