title: Cathepsin L mediates resveratrol-induced autophagy and apoptotic cell death in cervical cancer cells.
abstract: Cathepsins have long been considered as housekeeping molecules. However, specific functions have also been attributed to each of these lysosomal proteases. Squamous cell carcinoma antigen (SCCA) 1, widely expressed in various uterine cervical cells, is an endogenous cathepsin (cat) L inhibitor. In this study, we investigated whether the cat L-SCCA 1 lysosomal pathway and autophagy were involved in resveratrol (RSV)-induced cytotoxicity in cervical cancer cells. RSV induced GFP-LC3 aggregation as well as increased the presence of LC3-II and autophagosomes as was revealed by electron microscopy in cervical cancer cells. Prolonged treatment of RSV induced cytosolic translocation of cytochrome c, caspase 3 activation and apoptotic cell death. This apoptotic effect was abrogated by trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane, an inhibitor of cat B and L, but not by pepstatin A, an inhibitor of cat D. As cervical cancer cells express little cat B, we further studied the role of cat L. RSV induced dissipation of the lysosomal membrane permeability (LMP), leakage and increased cytosolic expression and activity of cat L. Inhibition of cat L by small interference RNA (siRNA) protected cells from RSV-induced cytotoxicity. In contrast, inhibition of SCCA 1 by siRNA promoted RSV-induced cytotoxicity. Inhibition of autophagic response by wortmannin (WT) or asparagine (ASP) resulted in decreased early LC3-II formation, reduced LMP, and abolishment of the increase in RSV-induced cell death. In conclusion, we have identified a new cytotoxic mechanism in which the lysosomal enzyme cat L acts as a death signal integrator in cervical cancer cells. Furthermore, SCCA 1 may play an antiapoptotic role through anti-cat L activity.
authors.affiliation: Institute of Clinical Medicine, Department of Obstetrics and Gynecology, National Cheng Kung University Medical College, 1 Dashiue Road, Tainan, Taiwan.
authors.forename: Keng-Fu
authors.initials: KF
authors.lastname: Hsu
authors.forename: Chao-Liang
authors.initials: CL
authors.lastname: Wu
authors.forename: Soon-Cen
authors.initials: SC
authors.lastname: Huang
authors.forename: Ching-Ming
authors.initials: CM
authors.lastname: Wu
authors.forename: Jenn-Ren
authors.initials: JR
authors.lastname: Hsiao
authors.forename: Yi-Te
authors.initials: YT
authors.lastname: Yo
authors.forename: Yu-Hung
authors.initials: YH
authors.lastname: Chen
authors.forename: Ai-Li
authors.initials: AL
authors.lastname: Shiau
authors.forename: Cheng-Yang
authors.initials: CY
authors.lastname: Chou
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D056668:Cathepsin L; D002403:Cathepsins / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000648:ultrastructure; D007501:Iron / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D010539:Permeability / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology*; D002583:Uterine Cervical Neoplasms / Q000201:enzymology* / Q000473:pathology* / Q000648:ultrastructure
chemical_list: D013267:Stilbenes; D045304:Cytochromes c; D007501:Iron; D002403:Cathepsins; D053148:Caspase 3; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L; D000077185:Resveratrol