TMEFF2 promoter hypermethylation is an unfavorable prognostic marker in gliomas

Sidi Xie,Songtao Qi,Jing Guo,Hai Wang,Yongfu Cao,Yawei Liu,Yunxiao Zhang,Yaqin Li,Xiaofeng Shi,Jinglin Guo,Tao Peng

doi:10.1186/s12935-021-01818-x

Abstract

BackgroundTransmembrane protein with EGF-like and two follistatin-like domains 2 (TMEFF2) is a transmembrane protein in the tomoregulin family. Little research has been performed to determine whether TMEFF2 methylation is a prognostic marker in adult diffuse gliomas.MethodsIn this study, we investigated TMEFF2 expression in surgical glioma tissue samples. In addition, we conducted bisulfite amplicon sequencing (BSAS) and methylation-specific PCR (MSP) to evaluate TMEFF2 methylation in glioblastoma (GBM) cells. Subsequently, we investigated the biological function of TMEFF2 in GBM cells. Moreover, we explored the prognostic significance of TMEFF2 in gliomas by analysing a cohort dataset from TCGA.ResultsImmunohistochemistry analysis of 75 paired glioma tumour and peritumoural tissues demonstrated that glioma tumour tissues expressed lower TMEFF2 levels than peritumoural tissues (P < 0.001). TMEFF2 promoter methylation levels were increased in glioblastoma cells compared with SVG p12 cells (P < 0.001). Inhibition of methylation reduced TMEFF2 methylation and increased its expression in LN229 and T98G cells (P < 0.05). Knockdown of TMEFF2 expression significantly promoted the proliferation of U87MG cells and primary GBM cells (P < 0.05). TMEFF2 methylation is negatively associated with IDH1, ATRX and TP53 mutations, and the subtype of glioma harbouring combined IDH1/ATRX/TP53 mutations was associated with low TMEFF2 methylation levels. Survival analysis confirmed that low TMEFF2 methylation levels are associated with good prognosis in glioma patients.ConclusionsOur results suggest that TMEFF2 DNA methylation might be associated with glioma tumour progression and could serve as a valuable prognostic marker for adult diffuse gliomas.

Highlights

Diffuse gliomas account for approximately 80 % of malignant tumours originating in the central nervous system (CNS) in adults
Using four pairs of different primers, we amplified the DNA sequences of four CpG islands in the TMEFF2 promoter and detected the methylation levels of all CpG sites involved in these islands to generate a landscape of TMEFF2 promoter methylation in GBM and SVG p12 cells
To further interrogate the methylation sites of TMEFF2 in glioma, we identified 49 differentially methylated cytosines (DMCs) in a total of 73 CpG sites in the TMEFF2 promoter that were hypermethylated in glioblastoma cells compared to SVG p12 cells (Additional file 1: Table S5, Fig. 1f, g, Additional file 1: Fig S1a–f )

Summary

Introduction

Diffuse gliomas account for approximately 80 % of malignant tumours originating in the central nervous system (CNS) in adults. The isocitrate dehydrogenase (IDH) gene is mutated in > 70 % of diffuse lower-grade gliomas and in some glioblastomas [5, 6]. Despite its role in tumour initiation, mutant IDH is a hallmark of favour prognosis in glioma patients [9,10,11]. The outcomes for glioma patients with IDH mutations are remarkably different [12]. Research on new markers would help us understand molecular events during adult diffuse glioma progression and provide better guidance for patient prognosis and treatment. Little research has been performed to determine whether TMEFF2 methylation is a prognostic marker in adult diffuse gliomas

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Discussion

Conclusion