The chimeric EWS-WT1 gene product in the desmoplastic small round cell tumor: Molecular detection and alternative transcripts
- Memorial Sloan-Kettering Cancer Center, New York, NY (United States)
The desmoplastic small round cell tumor (DSRCT) is a recently recognized aggressive type of primitive sarcoma occurring mainly in young males. Previous cytogenetic reports have identified a recurrent translocation in DSRCT, t(11;22)(p13;q12). We have recently shown that this translocation represents a rearrangement between the EWS and WT1 genes, normally located at 22q12 and 11p13, respectively, generating a fusion gene which encodes a chimeric RNA resulting from an in-frame junction of EWS exon 7 to WT1 exon 8. Thus, this chimeric RNA encodes a putative protein in which the RNA-binding domain of EWS is replaced by the three C-terminal zinc fingers of the WT1 DNA-binding domain. We have now assessed the molecular detection of this rearrangement in a panel of 7 DSRCTs and 38 other small round cell tumors, and we have examined the WT1 portion of the chimeric RNA for the presence of the previously reported splice variants of the zinc-finger DNA-binding domain of WT1. Reverse transcriptase PCR (RT-PCR) revealed a single identical product in 4/5 cases tested, including a case in which a t(11;22)(p13;q12) by karyotyping. By Southern blotting, rearrangement of both EWS and WT1 was detectable in 3/6 cases, EWS alone in 1/6, and neither in 2/6. Histologically, the sole sample negative by both methods contained very scanty viable tumor. EWS-WT1 RT-PCR was negative in 16 Wilms` tumors, 12 rhadomyosarcomas, and 10 Ewing`s sarcomas. RT-PCR with splice site-specific primers showed the chimeric EWS-WT1 transcripts to include both splice variants of the zinc-finger domain of WT1, {open_quotes}+KTS{close_quotes} and {open_quotes}-KTS{close_quotes}. The t(11;22)(p13;q12) of DSRCT is most reliably detected by RT-PCR, and results in a specific and structurally highly consistent EWS-WT1 chimeric transcript which may interact with the normal targets of both splice variants of WT1.
- OSTI ID:
- 133502
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0230
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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