Targeting p38 gamma signaling to advance Cutaneous T Cell Lymphoma Therapy

皮肤T细胞淋巴瘤（CTCL）是一种毁容，无法治愈的癌症。对于晚期疾病患者， 目前的治疗是不充分的，结果是差的。对CTCL分子的不完全理解 监管机构限制了有效靶向治疗的发展。一个候选调节因子是p38γ， 其表达在CTCL细胞系和患者样品中选择性增加，但在健康T细胞中不增加。我们 证明p38γ的抑制或沉默抑制增殖并诱导CTCL细胞死亡。NF-κB p38 γ通路在CTCL中是组成性活性的，为p38γ提供了互补的T细胞信号传导通路，并且可以 被组蛋白去乙酰化酶抑制剂（HDACi）抑制。HDACi是目前临床上最有效的 已批准的针对CTCL的细胞毒性化合物，当与p38γ 抑制作用我们的目的是了解和利用CTCL中的p38γ通路， 分子、化学和遗传方法。我们的首要目标是确定p38γ的作用机制 抑制诱导CTCL中的细胞死亡。我们将定义参与p38γ抑制诱导的 CTCL细胞杀伤和鉴定p38γ信号传导的磷酸化靶点;使用合成的致死RNAi筛选， 鉴定在p38γ抑制存在下耗尽时引起细胞死亡的信号传导组分;和 确定p38γ和互补途径（包括HDAC）的联合抑制程度， 诱导协同治疗作用。我们将验证鉴定的蛋白质影响下游的能力， 使用CTCL细胞系异种移植物和患者来源的异种移植物的体外和体内信号传导和细胞应答 (PDX)模型我们的第二个目标是开发具有潜在治疗应用的新型p38γ抑制剂。使用 通过高通量筛选和分子建模，我们鉴定了多激酶抑制剂F7（也称为 PIK 75），并显示其是ATP竞争性p38γ抑制剂，具有针对CTCL细胞的纳摩尔细胞毒性功效。 为了开发更有选择性的p38γ抑制剂，我们将结合联合收割机和基于配体和结构的计算方法 使用F7作为支架分子，我们将鉴定F7类似物并将F7衍生为具有 对p38γ的结合亲和力高于其他激酶。此外，我们将使用基于CRISPR的筛选来识别 用于开发下一代变构治疗剂的新功能结构域和非保守位点。我们将 合成各种类似物，并在体外验证CTCL细胞毒性和p38γ特异性激酶抑制的命中 和体内，使用CTCL异种移植物和PDX模型。我们希望，成功完成这项建议将 产生关于p38γ信号传导的独特生物学和临床相关性的机制信息， CTCL中的互补途径。重要的是，在CTCL中有效的特异性p38γ抑制剂的验证 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.