TELOMERASE ACTIVITY IN GASTRIC-CANCER

Although many genetic alterations have been reported in gastric cancer , it is not known whether all gastric tumors are capable of indefinite proliferative potential, e.g., immortality. The expression of telomer ase and stabilization of telomeres are concomitant with the attainment of immortality in tumor cells; thus, the measurement of telomerase ac tivity in clinically obtained tumor samples may provide important info rmation useful both as a diagnostic marker to detect immortal cancer c ells in clinical materials and as a prognostic indicator of patient ou tcome. Telomerase activity was analyzed in 66 primary gastric cancers with the use of a PCR-based assay. The majority of tumors (85%) displa yed telomerase activity, but telomerase was undetectable in 10 tumors (15%), 8 of which were early stage tumors. Most of the tumors with tel omerase activity were large and of advanced stages, including metastas es. Survival rate of patients of tumors with detectable telomerase act ivity was significantly shorter than that of those without telomerase activity. Alterations of telomere length (reduced/elongated terminal r estriction fragments) were detected in 14 of 66 (21%) gastric cancers, and all 14 had telomerase activity, Cellular DNA contents revealed th at all 22 aneuploid tumors had detectable telomerase activity. The pre sent results indicate that telomerase activation may be required as a critical step in the multigenetic process of tumorigenesis, and that t elomerase is frequently but not always activated as a late event in ga stric cancer progression.