[1074] Re-Evaluation of TFE3 Immunostaining in UOK 145 Cell Line and a Novel Subtype of PSF-TFE3 Translocation in Xp11 Translocation Renal Cell Carcinoma

Minghao Zhong, Bing Zhu, Maria Brassesco, Marston Linehan, Maria Merino, Carlos Cordon-Cardo, David Zhang, Stephen Rohan, Ximing Yang. Northwestern University, Chicago; University of São Paulo, São Paulo, Brazil; NCI, Bethesda; The Mount Sinai School of Medicine, New York

Background: Xp11 translocation renal cell carcinoma (RCC) is a subtype of RCC characterized by translocations involving a breakpoint at TFE3 gene (Xp11.2). Moderate or strong nuclear TFE3 immunoreactivity has been approved as a specific diagnostic marker for this type of tumor. However, exclusive cytoplasmic localization of TFE3 fusion protein was reported in UOK 145 cell, a RCC cell line harboring PSF-TFE3 translocation. The purpose of this study is to investigate the discrepancy of the literatures, regarding TFE3 staining pattern in Xp11 translocation RCC.
Design: UOK 145 cell line and two other fresh frozen tissues from cytogenetic proved PSF-TFE3 translocation RCC were collected. All samples were subject for histopathologic evaluation, TFE3 IHC, RT-PCR and Sanger sequencing analysis.
Results: Strong nuclear TFE3 staining was demonstrated on all samples including UOK 145 cell line which has been previously reported with exclusively cytoplasmic TFE3 pattern. Previously reported cytoplasmic TFE3 pattern may due to experimental artifacts, such as transient transfection, GFP interfering subcellular localization. On RT-PCR and Sanger sequencing, UOK 145 cell line and one of PSF-TFE3 translocation RCC were confirmed as previously reported PSF-TFE3 gene fusion with PSF exon 9 to TFE3 exon 6. Interestingly, a novel PSF-TFE3 gene fusion with PSF exon 9 to TFE3 exon 5 was detected in the other RCC sample.
Conclusions: 1. We demonstrated that UOK 145 cell, reported previously with exclusively cytoplasmic TFE3 pattern, is indeed with strong nuclear staining. In addition, one RCC sample with an identical gene fusion as UOK 145 cell line, showed the same nuclear staining.
2. We found a novel PSF-TFE3 gene fusion involving PSF exon 9 to TFE3 exon 5.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 104, Wednesday Morning

 

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