MLN4924 induces Noxa upregulation in acute myelogenous leukemia and synergizes with Bcl-2 inhibitors

Abstract

MLN4924 (pevonedistat), an inhibitor of the Nedd8 activating enzyme (NAE), has exhibited promising clinical activity in acute myelogenous leukemia (AML). Here we demonstrate that MLN4924 induces apoptosis in AML cell lines and clinical samples via a mechanism distinct from those observed in other malignancies. Inactivation of E3 cullin ring ligases (CRLs) through NAE inhibition causes accumulation of the CRL substrate c-Myc, which transactivates the PMAIP1 gene encoding Noxa, leading to increased Noxa protein, Bax and Bak activation, and subsequent apoptotic changes. Importantly, c-Myc knockdown diminishes Noxa induction; and Noxa siRNA diminishes MLN4924-induced killing. Because Noxa also neutralizes Mcl-1, an anti-apoptotic Bcl-2 paralog often upregulated in resistant AML, further experiments have examined the effect of combining MLN4924 with BH3 mimetics that target other anti-apoptotic proteins. In combination with ABT-199 or ABT-263 (navitoclax), MLN4924 exerts a synergistic cytotoxic effect. Collectively, these results provide new insight into MLN4924-induced engagement of the apoptotic machinery that could help guide further exploration of MLN4924 for AML.

Combination of Ibrutinib and ABT-199 in Diffuse Large B-Cell Lymphoma and Follicular Lymphoma

“…One approach to overcoming these obstacles is the use of combination therapy. BCL-2 inhibition in combination with other targeted therapies has demonstrated efficacy in several hematologic malignancies (21,22). Consistent with previous high-throughput analyses (19), we showed that ibrutinib and ABT-199 synergistically suppressed cell growth, reduced colony formation, increased apoptotic cell death, and inhibited tumor growth in an ABC-DLBCL mouse model.…”

Neddylation Inhibition Activates the Extrinsic Apoptosis Pathway through ATF4–CHOP–DR5 Axis in Human Esophageal Cancer Cells

“…Future study will be performed to elucidate how ATF3 is transactivated by MLN4924 and how it interacts with ATF4 to regulate Noxa expression in esophageal cancer cells. In addition, during the preparation of this article, Knorr and colleagues reported that MLN4924 could cause accumulation of the CRL substrate c-Myc to transactivate Noxa and trigger intrinsic apoptosis in acute myelogenous leukemia cells (50), indicating cell-type-specific mechanisms for the induction of Noxa expression upon MLN4924 treatment.…”

Measurement of BH3-only protein tolerance

“…As indicated in Figure 7a, transfection with BIM diminished the tolerance for EGFP-NOXA. Accordingly, when Jurkat cells were treated with tipifarnib, which upregulates BIM, and pevonedistat, which upregulates NOXA (Figures 1b and d), 34,38 low concentrations of tipifarnib synergistically enhanced pevonedistat-induced killing (Figures 7b and c).…”

“…After identifying drug concentrations that induce apoptosis in the sensitive Jurkat cell line (Supplementary Figure S1), we examined changes in BH3-only proteins previously shown to be critical for killing by these agents. 34,35,37,38 The proteasome inhibitor bortezomib induced 3-fold increases in BIM and 8-to 16-fold increases in NOXA ( Figure 1a); the Nedd8-activating enzyme inhibitor pevonedistat-induced negligible to 3-fold increases in BIM and 4-fold increases in NOXA ( Figure 1b); the mTOR dual inhibitor TAK-228 induced 2-to 3-fold increases in BIM and 2-to 10-fold increases in PUMA ( Figure 1c); and the farnesyltransferase inhibitor tipifarnib induced 2-to 3-fold increases in BIM in the sensitive Jurkat line but no discernible increase in BIM or NOXA in the resistant SKW6.4 line (Figure 1d). Given the critical role of these BH3-only protein increases in drug-induced killing, 34,35,37,38 these results suggested that cells can only tolerate a certain degree of BH3-only protein upregulation before dying.…”

“…For example, p53-dependent and -independent transcriptional processes upregulate NOXA and PUMA, 31,32 inhibition of mitogen activated protein kinase signaling enhances BIM stability, 33,34 inhibitors of the mechanistic target of rapamycin (mTOR) induce both BIM and PUMA, 35 and inhibition of the proteasome pathway upregulates NOXA through multiple mechanisms. [36][37][38] Importantly, downregulation of the indicated BH3-only proteins impairs killing by each of the indicated treatments, [32][33][34][35]37,38 indicating the critical role of BH3-only protein upregulation in the cytotoxicity of these stresses. Despite extensive qualitative observations such as these, however, quantitative information regarding the extent of BH3-only protein upregulation required to induce apoptosis and the ability of different cells to survive this upregulation is limited.…”