engleski

Molecular detection of the translocation t(11 ; 22) in patients with Ewing sarcoma and primitive neuroectodermal tumour

Purpose. The Ewing sarcoma tumour family includes peripheral neuroectodermal tumour also and appears as bone or soft tissue lesion in a child or young adult. A reciprocal translocation resulting in fusion of the EWS gene with a member of the ETS family of transcription factors is a highly specific diagnostic marker for this group of tumours. The most frequent translocation is EWS-FLI1 t(11 ; 22)(q24 ; q12) in 90 to 95% cases. Method. From October 2003 until January 2005 we received 7 tumour samples (fixed in 10% buffered formalin and paraffin-embedded), 7 blood samples (1 in pair) of patients diagnosed as Ewing sarcoma or PNET and 1 sample of bone marrow. Total RNA was isolated from deparafinized tissue sections and preserved blood samples by phenol/guanidine isothiocynate extraction. RNA sample with different diagnosis and one tube without RNA were used as negative control. The EWS-FLI1 fusion transcripts were detected by RT-PCR using primers EWS 22.2 Bam and FLI1C that specifically amplify both 125 pb type 1 fusion and 191 pb type 2 variant. Results. All samples were successfully amplified for phosphoglycerate kinase. Four paraffin samples were positive for type 1 EWS-FLI1 fusion, three for type 2. Non of the blood samples and bone marrow showed positivity for any of the two fusion transcripts. Conclusion. We introduced fast, reliable and specific RT-PCR assay for molecular detection of the t(11 ; 22) translocations. This assay could be useful tesdt for diagnostically difficult cases, for monitoring minimasl residual disease and micrometastatic disease in peripheral blood and bone marrow. Also distinguishing type 1 and type 2 EWS/FLI1 transcripts are important prognostic parameters - type 1 is better survival parameter.

Ewing sarcoma; translocation; molecular genetics

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