Department of Lung Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, PR China; Key Laboratory of Cancer Prevention and Therapy, Tianjin, PR China; Tianjin's Clinical Research Center for Cancer, Tianjin, PR China; Tianjin Lung Cancer Center, Tianjin, PR China.
Department of Lung Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, PR China; Key Laboratory of Cancer Prevention and Therapy, Tianjin, PR China; Tianjin's Clinical Research Center for Cancer, Tianjin, PR China; Tianjin Lung Cancer Center, Tianjin, PR China.
Life Sci. 2018 Sep 1;208:284-294. doi: 10.1016/j.lfs.2018.07.023. Epub 2018 Jul 23.
Bcell lymphoma 9 (BCL9)-Wnt/β-catenin pathway, a key signaling pathway related to epithelial-mesenchymal transition (EMT), is widely considered to be involved in invasion in various malignant tumors. However, the dysregulation of BCL9/β-catenin pathway in non-small cell lung cancer (NSCLC) has not been revealed. This study aimed to investigate the correlation between chemotherapy resistance and BCL9/Wnt/β-catenin signaling dysfunction.
We performed BCL9 knockdown using a lentivirus-mediated sh-RNA interference in cisplatin-resistant (CR) lung cancer cells. Subsequently, the migration and invasion were determined by wound-healing and Transwell assays. Furthermore, EMT markers and β-catenin were examined by Western blot. Immunofluorescence was used to investigate the subcellular localization of β-catenin. The chemotherapeutic sensitivity to cisplatin in A549/DDP cell lines after treatment with BCL9 sh-RNA was estimated by MTT assay.
The knockdown of BCL9 remarkably reduced the migration and invasion abilities of A549/DDP cells. Meanwhile, nuclear translocation of β-catenin was reduced after BCL9 was knocked down. BCL9 silencing also resulted in the downregulation of EMT-related proteins. Additionally, the Wnt/β-catenin agonist, CP21, significantly restored the expression of β-catenin and abilities of migration and invasion in BCL9-knockdown A549/DDP cell lines. Finally, we proved that the inhibition of BCL9 could partially attenuate the stemness of cancer cells and recover the chemotherapeutic sensitivity.
These findings indicated BCL9 induced the occurrence of EMT and enhancement of stemness, which resulted in cisplatin-resistance and promoted migration in NSCLC cells. Mechanically, Wnt/β-catenin pathway is crucial in BCL9-induced migration, invasion, and chemotherapy resistance.
B 细胞淋巴瘤 9（BCL9）-Wnt/β-连环蛋白通路是与上皮间质转化（EMT）相关的关键信号通路，被广泛认为参与多种恶性肿瘤的侵袭。然而，非小细胞肺癌（NSCLC）中 BCL9/β-连环蛋白通路的失调尚未被揭示。本研究旨在探讨化疗耐药与 BCL9/Wnt/β-连环蛋白信号功能障碍之间的相关性。
我们使用慢病毒介导的 sh-RNA 干扰在顺铂耐药（CR）肺癌细胞中敲低 BCL9。随后，通过划痕愈合和 Transwell 测定来测定迁移和侵袭。此外，通过 Western blot 检测 EMT 标志物和 β-连环蛋白。免疫荧光用于研究β-连环蛋白的亚细胞定位。用 MTT 测定法评估 A549/DDP 细胞系在用 BCL9 sh-RNA 处理后对顺铂的化疗敏感性。
BCL9 的敲低显著降低了 A549/DDP 细胞的迁移和侵袭能力。同时，BCL9 敲低后β-连环蛋白的核转位减少。BCL9 沉默也导致 EMT 相关蛋白的下调。此外，Wnt/β-连环蛋白激动剂 CP21 显著恢复了 BCL9 敲低的 A549/DDP 细胞系中β-连环蛋白的表达和迁移及侵袭能力。最后，我们证明抑制 BCL9 可部分减弱癌细胞的干性并恢复化疗敏感性。
这些发现表明，BCL9 诱导 EMT 的发生和干性增强，导致 NSCLC 细胞对顺铂耐药并促进迁移。机制上，Wnt/β-连环蛋白通路在 BCL9 诱导的迁移、侵袭和化疗耐药中起关键作用。
