Androgen-Independent Prostate Cancer: Mechanisms & Treat

这项建议将研究从雄激素依赖到雄激素非依赖性前列腺癌(AIPC)的进展机制。我们的假设是，AIPC发生的机制之一是雄激素受体(AR)的突变扩大了其配体结合的特异性，并允许非雄激素与其结合并激活它，从而刺激前列腺癌(PCA)的生长。因此，AIPC的这个亚群依赖于AR，我们将这一途径称为混杂AR。例子包括LNCaP细胞中的AR(突变T877A)和丙二醛前列腺癌细胞(突变T877A和L701H)。虽然通常被称为雄激素依赖，但这些细胞具有对雄激素反应但不依赖雄激素的异位AR，因为氟他胺和其他类固醇可以刺激它们的生长。这笔赠款有三个具体目标。目的我将进一步评估我们最近被描述为AIPC的原因之一的丙二醛、PCA2a和2b细胞，这是由于对皮质类固醇(ARccr)有反应的混杂AR所致。我们将进一步确定与ARccr结合的类固醇的特征，并开发阻断或抑制ARccr的治疗策略。我们将调查L701H突变和其他导致转移性AR表型混杂的AR突变的频率。最后，我们将利用基因芯片技术研究雄激素和皮质类固醇通过ARccr对基因的调控模式。在特定目的II中，我们将研究AR依赖的AIPC的新治疗策略。我们假设，能够选择性下调AR(SARD)的分子在治疗AR依赖的AIPC方面将是有用的。我们已经确定了许多与这种活性有关的激素和配体。在AIM II中，我们将进一步鉴定、表征和阐明SARD的作用机制，并展示它们减弱AR依赖的AIPC细胞的生长刺激的能力。在特定的AIM III中，我们将使用两个体内模型来研究在AIMS I和II中开发的治疗策略。模型1将在裸鼠身上使用经典的异种移植。模型2是一种新的方法，使用荧光素酶转基因的PCA细胞异种移植，可以用电荷耦合设备摄像机在活体小鼠身上观察到。生物发光模型将是对目前异种移植方法的重大改进，提供可重复的、可以检测微小转移的前列腺癌进展的定量成像。综上所述，我们提出了体外和体内实验来研究PCa从雄激素依赖向AIPC转变的机制，重点是AR的突变和防止AR依赖的PCa生长的治疗策略。

This proposal will investigate mechanisms of progression from androgen-dependent to androgen-independent prostate cancer (AIPC). Our hypothesis is that one mechanism for AIPC development is mutations in the androgen receptor (AR) that widen its ligand binding specificity, and allow non-androgens to bind to and activate it, thus stimulating prostate cancer (PCa) growth. This sub-group of AIPC is therefore dependent on the AR and we refer to this pathway as the promiscuous AR. Examples include the ARs in LNCaP cells (mutation T877A), and MDA PCa cells (mutations T877A and L701H). Although often referred to as androgen-dependent, these cells have promiscuous ARs that are androgen-responsive but not dependent on androgens since flutamide and other steroids can stimulate their growth. The grant has 3 Specific Aims. Aim I will further evaluate MDA PCa 2a and 2b cells that we have recently described as a cause of AIPC due to a promiscuous AR that responds to corticosteroids (ARccr). We will further characterize the steroids that bind to ARccr and develop treatment strategies to block or suppress the ARccr. We will investigate the frequency of the L701H mutation and other AR mutations that cause the promiscuous AR phenotype in metastatic specimens. Finally, we will investigate the pattern of gene regulation by androgens and corticosteroids via the ARccr using cDNA microarray technology. In Specific Aim II we will study a novel treatment strategy for AR-dependent AIPC. We hypothesize that molecules that can selectively down-regulate AR (SARDs) will be therapeutically useful in treating AR-dependent AIPCs. We have identified a number of hormones and ligands with this activity. In Aim II we will further identify, characterize and elucidate the mechanism of action of SARDs as well as demonstrate their ability to diminish growth stimulation of AR- dependent AIPC cells. In Specific Aim III we will employ two in vivo models to investigate the treatment strategies developed in Aims I and II. Model 1 will employ classic xenografts in nude mice. Model 2 is a new approach using luciferase-transfected PCa cell xenografts that can be observed in live mice with a charge coupled device camera. The bioluminescent model will be a major improvement over current xenograft approaches providing repeatable, quantitative imaging of prostate cancer progression that can detect microscopic metastases. In conclusion, we propose in vitro and in vivo experiments to investigate the mechanism of transition of PCa from androgen-dependent to AIPC, focusing on mutations in the AR and treatment strategies to prevent the growth of AR-dependent PCa.