Research Papers:

Cdc2-like kinase 2 is a key regulator of the cell cycle via FOXO3a/p27 in glioblastoma

Soon Young Park, Yuji Piao, Craig Thomas, Gregory N. Fuller and John F. de Groot _

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Oncotarget. 2016; 7:26793-26805. https://doi.org/10.18632/oncotarget.8471

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Soon Young Park1,*, Yuji Piao1,*, Craig Thomas1, Gregory N. Fuller2, John F. de Groot1

1Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA

2Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA

*These authors have contributed equally to this work

Correspondence to:

John F. de Groot, email: [email protected]

Keywords: CLK2, glioma, cell cycle, FOXO3a, p27

Received: November 23, 2015     Accepted: March 10, 2016     Published: March 30, 2016


Cdc2-like kinase 2 (CLK2) is known as a regulator of RNA splicing that ultimately controls multiple physiological processes. However, the function of CLK2 in glioblastoma progression has not been described. Reverse-phase protein array (RPPA) was performed to identify proteins differentially expressed in CLK2 knockdown cells compared to controls. The RPPA results indicated that CLK2 knockdown influenced the expression of survival-, proliferation-, and cell cycle-related proteins in GSCs. Thus, knockdown of CLK2 expression arrested the cell cycle at the G1 and S checkpoints in multiple GSC lines. Depletion of CLK2 regulated the dephosphorylation of AKT and decreased phosphorylation of Forkhead box O3a (FOXO3a), which not only translocated to the nucleus but also increased p27 expression. In two glioblastoma xenograft models, the survival duration of mice with CLK2-knockdown GSCs was significantly longer than mice with control tumors. Additionally, tumor volumes were significantly smaller in CLK2-knockdown mice than in controls. Knockdown of CLK2 expression reduced the phosphorylation of FOXO3a and decreased Ki-67 in vivo. Finally, high expression of CLK2 protien was significantly associated with worse patient survival. These findings suggest that CLK2 plays a critical role in controlling the cell cycle and survival of glioblastoma via FOXO3a/p27.

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