title: Nuclear Trapping through Inhibition of Exosomal Export by Indomethacin Increases Cytostatic Efficacy of Doxorubicin and Pixantrone.
abstract: OBJECTIVE
  Although R-CHOP-based immunochemotherapy cures significant proportions of patients with aggressive B-cell lymphoma, tumor cell susceptibility to chemotherapy varies, with mostly fatal outcome in cases of resistant disease. We and others have shown before that export of cytostatic drugs contributes to drug resistance. Now we provide a novel approach to overcome exosome-mediated drug resistance in aggressive B-cell lymphomas.
  
  
  METHODS
  We used well-established centrifugation protocols to purify exosomes from DLBCL cell lines and detected anthracyclines using FACS and HPLC. We used shRNA knockdown of ABCA3 to determine ABCA3 dependence of chemotherapy susceptibility and monitored ABCA3 expression after indomethacin treatment using qPCR. Finally, we established an in vivo assay using a chorioallantoic membrane (CAM) assay to determine the synergy of anthracycline and indomethacin treatment.
  
  
  RESULTS
  We show increased efficacy of the anthracycline doxorubicin and the anthracenedione pixantrone by suppression of exosomal drug resistance with indomethacin. B-cell lymphoma cells in vitro efficiently extruded doxorubicin and pixantrone, in part compacted in exosomes. Exosomal biogenesis was critically dependent on the expression of the ATP-transporter A3 (ABCA3). Genetic or chemical depletion of ABCA3 augmented intracellular retention of both drugs and shifted the subcellular drug accumulation to prolonged nuclear retention. Indomethacin increased the cytostatic efficacy of both drugs against DLBCL cell lines in vitro and in vivo in a CAM assay.
  
  
  CONCLUSIONS
  We propose pretreatment with indomethacin toward enhanced antitumor efficacy of anthracyclines and anthracenediones.
authors.affiliation: Department of Hematology and Oncology, Georg-August-University Goettingen, Germany. Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Raphael
authors.initials: R
authors.lastname: Koch
authors.affiliation: Department of Hematology and Oncology, Georg-August-University Goettingen, Germany. Division of Plastic Surgery, Department of Trauma Surgery, Plastic and Reconstructive Surgery, Georg-August-University Goettingen, Germany.
authors.forename: Thiha
authors.initials: T
authors.lastname: Aung
authors.affiliation: Department of Hematology and Oncology, Georg-August-University Goettingen, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Vogel
authors.affiliation: Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Bjoern
authors.initials: B
authors.lastname: Chapuy
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Goettingen, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Wenzel
authors.affiliation: Department of Hematology and Oncology, Georg-August-University Goettingen, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Becker
authors.affiliation: Department of Hematology and Oncology, Georg-August-University Goettingen, Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Sinzig
authors.affiliation: Department of Hematology and Oncology, Georg-August-University Goettingen, Germany.
authors.forename: Vivek
authors.initials: V
authors.lastname: Venkataramani
authors.affiliation: Boehringer Ingelheim Pharma GmbH & Co KG, Ingelheim, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: von Mach
authors.affiliation: Department of Cell Biology and Cell Pathology, Philipps-University Marburg, Marburg, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Jacob
authors.affiliation: Department of Hematology and Oncology, Georg-August-University Goettingen, Germany.
authors.forename: Lorenz
authors.initials: L
authors.lastname: Truemper
authors.affiliation: Department of Hematology and Oncology, Georg-August-University Goettingen, Germany. gerald.wulf@med.uni-goettingen.de.
authors.forename: Gerald G
authors.initials: GG
authors.lastname: Wulf
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D018943:Anthracyclines / Q000494:pharmacology; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism; D054697:Cytostatic Agents / Q000494:pharmacology*; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004357:Drug Synergism; D055354:Exosomes / Q000187:drug effects*; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology*; D007546:Isoquinolines / Q000494:pharmacology*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy / Q000378:metabolism
chemical_list: C441524:ABCA3 protein, human; D018528:ATP-Binding Cassette Transporters; D018943:Anthracyclines; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000903:Antibiotics, Antineoplastic; D054697:Cytostatic Agents; D007546:Isoquinolines; D004317:Doxorubicin; C086548:pixantrone; D007213:Indomethacin