Epigenetic DNA Modifications Upregulate SPRY2 in Human Colorectal Cancers.

Alexei J Stuckel,Xu Zhang,Urszula Dougherty,Shuai Zeng,Sharad Khare,Reba Mustafi,Wei Zhang,Trupti Joshi,Marc Bissonnette,Samrat Roy Choudhury,Qiong Zhang,Zhen Lyu

doi:10.3390/cells10102632

Abstract

Conventional wisdom is that Sprouty2 (SPRY2), a suppressor of Receptor Tyrosine Kinase (RTK) signaling, functions as a tumor suppressor and is downregulated in many solid tumors. We reported, for the first time, that increased expression of SPRY2 augments cancer phenotype and Epithelial-Mesenchymal-Transition (EMT) in colorectal cancer (CRC). In this report, we assessed epigenetic DNA modifications that regulate SPRY2 expression in CRC. A total of 4 loci within SPRY2 were evaluated for 5mC using Combined Bisulfite Restriction Analysis (COBRA). Previously sequenced 5hmC nano-hmC seal data within SPRY2 promoter and gene body were evaluated in CRC. Combined bioinformatics analyses of SPRY2 CRC transcripts by RNA-seq/microarray and 450K methyl-array data archived in The Cancer Genome Atlas (TCGA) and GEO database were performed. SPRY2 protein in CRC tumors and cells was measured by Western blotting. Increased SPRY2 mRNA was observed across several CRC datasets and increased protein expression was observed among CRC patient samples. For the first time, SPRY2 hypomethylation was identified in adenocarcinomas in the promoter and gene body. We also revealed, for the first time, increases of 5hmC deposition in the promoter region of SPRY2 in CRC. SPRY2 promoter hypomethylation and increased 5hmC may play an influential role in upregulating SPRY2 in CRC.

Highlights

Sprouty (SPRY) mammalian proteins consist of 4 evolutionarily conserved family members (SPRY 1–4) that exhibit tissue-specific expression patterns, apart from the most conserved sprouty isoform SPRY2 that is ubiquitously expressed [1,2]
Downstream mitogen-activated protein kinase (MAPK) signals are inhibited by SPRY2 as it negatively regulates receptor tyrosine kinase (RTK) signaling in response to cognate receptor ligands like vascular endothelial growth factor (VEGF) [3], platelet-derived growth factor (PDGF) [4], and fibroblast growth factor (FGF) [3]
We evaluated SPRY2 mRNA expression in benign adenomas and matched control tissue in a publicly available dataset using the GEO2R software tool located in the National

Summary

Introduction

Sprouty (SPRY) mammalian proteins consist of 4 evolutionarily conserved family members (SPRY 1–4) that exhibit tissue-specific expression patterns, apart from the most conserved sprouty isoform SPRY2 that is ubiquitously expressed [1,2]. Downstream mitogen-activated protein kinase (MAPK) signals are inhibited by SPRY2 as it negatively regulates receptor tyrosine kinase (RTK) signaling in response to cognate receptor ligands like vascular endothelial growth factor (VEGF) [3], platelet-derived growth factor (PDGF) [4], and fibroblast growth factor (FGF) [3]. This mechanism, is not uniformly observed across all cell types. SPRY2 is overexpressed in malignant gliomas (GBM) suggesting a potential oncogenic function in brain cancer [12]. Increased expression of SPRY2 in IBD was confirmed by other investigators [16]

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Conclusion