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  • Identification of a Novel SYK/c-MYC/MALAT1 Signaling Pathway and Its Potential Therapeutic Value in Ewing Sarcoma.

Identification of a Novel SYK/c-MYC/MALAT1 Signaling Pathway and Its Potential Therapeutic Value in Ewing Sarcoma.

Clinical cancer research : an official journal of the American Association for Cancer Research (2017-03-25)
Haibo Sun, De-Chen Lin, Qi Cao, Brendan Pang, David D Gae, Victor Kwan Min Lee, Huey Jin Lim, Ngan Doan, Jonathan W Said, Sigal Gery, Marilynn Chow, Anand Mayakonda, Charles Forscher, Jeffrey W Tyner, H Phillip Koeffler
ABSTRACT

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 both in vitro and in vivo Ectopic 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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Monoclonal Anti-β-Actin antibody produced in mouse, clone AC-74, ascites fluid
Sigma-Aldrich
Anti-phospho-SYK (pTyr525) antibody produced in rabbit, affinity isolated antibody
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Imprint® RNA Immunoprecipitation Kit, High-capacity Protein A magnetic beads for successful RNA Immunoprecipitation,suitable for use with mRNA and microRNA