MLN4924, an NAE inhibitor, suppresses AKT and mTOR signaling via upregulation of REDD1 in human myeloma cells

Abstract

• Blockade of NAE and bortezomib induces phosphatidylinositol 3-kinase/ mTOR inhibition.• NAE inhibition and bortezomib combined induce synergistic plasma cell apoptosis.The function and survival of normal and malignant plasma cells depends on the elaborately regulated ubiquitin proteasome system. Proteasome inhibitors such as bortezomib have proved to be highly effective in the treatment of multiple myeloma (MM), and their effects are related to normal protein homeostasis which is critical for plasma cell survival. Many ubiquitin ligases are regulated by conjugation with NEDD8. Therefore, neddylation may also impact survival and proliferation of malignant plasma cells. Here, we show that MLN4924, a potent NEDD8 activating enzyme (NAE) inhibitor, induced cytotoxicity in MM cell lines, and its antitumor effect is associated with suppression of the AKT and mammalian target of rapamycin (mTOR) signaling pathways through increased expression of REDD1. Combining MLN4924 with the proteasome inhibitor bortezomib induces synergistic apoptosis in MM cell lines which can overcome the prosurvival effects of growth factors such as interleukin-6 and insulin-like growth factor-1. Altogether, our findings demonstrate an important function for REDD1 in MLN4924-induced cytotoxicity in MM and also provide a promising therapeutic combination strategy for myeloma. (Blood. 2014;123(21):3269-3276)

The Neddylation Inhibitor Pevonedistat (MLN4924) Suppresses and Radiosensitizes Head and Neck Squamous Carcinoma Cells and Tumors

“…Pevonedistat inhibits all cullin-based E3 ligases and additionally exhibits cullin-independent activity (28,29,(63)(64)(65)(66)(67). However, the results described above suggest that the radiosensitizing activity of pevonedistat is due to its ability to induce rereplication, which can be enhanced by IR.…”

“…This significant apoptotic response was attributed to the induction of c-FLIP degradation, which the authors showed to be independent of NEDD8 inhibition (67). Furthermore, it is now abundantly clear that hundereds of cellular proteins are regulated through neddylation, and consistently, pevonedistat inhibits several signal transduction pathways, including the NFkB, AKT, and the mTOR signaling pathways, in addition to cullin-signaling (28,29,(63)(64)(65)(66). Thus, pevonedistat may exhibit differential toxicities in HNSCC cells and tumors depending on the genetic backgrounds of the cells or tumors as well as on the concentrations employed.…”

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

“…In view of recent studies showing that MLN4924 induces apoptosis in a subset of lymphomas and in myeloma through mechanisms distinct from the Cdt1 upregulation and re-replication seen in solid tumor cells, 10,12 we examined the mechanism of MLN4924-induced cytotoxicity in AML cells. In initial experiments, HL-60, U937, and ML-1 cells were treated with 30-1000 nM MLN4924 for 4-48 h, concentrations and times routinely used for MLN4924 in in vitro assays.…”

“…1,11 Other mechanisms of MLN4924-induced killing involving nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Redd1 have been described in a subset of diffuse large B-cell lymphoma and multiple myeloma cells, respectively. 10,12 The dominant stabilized CRL substrate and downstream steps governing the mechanism of MLN4924 cytotoxicity in AML are not as well defined, although induction of apoptosis has been observed. 3,5 The 'intrinsic' or 'mitochondrial' apoptotic pathway is activated when Bax and Bak proteins oligomerize in the outer mitochondrial membrane and induce cytoplasmic translocation of cytochrome c, which promotes caspase 9 activation.…”

“…1,3,9 The mechanistic basis for the cytotoxicity of NAE inhibition varies among malignancies and is dependent upon which of the CRL substrates accumulate and demonstrate activity. 1,[10][11][12] In colon and lung cancer cells, for example, accumulation of the CRL substrate chromatin licensing and DNA replication factor 1 (Cdt1), a DNA replication licensing factor, has the dominant role in MLN4924 cytotoxicity by causing DNA re-replication and subsequent apoptosis. 1,11 Other mechanisms of MLN4924-induced killing involving nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Redd1 have been described in a subset of diffuse large B-cell lymphoma and multiple myeloma cells, respectively.…”