A separate gene CSNK2B encodes the regulatory subunit CK2β, which regulates the substrate specificity of CK2 kinase and enhances the catalytic subunit stability in the tetrameric complex of CK2 (Bibby et al., 2005). In mouse tissues, expression levels of CK2α are higher than those of CK2α’ (Xu et al., 1999b). Its catalytic part is encoded by two genes, CK2α (CSNK2A1) and CK2α’ (CSNK2A2). CK2 kinase may act as a monomeric kinase alone or as a tetrameric complex, which consist of 2 catalytic subunits (CK2α and/or CK2α’) and 2 regulatory subunits CK2β. Protein kinase CK2 is a highly conserved serine/ threonine kinase that is ubiquitously expressed in a variety of eukaryotic cells. This article will review effects of CK2 and its inhibitors on common carcinomas in in vitro and pre-clinical studies. Some CK2 inhibitors have showed good results in in vitro and pre-clinical models, and have even entered in clinical trials. Various CK2 inhibitors have been developed with anti-neoplastic properties against a variety of carcinomas.
CK2 has become a potential anti-carcinoma target. CK2 plays essential roles in many key biological processes related to carcinoma, including cell apoptosis, DNA damage responses and cell cycle regulation.
Increased expression of CK2 in mice results in the development of various types of carcinomas (both solids and blood related tumors, such as (breast carcinoma, lymphoma, etc), which reveals its carcinogenic properties. CK2 protein is localized in the nucleus of many tumor cells and correlates with clinical features in many cases. The Protein kinase CK2 (formerly known as casein kinase 2) is a highly conserved serine/ threonine kinase overexpressed in various human carcinomas and its high expression often correlates with poor prognosis.