Inhibition of protein kinase CK2 suppresses tumor necrosis factor (TNF)-α-induced leukocyte–endothelial cell interaction

• Inhibition of CK2 reduces TNF-α-induced expression of E-selectin, ICAM-1 and VCAM-1.
• This is due to down-regulation of NF-κB dependent gene expression.
• Inhibition of CK2 decreases binding of MNC to TNF-α-stimulated HDMEC.
• CX-4945 reduces TNF-α-induced leukocyte binding to vascular endothelium in vivo.

Inflammatory endothelial processes are regulated by the nuclear factor-κB (NF-κB) pathway, which involves phosphorylation of p65. Because p65 is a substrate of CK2, we herein investigated, whether this pleiotropic protein kinase may be a beneficial anti-inflammatory target. For this purpose, we analyzed in human dermal microvascular endothelial cells (HDMEC) the effect of CK2 inhibition by quinalizarin and CX-4945 on cell viability, adhesion molecule expression and NF-κB pathway activation. Leukocyte binding to HDMEC was assessed in an in vitro adhesion assay. Dorsal skinfold chambers in BALB/c mice were used to study leukocyte–endothelial cell interaction and leukocyte transmigration by means of repetitive intravital fluorescence microscopy and immunohistochemistry. We found that quinalizarin and CX-4945 effectively suppressed the activity of CK2 in HDMEC without affecting their viability. This was associated with a significant down-regulation of tumor necrosis factor (TNF)-α-induced E-selectin, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 expression due to a reduction of shuttling, phosphorylation and transcriptional activity of the NF-κB complex. In consequence, leukocyte binding to quinalizarin- and CX-4945-treated HDMEC was diminished. Finally, CX-4945 treatment significantly decreased the numbers of adherent and transmigrated leukocytes in dorsal skinfold chambers exposed to TNF-α in vivo. These findings indicate that CK2 is a key regulator of leukocyte–endothelial cell interaction in inflammation by regulating the expression of E-selectin, ICAM-1 and VCAM-1 via affecting the transcriptional activity of the NF-κB complex. Accordingly, CK2 represents a promising target for the development of novel anti-inflammatory drugs.