Targeting p38 gamma signaling to advance Cutaneous T Cell Lymphoma Therapy

皮肤T细胞淋巴瘤(CTCL)是一种无法治愈的毁容癌症。对于患有晚期疾病的患者， 目前的治疗方法不够充分，结果很差。对CTCL分子的不完全理解 监管机构对有效的靶向疗法的开发有限。其中一个候选调节基因是p38γ，该基因 其在CTCL细胞系和患者样本中的表达选择性增加，但在健康T细胞中不表达。我们 证明抑制或沉默p38γ可抑制细胞增殖并诱导细胞死亡。核因子-κB 途径在CTCL中是结构性活跃的，为p38γ提供了一个互补的T细胞信号通路，并且可以 被组蛋白脱乙酰酶抑制剂(HDACi)抑制。HDACi是目前临床上最有效的 经批准的抗肿瘤细胞毒性化合物与p38γ联合应用显示协同杀伤作用 抑制力。我们的目标是了解和利用p38γ通路在结直肠癌中的作用。 分子、化学和遗传方法。我们的第一个目标是确定p38γ 抑制诱导CTCL细胞死亡。我们将定义参与p38γ抑制诱导的激酶级联 CTCL细胞杀伤和鉴定p38γ信号的磷酸化靶点；使用合成致命的RNAi筛选 确定在存在p38γ抑制的情况下，在耗尽时导致细胞死亡的信号成分；以及 确定联合抑制p38γ和包括HDAC在内的互补通路的程度， 诱导协同治疗效应。我们将验证识别出的蛋白质是否有能力影响下游 使用CTCL细胞系异种移植和患者来源的异种移植在体外和体内的信号和细胞反应 (PDX)型号。我们的第二个目标是开发新的p38γ抑制剂，用于潜在的治疗应用。vbl.使用 高通量筛选和分子模拟，我们鉴定了多激酶抑制剂F7(也称为 PIK75)，并证明它是一种三磷酸腺苷竞争性p38γ抑制剂，对CTCL细胞具有纳米级的细胞毒作用。 为了开发更有选择性的p38γ抑制剂，我们将结合基于配体和基于结构的计算方法 通过有机合成；使用F7作为支架分子，我们将识别F7类似物并将F7衍生化为 与p38γ的结合亲和力高于其他激酶。此外，我们将使用基于CRISPR的筛查来识别 开发变构下一代疗法的新功能结构域和非保守位点。我们会 合成多种类似物并在体外验证HITS对CTCL的细胞毒作用和对p38γ特异性激酶的抑制作用 在体内，采用CTCL异种移植和PDX模型。我们预计，这项提议的成功完成将 产生关于p38γ信号和临床独特的生物学意义的机制信息 CTCL中的互补通路。重要的是，一种特定的p38γ抑制剂在CTCL中的有效性的验证 动物模型将与CTCL治疗直接相关。

Cutaneous T cell lymphoma (CTCL) is a disfiguring, incurable cancer. For patients with advanced disease, current therapies are inadequate, and outcome is poor. An incomplete understanding of CTCL molecular regulators has limited development of effective targeted therapies. One candidate regulator is p38γ, the gene expression of which is selectively increased in CTCL cell lines and patient samples, but not healthy T cells. We demonstrate that inhibition or silencing of p38γ inhibits proliferation and induces CTCL cell death. The NF-κB pathway is constitutively active in CTCL, provides a complementary T cell signaling pathway to p38γ, and can be inhibited by histone deacetylase inhibitors (HDACi). HDACi, which are currently the most effective clinically approved cytotoxic compounds against CTCL, demonstrate synergistic killing when combined with p38γ Inhibition. Our objective is to understand and exploit the p38γ pathway in CTCL, using a combination of molecular, chemical, and genetic approaches. Our first Aim is to determine the mechanisms by which p38γ inhibition induces cell death in CTCL. We will define the kinase cascade involved in p38γ inhibition-induced CTCL cell killing and identify phosphorylation targets of p38γ signaling; use a synthetic lethal RNAi screen to identify signaling components that cause cell death upon depletion in the presence of p38γ inhibition; and determine the extent to which combined inhibition of p38γ and complementary pathways, including HDACs, induce synergistic therapeutic effects. We will validate identified proteins for the ability to affect downstream signaling and cellular responses in vitro and in vivo, using CTCL cell line xenograft and patient-derived xenograft (PDX) models. Our second Aim is to develop novel p38γ inhibitors for potential therapeutic application. Using high throughput screening and molecular modeling, we identified the multi-kinase inhibitor F7 (also known as PIK75), and showed it is an ATP-competitive p38γ inhibitor with nanomolar cytotoxic efficacy against CTCL cells. To develop a more selective p38γ inhibitor, we will combine ligand- and structure-based computational methods with organic synthesis; using F7 as a scaffold molecule, we will identify F7 analogs and derivatize F7 to have higher a binding affinity for p38γ than other kinases. In addition, we will use CRISPR-based screening to identify novel functional domains and non-conserved sites for developing allosteric next-generation therapeutics. We will synthesize the various analogs and validate hits for CTCL cytotoxicity and p38γ-specific kinase inhibition in vitro and in vivo, using CTCL xenograft and PDX models. We expect that successful completion of this proposal will yield mechanistic information about the unique biological and clinical relevance of p38γ signaling and complementary pathways in CTCL. Importantly, validation of a specific p38γ inhibitor with efficacy in CTCL animal models will have immediate relevance for CTCL therapy.