High telomerase activity and high HTRT mRNA expression differentiate pure myxoid and myxoid/round-cell liposarcomas.

Molecular markers characterizing the transition of a myxoid to a more round-cell liposarcoma have not been described. To examine whether telomerase activity, hTRT and hTR mRNA expression were associated with tumor progression in myxoid liposarcoma, we investigated a total of 28 myxoid liposarcomas (13 pure myxoid tumors, 14 mixed-type tumors, and 1 pure round-cell variant) from 19 patients. Telomerase activity was detected by using the fluorescent PCR-based TRAP-assay. Expression of hTRT and hTR mRNAs was determined by the semi-quantitative RT-PCR. On the basis of only one tumor sample per patient, telomerase activity was found in 9 of 9 myxoid/round-cell liposarcomas and in 3 of 10 pure myxoid tumors. Elevated hTRT expression was found in 13 of 17 liposarcomas. All telomerase-positive tumors showed hTRT expression, whereas there were 3 cases showing hTRT expression without telomerase activity. HTR mRNA expression was elevated in all 19 liposarcomas. Thus, only the levels of telomerase activity and of hTRT mRNA expression differentiated pure myxoid liposarcoma and myxoid/round-cell liposarcoma (p < 0.003 and p = 0.029, respectively). We believe that high levels of telomerase activity and of hTRT expression are associated with tumor progression from low-grade pure myxoid to higher-grade malignant round-cell liposarcoma, and may consequently represent a useful prognostic marker for this histological sub-type of soft-tissue tumors.