title: The NEDD8-activating enzyme inhibitor, MLN4924, cooperates with TRAIL to augment apoptosis through facilitating c-FLIP degradation in head and neck cancer cells.
abstract: TNF-related apoptosis-inducing ligand (TRAIL) is a tumor-selective cytokine with potential anticancer activity and is currently under clinical testing. Head and neck squamous cell carcinoma (HNSCC), like other cancer types, exhibits varied sensitivity to TRAIL. MLN4924 is a newly developed investigational small molecule inhibitor of NEDD8-activating enzyme with potent anticancer activity. This study reveals a novel function of MLN4924 in synergizing with TRAIL to induce apoptosis in HNSCC cells. MLN4924 alone effectively inhibited the growth of HNSCC cells and induced apoptosis. When combined with TRAIL, synergistic effects on decreasing the survival and inducing apoptosis of HNSCC cells occurred. MLN4924 decreased c-FLIP levels without modulating death receptor 4 and death receptor 5 expression. Enforced expression of c-FLIP substantially attenuated MLN4924/TRAIL-induced apoptosis. Thus c-FLIP reduction plays an important role in mediating MLN4924/TRAIL-induced apoptosis. Moreover, MLN4924 decreased c-FLIP stability, increased c-FLIP ubiquitination, and facilitated c-FLIP degradation, suggesting that MLN4924 decreases c-FLIP levels through promoting its degradation. MLN4924 activated c-jun-NH(2)-kinase (JNK) signaling, evidenced by increased levels of phospho-c-Jun in MLN4924-treated cells. Chemical inhibition of JNK activation not only prevented MLN4924-induced c-FLIP reduction, but also inhibited MLN4924/TRAIL-induced apoptosis, suggesting that JNK activation mediates c-FLIP downregulation and subsequent enhancement of TRAIL-induced apoptosis by MLN4924. Because knockdown of NEDD8 failed to activate JNK signaling and downregulate c-FLIP, it is likely that MLN4924 reduces c-FLIP levels and enhances TRAIL-induced apoptosis independent of NEDD8 inhibition.
authors.affiliation: Department of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute, 1365-C Clifton Road NE, C3088, Atlanta, GA 30322, USA.
authors.forename: Liqun
authors.initials: L
authors.lastname: Zhao
authors.forename: Ping
authors.initials: P
authors.lastname: Yue
authors.forename: Sagar
authors.initials: S
authors.lastname: Lonial
authors.forename: Fadlo R
authors.initials: FR
authors.lastname: Khuri
authors.forename: Shi-Yong
authors.initials: SY
authors.lastname: Sun
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D003517:Cyclopentanes / Q000008:administration & dosage / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D004357:Drug Synergism; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D059748:Proteolysis / Q000187:drug effects; D011743:Pyrimidines / Q000008:administration & dosage / Q000494:pharmacology*; D000077195:Squamous Cell Carcinoma of Head and Neck; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000008:administration & dosage / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D044764:Ubiquitin-Activating Enzymes; D054875:Ubiquitination / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D003517:Cyclopentanes; D004268:DNA-Binding Proteins; D011743:Pyrimidines; D053221:TNF-Related Apoptosis-Inducing Ligand; D044764:Ubiquitin-Activating Enzymes; C491802:NAE protein, human; C539933:pevonedistat