title: Acriflavine Inhibits Acquired Drug Resistance by Blocking the Epithelial-to-Mesenchymal Transition and the Unfolded Protein Response.
abstract: Epithelial-to-mesenchymal transition (EMT) is linked to tumor invasion, drug resistance and aggressive disease and this is largely dependent on the cell's microenvironment. Acriflavine (ACF) is an old antibacterial drug recently also suggested as anticancer agent and HIF inhibitor. We wanted to study the effect of acriflavine on EMT in different human cancer models. Pancreatic cancer cells (Panc-1) were exposed to TGF-β1 or cobalt chloride (to mimick severe hypoxia) to induce EMT. For our third model we exposed HepG2 liver cancer cells to sorafenib which resulted in development of acquired drug resistance with strong features of EMT and aggressive behavior. These models were morphologically and functionally (invasion assay) characterized. Markers of EMT were determined using qRT-PCR and Western blotting. Transcriptome analysis was performed following gene expression determination and combining the iRegulon tool and Gene Set Enrichment Analysis (GSEA). We made the following observations: (1) acriflavine inhibited EMT based on changes in cell morphology, invasive capacities and markers of EMT (at protein and gene expression level). (2) Transcriptome analysis revealed potent inhibition of ATF4 target genes and of the unfolded protein response. We showed that acriflavine blocked eIF2a phosphorylation and reduced ATF4 translation thereby inhibiting the PERK/eIF2a/ATF4 UPR pathway. (3) ACF restored drug sensitivity of cells that obtained acquired resistance.
  
  
  CONCLUSIONS
  We identified acriflavine as a potent inhibitor of EMT and the UPR, thereby re-sensitizing the cancer cells to antineoplastic drugs.
authors.affiliation: Laboratory of Hepatology, Department of Clinical and Experimental Medicine, KU Leuven.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Dekervel
authors.affiliation: Laboratory of Hepatology, Department of Clinical and Experimental Medicine, KU Leuven; Unit of Clinical Digestive Oncology, Department of Oncology, KU Leuven and Department of Gastroenterology/Digestive Oncology, University Hospitals g Leuven.
authors.forename: Ashenafi
authors.initials: A
authors.lastname: Bulle
authors.affiliation: Laboratory of Hepatology, Department of Clinical and Experimental Medicine, KU Leuven.
authors.forename: Petra
authors.initials: P
authors.lastname: Windmolders
authors.affiliation: Laboratory of Translational Genetics, Department of Oncology, KU Leuven, Leuven, Belgium; Vesalius Research Center, VIB, Leuven, Belgium.
authors.forename: Diether
authors.initials: D
authors.lastname: Lambrechts
authors.affiliation: Unit of Clinical Digestive Oncology, Department of Oncology, KU Leuven and Department of Gastroenterology/Digestive Oncology, University Hospitals g Leuven; Leuven Cancer Institute (LKI), Leuven, Belgium.
authors.forename: Eric
authors.initials: E
authors.lastname: Van Cutsem
authors.affiliation: Laboratory of Hepatology, Department of Clinical and Experimental Medicine, KU Leuven; Unit of Clinical Digestive Oncology, Department of Oncology, KU Leuven and Department of Gastroenterology/Digestive Oncology, University Hospitals g Leuven; Leuven Cancer Institute (LKI), Leuven, Belgium.
authors.forename: Chris
authors.initials: C
authors.lastname: Verslype
authors.affiliation: Laboratory of Hepatology, Department of Clinical and Experimental Medicine, KU Leuven; Unit of Clinical Digestive Oncology, Department of Oncology, KU Leuven and Department of Gastroenterology/Digestive Oncology, University Hospitals g Leuven; Leuven Cancer Institute (LKI), Leuven, Belgium. Electronic address: Jos.vanpelt@kuleuven.be.
authors.forename: Jos
authors.initials: J
authors.lastname: van Pelt