Androgen-Independent Prostate Cancer: Mechanisms & Treat

本研究将探讨雄激素依赖型前列腺癌（AIPC）向雄激素非依赖型前列腺癌发展的机制。我们的假设是AIPC发展的一个机制是雄激素受体（AR）的突变，该突变扩大了其配体结合特异性，并允许非雄激素结合并激活它，从而刺激前列腺癌（PCa）的生长。因此，AIPC的这一亚群依赖于AR，我们将这一途径称为混杂AR。例子包括LNCaP细胞（突变T877A）和MDA PCa细胞（突变T877A和L701H）中的AR。虽然通常被称为雄激素依赖性，但这些细胞具有混杂的ar，它们对雄激素有反应，但不依赖于雄激素，因为氟他胺和其他类固醇可以刺激它们的生长。该基金有3个具体目标。目的1将进一步评估MDA PCa 2a和2b细胞，我们最近将其描述为AIPC的原因，这是由于皮质类固醇反应的混杂AR （ARccr）。我们将进一步表征与ARccr结合的类固醇，并制定阻断或抑制ARccr的治疗策略。我们将研究导致转移标本中混杂AR表型的L701H突变和其他AR突变的频率。最后，我们将利用cDNA微阵列技术研究雄激素和皮质类固醇通过ARccr的基因调控模式。在Specific Aim II中，我们将研究一种新的治疗ar依赖性AIPC的策略。我们假设选择性下调AR （sard）的分子将在治疗AR依赖性AIPCs方面具有治疗作用。我们已经确定了许多具有这种活性的激素和配体。在Aim II中，我们将进一步识别、表征和阐明sard的作用机制，并证明它们能够减少AR依赖性AIPC细胞的生长刺激。在特定目标III中，我们将采用两种体内模型来研究目标I和II中开发的治疗策略。模型1将在裸鼠身上采用经典的异种移植物。模型2是一种使用荧光素酶转染的PCa细胞异种移植物的新方法，可以用电荷耦合器件相机在活小鼠中观察。生物发光模型将是目前异种移植方法的重大改进，提供可重复的、定量的前列腺癌进展成像，可以检测显微镜下的转移。总之，我们提出体外和体内实验来研究雄激素依赖性PCa向AIPC转变的机制，重点研究AR的突变和阻止AR依赖性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.