title: Inhibition of hypoxia inducible factor 1 and topoisomerase with acriflavine sensitizes perihilar cholangiocarcinomas to photodynamic therapy.
abstract: BACKGROUND
  Photodynamic therapy (PDT) induces tumor cell death by oxidative stress and hypoxia but also survival signaling through activation of hypoxia-inducible factor 1 (HIF-1). Since perihilar cholangiocarcinomas are relatively recalcitrant to PDT, the aims were to (1) determine the expression levels of HIF-1-associated proteins in human perihilar cholangiocarcinomas, (2) investigate the role of HIF-1 in PDT-treated human perihilar cholangiocarcinoma cells, and (3) determine whether HIF-1 inhibition reduces survival signaling and enhances PDT efficacy.
  
  
  RESULTS
  Increased expression of VEGF, CD105, CD31/Ki-67, and GLUT-1 was confirmed in human perihilar cholangiocarcinomas. PDT with liposome-delivered zinc phthalocyanine caused HIF-1α stabilization in SK-ChA-1 cells and increased transcription of HIF-1α downstream genes. Acriflavine was taken up by SK-ChA-1 cells and translocated to the nucleus under hypoxic conditions. Importantly, pretreatment of SK-ChA-1 cells with acriflavine enhanced PDT efficacy via inhibition of HIF-1 and topoisomerases I and II.
  
  
  METHODS
  The expression of VEGF, CD105, CD31/Ki-67, and GLUT-1 was determined by immunohistochemistry in human perihilar cholangiocarcinomas. In addition, the response of human perihilar cholangiocarcinoma (SK-ChA-1) cells to PDT with liposome-delivered zinc phthalocyanine was investigated under both normoxic and hypoxic conditions. Acriflavine, a HIF-1α/HIF-1β dimerization inhibitor and a potential dual topoisomerase I/II inhibitor, was evaluated for its adjuvant effect on PDT efficacy.
  
  
  CONCLUSIONS
  HIF-1, which is activated in human hilar cholangiocarcinomas, contributes to tumor cell survival following PDT in vitro. Combining PDT with acriflavine pretreatment improves PDT efficacy in cultured cells and therefore warrants further preclinical validation for therapy-recalcitrant perihilar cholangiocarcinomas.
authors.affiliation: Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.|Department of Controlled Drug Delivery, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500 AE Enschede, The Netherlands.
authors.forename: Ruud
authors.initials: R
authors.lastname: Weijer
authors.affiliation: Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Mans
authors.initials: M
authors.lastname: Broekgaarden
authors.affiliation: Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Massis
authors.initials: M
authors.lastname: Krekorian
authors.affiliation: Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Lindy K
authors.initials: LK
authors.lastname: Alles
authors.affiliation: Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Albert C
authors.initials: AC
authors.lastname: van Wijk
authors.affiliation: Department of Pathology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Claire
authors.initials: C
authors.lastname: Mackaaij
authors.affiliation: Department of Pathology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Joanne
authors.initials: J
authors.lastname: Verheij
authors.affiliation: Department of Pathology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Allard C
authors.initials: AC
authors.lastname: van der Wal
authors.affiliation: Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: van Gulik
authors.affiliation: Department of Controlled Drug Delivery, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500 AE Enschede, The Netherlands.|Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, 3584 CG Utrecht, The Netherlands.
authors.forename: Gert
authors.initials: G
authors.lastname: Storm
authors.affiliation: Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.|Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, 3584 CG Utrecht, The Netherlands.
authors.forename: Michal
authors.initials: M
authors.lastname: Heger
mesh_terms: D000167:Acriflavine / Q000494:pharmacology*; D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D017209:Apoptosis; D001650:Bile Duct Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D015153:Blotting, Western; D049109:Cell Proliferation; D004264:DNA Topoisomerases, Type I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D018285:Klatskin Tumor / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D010778:Photochemotherapy; D012333:RNA, Messenger / Q000235:genetics; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
chemical_list: D000891:Anti-Infective Agents, Local; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D011838:Radiation-Sensitizing Agents; D000167:Acriflavine; D004264:DNA Topoisomerases, Type I
keywords: cancer therapy; drug delivery system; extrahepatic cholangiocarcinoma; hypoxia; tumor targeting