A Novel Selective JAK2 Inhibitor Identified Using Pharmacological Interactions

Abstract

The JAK2/STAT signaling pathway mediates cytokine receptor signals that are involved in cell growth, survival and homeostasis. JAK2 is a member of the Janus kinase (JAK) family and aberrant JAK2/STAT is involved with various diseases, making the pathway a therapeutic target. The similarity between the ATP binding site of protein kinases has made development of specific inhibitors difficult. Current JAK2 inhibitors are not selective and produce unwanted side effects. It is thought that increasing selectivity of kinase inhibitors may reduce the side effects seen with current treatment options. Thus, there is a great need for a selective JAK inhibitor. In this study, we identified a JAK2 specific inhibitor. We first identified key pharmacological interactions in the JAK2 binding site by analyzing known JAK2 inhibitors. Then, we performed structure-based virtual screening and filtered compounds based on their pharmacological interactions and identified compound NSC13626 as a potential JAK2 inhibitor. Results of enzymatic assays revealed that against a panel of kinases, compound NSC13626 is a JAK2 inhibitor and has high selectivity toward the JAK2 and JAK3 isozymes. Our cellular assays revealed that compound NSC13626 inhibits colorectal cancer cell (CRC) growth by downregulating phosphorylation of STAT3 and arresting the cell cycle in the S phase. Thus, we believe that compound NSC13626 has potential to be further optimized as a selective JAK2 drug.

Analysis of Copy-Number Variations and Feline Mammary Carcinoma Survival

“…In this study, this aberration was observed in six patients including two normal-like TN and three basal-like TN tumours highlighting the genomic similarities between triple-negative molecular phenotypes across FMCs and HBCs. Tumours carrying this mutation are characterised by the co-gain of PD-L1, PD-L2, and JAK2, and might benefit from immune checkpoint targeted therapies 57,78,79 or adjuvant therapy with JAK2-specific inhibitors 80,81 . Interestingly, the Jak-STAT signalling pathway was the only KEGG pathway enriched with amplified genes in the basal-like TN subtype.…”

Structure-based virtual screening and biological evaluation of novel small-molecule BTK inhibitors

“…The docking pose of the 30 known BTK inhibitors was analysed to identify possible binding interactions. This study recognises a binding interaction if a residue was observed to form an interaction with ≥ 50% of the BTK inhibitors 17 . The calculation for binding interactions is as follows: where the binding interaction score, S ( i ), for a compound, i , equals the number of binding interactions the compound forms, N ( i ), plus the docking score , D ( i ), of a compound i generated using LeadIT.…”

“…For our study, a binding interaction was considered if ≥ 50% of the 30 diverse BTK inhibitors formed an interaction with a binding site residue 17 . As a result, two hydrogen-bonding and four hydrophobic interactions were identified ( Figure 1(A,B) ).…”

“…Compounds were then removed if they exhibited Pan Assay Interference Compounds (PAINS) structures. PAINS structures often display false positives in high-throughput screens 17 . The Lipinski Rule of Five estimates pharmacokinetics of compounds in the human body 20 .…”

“…For example, small-molecule kinase inhibitors targeting the ATP binding site typically form hydrogen bonds with hinge residues 16 . Filtering compounds based on both their docking scores and binding interactions has proven a useful strategy to not only better understand the protein-ligand binding mechanism, but to improve the hit rate for potential inhibitors 17 . Herein, we identified binding interactions within the BTK binding site by docking known BTK inhibitors.…”