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MeSH: nádorová transformace buněk-chemicky indukované

28 záznamů v Medvik Filtry

Článek

β-catenin signaling, the constitutive androstane receptor and their mutual interactions

Braeuning, Albert
Autor Braeuning, Albert Department Food Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589, Berlin, Germany. Albert.Braeuning@bfr.bund.de
Pavek, Petr
Autor Pavek, Petr Department of Pharmacology and Toxicology, Charles University, Faculty of Pharmacy, Heyrovskeho 1203, Hradec Kralove, 500 05, Prague, Czech Republic

Archives of toxicology. 2020 ; 94 (12) : 3983-3991. [pub] 20201024

Arch Toxicol
ISSN 1432-0738
Medvik
Zdroj

Aberrant signaling through β-catenin is an important determinant of tumorigenesis in rodents as well as in humans. In mice, xenobiotic activators of the constitutive androstane receptor (CAR), a chemo-sensing nuclear receptor, promote liver tumor growth by means of a non-genotoxic mechanism and, under certain conditions, select for hepatocellular tumors which contain activated β-catenin. In normal hepatocytes, interactions of β-catenin and CAR have been demonstrated with respect to the induction of proliferation and drug metabolism-related gene expression. The molecular details of these interactions are still not well understood. Recently it has been hypothesized that CAR might activate β-catenin signaling, thus providing a possible explanation for some of the observed phenomena. Nonetheless, many aspects of the molecular interplay of the two regulators have still not been elucidated. This review briefly summarizes our current knowledge about the interplay of CAR and β-catenin. By taking into account data and observations obtained with different mouse models and employing different experimental approaches, it is shown that published data also contain substantial evidence that xenobiotic activators of CAR do not activate, or do even inhibit signaling through the β-catenin pathway. The review highlights new aspects of possible ways of interaction between the two signaling cascades and will help to stimulate scientific discussion about the crosstalk of β-catenin signaling and the nuclear receptor CAR.

MeSH
beta-katenin metabolismus MeSH
hodnocení rizik MeSH
játra účinky léků metabolismus patologie MeSH
lidé MeSH
nádorová transformace buněk chemicky indukované metabolismus patologie MeSH
nádory jater chemicky indukované metabolismus patologie MeSH
receptory cytoplazmatické a nukleární agonisté metabolismus MeSH
rizikové faktory MeSH
signální dráha Wnt * MeSH
xenobiotika toxicita MeSH
zvířata MeSH
Check Tag
lidé MeSH
zvířata MeSH
Publikační typ
časopisecké články MeSH
práce podpořená grantem MeSH
přehledy MeSH

Článek

Tamoxifen-Dependent Induction of AGR2 Is Associated with Increased Aggressiveness of Endometrial Cancer Cells

Cancer investigation. 2017 ; 35 (5) : 313-324. [pub] 20170412

Cancer Invest
ISSN 1532-4192
Medvik
Zdroj

Tamoxifen treatment in breast cancer patients is associated with increased risk of endometrial malignancies. Significantly, higher AGR2 expression was found in endometrial cancers that developed in women previously treated with tamoxifen compared to those who had not been exposed to tamoxifen. An association of elevated AGR2 level with myometrial invasion occurrence and invasion depth was also found. In vitro analyses identified a stimulatory effect of AGR2 on cellular proliferation. Although adverse tamoxifen effects on endometrial cells remain elusive, our work identifies elevated AGR2 as a candidate tamoxifen-dependent mechanism of action responsible for increased incidence of endometrial cancer.

Článek

Ochratoxin A: 50 Years of Research

Toxins. 2016 ; 8 (7) : . [pub] 20160704

Toxins (Basel)
ISSN 2072-6651
Medvik
Zdroj

Since ochratoxin A (OTA) was discovered, it has been ubiquitous as a natural contaminant of moldy food and feed. The multiple toxic effects of OTA are a real threat for human beings and animal health. For example, OTA can cause porcine nephropathy but can also damage poultries. Humans exposed to OTA can develop (notably by inhalation in the development of acute renal failure within 24 h) a range of chronic disorders such as upper urothelial carcinoma. OTA plays the main role in the pathogenesis of some renal diseases including Balkan endemic nephropathy, kidney tumors occurring in certain endemic regions of the Balkan Peninsula, and chronic interstitial nephropathy occurring in Northern African countries and likely in other parts of the world. OTA leads to DNA adduct formation, which is known for its genotoxicity and carcinogenicity. The present article discusses how renal carcinogenicity and nephrotoxicity cause both oxidative stress and direct genotoxicity. Careful analyses of the data show that OTA carcinogenic effects are due to combined direct and indirect mechanisms (e.g., genotoxicity, oxidative stress, epigenetic factors). Altogether this provides strong evidence that OTA carcinogenicity can also occur in humans.

Článek

Interactive effects of inflammatory cytokine and abundant low-molecular-weight PAHs on inhibition of gap junctional intercellular communication, disruption of cell proliferation control, and the AhR-dependent transcription

Toxicology letters. 2015 ; 232 (1) : 113-21. [pub] 20140928

Toxicol Lett
ISSN 1879-3169
Medvik
Zdroj

Polycyclic aromatic hydrocarbons (PAHs) with lower molecular weight exhibit lesser genotoxicity and carcinogenicity than highly carcinogenic PAHs with a higher number of benzene rings. Nevertheless, they elicit specific effects linked with tumor promotion, such as acute inhibition of gap junctional intercellular communication (GJIC). Although inflammatory reaction may alter bioactivation and toxicity of carcinogenic PAHs, little is known about the impact of pro-inflammatory cytokines on toxic effects of the low-molecular-weight PAHs. Here, we investigated the impact of a pro-inflammatory cytokine, tumor necrosis factor-α (TNF-α), on the effects associated with tumor promotion and with induction of the aryl hydrocarbon receptor (AhR)-dependent gene expression in rat liver epithelial cells. We found that a prolonged incubation with TNF-α induced a down-regulation of GJIC, associated with reduced expression of connexin 43 (Cx43), a major connexin isoform found in liver epithelial cells. The Cx43 down-regulation was partly mediated by the activity of the mitogen-activated protein (MAP) p38 kinase. Independently of GJIC modulation, or p38 activation, TNF-α potentiated the AhR-dependent proliferative effect of a model low-molecular-weight PAH, fluoranthene, on contact-inhibited cells. In contrast, this pro-inflammatory cytokine repressed the fluoranthene-induced expression of a majority of model AhR gene targets, such as Cyp1a1, Ahrr or Tiparp. The results of the present study indicate that inflammatory reaction may differentially modulate various toxic effects of low-molecular-weight PAHs; the exposure to pro-inflammatory cytokines may both strengthen (inhibition of GJIC, disruption of contact inhibition) and repress (expression of a majority of AhR-dependent genes) their impact on toxic endpoints associated with carcinogenesis.

Článek

Aryl hydrocarbon receptor-mediated disruption of contact inhibition is associated with connexin43 downregulation and inhibition of gap junctional intercellular communication

Archives of toxicology. 2013 ; 87 (3) : 491-503.

Arch Toxicol
ISSN 1432-0738
Medvik
Zdroj

The aryl hydrocarbon receptor (AhR) contributes to the control of cell-to-cell communication, cell adhesion, migration or proliferation. In the present study, we investigated the regulation of connexin43 (Cx43) and Cx43-mediated gap junctional intercellular communication (GJIC) during the AhR-dependent disruption of contact inhibition in non-tumorigenic liver epithelial cells. The contact inhibition of cell proliferation is a process restricting the cell division of confluent non-transformed cells, which is frequently abolished in cancer cells; however, the mechanisms contributing to its disruption are still only partially understood. Disruption of contact inhibition, which was induced by toxic AhR ligands 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or polycyclic aromatic hydrocarbons in epithelial WB-F344 cells, reduced Cx43 protein levels, possibly via enhanced proteasomal degradation, significantly decreased the amount of gap junction plaques and downregulated GJIC, in an AhR-dependent manner. Although both intracellular and membrane Cx43 pools were markedly reduced in cells released from contact inhibition by TCDD, siRNA-mediated Cx43 knock-down was not sufficient to stimulate proliferation in contact-inhibited cells. Our data suggest that downregulation of Cx43/GJIC in non-transformed epithelial cells is an inherent part of disruption of contact inhibition, which occurs at the post-transcriptional level. This process runs in parallel with alterations of other forms of cell-to-cell communication, thus suggesting that toxic AhR agonists may simultaneously abrogate contact inhibition and reduce GJIC, two essential mechanisms linked to deregulation of cell-to-cell communication during tumor promotion and progression.

Článek

Kolorektální karcinom a mikrobiální a virové patogeny

Chrdle, Aleš
Autor Autorita

The lancet oncology CZ. 2011 ; 10 (3) : 236-245.

Lancet Oncol. (Čes. vyd.)
ISSN 1213-9432
Medvik
Zdroj

Článek

Expression profiles of proliferative and antiapoptotic genes in sporadic and colitis-related mouse colon cancer models

International journal of experimental pathology. 2010 ; 91 (1) : 44-53.

Medvik
Zdroj

Elevated levels of survivin, telomerase catalytic subunit (TERT), integrin-linked kinase (ILK), cyclooxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS) and the regulatory factors c-MYB and Tcf-4 are often found in human cancers including colorectal cancer (CRC) and have been implicated in the development and progression of tumorigenesis. The aim of this study was to determine the expression of these genes in mouse models of sporadic and colitis-associated CRC. To address these issues, we used qRT-PCR approach to determine changes in gene expression patterns of neoplastic cells (high-grade dysplasia/intramucosal carcinoma) and surrounding normal epithelial cells in A/J and ICR mouse strains using laser microdissection. Both strains were injected with azoxymethane and ICR mice were also given drinking water that contained 2% dextran sodium sulphate. In both sporadic (A/J mice) and colitis-associated (ICR mice) models of CRC, the levels of TERT mRNA, COX-2 mRNA and Tcf-4 mRNA were higher in neoplastic cells than in surrounding normal epithelial cells. In contrast, survivin mRNA was upregulated only in neoplastic cells from A/J mice and ILK mRNA was upregulated only in neoplastic cells from ICR mice. However, the expression of iNOS mRNA was similar in normal and neoplastic cells in both models and c-MYB mRNA was actually downregulated in neoplastic cells compared with normal cells in both models. These findings suggest that the genetic background and/or the molecular mechanisms of tumorigenesis associated with genotoxic insults and colonic inflammation influence the gene expression of mTERT, COX-2, Tcf-4, c-MYB, ILK and survivin in colon epithelial neoplasia.