Adenosine transporter ENT4 is a direct target of EWS/WT1 translocation product and is highly expressed in desmoplastic small round cell tumor.
BACKGROUND
Desmoplastic Small Round Cell Tumor (DSRCT) is a highly aggressive malignancy that affects mainly adolescents and young adults. A defining characteristic 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.


RESULTS
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 transcriptionally activated by both isoforms of EWS/WT1 as evidenced by promoter-reporter and chromatin immunoprecipitation (ChIP) analyses. Furthermore, ENT4 is highly and specifically expressed in primary tumors of DSRCT as well as in a 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-dependent manner.


CONCLUSIONS
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 transcript in DSRCT may represent an attractive pathway for targeting chemotherapeutic drugs into DSRCT.
Genetics of Development and Disease Branch, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
Hongjie
H
Li
Gromoslaw A
GA
Smolen
Lisa F
LF
Beers
Li
L
Xia
William
W
Gerald
Joanne
J
Wang
Daniel A
DA
Haber
Sean Bong
SB
Lee
D000241:Adenosine / Q000378:metabolism*; D001483:Base Sequence; D018288:Carcinoma, Small Cell / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers; D004305:Dose-Response Relationship, Drug; D033705:Equilibrative Nucleoside Transport Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011401:Promoter Regions, Genetic; D021381:Protein Transport; D034802:RNA-Binding Protein EWS / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025721:WT1 Proteins / Q000378:metabolism*
D017931:DNA Primers; D033705:Equilibrative Nucleoside Transport Proteins; D034802:RNA-Binding Protein EWS; C495988:SLC29A4 protein, human; D025721:WT1 Proteins; D000241:Adenosine