Characterization of Epigenetic Targets in Prostate Cancer

描述（由申请人提供）：组蛋白甲基转移酶（HMTases）是染色质修饰剂，在正常发育以及癌症等疾病中发挥重要作用。在我们小组发现EZH2过表达并与前列腺癌进展和不良预后相关后(1)，它已成为癌症中研究最多的HMTase，多个研究小组和制药公司都在寻求开发EZH2抑制剂用于临床。然而，直接靶向EZH2被认为是有问题的，因为它也在干细胞维持中起作用，并在髓系疾病中作为肿瘤抑制因子。最近，我们对包括原发性和转移性前列腺肿瘤在内的多种癌症的转录组和蛋白表达分析显示，另一种hmmtase MMSET过表达，与EZH2的表达、功能和临床特征相似(2)。EZH2与组蛋白H3K27三甲基化介导的基因沉默相关，被发现在介导H3K36二甲基化与主动转录相关的MMSET的上游协调表达和功能。鉴于MMSET作为ezh2介导的肿瘤发生效应因子的高表达和功能意义，以及MMSET通过调节AR信号和基因表达在前列腺癌中发挥关键作用的观察，我们假设MMSET可能是前列腺癌的重要治疗靶点。在治疗MMSET的过程中，我们发现了一种先导探针化合物，3-肼-2-喹啉硫醇（MCTP39），这是一种含有肼嗪（一种已知的表观遗传药物）异构体的硫基，可以在体内减弱MMSET的酶活性。此外，MCTP39被证明能够特异性地抑制过表达MMSET的癌细胞系的生长和侵袭特性。在此，我们提出以下具体目标：1)MMSET在前列腺癌中的综合功能研究；2)阐明MMSET在AR信号传导中的作用；3) MMSET先导抑制剂化合物MCTP39的表征。本提案中概述的目标的成功完成将提高对MMSET的作用及其在ar介导的前列腺癌进展中的重要性的理解，并可能产生一种有前途的小分子抑制剂，可以进一步开发用于临床应用。拟议的项目和支持初步数据是根据申请人的原始想法构思的。Chinnaiyan博士在密歇根转化病理学中心提供的跨学科环境，在应用高通量技术和生物信息学方法研究癌症突变景观以及识别相关生物标志物和治疗靶点方面拥有丰富的经验，为支持申请人的科学职业目标提供了理想的环境。申请人广泛的初步数据证明了这一点，这些数据导致了高影响力期刊上的多篇第一作者和共同作者论文。Chinnaiyan博士对申请人的职业目标表示全力支持，并鼓励他将来将这些项目转移到他的独立实验室。总的来说，NIH独立之路奖对于申请人过渡到癌症生物学领域的独立研究者，特别是在将基于基因组的发现转化为临床应用方面是必不可少的。

DESCRIPTION (provided by applicant): Histone methyltransferases (HMTases) are chromatin modifiers that play an important role in normal development as well as in diseases such as cancer. Following the discovery by our group that EZH2 is overexpressed and associates with prostate cancer progression and poor prognosis (1), it has become the most well-studied HMTase in cancer with multiple research groups and pharmaceutical companies in pursuit of developing EZH2 inhibitors for clinical use. However, direct targeting of EZH2 is deemed problematic since it also has a role in stem cell maintenance and acts as a tumor suppressor in myeloid diseases. More recently, our transcriptome and protein expression analysis across multiple cancers including primary and metastatic prostate tumors revealed overexpression of another HMTase, MMSET, that paralleled EZH2 expression, function and clinical attributes (2). EZH2, which is associated with gene silencing mediated through histone H3K27 trimethylation, was found to be coordinately expressed and function upstream of MMSET, which mediates H3K36 dimethylation associated with active transcription. Given the high expression and functional significance of MMSET as an effector of EZH2-mediated oncogenesis as well as the observation that MMSET plays a critical role in prostate cancer by regulating AR signaling and gene expression, we hypothesize that MMSET potentially represents an important therapeutic target in prostate cancer. In an effort to therapeutically target MMSET we have identified a lead probe compound, 3-hydraxino-2-quinoxalinethiol (MCTP39), a thiol group containing isomer of hydralazine (a known epigenetic drug), that was found to attenuate MMSET enzymatic activity in vivo. Further, MCTP39 was shown to inhibit growth and invasive properties specifically of cancer cell lines that overexpress MMSET. Here, we propose to carry out the following Specific Aims: 1) Integrative functional study of MMSET in prostate cancer; 2) Elucidation of the role of MMSET in AR signaling; 3) Characterization of a lead MMSET inhibitor compound MCTP39. Successful completion of the Aims outlined in this proposal will improve understanding of the role of MMSET and its importance in AR-mediated prostate cancer progression, and may yield a promising small molecule inhibitor that could be further developed for clinical use. The proposed projects and the supporting preliminary data were conceived based on the applicant's original ideas. The cross-disciplinary environment provided by Dr. Chinnaiyan at the Michigan Center of Translational Pathology, which has vast experience applying high-throughput technologies and bioinformatics approaches for studying the mutational landscape of cancer and identifying associated biomarkers and therapeutic targets, serves as an ideal environment for supporting the applicant's scientific career goals. This is exemplified by the applicant's extensive preliminary data that has led to multiple first author and co-author papers in high impact journals. Dr. Chinnaiyan has extended his full support towards the applicants' career goals and has encouraged him to transfer these projects to his independent lab in the future. Overall, an NIH Pathway to Independence Award will be indispensable for the applicant to transition into an independent investigator in the field of cancer biology specifically in translating genome-based discoveries into clinical applications.