Chemiluminescent measurement of telomere DNA content in archival biopsies of colon adenocarcinoma

Telomeres are nucleoprotein complexes that protect the ends of eucaryotic chromosomes from degradation and recombination. In humans, telomeres measure 10-12 kbp in normal somatic cells, but they scarcely reach 1-2 kbp in tumor cells of rapid growth, due to the incomplete replication of these structures in each mitotic division. Telomeres shorten with age, which can be associated to genomic instability and to an increment of the risk of suffering from cancer. The standard method to measure the telomere length is the analysis of telomeric restriction fragments by Southern blot. However, a precise determination is not possible when the DNA is broken into small fragments or if it is scarce. In this work, a slot blot assay was adapted to quantify the relative content, instead of the length, of telomeric DNA from paraffin-embedded archival specimens of colon adenocarcinoma. The telomeric DNA content could be reproducibly measured with hardly 75 ng of highly degraded genomic DNA by chemiluminescent detection for hybridization.