RESUMEN
The present study examined the relationship between methylation of five genes (p16(INK4a), RASSF1A, APC, RARbeta and CDH13) and patient survival in 351 cases of surgically resected lung cancers. While there was no relationship between the other genes and survival, p16(INK4a) methylation was significantly related to unfavourable prognosis in lung adenocarcinomas.
Asunto(s)
Adenocarcinoma/genética , Adenocarcinoma/patología , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/patología , Metilación de ADN , ADN de Neoplasias/metabolismo , Genes p16 , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Análisis de SupervivenciaRESUMEN
We investigated the aberrant promoter methylation profile of bladder cancers and correlated the data with clinicopathological findings. The methylation status of 10 genes was determined in 98 surgically resected bladder cancers, and we calculated the median methylation index (MI), a reflection of the methylated fraction of the genes tested. Methylation frequencies of the genes tested in bladder cancers were 36% for CDH1, 35% for RASSF1A and APC, 29% for CDH13, 16% for FHIT, 15% for RAR beta, 11% for GSTP1, 7% for p16(INK4A), 4% for DAPK, and 2% for MGMT. Methylation of four of the individual genes (CDH1, RASSF1A, APC, and CDH13) and the MI were significantly correlated with several parameters of poor prognosis (tumor grade, growth pattern, muscle invasion, tumor stage, and ploidy pattern). Methylation of CDH1, FHIT, and a high MI were associated with shortened survival. CDH1 methylation positive status was independently associated with poor survival in multivariate analyses. Our results suggest that the methylation profile may be a potential new biomarker of risk prediction in bladder cancer.
Asunto(s)
Carcinoma de Células Transicionales/genética , Carcinoma de Células Transicionales/patología , Metilación de ADN , Neoplasias de la Vejiga Urinaria/genética , Neoplasias de la Vejiga Urinaria/patología , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patología , Carcinoma de Células Escamosas/cirugía , Carcinoma de Células Transicionales/cirugía , Supervivencia sin Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Regiones Promotoras Genéticas , Factores de Riesgo , Neoplasias de la Vejiga Urinaria/cirugíaRESUMEN
Aberrant promoter methylation and resultant silencing of several genes plays an important role in the pathogenesis of many tumor types. We compared the methylation profile of 66 malignant mesotheliomas (MMs) and 40 lung adenocarcinomas using methylation-specific PCR for seven genes frequently methylated in lung cancer. We also compared the methylation frequencies of these genes as well as the methylation index, a reflection of all of the gene frequencies, with the presence of SV40 large T-antigen (Tag) sequences, histological subtype, and patient survival. Our major findings are: (a) with the exception of the RASSF1A promoter of the RASSF1 gene, frequencies of aberrant methylation were significantly lower in MMs than in adenocarcinomas; (b) the frequency of RASSF1A aberrant methylation and the value of the methylation index were significantly higher in SV40 sequence positive MM than in negative MM; and (c) the methylation index was higher in epithelial MM than in sarcomatous/mixed MM. Our results demonstrate a relationship between SV40 and aberrant methylation in MMs.
Asunto(s)
Antígenos Transformadores de Poliomavirus/genética , Metilación de ADN , Genes Supresores de Tumor , Mesotelioma/genética , Proteínas Supresoras de Tumor , Adenocarcinoma/genética , Adenocarcinoma/patología , Adulto , Anciano , Femenino , Gutatión-S-Transferasa pi , Glutatión Transferasa/genética , Humanos , Isoenzimas/genética , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Masculino , Mesotelioma/patología , Persona de Mediana Edad , Proteínas de Neoplasias/genética , Regiones Promotoras Genéticas/genética , Células Tumorales CultivadasRESUMEN
Expression of some members of the cadherin family is reduced in several human tumors, and CDH13 (H-cadherin), located on chromosome 16q24.2-3, may function as a tumor suppressor gene. In human tumors, loss of expression of many tumor suppressor genes occurs by aberrant promoter region methylation. We examined the methylation status of the CDH13 promoter in breast and lung cancers and correlated it with mRNA expression using methylation-specific PCR and reverse transcription-PCR. Methylation was frequent in primary breast tumors (18 of 55, 33%) and cell lines (7 of 20, 35%). In lung cancers, methylation was present more frequently in non-small cell lung cancer tumors (18 of 42, 43%) and cell lines (15 of 30, 50%) than in small cell lung cancer cell lines (6 of 30, 20%; P = 0.03). Only the methylated or unmethylated forms of the gene were present in most (73 of 80, 91%) tumor cell lines. CDH13 expression was present in 24 of 30 (80%) of nonmethylated tumor lines. All 18 methylated lines tested lacked expression irrespective of whether the unmethylated form was present, confirming biallelic inactivation in methylated lines. Gene expression was restored in all five methylated cell lines tested after treatment with the demethylating agent 5'-aza-2-deoxycytidine. Our results demonstrate frequent aberrant methylation of CDH13 in breast and lung cancers accompanied by loss of gene expression, although expression may occasionally be lost by other mechanisms.
Asunto(s)
Neoplasias de la Mama/genética , Cadherinas/genética , Metilación de ADN , Neoplasias Pulmonares/genética , Neoplasias de la Mama/metabolismo , Cadherinas/biosíntesis , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Carcinoma de Células Pequeñas/genética , Carcinoma de Células Pequeñas/metabolismo , ADN de Neoplasias/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Silenciador del Gen , Genes Supresores de Tumor , Humanos , Pérdida de Heterocigocidad , Neoplasias Pulmonares/metabolismo , Reacción en Cadena de la Polimerasa/métodos , Regiones Promotoras Genéticas , Análisis de Secuencia de ADN , Células Tumorales CultivadasRESUMEN
Aberrant methylation of CpG islands in promoter regions of tumor cells is one of the major mechanisms for silencing of tumor suppressor genes. We determined the frequency of aberrant promoter methylation of the p16, adenomatous polyposis coli (APC), H-cadherin (CDH13), glutathione S-transferase P1 (GSTP1), O6-methylguanine-DNA-methyltransferase (MGMT), retinoic acid receptor beta-2 (RAR beta), E-cadherin (CDH1), and RAS association domain family 1A (RASSF1A) genes in 198 tumors consisting of small cell lung cancers [SCLCs (n = 43)], non-small cell lung cancers [NSCLCs (n = 115)], and bronchial carcinoids (n = 40). The profile of methylated genes in the two neuroendocrine tumors (SCLC and carcinoids) were very different from that of NSCLC. However, whereas the overall pattern of aberrant methylation of carcinoids was similar to that of SCLC, carcinoids had lower frequencies of methylation for some of the genes tested. There were also significant differences in the methylation profiles between the two major types of NSCLC, adenocarcinoma and squamous cell carcinoma. We performed cluster analysis and found that SCLCs clustered with other SCLCs and carcinoids but not with NSCLCs, whereas the NSCLCs tended to cluster together. Within NSCLCs, adenocarcinomas and squamous cell carcinomas clustered with their respective histological types. Finally, we compared the methylation profiles of SCLC and NSCLC tumors and their respective cell lines (n = 44). In general, methylation frequencies were higher in tumor cell lines, but these differences were seldom significant. Thus, tumor cell lines appear to be suitable models to study aberrant DNA methylation. We conclude that SCLC, carcinoids, squamous cell carcinomas, and adenocarcinomas of the lung have unique profiles of aberrant methylation. Our findings should help us understand differences in the pathogenetic mechanisms of lung cancers.