Exploiting an Asp-Glu “switch” in glycogen synthase kinase 3 to design paralog-selective inhibitors for use in acute myeloid leukemia

Abstract

Glycogen synthase kinase 3 (GSK3), a key regulatory kinase in the wingless-type MMTV integration site family (WNT) pathway, is a therapeutic target of interest in many diseases. Although dual GSK3α/β inhibitors have entered clinical trials, none has successfully translated to clinical application. Mechanism-based toxicities, driven in part by the inhibition of both GSK3 paralogs and subsequent β-catenin stabilization, are a concern in the translation of this target class because mutations and overexpression of β-catenin are associated with many cancers. Knockdown of GSK3α or GSK3β individually does not increase β-catenin and offers a conceptual resolution to targeting GSK3: paralog-selective inhibition. However, inadequate chemical tools exist. The design of selective adenosine triphosphate (ATP)-competitive inhibitors poses a drug discovery challenge due to the high homology (95% identity and 100% similarity) in this binding domain. Taking advantage of an Asp→Glu "switch" in their kinase hinge, we present a rational design strategy toward the discovery of paralog-selective GSK3 inhibitors. These GSK3α- and GSK3β-selective inhibitors provide insights into GSK3 targeting in acute myeloid leukemia (AML), where GSK3α was identified as a therapeutic target using genetic approaches. The GSK3α-selective compound BRD0705 inhibits kinase function and does not stabilize β-catenin, mitigating potential neoplastic concerns. BRD0705 induces myeloid differentiation and impairs colony formation in AML cells, with no apparent effect on normal hematopoietic cells. Moreover, BRD0705 impairs leukemia initiation and prolongs survival in AML mouse models. These studies demonstrate feasibility of paralog-selective GSK3α inhibition, offering a promising therapeutic approach in AML.

Roles of glycogen synthase kinase 3 alpha and calcineurin in regulating the ability of sperm to fertilize eggs

“…19 Data above show that GSK3α, but not GSK3β, appears to be a substrate for calcineurin sperm. 43 As per their IC 50 values, BRD3731 has four times higher selectivity on GSK3β than what BRD0705 has on GSK3α; therefore, higher concentration of BRD0705 was used in the study to normalize their effect. The compounds BRD0705 and BRD3731 were recently identified as isoform-selective inhibitors of GSK3α and GSK3β, respectively ( Figure 7A) 23 BRD0705 has been shown to significantly reduce the stimulatory phosphorylation of Tyr-279 of GSK3α in acute myeloid leukemia (AML) cell lines.…”

“…The compounds BRD0705 and BRD3731 were recently identified as isoform-selective inhibitors of GSK3α and GSK3β, respectively ( Figure 7A) 23 BRD0705 has been shown to significantly reduce the stimulatory phosphorylation of Tyr-279 of GSK3α in acute myeloid leukemia (AML) cell lines. 43 As per their IC 50 values, BRD3731 has four times higher selectivity on GSK3β than what BRD0705 has on GSK3α; therefore, higher concentration of BRD0705 was used in the study to normalize their effect. Data in Figure 7B,C show that BRD0705, the GSK3αselective inhibitor significantly inhibited IVF by treated sperm.…”

“…A, Chemical structure of GSK3α inhibitor, BRD0705 and GSK3β inhibitor, BRD3731. 43 B, Spermatozoa were incubated with BRD0705 (20µM) and BRD3731 (10 µM) under capacitating condition for 90 minutes and used for IVF; BRD0705 significantly inhibited the fertilization of eggs, whereas the GSK3β inhibitor BRD3731 had no effect compared to control. C, Representative bright-field pictures of two-cell embryo formation corresponding to the treatments described above 1262 | DEY Et al.…”

Crosstalks of GSK3 signaling with the mTOR network and effects on targeted therapy of cancer

“…Usually, compounds targeting GSK3 inhibit both GSK3α and GSK3β with almost equal potency [71]. Nevertheless, selective inhibitors of GSK3α and GSK3β have been described, such as compound 27 and BRD0705 (that target GSK3α [72,73]) or TWS199 (that targets GSK3β [74]).…”

Inhibition of glycogen synthase kinase 3β protects liver against ischemia/reperfusion injury by activating 5′ adenosine monophosphate‐activated protein kinase‐mediated autophagy

“…Glycogen synthase kinase 3 is a ubiquitously expressed serine/threonine kinase with multiple functions, with two highly homologous GSK3 isoforms, α and β, in mammals . Glycogen synthase kinase 3β, constitutively active (in dephosphorylated form) in resting cells, has a broad range of substrates regulating cell activation, differentiation, and survival.…”