A Non-ATP-Competitive Dual Inhibitor of JAK2V617F and BCR-ABLT315I Kinases: Elucidation of a Novel Therapeutic Spectrum Based on Substrate Competitive Inhibition

Abstract

Here we report the discovery of ON044580, an α-benzoyl styryl benzyl sulfide that possesses potent inhibitory activity against two unrelated kinases, JAK2 and BCR-ABL, and exhibits cytotoxicity to human tumor cells derived from chronic myelogenous leukemia (CML) and myelodysplasia (MDS) patients or cells harboring a mutant JAK2 kinase. This novel spectrum of activity is explained by the non–ATP-competitive inhibition of JAK2 and BCR-ABL kinases. ON044580 inhibits mutant JAK2 kinase and the proliferation of JAK2V617F-positive leukemic cells and blocks the IL-3–mediated phosphorylation of JAK2 and STAT5. Interestingly, this compound also directly inhibits the kinase activity of both wild-type and imatinib-resistant (T315I) forms of the BCR-ABL kinase. Finally, ON044580 effectively induces apoptosis of imatinib-resistant CML patient cells. The apparently unrelated JAK2 and BCR-ABL kinases share a common substrate, STAT5, and such substrate competitive inhibitors represent an alternative therapeutic strategy for development of new inhibitors. The novel mechanism of kinase inhibition exhibited by ON044580 renders it effective against mutant forms of kinases such as the BCR-ABLT315I and JAK2V617F. Importantly, ON044580 selectively reduces the number of aneuploid cells in primary bone marrow samples from monosomy 7 MDS patients, suggesting another regulatory cascade amenable to this agent in these aberrant cells. Data presented suggest that this compound could have multiple therapeutic applications including monosomy 7 MDS, imatinib-resistant CML, and myeloproliferative neoplasms that develop resistance to ATP-competitive agents.

Curcumin derivative C817 inhibits proliferation of imatinib-resistant chronic myeloid leukemia cells with wild-type or mutant Bcr-Abl in vitro

“…Thus, it is urgent to To achieve this goal, some small molecule compounds have been designed to target Bcr-Abl motifs remote from the kinase domain. The activity of these drugs remains unaffected by the presence of mutations in the kinase domain of the enzyme, including ON012380, GNF-2, and GNF-5 [13,14,[28][29][30][31] . GNF-5, an analog of GNF-2 having improved pharmacokinetic properties, when combined with the ATP-competitive inhibitors imatinib or, can suppressed the emergence of resistance mutations in vitro, displayed inhibitory activity against T315I Bcr-Abl and displayed in vivo efficacy against the recalcitrant T315I Bcr-Abl mutant in a murine bone-marrow transplantation model.…”

JNK-associated Leucine Zipper Protein Functions as a Docking Platform for Polo-like Kinase 1 and Regulation of the Associating Transcription Factor Forkhead Box Protein K1

“…Kinase Assays-Kinase assays were performed as described previously (22). Briefly, 10 ng of His-PLK1 (PV3501; Invitrogen) or GST-PLK2 (PV4204; Invitrogen) was incubated with 2 g of purified substrate, and ATP mix (10 M cold ATP, 30 Ci of [␥-32 P]ATP) for 30 min at 30°C.…”

The Ins and Outs of Bcr-Abl Inhibition

“…ON44580 (Onconova Therapeutics, Newtown, PA) has shown promise in this regard as it appears to bind to the substrate binding surface rather than the ATP binding site. 23 GNF2/GNF-5 (Novartis Pharmaceuticals) is an example of an allosteric inhibitor that binds to the myristoyl pocket near the C-terminus of the Abl kinase domain and transmits structural changes to the ATP binding site (Fig. 2).…”