title: Lurbinectedin Inactivates the Ewing Sarcoma Oncoprotein EWS-FLI1 by Redistributing It within the Nucleus.
abstract: There is a great need to develop novel approaches to target oncogenic transcription factors with small molecules. Ewing sarcoma is emblematic of this need, as it depends on the continued activity of the EWS-FLI1 transcription factor to maintain the malignant phenotype. We have previously shown that the small molecule trabectedin interferes with EWS-FLI1. Here, we report important mechanistic advances and a second-generation inhibitor to provide insight into the therapeutic targeting of EWS-FLI1. We discovered that trabectedin functionally inactivated EWS-FLI1 by redistributing the protein within the nucleus to the nucleolus. This effect was rooted in the wild-type functions of the EWSR1, compromising the N-terminal half of the chimeric oncoprotein, which is known to be similarly redistributed within the nucleus in the presence of UV light damage. A second-generation trabectedin analogue lurbinectedin (PM01183) caused the same nuclear redistribution of EWS-FLI1, leading to a loss of activity at the promoter, mRNA, and protein levels of expression. Tumor xenograft studies confirmed this effect, and it was increased in combination with irinotecan, leading to tumor regression and replacement of Ewing sarcoma cells with benign fat cells. The net result of combined lurbinectedin and irinotecan treatment was a complete reversal of EWS-FLI1 activity and elimination of established tumors in 30% to 70% of mice after only 11 days of therapy. Our results illustrate the preclinical safety and efficacy of a disease-specific therapy targeting the central oncogenic driver in Ewing sarcoma. Cancer Res; 76(22); 6657-68. ©2016 AACR.
authors.affiliation: Department of Cancer Biology, Vanderbilt University, Nashville, Tennessee.
authors.forename: Matt L
authors.initials: ML
authors.lastname: Harlow
authors.affiliation: Department of Pediatrics, Vanderbilt University, Nashville, Tennessee.
authors.forename: Nichole
authors.initials: N
authors.lastname: Maloney
authors.affiliation: Epithelial Biology Center, Vanderbilt University School of Medicine, Nashville, Tennessee.
authors.forename: Joseph
authors.initials: J
authors.lastname: Roland
authors.affiliation: PharmaMar, Madrid, Spain.
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Guillen Navarro
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Easton
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Kitchen-Goosen
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Elissa A
authors.initials: EA
authors.lastname: Boguslawski
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Zachary B
authors.initials: ZB
authors.lastname: Madaj
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Ben K
authors.initials: BK
authors.lastname: Johnson
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Bowman
authors.affiliation: IRCCS - Instituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: D'Incalci
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Winn
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Lisa
authors.initials: L
authors.lastname: Turner
authors.affiliation: Van Andel Research Institute, Grand Rapids, Michigan.
authors.forename: Galen
authors.initials: G
authors.lastname: Hostetter
authors.affiliation: PharmaMar, Madrid, Spain.
authors.forename: Carlos María
authors.initials: CM
authors.lastname: Galmarini
authors.affiliation: PharmaMar, Madrid, Spain.
authors.forename: Pablo M
authors.initials: PM
authors.lastname: Aviles
authors.affiliation: Department of Pediatrics, Vanderbilt University, Nashville, Tennessee. patrick.grohar@vai.org.|Van Andel Research Institute, Grand Rapids, Michigan.|Helen De Vos Children's Hospital, Grand Rapids, Michigan.|Department of Pediatrics, Michigan State University, Grand Rapids, Michigan.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Grohar
mesh_terms: D000818:Animals; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D000077146:Irinotecan; D051379:Mice; D008819:Mice, Nude; D015513:Oncogene Proteins / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics*; D034802:RNA-Binding Protein EWS / Q000235:genetics*; D012512:Sarcoma, Ewing / Q000188:drug therapy* / Q000473:pathology
chemical_list: C106031:EWS-FLI fusion protein; D015513:Oncogene Proteins; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D000077146:Irinotecan; D002166:Camptothecin