Myeloblastosis-associated virus 2 (MAV-2) is a highly tumorigenic simple avian retrovirus. Chickens infected in ovo with MAV-2 develop tumors in the kidneys, lungs, and liver with a short latency, less than 8 weeks. Here we report the results of molecular analyses of MAV-2-induced liver tumors that fall into three classes: hepatic hemangiosarcomas (HHSs), intrahepatic cholangiocarcinomas (ICCs), and hepatocellular carcinomas (HCCs). Comprehensive inverse PCR-based screening of 92 chicken liver tumors revealed that in ca. 86% of these tumors, MAV-2 provirus had integrated into one of four gene loci: HRAS, EGFR, MET, and RON Insertionally mutated genes correlated with tumor type: HRAS was hit in HHSs, MET in ICCs, RON mostly in ICCs, and EGFR mostly in HCCs. The provirus insertions led to the overexpression of the affected genes and, in the case of EGFR and RON, also to the truncation of exons encoding the extracellular ligand-binding domains of these transmembrane receptors. The structures of truncated EGFR and RON closely mimic the structures of oncogenic variants of these genes frequently found in human tumors (EGFRvIII and sfRON).IMPORTANCE These data describe the mechanisms of oncogenesis induced in chickens by the MAV-2 retrovirus. They also show that molecular processes converting cellular regulatory genes to cancer genes may be remarkably similar in chickens and humans. We suggest that the MAV-2 retrovirus-based model can complement experiments performed using mouse models and provide data that could translate to human medicine.

• MeSH
• cholangiokarcinom genetika   virologie   MeSH
• geny erbB-1 * MeSH
• hemangiosarkom genetika   virologie   MeSH
• hepatocelulární karcinom genetika   virologie   MeSH
• integrace viru MeSH
• inzerční mutageneze * MeSH
• karcinogeneze * MeSH
• kur domácí genetika   MeSH
• lidé MeSH
• nádory jater genetika   virologie   MeSH
• onkogeny MeSH
• protoonkogenní proteiny c-met genetika   MeSH
• proviry genetika   fyziologie   MeSH
• ptačí proteiny genetika   MeSH
• tyrosinkinasové receptory genetika   MeSH
• virus ptačí myeloblastózy genetika   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Dietary phospholipids (PLs) and their derivatives have proved active in suppression of various health problems and conditions including cancer. In this work we compared the effect of dietary phospholipids from hen egg yolk enriched with N-acyl ether-phosphatidyl ethanolamine (NAEPE) termed bioactive phospholipids (BAP+ preparation) with PLs lacking NAEPE (BAP- preparation) on the growth of transformed cells in vitro and on the promotion and progression of experimental tumours in vivo. For the in vivo experiments we used the chicken model in which liver, lung, and kidney tumours arose via natural selection from single cells initiated by experimentally introduced somatic mutations caused by insertional mutagenesis. Mutagenized animals were fed BAP+ or BAP- diet in various regimens. We observed that BAP+ at low concentrations killed cells of various tumour cell lines in culture but did not compromise viability of non-transformed cells. Oral administration of the BAP+ preparation efficiently reduced progression of all tumour types. However, it did not significantly reduce the number of already initiated tumours and their growth when BAP+ was discontinued. Our data suggest that NAEPE combined with hen egg PLs significantly interferes with tumour progression, possibly through the inhibition of tumour cell viability.

• MeSH
• aplikace orální MeSH
• ethanolaminy chemie   farmakologie   MeSH
• fosfolipidy aplikace a dávkování   chemie   farmakologie   MeSH
• kultivované buňky MeSH
• kuřecí embryo MeSH
• modely nemocí na zvířatech MeSH
• nádorové buněčné linie MeSH
• nádory farmakoterapie   patofyziologie   MeSH
• proliferace buněk účinky léků   MeSH
• vaječný žloutek chemie   MeSH
• viabilita buněk účinky léků   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The neural crest (NC) is a transient dynamic structure of ectodermal origin, found in early vertebrate embryos. The multipotential NC cells migrate along well defined routes, differentiate to various cell types including melanocytes and participate in the formation of various permanent tissues. As there is only limited information about the molecular mechanisms controlling early events in melanocyte specification and development, we exploited the AMV v-Myb transcriptional regulator, which directs differentiation of in vitro chicken NC cells to the melanocyte lineage. This activity is strictly dependent on v-Myb specifically binding to the Myb recognition DNA element (MRE). The two tamoxifen-inducible v-Myb alleles were constructed one which recognizes the MRE and one which does not. These were activated in ex ovo NC cells, and the expression profiles of resulting cells were analyzed using Affymetrix microarrays and RT-PCR. These approaches revealed up-regulation of the BMP antagonist Gremlin 2 mRNA, and down-regulation of mRNAs encoding several epithelial genes including KRT19 as very early events following the activation of melanocyte differentiation by v-Myb. The enforced v-Myb expression in neural tubes of chicken embryos resulted in detectable presence of Gremlin 2 mRNA. However, expression of Gremlin 2 in NC cells did not promote formation of melanocytes suggesting that Gremlin 2 is not the master regulator of melanocytic differentiation.

• MeSH
• aktivace transkripce * MeSH
• alely MeSH
• buněčná diferenciace * MeSH
• crista neuralis cytologie   MeSH
• keratin-19 genetika   metabolismus   MeSH
• kostní morfogenetický protein 5 genetika   metabolismus   MeSH
• kultivované buňky MeSH
• kuřecí embryo MeSH
• melanocyty fyziologie   MeSH
• mezibuněčné signální peptidy a proteiny genetika   metabolismus   MeSH
• onkogenní proteiny v-myb fyziologie   MeSH
• ptačí proteiny genetika   metabolismus   MeSH
• regulace genové exprese MeSH
• sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů MeSH
• transkriptom MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A tumor cell is formed when a critical amount of endogenous and/or exogenous tumorigenic stimuli is exceeded. We have shown that the transient presence of nontumorigenic stray cells in tissues of experimental animals that contain cells with a subcritical set of genetic mutations can act as a tumor-promoting stimulus. To induce somatic mutations in all chicken tissues, we have used the MAV-2 retroviral insertion system that almost exclusively generates nephroblastomas. MAV-2 mutagenized animals i.v. inoculated with nonmalignant cells developed early clonal lung tumors before nephroblastomas. Importantly, the injected cells did not become a component of resultant tumors. Lung tumors displayed specific mutational signature characterized by an insertion of MAV-2 provirus into the fyn-related kinase (frk) promoter that results in the overexpression of the frk gene. In contrast, plag1, foxP, and twist genes were most often mutagenized in nephroblastomas. Based on such observations, we propose the mechanism termed industasis, a promotion of fully malignant phenotype of incipient tumor cell by stray cells, and hypothesize that it might be the underlying cause of human multiple primary tumors.

• MeSH
• biologické modely MeSH
• buňky patologie   virologie   MeSH
• fyziologie virů MeSH
• invazivní růst nádoru MeSH
• inzerční mutageneze fyziologie   MeSH
• kultivované buňky MeSH
• kur domácí MeSH
• kuřecí embryo MeSH
• mnohočetné primární nádory etiologie   MeSH
• nádorová transformace buněk patologie   MeSH
• nádory ledvin patologie   virologie   MeSH
• nádory plic patologie   virologie   MeSH
• pohyb buněk fyziologie   MeSH
• proviry fyziologie   účinky léků   MeSH
• Wilmsův nádor patologie   virologie   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH

OBJECTIVE: The primary objective of this study was to identify and clone the first nonmammalian thrombopoietin (TPO), chicken TPO, and its receptor c-Mpl for the purpose of characterizing their activities both in vitro and in vivo. MATERIALS AND METHODS: Chicken TPO was cloned using the methods of reverse transcriptase polymerase chain reaction and rapid amplification of cDNA ends. Northern blotting and RNAse protection assays were employed to analyze the levels of RNA expression in a panel of tissues and cell lines. To study cell surface expression of c-Mpl, polyclonal antibodies were prepared against bacterially derived c-Mpl. Both baculovirus-derived recombinant TPO and retrovirally expressed TPO and c-Mpl were used for the in vivo experiments. RESULTS: Both chicken TPO and its receptor c-Mpl were identified and cloned. Expression of chicken TPO was restricted to only the liver and spleen, while c-mpl was expressed in the bone marrow, lung, and spleen. In vitro experiments with sorted multipotent chicken bone marrow-derived progenitors demonstrated that TPO plays a role in the commitment of these cells to the thrombocytic lineage. Furthermore, TPO in cooperation with stem cell factor also supports proliferation of multipotent progenitors. In experimental animals, the intravenous application of recombinant chicken TPO or overexpression of TPO and c-mpl via retroviral infection lead to erythroblastosis and thromboblastosis. CONCLUSION: The characterized chicken thrombopoietin and its receptor c-Mpl will be valuable tools to further study thrombocytic differentiation and hematopoietic stem cell development. Moreover, the introduced experimental model of the chicken bipotent thrombo-/erythropoietic-progenitor can be used to identify key regulators of cell fate determination.

• MeSH
• buněčný rodokmen MeSH
• Escherichia coli genetika   MeSH
• fibroblasty cytologie   MeSH
• financování organizované MeSH
• hematopoéza fyziologie   MeSH
• klonování DNA MeSH
• kur domácí MeSH
• kuřecí embryo MeSH
• lidé MeSH
• messenger RNA biosyntéza   MeSH
• molekulární sekvence - údaje MeSH
• myši MeSH
• receptory thrombopoetinu biosyntéza   fyziologie   genetika   MeSH
• rekombinantní proteiny genetika   MeSH
• sekvence aminokyselin MeSH
• sekvenční seřazení MeSH
• thrombopoetin biosyntéza   fyziologie   genetika   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• lidé MeSH
• myši MeSH
• zvířata MeSH

The c-myb proto-oncogene and its oncogenic derivative v-mybAMV encode transcriptional regulators engaged in the commitment of hematopoietic cells. While the c-Myb protein is important for the formation and differentiation of various progenitors, the v-MybAMV oncoprotein induces in chicks a progression and transformation of the single (monoblastic) cell lineage. Here we present the first evidence of cell fate-directing abilities of c-Myb and v-MybAMV proteins in avian neural crest (NC), where both proteins determine melanocytogenesis. The increased concentration of c-Myb induces progression into dendritic melanocytes and differentiation. The v-myb oncogene converts essentially all NC cells into melanocytes and causes their transformation. Both Myb proteins activate in NC cells expression of the c-kit gene and stem cell factor c-Kit signaling--one of the essential pathways in melanocyte development. These observations suggest that the c-myb-c-kit pathway represents a common regulatory scheme for both hematopoietic and neural progenitors and establishes a novel experimental model for studies of melanocytogenesis and melanocyte transformation.

• MeSH
• buněčná diferenciace MeSH
• crista neuralis cytologie   metabolismus   MeSH
• DNA primery genetika   MeSH
• faktor růstu kmenových buněk genetika   metabolismus   MeSH
• financování organizované MeSH
• geny myb MeSH
• kuřecí embryo MeSH
• melanocyty cytologie   metabolismus   MeSH
• onkogenní proteiny v-myb genetika   metabolismus   MeSH
• protoonkogenní proteiny c-kit genetika   metabolismus   MeSH
• protoonkogenní proteiny c-myb genetika   metabolismus   MeSH
• sekvence nukleotidů MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH

• MeSH
• DNA vazebné proteiny genetika   MeSH
• financování organizované MeSH
• geny ras genetika   MeSH
• integrace viru genetika   MeSH
• koncové repetice MeSH
• kuřecí embryo MeSH
• lidé MeSH
• mapování chromozomů MeSH
• nádory ledvin genetika   virologie   MeSH
• nemoci drůbeže genetika   MeSH
• onkogenní proteiny genetika   MeSH
• onkogeny genetika   MeSH
• polymerázová řetězová reakce MeSH
• proviry genetika   MeSH
• ptačí proteiny genetika   MeSH
• transkripční faktor Twist MeSH
• tumor supresorové geny MeSH
• virus ptačí myeloblastózy genetika   MeSH
• Wilmsův nádor genetika   virologie   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• lidé MeSH
• zvířata MeSH

• MeSH
• erytroidní prekurzorové buňky cytologie   metabolismus   účinky léků   MeSH
• protoonkogenní proteiny c-myb metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH