title: Targeting Glutathione S-transferase M4 in Ewing sarcoma.
abstract: Ewing sarcoma is a malignant pediatric bone and soft tissue tumor. Although the 5-year survival rate of localized disease approaches 75%, the prognosis of metastatic and/or therapy-resistant disease remains dismal despite the wide use of aggressive therapeutic strategies. We previously reported that high expression of glutathione S-transferase M4 (GSTM4) in primary tumors correlates with poor patient outcomes. GSTM4 is required for oncogenic transformation and mediates resistance to chemotherapeutic drugs in Ewing sarcoma cells. Here, we performed RNA-sequencing analyses of Ewing sarcoma cells and combined our results with publicly available datasets to demonstrate that GSTM4 is a major GST specifically expressed in Ewing sarcoma. Pharmacological inhibition of GSTM4 activity using a pan GST inhibitor, 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio) hexanol (NBDHEX), significantly limited cellular proliferation and oncogenic transformation of Ewing sarcoma cells. Moreover, combined use of NBDHEX and etoposide synergistically increased cytotoxicity, suggesting a role for GSTM4 as an inhibitor of apoptosis. Mechanistic studies revealed that GSTM4 limits apoptosis owing to its ability to interact with Apoptosis Signal-regulating Kinase 1 (ASK1) and inhibit signaling via the c-Jun N-terminal Kinase axis. To exploit our observation that GSTM4 expression is specifically up-regulated in Ewing sarcoma, we tested the effect of a GSTM4-activated anti-cancer agent, O(2)-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate or JS-K, on tumor growth and survival. We found that JS-K robustly decreased Ewing sarcoma cell viability and xenograft tumor growth and improved overall survival of xenograft mice. Our data suggest that GSTM4 is a novel therapeutic target for the treatment of high GSTM4-expressing Ewing sarcoma. Strategies that combine standard chemotherapy with agents that inhibit GSTM4, that are activated by GSTM4, or that block GSTM4/ASK1 interactions, can potentially be more specific and/or efficacious than standard therapeutic approaches.
authors.affiliation: Center for Children's Cancer Research, Huntsman Cancer Institute, University of Utah , Salt Lake City, UT , USA.
authors.forename: Rupeng
authors.initials: R
authors.lastname: Zhuo
authors.affiliation: Department of Internal Medicine, Division of Hematology and Hematologic Malignancies, University of Utah , Salt Lake City, UT , USA.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Kosak
authors.affiliation: Center for Children's Cancer Research, Huntsman Cancer Institute, University of Utah , Salt Lake City, UT , USA.
authors.forename: Savita
authors.initials: S
authors.lastname: Sankar
authors.affiliation: Center for Children's Cancer Research, Huntsman Cancer Institute, University of Utah , Salt Lake City, UT , USA.
authors.forename: Elizabeth T
authors.initials: ET
authors.lastname: Wiles
authors.affiliation: Microarray and Genomic Analysis Core Facility, Huntsman Cancer Institute, University of Utah , Salt Lake City, UT , USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Medicinal Chemistry, University of Utah , Salt Lake City, UT , USA.
authors.forename: Jianxing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Pediatrics, New York Medical College , Valhalla, NY , USA.
authors.forename: Janet
authors.initials: J
authors.lastname: Ayello
authors.affiliation: Department of Medicinal Chemistry, University of Utah , Salt Lake City, UT , USA.
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Prestwich
authors.affiliation: Department of Internal Medicine, Division of Hematology and Hematologic Malignancies, University of Utah , Salt Lake City, UT , USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Shami
authors.affiliation: Department of Pediatrics, New York Medical College , Valhalla, NY , USA ; Department of Medicine, New York Medical College , Valhalla, NY , USA ; Department of Microbiology and Immunology, New York Medical College , Valhalla, NY , USA ; Department of Cell Biology and Anatomy, New York Medical College , Valhalla, NY , USA ; Department of Pathology, New York Medical College , Valhalla, NY , USA.
authors.forename: Mitchell S
authors.initials: MS
authors.lastname: Cairo
authors.affiliation: Center for Children's Cancer Research, Huntsman Cancer Institute, University of Utah , Salt Lake City, UT , USA ; Division of Pediatric Hematology/Oncology, School of Medicine, University of Utah , Salt Lake City, UT , USA.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Lessnick
authors.affiliation: Department of Pediatrics, New York Medical College , Valhalla, NY , USA ; Department of Pathology, New York Medical College , Valhalla, NY , USA.
authors.forename: Wen
authors.initials: W
authors.lastname: Luo
keywords: Ewing sarcoma; GSTM4; JS-K; NBDHEX; drug resistance