Cyclin Dependent Kinases as Epigenetic Therapy Targets

项目摘要 表观遗传学疗法旨在重新编程癌细胞中的基因表达以达到治疗效果。到目前为止， DNA甲基转移酶（DNMT）抑制（DNMTi）是表观遗传疗法的最有效形式， 特别是在骨髓性白血病中有活性。使用活细胞分析来筛选达到相同程度的药物 作为DNMTi的表观遗传重编程，我们发现了一类新的表观遗传药物， 通过抑制CDK 9的表达。细胞周期蛋白依赖性激酶（CDK）在临床上具有相当大的意义， 癌症治疗分为两类-细胞周期调节（例如CDK 1，2，4，6等）和转录 调节剂（例如CDK 7、9、12等）。我们的新数据将CDK 9置于调节两个基因的节点的中心。 沉默和激活。靶向CDK 9对基因表达具有多效性效应，从基因表达水平来看， 抗肿瘤的观点：一个观察同时基因激活（肿瘤抑制），抑制（肿瘤抑制）， 癌基因），以及诱导干扰素免疫特征，这可能是癌症的免疫增敏 疗法考虑到最近基于免疫的免疫系统的惊人发展，后一种效应特别令人感兴趣。 我们的初步数据表明，CDK 9靶向治疗可能是一种有用的新方法， 免疫增敏有趣的是，CDK 9可能不是参与免疫调节的唯一CDK。抑制 CDK 4/6和CDK 5已经显示在癌症中诱导IFN应答和/或免疫增敏 疗法此外，其他转录CDK（例如CDK 7）与CDK 9共享磷酸化靶点，从而提高了CDK的表达。 它们也可能同样影响基因沉默。考虑到靶向CDK 4和/或6的药物在临床上 在乳腺癌中的应用，以及靶向CDK 7和/或9的药物正在临床试验中，了解这一点变得很重要。 其他CDK是否也是免疫致敏的表观遗传调节因子。表观遗传效应可能导致不同的 这些药物的临床开发策略（例如，低剂量而不是MTD，预期反应缓慢 需要多个周期才能发生，等等）以及用于设计组合策略（组合表观遗传 治疗、与免疫检查点抑制剂的组合等）。因此，本项目旨在验证假设 靶向CDK导致免疫增敏的表观遗传效应。我们将证实这一假设并检验 癌症治疗的三个目的的机制和临床/转化意义：（i）免疫增敏， CDK 9抑制，其中我们将研究机制和增强效果的潜在方法;（ii）表观遗传学 CDK的作用，其中我们将询问靶向CDK 4、5、6和7是否具有类似的表观遗传和 作为靶向CDK 9的免疫增敏作用;和（iii）组合CDK 9的临床前研究和临床试验 抑制，DNMT抑制和免疫检查点抑制在AML和MDS中，我们将完成 将CDK靶向作为表观遗传疗法与DNMT结合应用于临床的必要研究 靶向和免疫检查点抑制。这些目标的成功实现将引入一种新的形式， 癌症和白血病的表观遗传疗法。

PROJECT SUMMARY Epigenetic therapy aims to reprogram gene expression in cancer cells to achieve a therapeutic effect. To date, DNA methyltransferase (DNMT) inhibition (DNMTi) is the most effective form of epigenetic therapy, being particularly active in myeloid leukemias. Using a live cell assay to screen for drugs that achieve the same degree of epigenetic reprogramming as DNMTi, we discovered a new class of epigenetic drugs that activate silenced expression through inhibition of CDK9. Cyclin Dependent Kinases (CDKs) are of considerable clinical interest in cancer therapy and fall into two classes – cell cycle regulatory (e.g. CDK1,2,4,6 etc.) and transcriptional regulators (e.g. CDK7,9,12 etc.). Our new data place CDK9 at the heart of a node that regulates both gene silencing and activation. Targeting CDK9 has pleotropic effects on gene expression that appear ideal from an anti-tumor perspective: One observes simultaneous gene activation (of tumor suppressors), repression (of oncogenes), and induction of an interferon immune signature, which may be immunosensitizing for cancer therapy. This latter effect is of particular interest given the phenomenal recent development of immune based therapies, and our preliminary data suggest that CDK9 targeting may be a useful new approach to immunosensitization. Interestingly, CDK9 may not be the only CDK involved in immune regulation. Inhibition of CDK4/6 and of CDK5 have been shown to induce an IFN response and/or to be immunosensitizing in cancer therapy. Moreover, other transcriptional CDKs (e.g. CDK7) share phosphorylation targets with CDK9, raising the possibility that they also similarly affect gene silencing. Given that drugs that target CDK4 and/or 6 are in clinical use in breast cancer, and drugs targeting CDK7 and/or 9 are in clinical trials, it becomes important to know whether other CDKs are also immunosensitizing epigenetic regulators. Epigenetic effects may lead to different strategies for clinical development of these drugs (e.g. low doses rather than MTD, expectation of slow responses that take multiple cycles to occur, etc.) and for the design of combination strategies (combined epigenetic therapy, combinations with immune checkpoint inhibitors etc.). This project therefore aims to test the hypothesis that targeting CDKs leads to immunosensitizing epigenetic effects. We will confirm this hypothesis and test mechanisms and clinical/translational implications for cancer therapy in three aims: (i) Immunosensitization by CDK9 inhibition, in which we will study mechanisms and potential ways to enhance the effects; (ii) Epigenetic effects of CDKs, in which we will ask whether targeting CDK4,5,6 and 7 has similar epigenetic and immunosensitizing effects as targeting CDK9; and (iii) Preclinical studies and a clinical trial of combined CDK9 inhibition, DNMT inhibition and Immune checkpoint inhibition in AML and MDS, in which we will complete the necessary studies to bring CDK targeting as epigenetic therapy into the clinic, in combination with DNMT targeting and immune checkpoint inhibition. Successful achievement of these aims will introduce a new form of epigenetic therapy for cancer and leukemias.