title: Inhibition of β-catenin signalling promotes DNA damage elicited by benzo[a]pyrene in a model of human colon cancer cells via CYP1 deregulation.
abstract: Deregulation of Wnt/β-catenin signalling plays an important role in the pathogenesis of colorectal cancer. Interestingly, this pathway has been recently implicated in transcriptional control of cytochrome P450 (CYP) family 1 enzymes, which are responsible for bioactivation of a number of dietary carcinogens. In the present study, we investigated the impact of inhibition of Wnt/β-catenin pathway on metabolism and genotoxicity of benzo[a]pyrene (BaP), a highly mutagenic polycyclic aromatic hydrocarbon and an efficient ligand of the aryl hydrocarbon receptor, which is known as a primary regulator of CYP1 expression, in cellular models derived from colorectal tumours. We observed that a synthetic inhibitor of β-catenin, JW74, significantly increased formation of BaP-induced DNA adducts in both colorectal adenoma and carcinoma-derived cell lines. Using the short interfering RNA (siRNA) targeting β-catenin, we then found that β-catenin knockdown in HCT116 colon carcinoma cells significantly enhanced formation of covalent DNA adducts by BaP and histone H2AX phosphorylation, as detected by (32)P-postlabelling technique and immunocytochemistry, respectively, and it also induced expression of DNA damage response genes, such as CDKN1A or DDB2. The increased formation of DNA adducts formed by BaP upon β-catenin knockdown corresponded with enhanced production of major BaP metabolites, as well as with an increased expression/activity of CYP1 enzymes. Finally, using siRNA-mediated knockdown of CYP1A1, we confirmed that this enzyme plays a major role in formation of BaP-induced DNA adducts in HCT116 cells. Taken together, the present results indicated that the siRNA-mediated inhibition of β-catenin signalling, which is aberrantly activated in a majority of colorectal cancers, modulated genotoxicity of dietary carcinogen BaP in colon cell model in vitro, via a mechanism involving up-regulation of CYP1 expression and activity.
authors: Department of Cytokinetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, Brno 61265, Czech Republic, Institute of Experimental Biology, Faculty of Science, Kotlarska 2, Brno 61137, Czech Republicx.
authors: Markéta
authors: M
authors: Kabátková
authors: Department of Cytokinetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, Brno 61265, Czech Republic, Institute of Experimental Biology, Faculty of Science, Kotlarska 2, Brno 61137, Czech Republicx.
authors: Ondřej
authors: O
authors: Zapletal
authors: Department of Cytokinetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, Brno 61265, Czech Republic, Institute of Experimental Biology, Faculty of Science, Kotlarska 2, Brno 61137, Czech Republicx.
authors: Zuzana
authors: Z
authors: Tylichová
authors: Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, Brno 62100, Czech Republic and.
authors: Jiří
authors: J
authors: Neča
authors: Department of Chemistry and Toxicology, Veterinary Research Institute, Hudcova 70, Brno 62100, Czech Republic and.
authors: Miroslav
authors: M
authors: Machala
authors: Department of Genetic Ecotoxicology, Institute of Experimental Medicine, Czech Academy of Sciences, Videnska 1083, Prague 14220, Czech Republic.
authors: Alena
authors: A
authors: Milcová
authors: Department of Genetic Ecotoxicology, Institute of Experimental Medicine, Czech Academy of Sciences, Videnska 1083, Prague 14220, Czech Republic.
authors: Jan
authors: J
authors: Topinka
authors: Department of Cytokinetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, Brno 61265, Czech Republic.
authors: Alois
authors: A
authors: Kozubík
authors: Department of Cytokinetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, Brno 61265, Czech Republic, vondracek@ibp.cz.
authors: Jan
authors: J
authors: Vondráček
mesh_terms: D017209:Apoptosis; D001564:Benzo(a)pyrene / Q000009:adverse effects*; D015153:Blotting, Western; D002274:Carcinogens, Environmental / Q000009:adverse effects; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology*; D019363:Cytochrome P-450 CYP1A1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018736:DNA Adducts / Q000009:adverse effects*; D004249:DNA Damage; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007124:Immunoenzyme Techniques; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D051176:beta Catenin / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D002274:Carcinogens, Environmental; D018736:DNA Adducts; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018336:Receptors, Aryl Hydrocarbon; C056612:benzo(a)pyrene-DNA adduct; D051176:beta Catenin; D001564:Benzo(a)pyrene; C569463:CYP1A1 protein, human; D019363:Cytochrome P-450 CYP1A1