RESUMEN
BACKGROUND: Gallbladder cancer is very common in Chile and is the leading cause of cancer deaths in women aged over 40 years. However, there is limited information about the molecular changes involved in its pathogenesis. Microsatellite analysis was performed using polymerase chain reaction (PCR)-based assays to identify genetic loci that were altered in neoplastic and preneoplastic conditions of early and advanced gallbladder cancer. Our findings were then correlated with clinicopathological variables and survival time. METHODS: We selected 59 surgical specimens of gallbladder adenocarcinomas (29 early cancers and 30 advanced cancers) and 22 surgical specimens from patients with chronic cholecystitis from a high-risk area for gallbladder cancer (Temuco, Chile). Laser capture microdissection (LCM) was used to harvest tumor cells and preneoplastic lesions. Microsatellite analysis was performed using 13 different markers. The tumors and preneoplastic lesions were also examined with immunohistochemistry for hMLH1, hMSH2, and hMSH6. RESULTS: We found that 10% (6/59) of gallbladder cancers showed high-frequency microsatellite instability (MSI-H), with identical proportions in both early and advanced cancers. In premalignant lesions adjacent to the six MSI-H tumors, we detected instability in two of six examples of intestinal metaplasia (33%) and five of six examples of dysplasia (83%). All MSI-H cases showed an altered pattern with the antibodies studied. MSI status was not associated with survival or other clinicopathological features. No MSI or immunohistochemical alterations were found in the chronic cholecystitis group. CONCLUSIONS: Microsatellite instability was observed in equal proportions in early and late cancers, and it was also found in premalignant lesions, indicating that inactivation of mismatch repair genes occurs early in gallbladder carcinogenesis.
Asunto(s)
Adenocarcinoma/genética , Adenocarcinoma/patología , Neoplasias de la Vesícula Biliar/genética , Neoplasias de la Vesícula Biliar/patología , Inestabilidad Genómica/genética , Repeticiones de Microsatélite/genética , Lesiones Precancerosas/genética , Lesiones Precancerosas/patología , Adenocarcinoma/mortalidad , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Anticuerpos Monoclonales/metabolismo , Biomarcadores de Tumor/metabolismo , Chile/epidemiología , Colecistitis/genética , Colecistitis/mortalidad , Colecistitis/patología , Proteínas de Unión al ADN/metabolismo , Femenino , Neoplasias de la Vesícula Biliar/mortalidad , Predisposición Genética a la Enfermedad/epidemiología , Predisposición Genética a la Enfermedad/genética , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Proteína 2 Homóloga a MutS/metabolismo , Estadificación de Neoplasias , Lesiones Precancerosas/mortalidad , Estadística como Asunto , Análisis de SupervivenciaRESUMEN
Background: The CDKN2A gene encodes a cyclin dependent kinase inhibitor, p16, which promotes cell cycle arrest. Methylation of the promoter region trans-criptionally inactivates the gene. Aim: To study the relationship between methylation status of the prometer region of p16 gene, the immunohistochemical expression of p16 and clinical and morphological features of gallbladder carcinoma. Material and methods: We analyzed the methylation status of the promoter region of the CDKN2A gene in gallbladder adenocarcinomas using methylation specific PCR (MSP). We also used microsatellite markers near the CDKN2A gene to detect allelic imbalance (AI) and examined the tumors by immunohistochemistry (IHC) for p16 expression. Results: Of 38 gallbladder adenocarcinomas analyzed by IHC, 11 cases (29%) were negative for p16 protein. Nine (24%) had methylation of the promoter region of the CDKN2A gene. Twenty nine cases were negative for methylation, but four (14%) of these 29 exhibited AI at one or more of the microsatellite markers. CDKN2A promoter methylation was not associated with microsatellite instability (MSI-H). Conclusions: The inactivation of CDKN2A by methylation and/or deletion might play an important role in gallbladder carcinogenesis.
Asunto(s)
Humanos , Masculino , Femenino , Adulto , Regiones Promotoras Genéticas , Carcinoma/genética , Metilación de ADN , Neoplasias de la Vesícula Biliar/genética , Silenciador del Gen , Inhibidor p16 de la Quinasa Dependiente de Ciclina , Desequilibrio Alélico/genética , Carcinoma/patología , Distribución de Chi-Cuadrado , Neoplasias de la Vesícula Biliar/patología , Inmunohistoquímica , Repeticiones de Microsatélite/genética , Reacción en Cadena de la Polimerasa , Biomarcadores de TumorRESUMEN
BACKGROUND: The CDKN2A gene encodes a cyclin dependent kinase inhibitor, p16, which promotes cell cycle arrest. Methylation of the promoter region transcriptionally inactivates the gene. AIM: To study the relationship between methylation status of the prometer region of p16 gene, the immunohistochemical expression of p16 and clinical and morphological features of gallbladder carcinoma. MATERIAL AND METHODS: We analyzed the methylation status of the promoter region of the CDKN2A gene in gallbladder adenocarcinomas using methylation specific PCR (MSP). We also used microsatellite markers near the CDKN2A gene to detect allelic imbalance (AI) and examined the tumors by immunohistochemistry (IHC) for p16 expression. RESULTS: Of 38 gallbladder adenocarcinomas analyzed by IHC, 11 cases (29%) were negative for p16 protein. Nine (24%) had methylation of the promoter region of the CDKN2A gene. Twenty nine cases were negative for methylation, but four (14%) of these 29 exhibited AI at one or more of the microsatellite markers. CDKN2A promoter methylation was not associated with microsatellite instability (MSI-H). CONCLUSIONS: The inactivation of CDKN2A by methylation and/or deletion might play an important role in gallbladder carcinogenesis.