title: Heat shock exerts anticancer effects on liver cancer via autophagic degradation of aquaporin 5.
abstract: Previous studies described that the expression of aquaporin 5 (AQP5) was altered in tumors of various organs. AQP5 is attracting attention as a new cancer therapeutic target. In the present study, heat shock-induced changes in AQP5 expression were evaluated by immunofluorescent staining (IF) and western blotting (WB) of liver cancer cells. AQP5 knockdown experiments or a heat shock treatment were conducted, and their effects on cell volume, proliferation, cell cycle, the activity of apoptosis and migration/invasion were compared. Cycloheximide (CHX) chase experiments and double IF of AQP5 and light chain 3B (LC3B) were performed to investigate the mechanisms underlying changes in AQP5 expression. The results showed that IF and WB revealed decrease in AQP5 expression on cellular membranes and in the cytoplasm of heated cells. AQP5 knockdown and heat shock similarly decreased cell volume, suppressed migration/invasion and proliferation, and induced early apoptosis and partial G0/G1 arrest. CHX chase experiments revealed that heat shock accelerated the degradation of AQP5, which was rescued under CHX and the autophagy inhibitor, bafilomycin A1 (BafA1). Double IF showed the co-localization of AQP5 and LC3B on BafA1-treated heated cells. In conclusion, we demonstrated that heat shock decreased AQP5 on cellular membranes and in the cytoplasm by activating autophagic degradation, and heat shock and AQP5 knockdown exerted similar anticancer effects, suggesting that heat shock exerts anticancer effects via the autophagic degradation of AQP5.
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Kudou
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shiozaki
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kosuga
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shimizu
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ichikawa
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Konishi
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Morimura
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Komatsu
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Ikoma
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Okamoto
authors.affiliation: Departments of Molecular Cell Physiology and Bio-Ionomics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Marunaka
authors.affiliation: Division of Digestive Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Eigo
authors.initials: E
authors.lastname: Otsuji
mesh_terms: D017209:Apoptosis / Q000235:genetics; D051402:Aquaporin 5 / Q000096:biosynthesis / Q000235:genetics*; D001343:Autophagy / Q000187:drug effects*; D002453:Cell Cycle / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D003513:Cycloheximide / Q000008:administration & dosage; D003593:Cytoplasm / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D055785:Gene Knockdown Techniques; D018869:Heat-Shock Response / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D018942:Macrolides / Q000008:administration & dosage; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics*; D059748:Proteolysis
chemical_list: D051402:Aquaporin 5; C502070:MAP1LC3B protein, human; D018942:Macrolides; D008869:Microtubule-Associated Proteins; C040929:bafilomycin A1; D003513:Cycloheximide