Helicobacter pylori is the most important carcinogen in human gastric cancer. However, the pathogenic molecular mechanism which underlies the carcinogenesis in gastric cancer by H. pylori remains largely unknown. In this study, we understand that molecular biological mechanism related to gastric carcinogenesis by investigating the role of CK2 in EMT. Casein kinase 2 is a serine/threonine protein kinase and consists of two catalytic subunits (α or α’) and regulatory subunits (β). CK2 regulates many substrates and its involved in cell growth, proliferation, survival, angiogenesis, invasion. Epithelial-to-mesenchymal transition (EMT) is involved in many signaling pathways, but the key regulatory kinases in this process have not been clearly identified. In our previous study, we reported the cytotoxin-associated gene A (CagA) protein of H. pylori induces cell migration and invasion through increased CK2α activity in gastric epithelial cells. Although the role of CK2 catalytic subunits has remained largely uncharacterized, several studies have recently focused on regulator subunits in EMT.

Here, we analyzed the expression level of CK2α did not altered, whereas CK2β decreased in CagA-dependent pathway. Moreover, expression of ectopic CK2β was downregulated by CagA. This suggests that CagA negatively regulates the stability of CK2β protein. We examined the level of ubiquitinated CK2β were higher in HP60190 infected cells than in control cells. Thus, CK2β is degraded by the proteasomal machinery following CagA of H. pylori. In addition, CagA binds both CK2α and CK2β, which results in suppression of CK2β binding by infected HP60190, but does not suppress CK2α binding. Furthermore, downregulation of CK2β increased Snail such as CK2 target genes, EMT-related marker in H. pylori-infected gastric cancer cells. Therefore, the role of Snail regulated by CK2β should be considered when developing cancer therapeutic. Overall, CK2 tetramer subunits might control the function of CagA and EMT related genes, thereby regulating CagA-dependent pathology. Taken together, the results of the present study suggest that the CK2 regulatory subunit has diverse effect on CagA-dependent cellular processes. A pharmacological activator or activator of CK2β may have potential as a therapeutic agent for gastric cancer associated with CagA.

Citation Format: SoDam Lee, Bo Ram Hwang, Jung Chang Yun, Byeong Min Yu, Yong Chan Lee. Casein kinase 2 modulates epithelial mesenchymal transition through Helicobacter pylori CagA dependent pathway in gastric cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1041.