DNA-based polymerase chain reaction for detecting FUS-CREB3L2 in low-grade fibromyxoid sarcoma using formalin-fixed, paraffin-embedded tissue specimens.

Detection of the tumor-specific fusion gene, FUS-CREB3L2, is useful in the diagnosis of low-grade fibromyxoid sarcoma (LGFMS), especially by reverse transcription (RT)-polymerase chain reaction (PCR) using formalin-fixed, paraffin-embedded (FFPE) tumor tissues. Because FUS and CREB3L2 gene segments with their break points within exons are fused without interposed introns in many LGFMSs, DNA-based PCR may also be applicable to detect the FUS-CREB3L2 fusion gene using FFPE specimens. In this study, DNA and RNA were extracted from FFPE specimens of 16 and 19 LGFMSs, respectively, and PCR and RT-PCR were performed using primers that specifically amplify most of the junctional regions of the FUS-CREB3L2 fusion gene. RT-PCR analysis revealed FUS-CREB3L2 fusion transcripts in 16 of the 19 (84%) LGFMSs. In 14 informative examples, including 11 with detectable fusion transcripts by RT-PCR, DNA-based PCR amplified the FUS-CREB3L2 fusion gene in 9 (64%) examples. Nucleotide sequence analysis confirmed that PCR products were identical to the respective RT-PCR products in 8 cases. Although the sensitivity was not as high as RT-PCR, DNA-based PCR can be used as an alternative molecular approach for detecting the FUS-CREB3L2 fusion gene.