Role of aryl hydrocarbon receptor in modulation of the expression of the hypoxia marker carbonic anhydrase IX.
Tumour-associated expression of CA IX (carbonic anhydrase IX) is to a major extent regulated by HIF-1 (hypoxia-inducible factor-1) which is important for transcriptional activation and consists of the oxygen-regulated subunit HIF-1alpha and the partner factor ARNT [AhR (aryl hydrocarbon receptor) nuclear translocator]. We have previously observed that HIF-1alpha competes with the AhR for interaction with ARNT under conditions when both conditionally regulated factors are activated. We have therefore investigated whether TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin)-induced activation of the AhR pathway might interfere with CA IX expression. The results from the present study suggest that TCDD treatment reduces hypoxic induction of both CA IX mRNA and protein expression. Moreover, the transcriptional activity of the CA9 promoter was significantly reduced by expression of CAAhR (constitutively active AhR), which activates transcription in a ligand-independent manner. Finally, we found that ARNT is critical for both hypoxic induction and the TCDD-mediated inhibition of CA9 expression.
Takacova
Martina
M
Institute of Virology, Centre of Molecular Medicine, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovak Republic.
Holotnakova
Tereza
T
Vondracek
Jan
J
Machala
Miroslav
M
Pencikova
Katerina
K
Gradin
Katarina
K
Poellinger
Lorenz
L
Pastorek
Jaromir
J
Pastorekova
Silvia
S
Kopacek
Juraj
J
D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics; D001665:Binding Sites; D015153:Blotting, Western; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia / Q000235:genetics / Q000502:physiology*; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051379:Mice; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects
D000951:Antigens, Neoplasm; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases