Identification of a Novel SYK/c-MYC/MALAT1 Signaling Pathway and Its Potential Therapeutic Value in Ewing Sarcoma.
Purpose:Ewing sarcoma (EWS) is a devastating soft tissue sarcoma affecting predominantly young individuals. Tyrosine kinases (TK) and associated pathways are continuously activated in many malignancies, including EWS; these enzymes provide candidate therapeutic targets.Experimental Design:Two high-throughput screens (a siRNA library and a small-molecule inhibitor library) were performed in EWS cells to establish candidate targets. Spleen tyrosine kinase (SYK) phosphorylation was assessed in EWS patients and cell lines. SYK was inhibited by a variety of genetic and pharmacological approaches, and SYK-regulated pathways were investigated by cDNA microarrays. The transcriptional regulation of MALAT1 was examined by ChIP-qPCR, luciferase reporter, and qRT-PCR assays.Results:SYK was identified as a candidate actionable target through both high-throughput screens. SYK was highly phosphorylated in the majority of EWS cells, and SYK inhibition by a variety of genetic and pharmacologic approaches markedly inhibited EWS cells bothin vitroandin vivoEctopic expression of SYK rescued the cytotoxicity triggered by SYK-depletion associated with the reactivation of both AKT and c-MYC. A long noncoding RNA, MALAT1, was identified to be dependent on SYK-mediated signaling. Moreover, c-MYC, a SYK-promoted gene, bound to the promoter of MALAT1 and transcriptionally activated MALAT1, which further promoted the proliferation of EWS cells.Conclusions:This study identifies a novel signaling involving SYK/c-MYC/MALAT1 as a promising therapeutic target for the treatment of EWS.Clin Cancer Res; 23(15); 4376-87. ©2017 AACR.
Immunogenetics and Transplantation Laboratory, Department of Surgery, University of California San Francisco, San Francisco, California. Haibo.Sun@ucsf.edu De-chen.Lin@cshs.org.|Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California.
Haibo
H
Sun
Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California. Haibo.Sun@ucsf.edu De-chen.Lin@cshs.org.
De-Chen
DC
Lin
Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California.
Qi
Q
Cao
Department of Pathology, National University Hospital Singapore, Singapore.
Brendan
B
Pang
Immunogenetics and Transplantation Laboratory, Department of Surgery, University of California San Francisco, San Francisco, California.
David D
DD
Gae
Department of Pathology, National University Hospital Singapore, Singapore.
Victor Kwan Min
VKM
Lee
Department of Pathology, National University Hospital Singapore, Singapore.
Huey Jin
HJ
Lim
Department of Pathology and Laboratory Medicine, UCLA School of Medicine, Los Angeles, California.
Ngan
N
Doan
Department of Pathology and Laboratory Medicine, UCLA School of Medicine, Los Angeles, California.
Jonathan W
JW
Said
Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California.
Sigal
S
Gery
Department of Cell, Developmental & Cancer Biology, Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon.
Marilynn
M
Chow
Cancer Science Institute of Singapore, National University of Singapore, Singapore.
Anand
A
Mayakonda
Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California.
Charles
C
Forscher
Department of Cell, Developmental & Cancer Biology, Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon.
Jeffrey W
JW
Tyner
Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California.|Cancer Science Institute of Singapore, National University of Singapore, Singapore.|National University Cancer Institute, National University Hospital Singapore, Singapore.
H Phillip
HP
Koeffler
D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D057166:High-Throughput Screening Assays; D006801:Humans; D051379:Mice; D058990:Molecular Targeted Therapy; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D062085:RNA, Long Noncoding / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics; D012512:Sarcoma, Ewing / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D015398:Signal Transduction / Q000235:genetics; D054852:Small Molecule Libraries / Q000008:administration & dosage; D000072377:Syk Kinase / Q000037:antagonists & inhibitors / Q000235:genetics*; D023041:Xenograft Model Antitumor Assays
C557041:MALAT1 long non-coding RNA, human; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D062085:RNA, Long Noncoding; D034741:RNA, Small Interfering; D054852:Small Molecule Libraries; C000606896:SYK protein, human; D000072377:Syk Kinase