Liu Lei, Zhang Lin, Zhao Shuo, Zhao Xu-Yang, Min Peng-Xiang, Ma Ya-Dong, Wang Yue-Yuan, Chen Yan, Tang Si-Jie, Zhang Yu-Jie, Du Jun, Gu Luo
Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, China.
Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.
Front Pharmacol. 2019 Apr 16;10:370. doi: 10.3389/fphar.2019.00370. eCollection 2019.
Tumor cell migration is a critical step in cancer metastasis. Over-activated Notch pathway can promote the migration of cancer cells, especially in the breast cancer. However, the underlying mechanism of non-canonical Notch signaling in modulating the migration has not yet been clearly characterized. Here we demonstrated that DAPT, a gamma secretase inhibitor, inhibited protrusion formation and cell motility, and then reduced the migration of triple-negative breast cancer cells, through increasing the activity of Cdc42 by non-canonical Notch pathway. Phosphorylation of AKT on S473 was surprisingly increased when Notch signaling was inhibited by DAPT. Inhibition of PI3K and AKT by LY294002 and MK2206, respectively, or knockdown of AKT expression by siRNA blocked DAPT-induced activation of Cdc42. Moreover, immunofluorescence staining further showed that DAPT treatment reduced the formation of lamellipodia and induced actin cytoskeleton remodeling. Taken together, these results indicated that DAPT inhibited Notch signaling and consequently activated PI3K/AKT/Cdc42 signaling by non-canonical pathway, facilitated the formation of filopodia and inhibited the assembly of lamellipodia, and finally resulted in the decrease of migration activity of breast cancer cells.
肿瘤细胞迁移是癌症转移的关键步骤。过度激活的Notch信号通路可促进癌细胞迁移，尤其是在乳腺癌中。然而，非经典Notch信号调节迁移的潜在机制尚未明确。在此我们证明，γ-分泌酶抑制剂DAPT通过非经典Notch信号通路增加Cdc42的活性，从而抑制突起形成和细胞运动，进而减少三阴性乳腺癌细胞的迁移。当DAPT抑制Notch信号时，AKT在S473位点的磷酸化令人惊讶地增加。分别用LY294002和MK2206抑制PI3K和AKT，或用siRNA敲低AKT表达，均可阻断DAPT诱导的Cdc42激活。此外，免疫荧光染色进一步显示，DAPT处理减少了片状伪足的形成并诱导了肌动蛋白细胞骨架重塑。综上所述，这些结果表明，DAPT抑制Notch信号，进而通过非经典途径激活PI3K/AKT/Cdc42信号，促进丝状伪足形成并抑制片状伪足组装，最终导致乳腺癌细胞迁移活性降低。
