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Published on: May 26, 2017
Cortactin Phosphorylation by Casein Kinase 2 Regulates Actin-Related Protein 2/3 Complex Activity, Invadopodia
Steven M Markwell1, Amanda G Ammer1, Erik T Interval2
1Program in Cancer Cell Biology, Department of Biochemistry, West Virginia University, Morgantown, West Virginia.
Casein kinase 2 alpha (CK2α) phosphorylates cortactin, inhibiting its binding to the Arp2/3 complex. This discovery reveals a new pathway to target cancer cell invasion, particularly in head and neck squamous cell carcinoma (HNSCC).
Area of Science:
- Molecular oncology
- Cellular motility and invasion mechanisms
- Signal transduction in cancer
Background:
- Aberrant actin cytoskeleton regulation promotes tumor cell motility and invasion.
- Cortactin enhances actin network formation via the Arp2/3 complex, and its overexpression correlates with poor prognosis in head and neck squamous cell carcinoma (HNSCC).
- Arp2/3 complex activation drives cancer cell migration and extracellular matrix degradation through invadopodia.
Purpose of the Study:
- To identify signaling pathways regulating cortactin binding to the Arp2/3 complex.
- To investigate the role of casein kinase 2 alpha (CK2α) in cortactin-Arp2/3 interaction and its impact on cancer invasion.
- To evaluate the therapeutic potential of targeting this pathway in HNSCC.
Main Methods:
- Investigated casein kinase 2 alpha (CK2α) phosphorylation of cortactin at threonine 24 (T24).
- Utilized cortactin phosphorylation-null mutants, shRNA-mediated CK2α knockdown, and the CK2α inhibitor Silmitasertib in HNSCC cell lines.
- Assessed invadopodia activity and collective invasion in 3D tumor spheroids and orthotopic mouse models.
Main Results:
- CK2α directly phosphorylates cortactin at T24, impairing its binding to the Arp2/3 complex and reducing actin nucleation.
- Expression of phosphorylation-null cortactin mutants and CK2α knockdown decreased invadopodia activity.
- Silmitasertib treatment inhibited invadopodia activity, collective invasion in vitro, and tumor growth in vivo.
Conclusions:
- CK2α-mediated phosphorylation of cortactin at T24 is a critical negative regulator of Arp2/3 complex binding and pro-invasive activity.
- Targeting the CK2α-cortactin signaling axis represents a potential therapeutic strategy to impair HNSCC invasion.
- This study uncovers a novel signaling pathway contributing to cancer cell invasion.
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