title: Mammalian target of rapamycin regulates isoliquiritigenin-induced autophagic and apoptotic cell death in adenoid cystic carcinoma cells.
abstract: Previous studies, including those from our laboratory, have demonstrated that isoliquiritigenin (ISL), a flavonoid isolated from licorice, is a promising cancer chemotherapeutic agent. However the mechanisms underlying its anticancer effects are still far from clear. We now show, for the first time, that ISL triggers the mammalian target of rapamycin (mTOR)-dependent autophagic and apoptotic cell death in adenoid cystic carcinoma (ACC). Exposure of both ACC-2 and ACC-M cells to ISL resulted in several specific features for autophagy, including the appearance of membranous vacuoles, formation of acidic vesicular organelles, punctate pattern of LC3 immunostaining, and an increase in autophagic flux. Moreover, ISL treatment also resulted in significantly increased apoptosis in ACC cells. The ISL-mediated autophagic and apoptotic cell death were obviously attenuated by transfection with dominant negative Atg5 (DN-Atg5(K130R)) plasmids or treatment with 3-methyladenine(3-MA). In additon, the data also revealed that the autophagic and apoptotic cell death induced by ISL occurred through a mTOR-dependent pathway. More importantly, the xenograft model using ACC-M cells provided further evidence of the occurrence of ISL-induced autophagy and apoptosis in vivo, correlating with the suppresson of mTOR activation as well as up-regulation of Atg5 expression. Taken together, these findings in our study suggest that induction of mTOR-dependent autophagic and apoptotic cell death may be an important mechanism in cancer chemotherapy by ISL.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST), Key Laboratory of Oral Biomedicine Ministry of Education, Department of Oral and Maxillofacial Surgery, School & Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.forename: Xiang
authors.initials: X
authors.lastname: Hu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Ning
authors.initials: N
authors.lastname: Xu
authors.forename: Feng-Qin
authors.initials: FQ
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Jia
authors.forename: Wen-Feng
authors.initials: WF
authors.lastname: Zhang
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Sun
authors.forename: Yi-Fang
authors.initials: YF
authors.lastname: Zhao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D003528:Carcinoma, Adenoid Cystic / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology*; D045744:Cell Line, Tumor; D047188:Chalcones / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D012468:Salivary Gland Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D047188:Chalcones; C040920:isoliquiritigenin; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases