title: Giant Lysosomes as a Chemotherapy Resistance Mechanism in Hepatocellular Carcinoma Cells.
abstract: Despite continuous improvements in therapeutic protocols, cancer-related mortality is still one of the main problems facing public health. The main cause of treatment failure is multi-drug resistance (MDR: simultaneous insensitivity to different anti-cancer agents), the underlying molecular and biological mechanisms of which include the activity of ATP binding cassette (ABC) proteins and drug compartmentalisation in cell organelles. We investigated the expression of the main ABC proteins and the role of cytoplasmic vacuoles in the MDR of six hepatocellular carcinoma (HCC) cell lines, and confirmed the accumulation of the yellow anti-cancer drug sunitinib in giant (four lines) and small cytoplasmic vacuoles of lysosomal origin (two lines). ABC expression analyses showed that the main ABC protein harboured by all of the cell lines was PGP, whose expression was not limited to the cell membrane but was also found on lysosomes. MTT assays showed that the cell lines with giant lysosomes were more resistant to sorafenib treatment than those with small lysosomes (p<0.01), and that verapamil incubation can revert this resistance, especially if it is administered after drug pre-incubation. The findings of this study demonstrate the involvement of PGP-positive lysosomes in drug sequestration and MDR in HCC cell lines. The possibility of modulating this mechanism using PGP inhibitors could lead to the development of new targeted strategies to enhance HCC treatment.
authors.affiliation: Clinical Chemistry and Microbiology Laboratory, Flow Cytometry and Experimental Hepatology Service, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Colombo
authors.affiliation: Clinical Chemistry and Microbiology Laboratory, Flow Cytometry and Experimental Hepatology Service, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Trombetta
authors.affiliation: Clinical Chemistry and Microbiology Laboratory, Flow Cytometry and Experimental Hepatology Service, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Cetrangolo
authors.affiliation: Clinical Pathology Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Maggioni
authors.affiliation: Stem Cell Laboratory, University of Milan, Department of Pathophysiology and Transplantation, Centro Dino Ferrari, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Razini
authors.affiliation: Stem Cell Laboratory, University of Milan, Department of Pathophysiology and Transplantation, Centro Dino Ferrari, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: De Santis
authors.affiliation: Stem Cell Laboratory, University of Milan, Department of Pathophysiology and Transplantation, Centro Dino Ferrari, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Yvan
authors.initials: Y
authors.lastname: Torrente
authors.affiliation: Department of Transfusion Medicine and Hematology, Ospedale A. Manzoni, Lecco, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Prati
authors.affiliation: Clinical Chemistry and Microbiology Laboratory, Flow Cytometry and Experimental Hepatology Service, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Erminio
authors.initials: E
authors.lastname: Torresani
authors.affiliation: Clinical Chemistry and Microbiology Laboratory, Flow Cytometry and Experimental Hepatology Service, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Porretti
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000503:physiopathology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000502:physiology; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007211:Indoles / Q000627:therapeutic use; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000503:physiopathology; D008247:Lysosomes / Q000187:drug effects / Q000502:physiology*; D011758:Pyrroles / Q000627:therapeutic use; D000077210:Sunitinib
chemical_list: D018528:ATP-Binding Cassette Transporters; D007211:Indoles; D011758:Pyrroles; D000077210:Sunitinib