RESUMO
Imprinting analyses of IGF2 and H19, loss of heterozygosity (LOH) analyses of IGF2R and CTCF and Helicobacter pylori detection, were performed on 35 human laryngeal squamous cell carcinomas (LSCC). Forty-six percent of the tumors were heterozygous for IGF2, and 54% were informative for the H19. Biallelic expression of IGF2 was observed in 33% (5 out of 15) of the tumors and in 27% (4 out of 15) of adjacent non-tumorous laryngeal tissues. H19 loss of imprinting (LOI) was observed in 24% (4 out of 17) of the tumors. For IGF2R and CTCF, 71% (25 out of 35) and 50% (17/34), respectively, of the samples were heterozygous, and LOH was detected in 12% (3 out of 25) and 6% (1 out of 17), respectively, of the tumors. H. pylori was found in 26% (9/35) of these tumors. Among them, four were informative for the imprinting analysis. The presence of H. pylori had no effect on IGF2/H19 imprinting. Only the H. pylori detection was further broadened with an additional 47 laryngeal tumors, resulting in a total final positivity of close to 16% (13 out of 82). This study represents the largest comprehensive IGF2/H19 imprinting study done to date on well-defined samples of human laryngeal carcinomas and corresponding non-tumorous tissue. For the first time, the analyses of IGF2/H19 imprinting have been broadened with LOH analyses of IGF2R and CTCF, with both of these genes acting as modulators of IGF2 and H19 activity. Although there were indications that H. pylori may be present in LSCC, we are the first to show its presence in LSCC by two direct techniques: Giemsa staining and nested-PCR.
Assuntos
Carcinoma de Células Escamosas , Proteínas de Ligação a DNA/genética , Impressão Genômica , Infecções por Helicobacter , Fator de Crescimento Insulin-Like II/genética , Neoplasias Laríngeas , RNA não Traduzido/genética , Receptor IGF Tipo 2/genética , Proteínas Repressoras/genética , Fator de Ligação a CCCTC , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/microbiologia , Carcinoma de Células Escamosas/patologia , Proteínas de Ligação a DNA/metabolismo , Helicobacter pylori/metabolismo , Helicobacter pylori/patogenicidade , Humanos , Fator de Crescimento Insulin-Like II/metabolismo , Neoplasias Laríngeas/genética , Neoplasias Laríngeas/microbiologia , Neoplasias Laríngeas/patologia , Perda de Heterozigosidade , RNA Longo não Codificante , RNA não Traduzido/metabolismo , Receptor IGF Tipo 2/metabolismo , Proteínas Repressoras/metabolismoRESUMO
Several oncogenes and tumor-suppressor genes are involved either as early or late event in thyroid gland carcinogenesis. Human FHIT (fragile histidine triad) gene is highly conserved gene whose loss of function may be important in the development and/or progression of various types of cancer. We undertook this study to analyze FHIT and p53 gene status in different benignant and malignant thyroid tumors. Status of these genes as well as intensity of apoptosis was analyzed in tumor tissues by molecular genetic methods, immunohistochemistry, and FACS-scan analysis. The majority of the malignant thyroid cancers displayed aberrant expression of FHIT gene, concominant with p53 gene inactivation. This is followed by low rate of apoptosis, which may be important in the development and/or progression of thyroid cancer. We found higher incidence of p53 mutation and aberrant processing of FHIT mRNA in malignant tumors (papillary, follicular, medullary and anaplastic carcinomas) and in those tumors with distant metastasis. The growth of p53(-)/FHIT(-) follicular carcinoma of human origin was much faster in nude mice than p53(+)/FHIT(+) follicular carcinoma, and mice had shorter survival rate. Our results show a correlation between aberrant FHIT and p53 expression, low rate of apoptosis, and malignancy. Concomitant aberration of FHIT gene and p53 could be responsible for development of highly malignant types of thyroid cancer and may be considered as a prognostic marker for these tumors.
Assuntos
Hidrolases Anidrido Ácido/genética , Genes p53 , Mutação , Proteínas de Neoplasias/genética , Doenças da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/genética , Hidrolases Anidrido Ácido/metabolismo , Adolescente , Adulto , Idoso , Animais , Apoptose , Feminino , Citometria de Fluxo , Expressão Gênica , Humanos , Imuno-Histoquímica , Perda de Heterozigosidade , Masculino , Camundongos , Camundongos Nus , Pessoa de Meia-Idade , Biologia Molecular , Proteínas de Neoplasias/metabolismo , Transplante de Neoplasias , Doenças da Glândula Tireoide/metabolismo , Doenças da Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/metabolismo , Neoplasias da Glândula Tireoide/patologia , Transplante HeterólogoRESUMO
The gene for insulin-like growth factor two, IGF2 is maternally imprinted. Fifteen heterozygous samples were analyzed for the IGF2 imprinting status and promoter usage. IGF2 LOI was detected in four non-tumorous tissues and in six laryngeal squamous cell carcinoma (LSCC) tumors. There was no clear pattern of specific promoter activity in LSCC tumors and the adjacent normal tissues. P1 promoter usage was active in eight LSCCs, among them four with LOI. As it was activated in four tumors with maintenance of imprinting (MOI) and four non-tumors, we concluded that P1 promoter is not exclusively connected with IGF2 LOI in LSCC.