RESUMO
The p53 target gene WIG-1 (ZMAT3) is located in chromosomal region 3q26, that is frequently amplified in human tumors, including cervical cancer. We have examined the status of WIG-1 and the encoded Wig-1 protein in cervical carcinoma cell lines and tumor tissue samples. Our analysis of eight cervical cancer lines (Ca Ski, ME-180, MS751, SiHa, SW756, C-4I, C-33A, and HT-3) by spectral karyotype, comparative genomic hybridization and Southern blotting revealed WIG-1 is not the primary target for chromosome 3 gains. However, WIG-1/Wig-1 were readily expressed and WIG-1 mRNA expression was higher in the two HPV-negative cervical cell lines (C33-A, HT-3) than in HPV-positive lines. We then assessed Wig-1 expression by immunohistochemistry in 38 cervical tumor samples. We found higher nuclear Wig-1 expression levels in HPV-negative compared to HPV positive cases (p = 0.002) and in adenocarcinomas as compared to squamous cell lesions (p<0.0001). Cases with moderate nuclear Wig-1 staining and positive cytoplasmic Wig-1 staining showed longer survival than patients with strong nuclear and negative cytoplasmic staining (p = 0.042). Nuclear Wig-1 expression levels were positively associated with age at diagnosis (p = 0.023) and histologic grade (p = 0.034). These results are consistent with a growth-promoting and/or anti-cell death function of nuclear Wig-1 and suggest that Wig-1 expression can serve as a prognostic marker in cervical carcinoma.
Assuntos
Proteínas de Transporte/genética , Regulação Neoplásica da Expressão Gênica , Proteínas Nucleares/genética , Papillomaviridae/fisiologia , Proteína Supressora de Tumor p53/metabolismo , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/virologia , Proteínas de Transporte/metabolismo , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Cromossomos Humanos Par 3/genética , Feminino , Loci Gênicos/genética , Humanos , Gradação de Tumores , Estadiamento de Neoplasias , Proteínas Nucleares/metabolismo , Prognóstico , Proteínas de Ligação a RNA , Análise de Sobrevida , Neoplasias do Colo do Útero/diagnóstico , Neoplasias do Colo do Útero/patologiaRESUMO
The p53-induced wig-1 gene encodes an unusual nuclear zinc finger protein with high sequence similarity between human, rat and mouse. Wig-1 belongs to a group of proteins with widely spaced zinc fingers that bind double stranded (ds) RNA. We show here that wig-1 is present in Gallus gallus (chicken), Silurana tropicalis (frog) and Fugu rubripes (fish) by assembly of EST sequence data from a range of data bases into putative cDNAs. The zinc finger regions of Wig-1 are almost completely conserved from fish to man. A short upstream open reading frame is conserved in mammals and birds but not in amphibians. Sequence information from clones of Macaca mulatta (Rhesus macaque), Sus scrofa (pig), Danio rerio (Zebra fish) and Tetraodon nigroviridis (fresh water puffer fish) indicates that Wig-1 orthologs exist also in these species. No genes with striking similarities to wig-1 were found in invertebrates. Our results suggest that Wig-1 and particularly the zinc finger domains have an important biological function in the p53 pathway in vertebrates.
Assuntos
Proteínas de Transporte/genética , Proteínas de Ligação a DNA/genética , Peixes/genética , Proteínas Nucleares/genética , Proteínas/genética , Proteína Supressora de Tumor p53/farmacologia , Xenopus laevis/genética , Sequência de Aminoácidos , Animais , Galinhas , Sequência Conservada , Humanos , Macaca mulatta/genética , Dados de Sequência Molecular , Fases de Leitura Aberta , Proteínas de Ligação a RNA , Homologia de Sequência de Aminoácidos , Suínos/genética , Fatores de Transcrição , Proteínas de Xenopus , Dedos de Zinco/genéticaRESUMO
The p53-induced mouse wig-1 gene encodes a Cys2His2-type zinc finger protein of unknown function. The zinc fingers in wig-1 are connected by long (56-75) amino acid linkers. This distribution of zinc finger domains resembles that of the previously described double-stranded (ds)RNA-binding proteins dsRBP-ZFa and JAZ. Ectopically expressed FLAG-tagged mouse wig-1 protein localized to nuclei and in some cells to nucleoli, whereas GFP-tagged mouse wig-1 localized primarily to nucleoli. Electrophoretic mobility shift assay using a recombinant GST-wig-1 fusion protein showed that wig-1 preferentially binds dsRNA rather than single-stranded RNA or dsDNA. A set of deletion/truncation mutants of wig-1 was tested to determine the dsRNA-binding domain(s) or region(s) in wig-1 that is involved in the stabilization of wig-1-dsRNA complexes in vitro. This revealed that the first zinc finger in wig-1 is essential for binding to dsRNA, whereas zinc fingers 2 and 3 are dispensable. wig-1 protein expressed in mammalian cells also showed a high affinity for dsRNA. wig-1 represents the first confirmed p53-induced gene that encodes a dsRNA-binding protein. This suggests that dsRNA binding plays a role in the p53-dependent stress response.
