Department of Gastrointestinal Surgery, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital & Institute, Beijing, China.
Department of Gastrointestinal Translational Research, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital & Institute, Beijing, China.
J Investig Med. 2019 Jun;67(5):856-861. doi: 10.1136/jim-2018-000934. Epub 2019 Feb 20.
Previously, we demonstrated that death-associated protein-3 (DAP3) loss drives chemoresistance in gastric cancer cells. In the present study, we aimed to determine the underlying molecular mechanism. The effect of DAP3 silencing on β-catenin signaling was assessed. The direct mediator of DAP3 silencing-induced chemoresistance was identified. Depletion of DAP3 stimulates nuclear accumulation of β-catenin and enhances β-catenin-dependent transcriptional activity in gastric cancer cells. However, the protein kinase B , , extracellular regulated protein kinase and signal transducer and activator of transcription 3 signaling pathways remain unaffected by DAP3 loss. We found that the downstream target gene LGR5 (leucine-rich G-protein coupled receptor 5) is upregulated in DAP3-depleted gastric cancer cells. Moreover, knockdown of LGR5 resensitizes DAP3-depleted gastric cancer cells to 5-fluorouracil (5-FU) and oxaliplatin. We also observed that ectopic expression of LGR5 reduces apoptosis in gastric cancer cells on treatment with 5-FU and oxaliplatin, which is accompanied by prevention of caspase-3 cleavage. The antiapoptotic protein Bcl-2 is identified as a key mediator of LGR5-induced apoptosis resistance in gastric cancer cells. The present findings indicate that DAP3 deficiency-induced chemoresistance in gastric cancer is at least partially mediated through the β-catenin/LGR5/Bcl-2 axis. Targeting LGR5 may provide a novel strategy to overcome chemoresistance in DAP3-deficient gastric cancer cells.
先前，我们证明了死亡相关蛋白 3（DAP3）缺失可导致胃癌细胞产生化疗耐药性。在本研究中，我们旨在确定其潜在的分子机制。评估了 DAP3 沉默对 β-连环蛋白信号的影响。确定了 DAP3 沉默诱导的化疗耐药性的直接介导因子。DAP3 耗竭可刺激β-连环蛋白在胃癌细胞中的核积累，并增强β-连环蛋白依赖性转录活性。然而，DAP3 缺失对蛋白激酶 B、细胞外调节蛋白激酶和信号转导和转录激活因子 3 信号通路没有影响。我们发现，DAP3 耗尽的胃癌细胞中下游靶基因 LGR5（富含亮氨酸的 G 蛋白偶联受体 5）上调。此外，LGR5 的敲低可使 DAP3 耗尽的胃癌细胞对 5-氟尿嘧啶（5-FU）和奥沙利铂重新敏感。我们还观察到，LGR5 的异位表达可减少胃癌细胞在用 5-FU 和奥沙利铂治疗时的凋亡，同时防止半胱天冬酶-3 的裂解。抗凋亡蛋白 Bcl-2 被鉴定为 LGR5 诱导的胃癌细胞凋亡抵抗中的关键介质。这些发现表明，DAP3 缺失诱导的胃癌化疗耐药性至少部分是通过 β-连环蛋白/LGR5/Bcl-2 轴介导的。靶向 LGR5 可能为克服 DAP3 缺陷型胃癌细胞的化疗耐药性提供一种新策略。
