NoEWS/FLI1 fusion transcripts in giant-cell tumors of bone

Abstract

Giant-cell tumor of bone (GCT) is a locally aggressive neoplasm of unknown etiology and pathogenesis. Cytogenetically, no consistent chromosomal alterations, apart from telomeric associations involving various chromosome ends, have been described. Recently, however, it was reported that by using highly sensitive nested RT-PCR, a high proportion of GCT displays chimeric EWS/FLI1 fusion transcripts, i.e., the molecular genetic feature previously known to be strongly associated with the Ewing family of tumors. Thus, we decided to perform single-step and nested RT-PCR analyses on fresh frozen samples from 10 cases of GCT, all of which had also been subjected to cytogenetic analysis. After short-term culturing, none of the samples displayed any t Giant-cell tumor of bone (GCT) is a relatively uncommon neoplasm, usually presenting between 20 -40 years of age. It preferentially involves the ends of the long bones, may be locally aggressive, but rarely metastasizes. 1 The etiology and pathogenesis are largely unknown and, so far, no consistent genetic alterations have been detected in GCT. Of the 35 cytogenetically abnormal cases that are included in the Mitelman Database of Chromosome Aberrations in Cancer, 2 all but 2 have near diploid chromosome numbers, and the most common type of alteration is telomeric association, i.e., end-to-end fusions of 2 chromosomes, most often affecting chromosome arms 11p, 15p, 19q, 20q, and 21p. 3 In addition to the telomeric associations, detected in 20 of the 35 cases described in the literature, a few recurrent numerical alterations have been described, the most common being loss of chromosome 12, detected in 4 cases. Thus, at the cytogenetic level, GCT is different from other bone tumors, which either show characteristic patterns of chromosomal imbalances (e.g., chondrosarcoma, osteosarcoma, and chordoma) or recurrent structural rearrangements (e.g., Ewing sarcoma, aneurysmal bone cysts and chondroma). 2 The notion that the pathogenesis of GCT is different from that of other bone tumors was recently challenged by a report claiming that fusion of the EWS and FLI1 genes, a molecular genetic event caused by the translocation t(11;22)(q24;q12) and a characteristic feature of the Ewing family of tumors, could be detected also in a large subset (13 of 15 analyzed cases) of GCT. 4 Although the chimeric EWS/FLI1 transcript was expressed at very low levels, requiring the use of highly sensitive, nested reverse transcriptase polymerase chain reaction (RT-PCR) analysis, the detected fusion transcripts were of the same type as previously described for Ewing tumors. Based on these findings, it was argued that EWS/ FLI1-positive tumor cell populations may influence the clinical behavior of GCT.To find out whether we could reproduce the results obtained by Scotlandi et al., 4 we subjected frozen tissue from 10 cases of GCT to single-step and nested RT-PCR analysis for the EWS/FLI1 fusion. MATERIAL AND METHODS PatientsClinical data on the 10 patients are summarized in Table I. RNA isolation and ele...

POU5F1, encoding a key regulator of stem cell pluripotency, is fused to EWSR1 in hidradenoma of the skin and mucoepidermoid carcinoma of the salivary glands

“…Partial chromatogram showing the EWSR1-POU5F1 junctions (arrow) and the predicted amino acid sequence of the chimaeric transcripts where a part of EWSR1 exon 6 is fused inframe to POU5F1 exon 2. (C) The quality of the cDNA synthesis was examined by amplification of 300 bp ABL cDNA fragments as previously described [19]. M = 1 kbp ladder.…”

Consistent Rearrangement of Chromosomal Band 6p21 with Generation of Fusion GenesJAZF1/PHF1andEPC1/PHF1in Endometrial Stromal Sarcoma

“…The primers used for PCR amplification and sequencing are listed in Table 2. cDNA quality was checked in each case using ABL1-specific primers (19).…”

Recurrent PRDM10 Gene Fusions in Undifferentiated Pleomorphic Sarcoma

“…Reverse transcription and PCR amplifications were performed as described previously (11,17). Primers specific for MED12, CITED2, and PRDM10 were designed to detect possible fusion transcripts (Supplementary Table S2).…”