RESUMEN
Many molecular investigations of colorectal cancer (CRC) have suggested that the accumulation of specific mutations in proto-oncogenes and tumor suppressor genes regulating cell growth via signal transduction trigger the stagewise progression to malignancy. In this study, the frequency, location, and type of mutations of the K-ras proto-oncogene exon I and p53 tumor suppressor gene exons 5-8 were analyzed in colorectal carcinomas of 65 patients from Central Europe, using polymerase chain reaction (PCR)-cold single-strand conformation polymorphism (SSCP) screening and direct sequencing. The incidence of K-ras activating mutations in these Central European samples was lower (25%) compared to that obtained in American and western European populations (40-50% at least), while the incidence of p53 inactivating mutations was similar (58%). These results suggest that some other genetically linked mechanisms may play a role in CRC development and progression, and hence K-ras and p53 mutations cannot be considered to be universal genetic markers for CRC.
Asunto(s)
Neoplasias Colorrectales/genética , Genes ras/genética , Proteína p53 Supresora de Tumor/genética , Neoplasias Colorrectales/metabolismo , Cartilla de ADN , ADN de Neoplasias/genética , ADN de Neoplasias/aislamiento & purificación , Europa (Continente) , Exones/genética , Humanos , Intrones/genética , Polimorfismo Conformacional Retorcido-Simple , Proto-Oncogenes Mas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de ADNRESUMEN
The authors have studied the AgNORs counts in intraepithelial lesions of the uterine cervix. The following values were obtained (mean +/- SD AgNORs/cell): normal specimens--2.11 +/- 0.98; mild dysplasia--2.83 +/- 1.12; moderate dysplasia--3.42 +/- 1.13; severe dysplasia--3.55 +/- 1.28; carcinoma in situ--4.63 +/- 1.34; glandular extensions of carcinoma in situ--4.64 +/- 0.98. The values in moderate and severe dysplasia were similar, an argument for grouping these categories in the high-grade lesions. AgNORs counts in carcinoma in situ were, however, higher than in severe dysplasia, suggesting a continuous evolution of the neoplastic process.
