Inhibition of β-catenin signalling promotes DNA damage elicited by benzo[a]pyrene in a model of human colon cancer cells via CYP1 deregulation
Language English Country Great Britain, England Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
25805023
DOI
10.1093/mutage/gev019
PII: gev019
Knihovny.cz E-resources
- MeSH
- DNA Adducts adverse effects MeSH
- Apoptosis MeSH
- Benzo(a)pyrene adverse effects MeSH
- beta Catenin antagonists & inhibitors genetics metabolism MeSH
- Cytochrome P-450 CYP1A1 antagonists & inhibitors genetics metabolism MeSH
- Immunoenzyme Techniques MeSH
- Carcinogens, Environmental adverse effects MeSH
- Real-Time Polymerase Chain Reaction MeSH
- Humans MeSH
- RNA, Small Interfering genetics MeSH
- RNA, Messenger genetics MeSH
- Tumor Cells, Cultured MeSH
- Colonic Neoplasms drug therapy etiology pathology MeSH
- Reverse Transcriptase Polymerase Chain Reaction MeSH
- DNA Damage * MeSH
- Cell Proliferation MeSH
- Receptors, Aryl Hydrocarbon genetics metabolism MeSH
- Gene Expression Regulation, Enzymologic drug effects MeSH
- Gene Expression Regulation, Neoplastic drug effects MeSH
- Blotting, Western MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- DNA Adducts MeSH
- benzo(a)pyrene-DNA adduct MeSH Browser
- Benzo(a)pyrene MeSH
- beta Catenin MeSH
- CYP1A1 protein, human MeSH Browser
- Cytochrome P-450 CYP1A1 MeSH
- Carcinogens, Environmental MeSH
- RNA, Small Interfering MeSH
- RNA, Messenger MeSH
- Receptors, Aryl Hydrocarbon MeSH
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.
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