Adenosine transporter ENT4 is a direct target of EWS/WT1 translocation product and is highly expressed in desmoplastic small round cell tumor

Abstract

Background: Desmoplastic Small Round Cell Tumor (DSRCT) is a highly aggressive malignancy that affects mainly adolescents and young adults. A defining charateristics of DSRCT is a specific chromosomal translocation, t(11;22)(p13;q12), that fuses EWS with WT1, leading to a production of two isoforms of chimeric transcription factor, EWS/ WT1(-KTS) and EWS/WT1(+KTS). The chimeric proteins are thought to play critical roles in various stages of oncogenesis through aberrant transcription of different genes, but only a few of these genes have been identified. Methodology/Principal Findings: We report the identification of a new target of EWS/WT1, ENT4 (equilibrative nucleoside transporter 4) which encodes a pH-dependent adenosine transporter. ENT4 is transcriptioanlly activated by both isoforms of EWS/WT1 as evidenced by promoter-reporter and chromatin immunoprecipitation (Ch1P) analyses. Furthermore, ENT4 is highly and specifically expressed in primarily tumors of DSRCT as well as in DSRCT cell line, JN-DSRCT-1. Treatment of JN-DSRCT-1 cells with adenosine analogs, such as 2-chloro-2′-deoxyadenosine (2-CdA), resulted in an increased cytotoxic response in dose- and pH-depoendent manner. Conclusions/Significance: Our detailed analyses of a novel target of EWS/ WT1 in DSRCT reveal an insight into the oncogenic mechanism of EWS-fusion chromosomal translocation gene products and provide a new marker for DSRCT. Furthermore, identification of ENT4 as a highly expressed trancript in DSRCT may represent an attractive pathway for targeting chemotherapeutic drugs into DSRCT.