Radiosensitization of Human Pancreatic Cancer Cells by MLN4924, an Investigational NEDD8-Activating Enzyme Inhibitor

Abstract

Radiotherapy is used in locally advanced pancreatic cancers where it can improve survival in combination with gemcitabine. However, prognosis is still poor in this setting where more effective therapies remain needed. MLN4924 is an investigational small molecule currently in Phase I clinical trials. MLN4924 inhibits NAE (NEDD8 Activating Enzyme), a pivotal regulator of the E3 ubiquitin ligase SCF (SKP1, Cullins, and F-box protein), that has been implicated recently in DNA repair. In this study, we provide evidence that MLN4924 can be used as an effective radiosensitizer in pancreatic cancer. Specifically, MLN4924 (20–100 nM) effectively inhibited cullin neddylation and sensitized pancreatic cancer cells to ionizing radiation in vitro with a sensitivity enhancement ratio (SER) of ~1.5. Mechanistically, MLN4924 treatment stimulated an accumulation of several SCF substrates, including CDT1, WEE1 and NOXA, in parallel with an enhancement of radiation-induced DNA damage, aneuploidy, G2/M phase cell cycle arrest and apoptosis. RNAi-mediated knockdown of CDT1 and WEE1 partially abrogated MLN4924-induced aneuploidy, G2/M arrest, and radiosensization, indicating a causal effect. Further, MLN4924 was an effective radiosensitizer in mouse xenograft models of human pancreatic cancer. Our findings offer proof of concept for use of MLN4924 as a novel class of radiosensitizer for the treatment of pancreatic cancer.

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

“…Recent studies demonstrated that pevonedistat enhances the sensitivity of pancreatic, breast, and colorectal cancer cells to IR (30,54,55). As HPV-ve HNSCC cells and tumors are extremely resistant to IR (56-62), we tested whether pevonedistat radiosensitizes Cal27 or FaDu HNSCC cells by measuring cell survival Figure 1.…”

“…In pancreatic cells, however, pevonedistat induced rereplication, which was stimulated by IR (30). To understand the mechanistic basis of pevonedistat-enhanced D and E, Cal27 or FaDu cells were treated with 40 nmol/L pevonedistat, irradiated at 2 Gy (D) or 4 Gy (E) 24 hours after pevonedistat exposure and harvest for FACS analysis 48 hours post-IR.…”

“…11,26). Finally, the discovery that treatment of cancer cells with the neddylation inhibitor pevonedistat (also known as MLN4924) inhibits cancer cell lines and tumors and is associated with significant induction of rereplication demonstrated that rereplication can be induced pharmacologically, and this may have an anticancer activity (27)(28)(29)(30)(31).…”

High Efficiency Apoptosis Induction in Breast Cancer Cell Lines by MLN4924/2DG Co-Treatment

“…MLN4924 is an investigational and a newly discovered small molecule that binds to NAE at its active site to create a covalent NEDD8-MLN4924 adduct that cannot be further utilized in subsequent intra enzyme reactions. In this way, it leads to inhibiting NAE activity and prevents the neddylation (Edelmann et al, 2011;Liao et al, 2011;Wei et al, 2012). By blocking cullin neddylation, MLN4924 inactivates CRLs/SCF E3 ubiquitin ligase (SKP1, Cullins, and F-box protein).…”

“…This causes accumulation of its substrates (Zhao et al, 2012), which causes DNA rereplication stress and DNA damage response (DDR), apoptosis and/or senescence (Milhollen et al, 2011;Luo et al, 2012b;Yang et al, 2012a). Various substrates accumulate upon MLN4924 treatment, including cell-cycle regulators, DNA licensing proteins , and apoptosis regulators, oncogenic proteins in a cell line-dependent manner (Lin et al, 2010b;Tan et al, 2011;Wei et al, 2012;Yang et al, 2012a;Zhao et al, 2012;Sun and Li, 2013;Yao et al, 2014). Generally MLN4924 effectively inhibits tumor cell growth by inducing all three common types of death, namely apoptosis (Soucy et al, 2009;Milhollen et al, 2010;Mackintosh et al, 2013), autophagy (Duan et al, 2011;Luo et al, 2012a;Zhao et al, 2012), and senescence (Lin et al, 2010a;Duan et al, 2011;Jia et al, 2011).…”