Apoptosis inducing and telomerase activity of serum-free mouse embryo in epidermal growth factor deprivation

Zwe-Ling Kong, PhD, Fulong Yeh, PhD

Cellular Immunology Laboratory, Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan, R.O.C.

Telomere shortening and telomerase activation in human somatic cells have been implicated in cell carcinogensis and cellular senescence. However, very little is known of the relation between telomerase activity and apoptosis. To study the role of telomerase in apoptosis, we assayed telomerase activity in Serum-free mouse embryo (SFME) cells line. SFME cells have remained diploid for more than 200 generations, they are acutely dependent on epidermal growth factor (EGF) for survival, and lack gross chromosomal alterations and they are nontumorigeneic in vivo. We confirmed that without EGF, the cells became small and severely degenerate with time and their genomic DNA exhibited a pattern of fragmentation resulting from endonuclease activation characteristic of cells undergoing apoptosis. A PCR-based assay (designated TRAP) was used to measure telomerase activity in SFME, ras-myc-SFME, ras-SFME, ras-myc-Liver (BALB/c liver cells metathesis from ras-myc-SFME) cells line and 16-old-day-BALB/c mouse embryo. This assay detected no telomerase activity in these cell lines and the embryo tissue. The data suggest that the stabilized telomeres of these cell lines and mouse embryo by a novel and as yet unidentified mechanism. The findings suggest that this specific activity came from RNA but DNA. The specific activities were also found in adult and newborn BALB/c liver extracts.

KEY WORDS: differentiation, Oncogene.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Apoptosis - Molecular Mechanisms.