title: Single enantiomer of YK-4-279 demonstrates specificity in targeting the oncogene EWS-FLI1.
abstract: Oncogenic fusion proteins, such as EWS-FLI1, are excellent therapeutic targets as they are only located within the tumor. However, there are currently no agents targeted toward transcription factors, which are often considered to be 'undruggable.'  A considerable body of evidence is accruing that refutes this claim based upon the intrinsic disorder of transcription factors.  Our previous studies show that RNA Helicase A (RHA) enhances the oncogenesis of EWS-FLI1, a putative intrinsically disordered protein.  Interruption of this protein-protein complex by small molecule inhibitors validates this interaction as a unique therapeutic target.  Single enantiomer activity from a chiral compound has been recognized as strong evidence for specificity in a small molecule-protein interaction.  Our compound, YK-4-279, has a chiral center and can be separated into two enantiomers by chiral HPLC.  We show that there is a significant difference in activity between the two enantiomers.  (S)-YK-4-279 is able to disrupt binding between EWS-FLI1 and RHA in an immunoprecipitation assay and blocks the transcriptional activity of EWS-FLI1, while (R)-YK-4-279 cannot.  Enantiospecific effects are also established in cytotoxicity assays and caspase assays, where up to a log-fold difference is seen between (S)-YK-4-279 and the racemic YK-4-279.  Our findings indicate that only one enantiomer of our small molecule is able to specifically target a protein-protein interaction. This work is significant for its identification of a single enantiomer effect upon a protein interaction suggesting that small molecule targeting of intrinsically disordered proteins can be specific. Furthermore, proving YK-4-279 has only one functional enantiomer will be helpful in moving this compound towards clinical trials.
authors.affiliation: Department of Oncology, Georgetown University Lombardi Comprehensive Cancer Center, Washington, DC, USA.
authors.forename: Julie S
authors.initials: JS
authors.lastname: Barber-Rotenberg
authors.forename: Saravana P
authors.initials: SP
authors.lastname: Selvanathan
authors.forename: Yali
authors.initials: Y
authors.lastname: Kong
authors.forename: Hayriye V
authors.initials: HV
authors.lastname: Erkizan
authors.forename: Tara M
authors.initials: TM
authors.lastname: Snyder
authors.forename: S Peter
authors.initials: SP
authors.lastname: Hong
authors.forename: Christina L
authors.initials: CL
authors.lastname: Kobs
authors.forename: Natalie L
authors.initials: NL
authors.lastname: South
authors.forename: Steven
authors.initials: S
authors.lastname: Summer
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Monroe
authors.forename: Maksymilian
authors.initials: M
authors.lastname: Chruszcz
authors.forename: Veselin
authors.initials: V
authors.lastname: Dobrev
authors.forename: Perrer N
authors.initials: PN
authors.lastname: Tosso
authors.forename: Lauren J
authors.initials: LJ
authors.lastname: Scher
authors.forename: Wladek
authors.initials: W
authors.lastname: Minor
authors.forename: Milton L
authors.initials: ML
authors.lastname: Brown
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Metallo
authors.forename: Aykut
authors.initials: A
authors.lastname: Üren
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Toretsky
mesh_terms: D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D015514:Oncogene Proteins, Fusion / Q000037:antagonists & inhibitors*; D051789:Proto-Oncogene Protein c-fli-1 / Q000037:antagonists & inhibitors*; D034802:RNA-Binding Protein EWS / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012512:Sarcoma, Ewing / Q000188:drug therapy*; D013237:Stereoisomerism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D014183:Transplantation, Heterologous
chemical_list: C106031:EWS-FLI fusion protein; D007211:Indoles; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors; C562345:YK 4-279; D053148:Caspase 3