Targeting MED31-driven transcription recycling in lethal prostate cancer

项目摘要/摘要 致命的去势抵抗前列腺癌(CRPC)患者目前正在使用靶向药物进行治疗。 雄激素受体(AR)信号传导。然而，AR抑制并没有显著提高CRPC患者的存活率， 强调需要在CRPC中发现新的致癌机制并开发新的靶向治疗 这些机制。癌细胞对异常的RNA聚合酶II(POL II)转录上瘾，包括 起始、延伸和终止阶段，以及重复POL II转录的关键循环步骤 在最初的转录周期之后，相同基因的同源性。虽然研究已经表明，不受控制的 转录起始和延伸具有致癌作用，目前尚不清楚是否有其他Pol II转录 过程有助于癌症相关的转录结果和癌症的生长。在初步研究中，我们的 新开发的体外和基于细胞的转录循环分析发现，Pol II循环是一个关键 却忽视了与前列腺癌相关的转录过程。我们发现调解人情结 亚基31(MED31)在CRPC细胞中驱动Pol II循环，在循环过程中增强mRNA输出。 重要的是，MED31的高表达是前列腺癌抵抗去势的充分和必要的。 生长发育与CRPC患者预后不良有关。虽然这些发现确定了致癌因素 MED31作为CRPC的新治疗靶点，通常被认为是转录调节因子，如MED31 传统的、基于小分子的药物设计无法达到目标。我们已经开发出一种安全的脂质纳米颗粒 (LNP)用于定向交付CRISPR/Cas13d系统的系统，以有效和具体地拆除 在mRNA水平上的致癌转录调节因子。在初步研究中，我们已经证明 LNP-Cas13d系统有效安全地敲除MED31mRNA并抑制体内CRPC细胞的生长， 建立了CRPC靶向MED31的治疗窗口存在的概念的证据。一起， 我们的初步发现支持这样一种假设，即MED31支配的转录循环是一种新的 CRPC进展的致癌驱动因素和基于LNP-Cas13d的RNA靶向系统可以中和 MED31在CRPC中驱动的癌基因转录具有安全性、特异性和有效性。在目标1中，我们将描述 MED31介导的转录循环的分子机制、生物学功能和临床意义。 在目标2中，我们将使用基于CRISPR/Cas13d的纳米颗粒来定位MED31介导的转录循环 系统。这些目标的成功实现将极大地阐明POL II回收在 并将为未来的临床试验测试LNP的效用提供实验基础- Cas13d RNA靶向系统在CRPC患者中靶向这一新的致癌机制。

Project Summary/Abstract Patients with lethal castration-resistant prostate cancer (CRPC) are currently treated with agents targeting androgen receptor (AR) signaling. However, AR inhibition has not dramatically improved CRPC patient survival, underscoring the need to discover novel oncogenic mechanisms in CRPC and develop new therapies targeting these mechanisms. Cancer cells are addicted to aberrant RNA polymerase II (Pol II) transcription, which includes initiation, elongation, and termination phases, as well as a recycling step critical to repeated Pol II transcription of the same gene after the initial transcription cycle. While studies have already indicated that uncontrolled transcriptional initiation and elongation have oncogenic roles, it is unknown whether other Pol II transcription processes contribute to cancer-relevant transcriptional outcomes and cancer growth. In preliminary studies, our newly developed in vitro and cell-based transcription recycling assays have found that Pol II recycling is a key yet overlooked transcription process with relevance to prostate cancer. We have found that Mediator complex subunit 31 (MED31) drives Pol II recycling in CRPC cells, enhancing mRNA output during the recycling process. Importantly, high expression of MED31 is both sufficient and necessary for prostate cancer castration-resistant growth and is associated with poor prognosis of CRPC patients. While these findings identify the oncogenic MED31 as a new therapeutic target for CRPC, transcription regulators such as MED31 are generally considered untargetable by traditional, small molecule-based drug design. We have developed a safe lipid nanoparticle (LNP) system for targeted delivery of the CRISPR/Cas13d system to efficiently and specifically knock down oncogenic transcription regulators at the mRNA level. In preliminary studies, we have demonstrated that the LNP-Cas13d system effectively and safely knocks down MED31 mRNA and decreases CRPC cell growth in vivo, establishing the proof of the concept that the therapeutic window exists for targeting MED31 in CRPC. Together, our preliminary findings support the hypothesis that MED31-governed transcription recycling is a novel oncogenic driver for CRPC progression and that an LNP-Cas13d-based RNA targeting system can counteract oncogenic transcription driven by MED31 in CRPC with safety, specificity, and efficacy. In Aim 1, we will delineate the molecular mechanism, biological function, and clinical relevance of MED31-mediated transcription recycling. In Aim 2, we will target MED31-mediated transcription recycling using a CRISPR/Cas13d-based nanoparticle system. The successful completion of these aims will significantly elucidate the critical role of Pol II recycling in lethal prostate cancer and will provide an experimental basis for future clinical trials testing the utility of an LNP- Cas13d RNA targeting system to target this novel oncogenic mechanism in CRPC patients.