研究基因转录调节酶CDK7抑制剂THZ1在胰腺癌中的治疗潜力及分子机制

Pancreatic cancer (Pancreatic ductal adenocarcinoma (PDAC) is the predominant form of pancreatic cancer) is the third-leading cause of cancer-related mortality in the United States. It commonly presents at an advanced stage, with median survival times of <12 months and 5-year survival rate of less than 5%. Additionally, pancreatic cancer is a highly chemo-resistant malignancy. Recent efforts to sequence pancreatic cancer tissues have revealed four genes that are commonly mutated or lost (KRAS, TP53, CDKN2A, SMAD4), but few targetable mutations to guide therapeutic decisions. Thus, new treatment approaches are urgently needed. .Deregulation of cyclin-dependent kinases (CDKs) has been associated with many cancer types and has evoked an interest in chemical inhibitors. Besides cell cycle control CDKs, transcriptional CDKs are also critical anti-cancer targets. CDK7 is a subunit of the multi-protein basal transcription factor TFIIH, and plays dual roles in the regulation of cell-cycle progression and transcription. .Targeting gene transcription for cancer therapy has long been considered difficult, due to a presumably universal role of transcription in non-malignant cells or tissues, leading to concerns regarding on-target toxicity. Recent studies, however, have challenged this paradigm and found that transcription of certain genes is disproportionately sensitive to transcriptional inhibition..A series of studies have described super-enhancers, large clusters of transcriptional enhancers that are densely occupied by transcriptional factors, cofactors and chromatin regulators. These super-enhancers are acquired by cancer cells through gene amplification, translocation or transcription factor overexpression. A novel phenylaminopyrimidine, developed by the Gray labloratory, named THZ1 is characterized to be a covalent CDK7 inhibitor and directly suppresses super-enhancers associated oncogenic transcription in T-cell acute lymphoblastic leukemia, neuroblastoma, small cell lung cancer and triple-negative breast cancer. .We propose to study the selectively targeting of anti-cancer CDK7 inhibitor, THZ1, in pancreatic cancer with the goal developing new precision therapeutic approaches to pancreatic cancer. The current project will provide valuable data on the efficacy of CDK7 inhibition in model systems and the clinical significances of deregulation of CDK7 in patients with pancreatic cancer.

在世界范围内，胰腺癌是癌症相关死亡的一大原因。发现时多为中晚期，中位生存期<12个月，5年生存率<5％。胰腺癌对化疗耐药程度很高。基因测序的研究成果揭示了胰腺癌中普遍性突变或丢失的四个基因（KRAS，TP53，CDKN2A，SMAD4），然而没有发现对治疗策略有指导意义的靶点。急需研发新的治疗方法。. 细胞周期蛋白依赖性激酶（CDK）的失调与许多癌有关。除了细胞周期调控CDK，基因转录CDK也是关键的抗癌靶点。CDK7是多蛋白转录因子（TFIIH）的亚基，在调节细胞周期和基因转录中起双重作用。由Gray实验室开发的一种新型苯基氨基嘧，啶，THZ1，CDK7的抑制剂，在多种癌症中可直接抑制与超促进子(Super-enhancers)相关的原癌基因（Oncogene）的转录。. 本研究将在体外和体内胰腺癌模型系统中确定THZ1的疗效和抗癌分子机制，目标是开发新的精准治疗胰腺癌的新方法。

胰腺癌是一种多发现于中晚期的恶性肿瘤。胰腺癌对化疗耐药程度高，且暂未发现有效的治疗靶点，治疗效果不理想，预后差，急需探索新的治疗方法。细胞周期蛋白依赖性激酶CDK7介导癌基因的持续性转录，其抑制剂THZ1在多种癌症中可直接抑制与超级增强子相关的原癌基因的转录。然而，THZ1具有半衰期短，生物利用度差和潜在毒性的缺点，因此本课题开发了一种提高THZ1疗效的策略，增加其治疗应用的机会。本研究发现纳米磷酸钙作为药物载体能明显提高传统化疗药物5Fu在胰腺癌中的治疗效果。5Fu/CaPO-NH2颗粒进入细胞后，分解成Ca2+并在细胞质中释放5Fu药物，细胞中钙超载以及5Fu诱导活性氧(ROS)积累可通过内质网应激、脂质过氧化和线粒体凋亡等一系列生化反应诱导细胞膜损伤并引起细胞凋亡。在PSN1胰腺癌异种移植模型中，5Fu/CaPO-NH2体系通过化疗和钙过载诱导的凋亡实现了高度的肿瘤抑制。本课题组进一步研究发现钙基纳米材料载化疗药策略同样适用于载THZ1。在本研究中，我们开发了一种由阿仑膦酸盐、钙离子和THZ1组成的新型ACaT纳米药物，该纳米球能被肿瘤细胞选择性内化，并有效地聚集在肿瘤部位。RNA测序和体外实验结果表明，ACaT可通过阻断细胞周期、增加ROS、影响钙稳态等途径促进肿瘤细胞凋亡，抑制肿瘤细胞迁移。体外实验证明ACaT可明显延长荷瘤小鼠的生存期。总的来说，化疗药物纳米化可以明显增强对胰腺癌的抗肿瘤作用，THZ1与钙基纳米材料联合可提高对肿瘤的治疗效果，这些研究为临床上治疗胰腺癌提供了新的治疗策略和理论依据。

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