Up-Regulation of the Alpha Prime Subunit of Protein Kinase CK2 as a Marker of Fast Proliferation in GL261 Cultured Cells
Glioblastoma (GB) is the most prevalent malignant primary brain tumor in adults. The preclinical glioblastoma model GL261 is widely used for investigating new therapeutic strategies. GL261 cultured cells are used for assessing preliminary in vitro data for this model although very little is known about the molecular characteristics of this cell line. Protein Kinase CK2 is a pleiotropic serine-threonine kinase and its inhibition may be a promising therapeutic strategy for GB treatment. In our group we follow treatment response with CK2 inhibitors in vivo using the GL261 murine model. For that, it is of our interest to assess the differential expression of α, α’, β CK2 subunits as well as CK2 activity in the GL261 GB model. CK2α’ expression changed along the growth curve of GL261 cells, undergoing downregulation in postconfluent phase cells, whereas CK2α and CK2β expression remained essentially unchanged. Furthermore, a marked decrease in CK2 activity in slowly proliferating postconfluent phase GL261 cells was observed. Finally, CK2α’ expression in orthotopic GL261 tumors was intermediate between CK2α’ expression found in cultured cells in exponentially growing or postconfluent phase, reflecting the heterogeneous nature of GL261 tumours growing in vivo. The results obtained suggest that, in the GL261 cell line, CK2α’ could play a specific role in highly proliferative cells. Also, the decrease in CK2 activity in slowly proliferating GL261 cells could imply a differential susceptibility to subunit-specific CK2 inhibitors in this cell line, although further studies are needed to confirm this hypothesis.
KeywordsCell cycle GL261 glioma Cyclin D1 Preclinical brain tumour model CK2 alpha prime
Casein Kinase 2
Phosphate buffered saline
sodium dodecyl sulfate polyacrylamide gel electrophoresis
Time allocation in the joint NMR facility of UAB and CIBER-BBN, Unit 25 of NANBIOSIS, for MRI follow-up of GL261 murine tumour evolution, is gratefully acknowledged.
Conception and design, A.C., C.A., E.A., E.I. and M.P.; analysis and interpretation, L.V.; Writing-Drafting, L.V., A.C: and C.A.; Revising, L.P and M.R..; Supervision, A.C. and C.A.; Guarantor: A.C.
Lucia Villamañan held a PIF predoctoral fellowship from Universitat Autònoma de Barcelona. This work was funded by the Ministerio de Economía y Competitividad (MINECO) grant MOLIMAGLIO (SAF2014–52332-R). Also funded by Centro de Investigación Biomédica en Red- Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN, (http://www.ciber-bbn.es/en)), an initiative of the Instituto de Salud Carlos III (Spain) co-funded by EU Fondo Europeo de Desarrollo Regional (FEDER). Also funded by AIRC IG 18756 to LAP.
Compliance with Ethical Standards
The authors declare that they have no competing interests.
All applicable regional and national guidelines for the care and use of animals were followed. The studies described in this paper were approved by the local ethics committee Comissió d’Ètica en Experimentació Animal i Humana (CEEAH) (http://www.uab.cat/etica-recerca/) (protocol CEEAH-3665).
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