Detection of COL1 A1-PDGFB Fusion Transcripts in Dermatofibrosarcoma Protuberans by Reverse Transcription-Polymerase Chain Reaction Using Archival Formalin-Fixed, Paraffin-Embedded Tissues

Abstract

The reciprocal translocation t(17;22)(q22;q13) and a supernumerary ring chromosome, r(17;22), derived from the translocation, have been shown to be highly characteristic of dermatofibrosarcoma protuberans (DFSP). Its consequence is a fusion of two genes, a collagen type I alpha 1 gene (COL1A1) and platelet-derived growth factor B-chain gene (PDGFB). The COL1A1-PDGFB fusion gene, is expected to be a diagnostic molecular assay. However, previous studies on this subject were mostly based on frozen tissue specimens or cultured tumor cells. In this present study, the investigators conducted a reverse transcription (RT)-polymerase chain reaction (PCR) assay to detect the COL1A1-PDGFB fusion transcripts using archival formalin-fixed, paraffin-embedded tumor specimens from 12 patients with DFSP. To amplify the fusion transcripts, a specific COL1A1 forward and PDGFB reverse primers were designed for single step PCR. The COL1A1-PDGFB fusion transcripts could be detected in 10 of 12 paraffin-embedded DFSP tumor specimens (83%). Subsequent sequence analysis using the PCR products confirmed that the detected messages were derived from gene fusions composed of PDGFB exon 2 and different regions of the COL1A1 gene (exon 8, 10, 22, 24, 32, 38, 45 or 46). Two samples of Bednar tumor included in this series also contained the fusion transcripts. In sample of DFSP with fibrosarcomatous transformation, the COL1A1-PDGFB could not be detected in the fibrosarcoma areas of the third recurrence, though the chimeric transcripts were identified in the ordinary DFSP areas of the first recurrence. No fusion transcripts could be amplified in non-DFSP lesions, including 10 dermatofibromas and 9 malignant fibrous histiocytomas. These results indicate that this molecular assay could be applied to archival formalin-fixed, paraffin-embedded tumor tissues as a diagnostic aid for DFSP.

Low-grade Sarcomas with CD34-Positive Fibroblasts and Low-Grade Myofibroblastic Sarcomas

“…The same abnormalities have also been shown in fibrosarcoma arising in DFS, in which COL1A1-PDGFB transcripts have been demonstrated [18,20]. Other rearrangements, including t(2;17) and t(9;22), have rarely been found in DFS [21].…”

“…DFS has a reciprocal translocation, t(17;22) (q22;q13) (with a supernumerary ring chromosome) resulting in fusion of the genes COL1A (17q21-22) and PDGFB1 (22q13) [16][17][18][19]. The same abnormalities have also been shown in fibrosarcoma arising in DFS, in which COL1A1-PDGFB transcripts have been demonstrated [18,20].…”

Current treatment options in dermatofibrosarcoma protuberans

“…The pathogenetically important result of the speciWc aberration of DFSP is the expression of the fusion gene COL1A1-PDGFB (Wang et al 1999;Maki et al 2002;Sandberg and Bridge 2003). PDGFB is placed under the control of the COL1A1 promoter.…”

Detection of COL1A1-PDGFB fusion transcripts and PDGFB/PDGFRB mRNA expression in dermatofibrosarcoma protuberans

“…The COL1A1 primers corresponded to the alpha-helical domain of the COL1A1 gene (exons 6-49). Some primers were the same as described previously; 7 however, other primers were designed using primer 3 (http:// frodo.wi.mit.edu/cgi-bin/primer3/primer3_www.cgi). The PCR profile consisted of 45 cycles of denaturation at 941C for 1 min, annealing at 661C for 45 s, and elongation at 721C for 50 s, followed by a final extension at 721C for 10 min.…”