Background: Telomerase is a ribonucleoprotein that adds TTAGCG nucleot
ide repeats onto the ends of eukaryotic chromosomes to maintain telome
re integrity. Somatic cells do not express telomerase and stop dividin
g when the chromosomal ends are shortened critically after many cell d
ivisions. Immortal cell lines and cancer cells apparently have telomer
ase activity that contributes to an unlimited number of cell cycles. T
he purpose of our study is to investigate whether telomerase activity
is expressed in primary malignant turners of the skeletal system when
compared to adjacent normal tissue. Methods: Fresh tumor and normal ti
ssue was collected from 14 patients (10 males, 4 females; age range, 8
to 76 years) and protein extraction performed. The tumors included se
ven osteosarcomas (three examined before and after chemotherapy), two
chondrosarcomas, two spindle cell tumors, one hemangiopericytoma, one
chordoma, and one adamantinoma. Telomerase activity was analyzed by us
ing a highly sensitive polymerase chain reaction (PCR)-based assay (te
lomere repeat amplification protocol [TRAP]). Results: Telomerase acti
vity was found in 8 of 14 sarcoma patients (57%) using the TRAP assay.
Compared to HeLa cell extract (positive control), telomerase activity
in the tumor specimen ranged from 0 (in osteosarcoma) to 11.7% (in he
mangiopericytoma). There was variation in the number of telomeric repe
ats generated by telomerase. At least five telomeric bands (e.g. 50, 5
6, 62, 68, 74 bp) in a ladder pattern had to be present before telomer
ase activity was considered positive in our analysis. Conclusions: Tel
omerase activity may be an oncogenic sustaining event helping to maint
ain the transformed phenotype seen in malignant tumors of the bone. Th
e degree of telomerase activity varies among skeletal malignancies, bu
t was less than that observed in HeLa cells. The majority of osteosarc
omas showed no telomerase activity.