Pharmacological Inhibition of Casein Kinase 2 Enhances the Effectiveness of PI3K Inhibition in Colon Cancer Cells.

Abstract

Serine/threonine kinase B-Raf proto-oncogene (BRAF) mutant colon cancer has a poor prognosis and there is an absence of targeted treatments for this subtype. Here, we investigated the effects of inhibition of casein kinase 2 (CK2) on the inhibitory effects of BRAF and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) inhibition in BRAF-mutant colon cancer cells. Colon cancer cell lines with mutations in components of the mitogen-activated protein kinase (MAPK) and PI3K signalling pathway were used. Cell viability was determined after exposure to single agent and combinations of erlotinib (EGFR inhibitor), dabrafenib (MEK inhibitor), GDC0941 (PI3K inhibitor) and CX4945 (CK2 inhibitor). Western blots were used to examine MAPK and AKT serine/threonine kinase (AKT) pathway activation. Addition of CX4945 to dabrafenib did not enhance the antiproliferative effects of single-agent dabrafenib. Use of GDC0941 alone was highly effective in controlling growth of both BRAF-mutant and wild-type cells and this effect was enhanced by CK2 inhibition. Inhibition of the PI3K/AKT pathway is central to regulating growth of colon cancer cells and this can be enhanced by CK2 inhibition.