Xiaxia Fan,Dan Guo,Songtao Li,Jinmiao Tian,Chaotong Zhang,Zhuoyu Li
ABC transporter protein-mediated drug efflux is a significant contributor to induced resistance in breast cancer (BC). Novel therapies are therefore urgently needed to thwart chemoresistance. Herein, it is demonstrated that fusidic acid (FA) reduces the expression of ABC transporter proteins MRP1, P-gp, and BCRP, promotes the in vivo accumulation of agents, and exertes chemosensitizing effects. Further, DDX6 is identified as a direct target of FA by DARTS and biotin pull-down. Mechanistically, the results indicates that FA directly binds to H378 of DDX6, promotes its degradation, and downregulates its downstream p-GSK-3β, which in turn enhances the phosphorylation and ubiquitin-dependent hydrolysis of β-catenin S33/37/45/T41, blocks pro-resistance β-catenin signaling, and further prevents chemoresistance. The inhibitory effect of FA on chemoresistance is blocked following the knockout of DDX6 using CRISPR/Cas9. More importantly, FA also enhances the interaction between DDX6 and HSC70, while it facilitates DDX6 degradation via chaperone-mediated autophagy (CMA), thereby impairing the GSK-3β/β-catenin axis to enhance the efficacy of FA. Consistently, the effect of FA in combating chemoresistance by targeting DDX6 is evident in a xenograft mouse model. These findings reveal a direct protein target and molecular mechanism for FA to reverse chemoresistance, thus supporting the further development of FA as a chemosensitizing agent. Graphical FA directly binds to residue H378 of DDX6 and promotes its interaction with HSC70, leading to CMA degradation of DDX6, thereby impairing GSK-3β/β-catenin signaling, inhibiting ABC transporter proteins, and enhancing chemosensitivity.
Epithelial-mesenchymal transition (EMT) is a fundamental cellular process frequently hijacked by cancer cells to promote tumor progression, especially metastasis. EMT is orchestrated by a complex molecular network acting at different layers of gene regulation. In addition to transcriptional regulation, post-transcriptional mechanisms may also play a role in EMT. Here, we performed a pooled CRISPR screen analyzing the influence of 1547 RNA binding proteins (RBPs) on cell motility in colon cancer cells and identified multiple core components of P-bodies (PBs) as negative modulators of cancer cell migration. Further experiments demonstrated that PB depletion by silencing DDX6 or EDC4 could activate hallmarks of EMT thereby enhancing cell migration in vitro as well as metastasis formation in vivo. Integrative multi-omics analysis revealed that PBs could repress the translation of the EMT-driver gene HMGA2, which contributed to PB-meditated regulation of EMT. This mechanism is conserved in other cancer types. Furthermore, endoplasmic reticulum (ER) stress was an intrinsic signal that induced PB disassembly and translational derepression of HMGA2. Taken together, this study has identified a function of PBs in regulation of EMT in cancer.
危险品化学品经营许可证（带存储）