This article reports three renal PNET that expressed EWS/FLI-1 fusion transcripts by RT-PCR, in addition to positive staining for MIC2 protein and neuron-specific enolase (NSE).
In conclusion, the detection of t(11;22) and EWS/FLI-1 fusion transcripts is considered to provide a novel adjunctive method for diagnosing renal PNET.
The chimeric gene EWS/FLI-1, the hallmark of the Ewing's sarcoma and primitive neuroectodermal tumor family, encodes a fusion protein with enhanced transcriptional activation properties and preserved recognition of canonical ETS binding sites.
These results suggest that EWS-Fli1 may play an important role in the proliferation of the tumor cells, and the EWS-Fli1 fusion RNA could be used as a target to inhibit the growth of Ewing's sarcoma and primitive neuroectodermal tumor with the specific antisense oligonucleotide.
EWSR1 FISH was sensitive among high-grade round cell sarcomas (positive in 100% of desmoplastic small round cell tumors and 96% of Ewing sarcoma/primitive neuroectodermal tumors) but not specific because clear cell sarcoma, extraskeletal myxoid chondrosarcoma, and a subset of round cell liposarcomas also harbor rearrangements of EWSR1.
However, the reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated EWS/FLI-1 fusion transcripts, confirming the histopathologic diagnosis of PNET.
EWS-FLI1 fusion transcripts were detected by reverse transcriptase polymerase chain reaction and direct sequencing, confirming the diagnosis of PNET/ES.
PNET arising in the mesentery is very rare, and we distinguished PNET from other tumors by immunohistochemical examination and by demonstration of the presence of EWS-FLI1 chimeric mRNA in the tumor.
This case of PNET/EWS is unique in the sense of showing the typical fusion transcript associated with this tumor both in the morphologically typical pretherapy tumor and in the sample from the post-therapy specimen showing neuroblastoma-like features.
We detected 2 types of EWS-ERG chimeric mRNA in 2 ES cell lines and 1 PNET tumor sample in addition to 4 types of EWS-FLI-1 chimeric mRNA in 11 ESs (4 cell lines and 7 tumor samples) and 4 PNETs (2 cell lines and 2 tumor samples).
Significantly, the DNA binding portion of FLI-1 is the 3' part of an oncogenic fusion transcript (termed EWS-FLI) in human Ewing's sarcoma and neuroepithelioma.
We obtained the final diagnosis of ES/PNET by immunohistochemical molecular study with positive staining for the MIC2 gene product (CD99) and a Ewing sarcoma breakpoint region 1 (EWSR1) gene rearrangement.
The EWS/FLI1 fusion gene found in Ewing's sarcoma and primitive neuroectodermal tumor, is able to transform certain cell lines by acting as an aberrant transcription factor.
The EWS gene, which maps to band q12 of human chromosome 22, is involved in a wide variety of human solid tumors including Ewing sarcoma, related primitive neuroectodermal tumors, malignant melanoma of soft parts and desmoplastic small round cell tumors.
EWS/FLI-1 is a chimeric protein formed by a tumor-specific 11;22 translocation found in both Ewing's sarcoma and primitive neuroectodermal tumor of childhood.
Ewing's sarcoma (ES) and primitive neuroectodermal tumor (PNET) are members of a tumor family consistently associated with chromosomal translocation and functional fusion of the EWS gene to any of several structurally related transcription factor genes.
EWS-Fli1, a fusion gene resulting from the chromosomal translocation t(11;22, q24;q12), encodes a transcriptional activator, promotes cellular transformation, and is often found in Ewing sarcoma and primitive neuroectodermal tumor.
Fluorescence in situ hybridization analysis of paraffin-embedded tissue revealed that three of four tumors were positive for a chromosomal translocation involving the EWS locus at 22q12, seen in more than 90% of cases of Ewing's sarcoma/malignant primitive neuroectodermal tumor.One case was not analyzable.
We found disagreement in only three samples: one ES/pPNET and one embryonal rhabdomyosarcoma harbor a PAX3-FOXO1 translocation (for ARMS), and one neuroepithelioma harboring a EWS-WT1 (for DSRCT).
The t(11;22) chromosomal translocation specifically linked to Ewing sarcoma and primitive neuroectodermal tumor results in a chimeric molecule fusing the amino-terminus-encoding region of the EWS gene to the carboxyl-terminal DNA-binding domain encoded by the FLI-1 gene.
Molecular testing demonstrated the expression of EWS/FLI1 fusion transcripts corresponding to the t(11;22)(q24;q12) translocation, which confirmed the diagnosis of PNET of the uterine cervix.
The EWS/Fli-1 fusion gene, a product of the translocation t(11;22, q24;q12), is detected in 85% of Ewing sarcomas and primitive neuroectodermal tumors.