Extracellular lumican augments cytotoxicity of chemotherapy in pancreatic ductal adenocarcinoma cells via autophagy inhibition
Extracellular lumican augments cytotoxicity of chemotherapy in pancreatic ductal adenocarcinoma cells via autophagy inhibition
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DOI：
10.1038/onc.2016.20
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发表时间：
2016-09-15
期刊：
影响因子：
8
通讯作者：
Fleming, J. B.
中科院分区：
文献类型：
--
作者：
Li, X.;Roife, D.;Fleming, J. B.
Lumican是一种细胞外基质蛋白多糖，由胰腺星状细胞（PSCs）和胰腺导管腺癌细胞（pdac）过度表达，可驱动肿瘤特异性微环境的形成。我们最近发现，细胞外的lumican抑制胰腺癌细胞生长，并与手术后延长生存期有关。在这里，我们研究了细胞外肿瘤细胞在化疗介导的癌症治疗中的作用。化疗药物增加了PDAC中Lumican的分泌，特别是在PSCs中，并且似乎与细胞对化疗诱导的生长抑制的反应程度有关。在多种PDAC模型中，包括细胞系、患者来源的异种移植物和lumican基因敲除小鼠，lumican显著增强了化疗的抗肿瘤作用。这种作用与DNA损伤、细胞凋亡和抑制细胞活力、葡萄糖消耗、乳酸生成和血管内皮生长因子分泌有关。在PDAC细胞中，化疗药物通过活性氧介导的amp活化激酶（AMPK）信号通路触发自噬体形成并增加LC3表达。AMPK抑制剂化合物C、溶酶体抑制剂氯喹或自噬抑制剂3MA对吉西他滨诱导的癌细胞自噬的抑制作用增强了吉西他滨诱导的细胞凋亡，提示自噬是吉西他滨治疗后的一种保护性细胞反应。重要的是，在体外和体内PDAC模型中，lumican显著降低AMPK活性，抑制化疗诱导的自噬。鲁米肯和吉西他滨共同处理PDAC细胞增加了线粒体损伤、活性氧（ROS）产生和细胞色素c释放，表明鲁米肯诱导的线粒体功能破坏可能是吉西他滨致敏的机制。总之，我们的研究结果表明，细胞外lumican通过抑制化疗药物诱导的自噬来增强化疗在PDAC细胞中的细胞毒性。
Lumican, an extracellular matrix proteoglycan overexpressed by pancreatic stellate cells (PSCs) and pancreatic ductal adenocarcinoma cells (PDACs), drives the formation of a tumor-specific microenvironment. We recently showed that extracellular lumican inhibits pancreatic cancer cell growth and is associated with prolonged survival after surgery. Here we investigated the role of extracellular lumican in chemotherapy-mediated cancer therapy. Lumican secretion was increased by chemotherapeutic agents in PDAC, and especially in PSCs, and appeared to be linked to the extent of cells' response to chemotherapy-induced growth inhibition. In multiple PDAC models, including cell lines, patient-derived xenografts and lumican knockout mice, lumican significantly increased antitumor effect of chemotherapy. This effect was associated with DNA damage, apoptosis and inhibition of cell viability, glucose consumption, lactate production and vascular endothelial growth factor secretion. In PDAC cells, chemotherapeutic agents triggered autophagosome formation and increased LC3 expression through the reactive oxygen species-mediated AMP-activated kinase (AMPK) signaling pathway. Inhibition of gemcitabine-induced autophagy in cancer cells by treatment with AMPK inhibitor compound C, lysosomal inhibitor chloroquine or autophagy inhibitor 3MA enhanced gemcitabine-induced apoptosis, suggesting that autophagy is a protective cellular response to gemcitabine treatment. Importantly, lumican dramatically decreased AMPK activity, inhibiting chemotherapy-induced autophagy in both in vitro and in vivo PDAC models. Co-treatment of PDAC cells with lumican and gemcitabine increased mitochondrial damage, reactive oxygen species (ROS) production and cytochrome c release, indicating that lumican-induced disruption of mitochondrial function may be the mechanism of sensitization to gemcitabine. Together, our findings demonstrate that extracellular lumican augments cytotoxicity of chemotherapy in PDAC cells through inhibition of chemotherapeutic agent-induced autophagy.