Inhibition of the MAP2K7-JNK pathway with 5Z-7-oxozeaenol induces apoptosis in T-cell acute lymphoblastic leukemia

Abstract

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive pediatric leukemia with a worse prognosis than most frequent B-cell ALL due to a high incidence of treatment failures and relapse. Our previous work showed that loss of the pioneer factor KLF4 in a NOTCH1-induced T-ALL mouse model accelerated the development of leukemia through expansion of leukemia-initiating cells and activation of the MAP2K7 pathway. Similarly, epigenetic silencing of the KLF4 gene in children with T-ALL was associated with MAP2K7 activation. Here, we showed the small molecule 5Z-7-oxozeaenol (5Z7O) induces dose-dependent cytotoxicity in a panel of T-ALL cell lines mainly through inhibition of the MAP2K7-JNK pathway, which further validates MAP2K7 as a therapeutic target. Mechanistically, 5Z7O-mediated apoptosis was caused by the downregulation of regulators of the G2/M checkpoint and the inhibition of survival pathways. The anti-leukemic capacity of 5Z7O was evaluated using leukemic cells from two mouse models of T-ALL and patient-derived xenograft cells generated using lymphoblasts from pediatric T-ALL patients. Finally, a combination of 5Z7O with dexamethasone, a drug used in frontline therapy, showed synergistic induction of cytotoxicity. In sum, we report here that MAP2K7 inhibition thwarts survival mechanisms in T-ALL cells and warrants future pre-clinical studies for high-risk and relapsed patients.

Phospho-Specific Flow Cytometry Reveals Signaling Heterogeneity in T-Cell Acute Lymphoblastic Leukemia Cell Lines

“…Although the role of JNK activity in T-ALL remains largely unknown, we have previously shown that JNK activation is required for upregulating interleukin 8 expression induced by CXCL12 in primary T-ALL cells [18]. Moreover, inhibition of JNK activity has been shown to lead to cell cycle arrest and apoptosis [83,84]. Our data showing hyperphosphorylation of JNK in T-ALL cell lines suggests a role for JNK in sustaining leukemia.…”

Antileukemic properties of the kinase inhibitor OTSSP167 in T-cell acute lymphoblastic leukemia

“…Comparative analysis of MAP2K7-JNK inhibitors against the KOPT-K1 cell line demonstrated that OTSSP167 (IC 50 12 nM) is more potent than 5Z-7-Oxozeaenol (IC 50 0.81 μM) and JNK-IN8 (IC 50 8.55 μM) ( Figure 1 E). 11 , 16 This difference in potency was also evident in other cell lines, such as ALL-SIL and RPMI-8402 ( supplemental Figure 1 ). Collectively, the compound OTSSP167 emerges as a powerful antileukemic agent in T-ALL.…”

“… 15 Although more potent than JNK inhibitors, 5Z-7-oxozeaenol toxicity limited the capacity of this compound to control leukemia efficiently in preclinical mouse models. 16 …”

Rational Design of Highly Potent and Selective Covalent MAP2K7 Inhibitors

“…25 Inhibition of MAP2K7 by 5Z7O induced apoptosis in T-ALL in a dose-dependent manner. 18 However, 5Z7O potently inhibits a variety of other kinases, including TAK1, which is a MAP3K. 26 Furthermore, 1 boasts only moderate potency against MEK7 (IC 50 = 1.3 μM).…”

“…Additional assays confirmed a lack of binding at MEK3, MEK5, and MEK6 (Figure SI-1). Notably, 25 had no appreciable activity on MEK1/2, p38α/β, or JNK1/2/3, which are relevant kinases in our model for molecular pathophysiology in T-ALL. ,,, This compound also did not engage FLT3, a potential anticipated pitfall given the structural similarities between 25 and 5 , a reversible FLT3 inhibitor. MAP2K7 was not among the 90 wildtype kinases assayed and represented in Figure .…”