Department of Surgery, University of California, Los Angeles, CA 90095.
Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA 90095.
Proc Natl Acad Sci U S A. 2019 Apr 2;116(14):6842-6847. doi: 10.1073/pnas.1812410116. Epub 2019 Mar 20.
Functional lysosomes mediate autophagy and macropinocytosis for nutrient acquisition. Pancreatic ductal adenocarcinoma (PDAC) tumors exhibit high basal lysosomal activity, and inhibition of lysosome function suppresses PDAC cell proliferation and tumor growth. However, the codependencies induced by lysosomal inhibition in PDAC have not been systematically explored. We performed a comprehensive pharmacological inhibition screen of the protein kinome and found that replication stress response (RSR) inhibitors were synthetically lethal with chloroquine (CQ) in PDAC cells. CQ treatment reduced de novo nucleotide biosynthesis and induced replication stress. We found that CQ treatment caused mitochondrial dysfunction and depletion of aspartate, an essential precursor for de novo nucleotide synthesis, as an underlying mechanism. Supplementation with aspartate partially rescued the phenotypes induced by CQ. The synergy of CQ and the RSR inhibitor VE-822 was comprehensively validated in both 2D and 3D cultures of PDAC cell lines, a heterotypic spheroid culture with cancer-associated fibroblasts, and in vivo xenograft and syngeneic PDAC mouse models. These results indicate a codependency on functional lysosomes and RSR in PDAC and support the translational potential of the combination of CQ and RSR inhibitors.
功能性溶酶体介导自噬和巨胞饮作用以获取营养。胰腺导管腺癌 (PDAC) 肿瘤表现出高基础溶酶体活性，抑制溶酶体功能会抑制 PDAC 细胞增殖和肿瘤生长。然而，PDAC 中溶酶体抑制诱导的协同依赖性尚未得到系统探索。我们对蛋白激酶组进行了全面的药理学抑制筛选，发现复制应激反应 (RSR) 抑制剂与 PDAC 细胞中的氯喹 (CQ) 具有合成致死性。CQ 处理降低了从头核苷酸合成，并诱导了复制应激。我们发现 CQ 处理导致线粒体功能障碍和天冬氨酸耗竭，天冬氨酸是从头核苷酸合成的必需前体，这是一种潜在的机制。用天冬氨酸进行补充部分挽救了 CQ 诱导的表型。CQ 和 RSR 抑制剂 VE-822 的协同作用在 PDAC 细胞系的 2D 和 3D 培养物、具有癌症相关成纤维细胞的异质球体培养物以及体内异种移植和同基因 PDAC 小鼠模型中得到了全面验证。这些结果表明 PDAC 中存在对功能性溶酶体和 RSR 的依赖性，并支持 CQ 和 RSR 抑制剂联合应用的转化潜力。
