The renal cell carcinomas associated with Xp11 translocations (Xp11 translocation RCCs) harbor gene fusions involving TFE3, a member of the microphthalmia-associated transcription factor (MiTF) family. In the present study, we identified a novel partner of TFE3, Ewing sarcoma breakpoint region 1 (EWSR1), in an Xp11 translocation RCC. A 57-year-old Japanese woman without special disease history was referred to us for treatment of an RCC. The resected tumor displayed an alveolar growth pattern with high-grade nuclei. The tumor was diffusely positive for TFE3 and cathepsin K. Anchored multiplex PCR revealed a novel fusion, EWSR1-TFE3. Fluorescent in situ hybridization analysis demonstrated the rearrangements of EWSR1 and TFE3. RT-PCR analysis confirmed the chimeric transcript. No neoplasm with EWSR1-TFE3 has been reported so far, in any organ. The results will expand the genomic spectrums of Xp11 translocation RCCs and contribute to better understanding of the roles of the MiTF family in the oncogenic process.
Keywords: Chimeric transcript; EWSR1; Microphthalmia-associated transcription factor (MiTF); TFE3; Xp11 translocation renal cell carcinoma.