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World J Gastroenterol. Jul 28, 2007; 13(28): 3868-3872
Published online Jul 28, 2007. doi: 10.3748/wjg.v13.i28.3868
Telomerase activity in colorectal cancer, prognostic factor and implications in the microsatellite instability pathway
M Vidaurreta, ML Maestro, S Rafael, S Veganzones, MT Sanz-Casla, J Cerdán, M Arroyo
M Vidaurreta, ML Maestro, S Rafael, S Veganzones, MT Sanz-Casla, J Cerdán, M Arroyol, Servicio de Análisis Clínicos, Hospital Clínico San Carlos, Madrid 28040, Spain
J Cerdán, Servicio de Cirugía General III, Hospital Clínico San Carlos, Madrid 28040, Spain
Author contributions: All authors contributed equally to the work.
Supported by grants from the Comunidad Autonoma de Madrid, Madrid, Spain, No. 08.1/0012/1999 and from the Fondo de Investigaciones Sanitarias, Spain, PI030514
Correspondence to: Dr. ML Maestro, Department of Clinical Analysis, Hospital Clínico San Carlos, c/Martín Lagos s/n, Madrid 28040, Spain. mmaestro.hcsc@salud.madrid.org
Telephone: +34-91-3303171 Fax: +34-91-3303280
Received: March 6, 2007
Revised: March 23, 2007
Accepted: March 31, 2007
Published online: July 28, 2007
Abstract

AIM: To determine whether the telomerase activity is related to the Microsatellite instability (MSI) genetic pathway and whether it means a difference in the survival.

METHODS: The population consisted of 97 colorectal cancer patients. MSI determination was performed in accordance with the NCI criteria using PCR and Genescan. Telomerase activity was determined by the TRAP-assay, an ELISA procedure based on the amplification of telomeric repeat sequences.

RESULTS: 6.2% showed high MSI (MSI-H), 10.3% showed low MSI (MSI-L) and 83.5% did not show this alteration (MSS). Positive telomerase activity was detected in 92.8% of the patients. 83.3% of MSI-H tumors showed positive telomerase against 93.8% of MSS tumors. In the overall survival analysis the absence of telomerase activity conferred a better prognosis.

CONCLUSION: Previous works have shown that tumors which develop via the MSI pathway present a better prognosis. No link between telomerase activity and MSI status is observed, although sample sizes are small. Patients with telomerase negative tumors had better overall survival than patients with telomerase positive tumors.

Keywords: Microsatellite instability; Telomerase; Colore-ctal cancer; Prognosis