Diagnostic significance of telomerase activity and telomere length in endoscopic sample of colorectal cancer

Telomeres are located on both ends of individual chromosomes in eukaryotes. It has been reported that telomerase activity and telomere reduction can be detected in most human cancers. We examined telomerase activity and telomere length in colorectal cancer tissues obtained by colonoscopy. Telomerase activity was examined by the TRAP (telomeric repeat amplification protocol) assay and was detected in 21 of 26 (81%) primary colorectal carcinoma tissues. Two of 9 (22%) colorectal polyp were telomerase positive. Telomere length was analyzed by Southern blotting and there was reduction in telomere lengths in 12 of 15 (80%) primary colorectal carcinoma and 3 of 6 colorectal polyp, compared to the corresponding normal colonic mucosa. Therefore, telomerase activity and telomere length may serve as an useful tool for preoperative cancer diagnosis.