title: The aryl hydrocarbon receptor-dependent disruption of contact inhibition in rat liver WB-F344 epithelial cells is linked with induction of survivin, but not with inhibition of apoptosis.
abstract: Inhibition of apoptosis by the ligands of the aryl hydrocarbon receptor (AhR) has been proposed to play a role in their tumor promoting effects on liver parenchymal cells. However, little is presently known about the impact of toxic AhR ligands, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on apoptosis in other liver cell types, such as in liver epithelial/progenitor cells. In the present study, we focused on the effects of TCDD on apoptosis regulation in a model of liver progenitor cells, rat WB-F344 cell line, during the TCDD-elicited release from contact inhibition. The stimulation of cell proliferation in this cell line was associated with deregulated expression of a number of genes known to be under transcriptional control of the Hippo signaling pathway, a principal regulatory pathway involved in contact inhibition of cell proliferation. Interestingly, we found that mRNA and protein levels of survivin, a known Hippo target, which plays a role both in cell division and inhibition of apoptosis, were significantly up-regulated in rat liver epithelial cell model, as well as in undifferentiated human liver HepaRG cells. Using the short interfering RNA-mediated knockdown, we confirmed that survivin plays a central role in cell division of WB-F344 cells. When evaluating the effects of TCDD on apoptosis induction by camptothecin, a genotoxic topoisomerase I inhibitor, we observed that the pre-treatment of WB-F344 cells with TCDD increased number of cells with apoptotic nuclear morphology, and it potentiated cleavage of both caspase-3 and poly(ADP-ribose) polymerase I. This indicated that despite the observed up-regulation of survivin, apoptosis induced by the genotoxin was potentiated in the model of rat liver progenitor cells. The present results indicate that, unlike in hepatocytes, AhR agonists may not prevent induction of apoptosis elicited by DNA-damaging agents in a model of rat liver progenitor cells.
authors.affiliation: Department of Cytokinetics, Institute of Biophysics AS CR, 61265 Brno, Czech Republic; Institute of Experimental Biology, Faculty of Science, Masaryk University, 61137 Brno, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Svobodová
authors.affiliation: Department of Cytokinetics, Institute of Biophysics AS CR, 61265 Brno, Czech Republic; Institute of Experimental Biology, Faculty of Science, Masaryk University, 61137 Brno, Czech Republic.
authors.forename: Markéta
authors.initials: M
authors.lastname: Kabátková
authors.affiliation: Department of Cytokinetics, Institute of Biophysics AS CR, 61265 Brno, Czech Republic.
authors.forename: Lenka
authors.initials: L
authors.lastname: Šmerdová
authors.affiliation: Department of Chemistry and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Brenerová
authors.affiliation: Department of Cell Biology and Genetics, Faculty of Science, Palacky University, 78371 Olomouc, Czech Republic.
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Dvořák
authors.affiliation: Department of Chemistry and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Machala
authors.affiliation: Department of Cytokinetics, Institute of Biophysics AS CR, 61265 Brno, Czech Republic. Electronic address: vondracek@ibp.cz.
authors.forename: Jan
authors.initials: J
authors.lastname: Vondráček
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051792:Basic Helix-Loop-Helix Proteins / Q000819:agonists* / Q000378:metabolism; D002166:Camptothecin / Q000633:toxicity*; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D003260:Contact Inhibition / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D034622:RNA Interference; D011916:Rats, Inbred F344; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D000077022:Survivin; D013997:Time Factors; D059004:Topoisomerase I Inhibitors / Q000633:toxicity*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D015854:Up-Regulation
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002166:Camptothecin; D053148:Caspase 3; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D000077022:Survivin; D059004:Topoisomerase I Inhibitors; C000595703:Ahr protein, rat; C107489:BIRC5 protein, human; C516989:Birc5 protein, rat; C499322:Parp1 protein, rat; C505410:Casp3 protein, rat
keywords: AhR; Apoptosis; BIRC5/survivin; Contact inhibition; Hippo signaling; TCDD