RESUMEN
DNA methylation, the addition of a methyl group to cytosines and adenosines, regulates gene expression on a level that is usually referred to as epigenetic, that is, stably maintained during cell divisions. In humans, aberrant DNA methylation is associated with several malignancies, including cancer and so-called imprinting disorders, making it an attractive target for diagnostic purposes. Here we give a brief introduction to the biology of DNA methylation and present the use of methylation biomarkers in laboratory medicine. DNA methylation assays have become the standard procedure in the diagnosis of imprinting disorders, and they are about to shift cancer diagnostics and prognostics to the next level of molecular medicine. However, there is evidence of problems associated with the introduction of such cancer assays in routine diagnostics. We review several assays that have been proposed for DNA methylation analysis. The assays presented analyse the methylation status of single loci and are based either on a bisulphite-treatment or on methylation-sensitive restriction of the DNA under investigation.
Asunto(s)
Metilación de ADN/genética , ADN/análisis , Impresión Genómica/genética , Neoplasias/genética , Epigénesis Genética , Humanos , Reacción en Cadena de la Polimerasa , SulfitosRESUMEN
Telomerase is a specialized ribonucleoprotein enzyme complex which prevents the loss of the telomere. The activity of telomerase can be up- and down-regulated by various oxidative stresses but the effect of physical exercise is not known, whereas the modifying effect of cancer on telomerase activity is well documented. In the first study, we investigated the effect of mild and strenuous exercise training on telomerase activity, assessed by a PCR ELISA kit. No alteration in telomerase activity was detected. In the second investigation, solid sarcoma cells were transplanted to control, exercise trained or exercise trained and still exercising mice. On the 16th day after the transplantation, the size of tumors in the exercise trained group was 72% and in the exercising group 57% (P < 0.05) of that in the controls. Telomerase activity and 8-hydroxy-2'-deoxyguanosine levels in the liver were not significantly altered by exercise and/or sarcoma. We conclude that mild and strenuous exercise training does not significantly affect the activity of telomerase in the systems studied. Exercise training during sarcoma significantly retards the development of tumors and could possibly serve as a positive adjunct to treatment.