Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington.
Quellos High Throughput Facility, Institute for Stem Cell and Regenerative Medicine, University of Washington Medicine Research, Seattle, Washington.
Cancer Res. 2022 Sep 16;82(18):3375-3393. doi: 10.1158/0008-5472.CAN-21-4222.
Pancreatic ductal adenocarcinoma (PDAC) typically presents as metastatic disease at diagnosis and remains refractory to treatment. Next-generation sequencing efforts have described the genomic landscape, classified molecular subtypes, and confirmed frequent alterations in major driver genes, with coexistent alterations in KRAS and TP53 correlating with the highest metastatic burden and poorest outcomes. However, translating this information to guide therapy remains a challenge. By integrating genomic analysis with an arrayed RNAi druggable genome screen and drug profiling of a KRAS/TP53 mutant PDAC cell line derived from a patient-derived xenograft (PDCL), we identified numerous targetable vulnerabilities that reveal both known and novel functional aspects of pancreatic cancer biology. A dependence on the general transcription and DNA repair factor TFIIH complex, particularly the XPB subunit and the CAK complex (CDK7/CyclinH/MAT1), was identified and further validated utilizing a panel of genomically subtyped KRAS mutant PDCLs. TFIIH function was inhibited with a covalent inhibitor of CDK7/12/13 (THZ1), a CDK7/CDK9 kinase inhibitor (SNS-032), and a covalent inhibitor of XPB (triptolide), which led to disruption of the protein stability of the RNA polymerase II subunit RPB1. Loss of RPB1 following TFIIH inhibition led to downregulation of key transcriptional effectors of KRAS-mutant signaling and negative regulators of apoptosis, including MCL1, XIAP, and CFLAR, initiating caspase-8 dependent apoptosis. All three drugs exhibited synergy in combination with a multivalent TRAIL, effectively reinforcing mitochondrial-mediated apoptosis. These findings present a novel combination therapy, with direct translational implications for current clinical trials on metastatic pancreatic cancer patients. Significance: This study utilizes functional genetic and pharmacological profiling of KRAS-mutant pancreatic adenocarcinoma to identify therapeutic strategies and finds that TFIIH inhibition synergizes with TRAIL to induce apoptosis in KRAS-driven pancreatic cancer.
胰腺导管腺癌（PDAC）通常在诊断时就已出现转移病变，且对治疗仍具有抗性。新一代测序技术已经描述了基因组景观，对分子亚型进行了分类，并证实了主要驱动基因的频繁改变，同时 KRAS 和 TP53 的共存改变与最高的转移负担和最差的结果相关。然而，将这些信息转化为指导治疗仍然是一个挑战。通过将基因组分析与阵列 RNAi 可用药基因组筛选以及源自患者来源异种移植（PDCL）的 KRAS/TP53 突变 PDAC 细胞系的药物分析相结合，我们确定了许多可靶向的弱点，这些弱点揭示了胰腺癌生物学的既有和新的功能方面。发现了对一般转录和 DNA 修复因子 TFIIH 复合物（特别是 XPB 亚基和 CAK 复合物（CDK7/CyclinH/MAT1））的依赖性，并利用一组基因组亚分型 KRAS 突变 PDCL 对其进行了进一步验证。使用 CDK7/12/13（THZ1）的共价抑制剂、CDK7/CDK9 激酶抑制剂（SNS-032）和 XPB 的共价抑制剂（雷公藤内酯）抑制 TFIIH 功能，导致 RNA 聚合酶 II 亚基 RPB1 的蛋白稳定性受到破坏。TFIIH 抑制后 RPB1 的丢失导致 KRAS 突变信号的关键转录效应因子和细胞凋亡的负调节剂（包括 MCL1、XIAP 和 CFLAR）下调，引发 caspase-8 依赖性细胞凋亡。三种药物与多价 TRAIL 联合使用均表现出协同作用，有效地增强了线粒体介导的细胞凋亡。这些发现提出了一种新的联合治疗方法，对目前转移性胰腺癌患者的临床试验具有直接的转化意义。意义：本研究利用 KRAS 突变胰腺导管腺癌的功能遗传和药理学分析，确定了治疗策略，并发现 TFIIH 抑制与 TRAIL 协同作用，可诱导 KRAS 驱动的胰腺癌凋亡。
