casein-kinase-ii and coumarin

Protein kinase 2 (CK2) is a potential target, and the coumarins were identified as the attractive CK2 inhibitors. In this study, two models (CoMFA and CoMSIA) were established, and their reliabilities were supported by statistical parameters. From the CoMFA and CoMSIA models, the hydrophobic and hydrogen bonds play very important roles in the interactions between inhibitors and CK2, which were confirmed sufficiently by molecular docking. Furthermore, the binding mode of the inhibitors at the active sites of CK2 was also investigated by docking study. The hydroxyl at the position R(5) is more important for coumarins inhibitors because it forms hydrogen bonds not only with Lys68 as hydrogen acceptor but also with H(2) O as hydrogen donor. In addition, hydroxyl can make electrostatic interactions with electropositive Lys68 residue. The large group at the R(6) position is not conducive to inhibitor dock into the groove of the binding site of CK2. When there is nitro group, the electrostatic interaction between ligand and receptor is enhanced significantly, and the nitro oxygen can form hydrogen bonds with the backbone NH of Lys68 and Asp175 simultaneously. The results obtained from molecular modeling techniques not only provide the models to predict the activity of inhibitors but also lead to a better understanding of the interactions between inhibitors and CK2, which will be very helpful for drug design.

Topics: Antineoplastic Agents; Casein Kinase II; Coumarins; Drug Design; Enzyme Inhibitors; Humans; Models, Molecular; Neoplasms; Protein Binding; Quantitative Structure-Activity Relationship

Casein kinase 2 (CK2) is a ubiquitous, essential, and highly pleiotropic protein kinase; its abnormally high constitutive activity is suspected to underlie its pathogenic potential in neoplasia and other relevant diseases. Previously, using different in silico screening approaches, two potent and selective CK2 inhibitors were identified by our group: ellagic acid, a naturally occurring tannic acid derivative (K(i)=20 nM) and 3,8-dibromo-7-hydroxy-4-methylchromen-2-one (DBC, K(i)=60 nM). Comparing the crystallographic binding modes of both ellagic acid and DBC, an X-ray structure-driven merging approach was taken to design novel CK2 inhibitors with improved target affinity. A urolithin moiety is proposed as a possible bridging scaffold between the two known CK2 inhibitors, ellagic acid and DBC. Optimization of urolithin A as the bridging moiety led to the identification of 4-bromo-3,8-dihydroxy-benzo[c]chromen-6-one as a novel, potent and selective CK2 inhibitor, which shows a K(i) value of 7 nM against the protein kinase, representing a significant improvement in affinity for the target compared with the two parent fragments.

Topics: Apoptosis; Binding Sites; Casein Kinase II; Catalytic Domain; Cell Line, Tumor; Coumarins; Crystallography, X-Ray; Drug Design; Ellagic Acid; Humans; Protein Kinase Inhibitors