RESUMEN
Progressive telomere shortening with aging was studied in the normal liver tissue of 94 human subjects aged between 0 and 101 years old to determine the rate of telomere loss in 1 year. Telomere length demonstrated accelerated shortening with reduction of 55 base pairs (bp) per year. The mean telomere length in five neonates was 12.9 +/- 2.6 kilobase pairs (kbp), and that in one centenarian was 8.3 kbp. Mean telomere lengths by age group were 13.2 +/- 2.0 kbp (< or = 8 years; 10 subjects), 7.8 +/- 1.9 kbp (40-79 years; 29 subjects), and 7.5 +/- 2.0 kbp (> or = 80 years; 53 subjects), with reduction thus appearing to show slowing on the attainment of middle age. The difference of mean telomere lengths for two groups with or without advanced malignancies of other than liver origin was not significant in the older two groups. Despite the slow turnover of liver tissue, the overall reduction rate of telomere length decrease in 1 year was almost the same as that of digestive tract mucosa, with its very rapid renewal.
Asunto(s)
Envejecimiento/patología , Hígado/ultraestructura , Telómero , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana EdadRESUMEN
The hypothesis that telomeres in colorectal cancer cells exhibit age-related shortening, as in normal cells of the colorectal epithelium, was tested with samples of non-cancerous mucosa and cancer tissue from 124 patients (aged 29-97 years). Shortening with aging could be demonstrated for both normal and cancer tissues; regression analysis showed rates for length reduction of 44 and 50 base pair/year, respectively. Straight, essentially parallel, lines were obtained for the two cases, normal tissue values being about 2 kilobase pairs (kbp) higher, with a significant correlation between data at the individual patient level.
Asunto(s)
Neoplasias Colorrectales/genética , Intestino Grueso/metabolismo , Telómero/genética , Adulto , Anciano , Anciano de 80 o más Años , Southern Blotting , Neoplasias Colorrectales/patología , ADN/genética , ADN de Neoplasias/genética , Femenino , Humanos , Lactante , Mucosa Intestinal/metabolismo , Masculino , Persona de Mediana Edad , Análisis de RegresiónRESUMEN
In the present study, we analyzed both telomere length and telomerase activity in surgical and autopsy samples of non-neoplastic mucosa and carcinomas of the stomach. Telomere length, determined by Southern blot analysis, demonstrated progressive shortening with age in non-neoplastic gastric mucosal specimens from 38 human subjects aged between 0 and 99 years, with an average annual loss rate of 46 base pairs (bp). The mean (+/- SD) telomere length in 21 gastric carcinomas was 7.0 +/- 1.6 x 10(3) base pairs (1.6 kbp). In 20 (95%) of the 21 subjects, the values were smaller than those in the nonneoplastic gastric mucosa (mean shortening 1.8 kbp), although a strong correlation was observed for the paired data (r = 0.69, P = 0.0004). Similarly, telomere lengths in carcinomas were shorter than those for intestinal metaplasia (a mean difference of 1.1 kbp). Telomerase activity, estimated using the telomeric repeat amplification protocol assay, was positive in 18 (86%) of the 21 gastric carcinomas, without significant differences among the three histological types (well, moderately, and poorly differentiated adenocarcinomas) or with sex or age. The results suggest that telomere length and possibly shortening rates vary with the individual, and that examination of both non-neoplastic mucosa and tumors is necessary to improve our understanding of the significance of telomerase in neoplasia.
