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 ac tivity, 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 fluorescen t 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 pat ient, telomerase activity was found in 9 of 9 myxoid/round-cell liposarcoma s and in 3 of 10 pure myxoid tumors. Elevated hTRT expression was found in 13 of 17 liposarcomas. All telomerase-positive tumors showed hTRT expressio n, whereas there were 3 cases showing hTRT expression without telomerase ac tivity. HTR mRNA expression was elevated in all 19 liposarcomas. Thus, only the levels of telomerase activity and of hTRT mRNA expression differentiat ed pure myxoid liposarcoma and myxoid/round-cell liposarcoma (p < 0.003 and p = 0.029, respectively). We believe that high levels of telomerase activi ty and of hTRT expression are associated with tumor progression from low-gr ade pure myxoid to highergrade malignant round-cell liposarcoma, and may co nsequently represent a useful prognostic marker for this histological sub-t ype of soft-tissue tumors. (C) 2000 Wiley-Liss Inc.