Reactivation of
telomerase, an
enzyme which elongates human telomeres, is associated with cell immortilization. In approximately 90% of malignant tumours
telomerase activity can be demonstrated, whereas in benign tumours it is mostly absent.
Chondrosarcomas are relatively rare malignant cartilaginous
neoplasms. A small number of
chondrosarcomas located centrally in bone arise secondarily to an
enchondroma, while the majority of
chondrosarcomas developing from the surface arise within the cartilage cap of an
osteochondroma. The histological distinction between a benign lesion and low-grade
chondrosarcoma is generally considered difficult. To investigate whether the progression towards
chondrosarcoma is characterized by reactivation of
telomerase activity, this study determined
telomerase activity in ten
enchondromas, five
osteochondromas, and 37
chondrosarcomas using the TRAP assay. In all tumour samples except one,
telomerase activity was absent. By adding tumour lysates to the positive control, an increasing inhibition of
telomerase activity was found with an increasing chondroid matrix, suggesting that it may contain inhibitory factors. Inhibition due to endogenous
RNAse or
Taq-polymerase inhibitors was excluded. The lack of detectable
telomerase activity in the high-grade component of a dedifferentiated
chondrosarcoma without matrix favours the possibility that
telomerase is truly absent. Either its true absence or inhibitory effects disabling
telomerase detection exclude the
telomerase TRAP assay as a diagnostic tool in the differential diagnosis of benign and low-grade malignant cartilaginous tumours.