Downing J R, Khandekar A, Shurtleff S A, Head D R, Parham D M, Webber B L, Pappo A S, Hulshof M G, Conn W P, Shapiro D N
Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105.
Am J Pathol. 1995 Mar;146(3):626-34.
Cytogenetic analysis has defined specific translocations associated with two of the most common small round cell tumors of childhood, t(11;22) in Ewing's sarcoma and t(2;13) in alveolar rhabdomyosarcoma. We and others have previously demonstrated the diagnostic utility of a reverse transcriptase polymerase chain reaction (RT-PCR) assay for the detection of the t(11;22) encoded EWS/FLI-1 chimeric message in Ewing's sarcoma. More recently, we have cloned the t(2;13)(q35;q14) translocation and have shown that it results in the fusion of the PAX3 gene on chromosome 2 to FKHR, a novel member of the fork-head family of transcription factors on chromosome 13. To define the morphological spectrum of childhood sarcomas that express the t(2;13) encoded PAX3/FKHR chimeric message, we have performed RT-PCR analysis on samples from 44 primary pediatric sarcomas and 8 sarcoma cell lines. PAX3/FKHR chimeric messages were detected in 24 of 27 alveolar, 2 of 12 embryonal, and 0 of 1 pleomorphic rhabdomyosarcoma and in 1 of 2 ectomesenchymomas. In contrast, none of 8 Ewing's sarcomas or 2 undifferentiated sarcomas expressed this message. Chimeric transcripts were detected in all cases with cytogenetic evidence of the (2;13) translocation, and in each case the chimeric PAX3/FKHR message had the identical junction sequence, suggesting that genomic chromosome breaks were clustered in a single intron in both genes. By combining the PAX3/FKHR RT-PCR assay with primers for detection of the Ewing's sarcoma t(11;22) encoded EWS/FLI-1 chimeric transcript, we have developed a multiplex RT-PCR reaction that allows the rapid and accurate identification of either translocation in a biopsy sample.
细胞遗传学分析已经明确了与儿童期两种最常见的小圆细胞肿瘤相关的特定易位，即尤因肉瘤中的t(11;22)和肺泡横纹肌肉瘤中的t(2;13)。我们和其他人之前已经证明了逆转录酶聚合酶链反应（RT-PCR）检测法在检测尤因肉瘤中t(11;22)编码的EWS/FLI-1嵌合信息方面的诊断效用。最近，我们克隆了t(2;13)(q35;q14)易位，并表明它导致2号染色体上的PAX3基因与13号染色体上叉头转录因子家族的一个新成员FKHR融合。为了确定表达t(2;13)编码的PAX3/FKHR嵌合信息的儿童肉瘤的形态学谱，我们对44例原发性儿科肉瘤样本和8个肉瘤细胞系进行了RT-PCR分析。在27例肺泡横纹肌肉瘤中的24例、12例胚胎性横纹肌肉瘤中的2例、1例多形性横纹肌肉瘤中的0例以及2例外间充质瘤中的1例中检测到了PAX3/FKHR嵌合信息。相比之下，8例尤因肉瘤或2例未分化肉瘤中均未表达此信息。在所有具有(2;13)易位细胞遗传学证据的病例中均检测到了嵌合转录本，并且在每种情况下，嵌合的PAX3/FKHR信息都具有相同的连接序列，这表明基因组染色体断裂聚集在两个基因的单个内含子中。通过将PAX3/FKHR RT-PCR检测法与用于检测尤因肉瘤t(11;22)编码的EWS/FLI-1嵌合转录本的引物相结合，我们开发了一种多重RT-PCR反应，该反应能够快速准确地鉴定活检样本中的任何一种易位。
