title: Deprivation of asparagine triggers cytoprotective autophagy in laryngeal squamous cell carcinoma.
abstract: Laryngeal squamous cell carcinoma (LSCC), one of the most common malignancies in the head and neck, has poor prognosis and high mortality. The need of novel and effective treatment for LSCC is urgent. Asparaginase, an enzyme-depriving asparagine, has been employed for the treatment of various cancers. In this study, we reported for the first time that asparaginase could induce remarkable cytotoxicity and caspase-dependent apoptosis in human LSCC Tu212 and Tu686 cells. Meanwhile, autophagy was triggered by asparaginase in LSCC cells, which was confirmed by accumulation of autophagosomes and the conversion of light chain 3-I (LC3-I) to LC3-II. Importantly, inhibition of autophagy by chloroquine (CQ) significantly enhanced asparaginase-induced cytotoxicity, indicating that autophagy has a cytoprotective role in asparaginase-treated LSCC cells. Meanwhile, we found that mitochondrial-originated reactive oxygen species (ROS) participated in asparaginase-induced autophagy and cytotoxicity. N-acetyl-L-cysteine (NAC), a common antioxidant, was employed to scavenge ROS, and our results demonstrated that NAC could significantly block asparaginase-induced autophagy and attenuate asparaginase-induced cytotoxicity, indicating that intracellular ROS played a crucial role in asparagine deprivation therapy. Furthermore, western blot analysis showed that asparaginase-induced autophagy was mediated by inactivation of Akt/mTOR and activation of the Erk signaling pathway in Tu212 and Tu686 cells. Therefore, these results indicated the protective role of autophagy in asparaginase-treated LSCC cells and provided a new attractive therapeutic strategy for LSCC by asparaginase alone or in combination with autophagic inhibitors.
authors.affiliation: Department of Otolaryngology, Changzheng Hospital, The Second Military Medical University, No. 415 Fengyang Road, Shanghai, 200003, People's Republic of China.
authors.forename: Yunxiang
authors.initials: Y
authors.lastname: Ji
authors.affiliation: Department of Otolaryngology, Changzheng Hospital, The Second Military Medical University, No. 415 Fengyang Road, Shanghai, 200003, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Otolaryngology, Changzheng Hospital, The Second Military Medical University, No. 415 Fengyang Road, Shanghai, 200003, People's Republic of China.
authors.forename: Qilei
authors.initials: Q
authors.lastname: Tao
authors.affiliation: Department of Microbiological and Biochemical Pharmacy & The Key Laboratory of Smart Drug Delivery, Ministry of Education, School of Pharmacy, Fudan University, No. 826 Zhangheng Road, Shanghai, 201203, People's Republic of China.
authors.forename: Xuyao
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Microbiological and Biochemical Pharmacy & The Key Laboratory of Smart Drug Delivery, Ministry of Education, School of Pharmacy, Fudan University, No. 826 Zhangheng Road, Shanghai, 201203, People's Republic of China.
authors.forename: Jingyun
authors.initials: J
authors.lastname: Luan
authors.affiliation: Department of Otolaryngology, Changzheng Hospital, The Second Military Medical University, No. 415 Fengyang Road, Shanghai, 200003, People's Republic of China. shuweizhao@yahoo.com.
authors.forename: Shuwei
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Otolaryngology, Changzheng Hospital, The Second Military Medical University, No. 415 Fengyang Road, Shanghai, 200003, People's Republic of China. Liuhuanhaiok@126.com.
authors.forename: Huanhai
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Microbiological and Biochemical Pharmacy & The Key Laboratory of Smart Drug Delivery, Ministry of Education, School of Pharmacy, Fudan University, No. 826 Zhangheng Road, Shanghai, 201203, People's Republic of China. dianwenju@fudan.edu.cn.
authors.forename: Dianwen
authors.initials: D
authors.lastname: Ju
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001215:Asparaginase / Q000378:metabolism / Q000494:pharmacology*; D001216:Asparagine / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000503:physiopathology*; D045744:Cell Line, Tumor; D002738:Chloroquine / Q000494:pharmacology; D006801:Humans; D007822:Laryngeal Neoplasms / Q000503:physiopathology* / Q000628:therapy*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D001216:Asparagine; D002738:Chloroquine; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D001215:Asparaginase; D000111:Acetylcysteine
keywords: Apoptosis; Asparaginase; Autophagy; Laryngeal squamous cell carcinoma; Reactive oxygen species