title: Autophagy contributes to gefitinib-induced glioma cell growth inhibition.
abstract: Epidermal growth factor receptor tyrosine kinase inhibitors, including gefitinib, have been evaluated in patients with malignant gliomas. However, the molecular mechanisms involved in gefitinib-mediated anticancer effects against glioma are incompletely understood. In the present study, the cytostatic potential of gefitinib was demonstrated by the inhibition of glioma cell growth, long-term clonogenic survival, and xenograft tumor growth. The cytostatic consequences were accompanied by autophagy, as evidenced by monodansylcadaverine staining of acidic vesicle formation, conversion of microtubule-associated protein-1 light chain 3-II (LC3-II), degradation of p62, punctate pattern of GFP-LC3, and conversion of GFP-LC3 to cleaved-GFP. Autophagy inhibitor 3-methyladenosine and chloroquine and genetic silencing of LC3 or Beclin 1 attenuated gefitinib-induced growth inhibition. Gefitinib-induced autophagy was not accompanied by the disruption of the Akt/mammalian target of rapamycin signaling. Instead, the activation of liver kinase-B1/AMP-activated protein kinase (AMPK) signaling correlated well with the induction of autophagy and growth inhibition caused by gefitinib. Silencing of AMPK suppressed gefitinib-induced autophagy and growth inhibition. The crucial role of AMPK activation in inducing glioma autophagy and growth inhibition was further supported by the actions of AMP mimetic AICAR. Gefitinib was shown to be capable of reducing the proliferation of glioma cells, presumably by autophagic mechanisms involving AMPK activation.
authors.affiliation: Department of Surgery, Fong-Yuan Hospital, Taichung 420, Taiwan; Graduate Institute of Pharmaceutical Science and Technology, Central Taiwan University of Science and Technology, Taichung 406, Taiwan.
authors.forename: Cheng-Yi
authors.initials: CY
authors.lastname: Chang
authors.affiliation: Department of Pharmacology, School of Medicine, Chung Shan Medical University, Taichung 402, Taiwan; Department of Pharmacy, Chung Shan Medical University Hospital, Taichung 402, Taiwan.
authors.forename: Yu-Hsiang
authors.initials: YH
authors.lastname: Kuan
authors.affiliation: Division of Urology, Taichung Veterans General Hospital, Taichung 407, Taiwan.
authors.forename: Yen-Chuan
authors.initials: YC
authors.lastname: Ou
authors.affiliation: Division of Urology, Taichung Veterans General Hospital, Taichung 407, Taiwan.
authors.forename: Jian-Ri
authors.initials: JR
authors.lastname: Li
authors.affiliation: Department of Anesthesiology, Taichung Veterans General Hospital, Taichung 407, Taiwan; Department of Financial and Computational Mathematics, Providence University, Taichung 433, Taiwan.
authors.forename: Chih-Cheng
authors.initials: CC
authors.lastname: Wu
authors.affiliation: Department of Pediatrics, Tungs' Taichung MetroHarbor Hospital, Taichung 435, Taiwan.
authors.forename: Pin-Ho
authors.initials: PH
authors.lastname: Pan
authors.affiliation: Department of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan.
authors.forename: Wen-Ying
authors.initials: WY
authors.lastname: Chen
authors.affiliation: Department of Surgery, Fong-Yuan Hospital, Taichung 420, Taiwan.
authors.forename: Hsuan-Yi
authors.initials: HY
authors.lastname: Huang
authors.affiliation: Department of Medical Research, Taichung Veterans General Hospital, Taichung 407, Taiwan; Institute of Biomedical Sciences, National Chung Hsing University, Taichung 402, Taiwan; Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung 402, Taiwan; Center for General Education, Tunghai University, Taichung 407, Taiwan; Department of Nursing, HungKuang University, Taichung 433, Taiwan. Electronic address: cjchen@vghtc.gov.tw.
authors.forename: Chun-Jung
authors.initials: CJ
authors.lastname: Chen
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects*; D045744:Cell Line, Tumor; D000077156:Gefitinib; D005910:Glioma / Q000188:drug therapy* / Q000378:metabolism; D006131:Growth Inhibitors / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology*; D012265:Ribonucleotides / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D006131:Growth Inhibitors; D008869:Microtubule-Associated Proteins; D011799:Quinazolines; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D000077156:Gefitinib
keywords: AMPK; Autophagy; EGFR; Gefitinib; Glioma