Microarray analysis of gene expression in vestibular schwannomas reveals SPP1/MET signaling pathway and androgen receptor deregulation

Abstract

Vestibular schwannomas are benign neoplasms that arise from the vestibular nerve. The hallmark of these tumors is the biallelic inactivation of neurofibromin 2 (NF2). Transcriptomic alterations, such as the neuregulin 1 (NRG1)/ErbB2 pathway, have been described in schwannomas. In this study, we performed a whole transcriptome analysis in 31 vestibular schwannomas and 9 control nerves in the Affymetrix Gene 1.0 ST platform, validated by quantitative real-time PCR (qRT-PCR) using TaqMan Low Density arrays. We performed a mutational analysis of NF2 by PCR/denaturing high-performance liquid chromatography (dHPLC) and multiplex ligation-dependent probe amplification (MLPA), as well as a microsatellite marker analysis of the loss of heterozygosity (LOH) of chromosome 22q. The microarray analysis demonstrated that 1,516 genes were deregulated and 48 of the genes were validated by qRT-PCR. At least 2 genetic hits (allelic loss and/or gene mutation) in NF2 were found in 16 tumors, seven cases showed 1 hit and 8 tumors showed no NF2 alteration. MET and associated genes, such as integrin, alpha 4 (ITGA4)/B6, PLEXNB3/SEMA5 and caveolin-1 (CAV1) showed a clear deregulation in vestibular schwannomas. In addition, androgen receptor (AR) downregulation may denote a hormonal effect or cause in this tumor. Furthermore, the osteopontin gene (SPP1), which is involved in merlin protein degradation, was upregulated, which suggests that this mechanism may also exert a pivotal role in schwannoma merlin depletion. Finally, no major differences were observed among tumors of different size, histological type or NF2 status, which suggests that, at the mRNA level, all schwannomas, regardless of their molecular and clinical characteristics, may share common features that can be used in their treatment.

Global Proteome and Phospho-proteome Analysis of Merlin-deficient Meningioma and Schwannoma Identifies PDLIM2 as a Novel Therapeutic Target

“…Prior to this study, there was only one comparative analysis between meningioma and schwannoma at the genomic level reported in the literature (Torres-Martin et al, 2013b, Torres-Martin et al, 2014). …”

Gene-expression profiling elucidates molecular signaling networks that can be therapeutically targeted in vestibular schwannoma

“…Additionally, an independent study analyzing 31 schwannomas revealed no clear distinctions of germline and sporadic schwannomas. 36 Given the observation that sporadic VS tissue harbors 60%-100% inactivation of NF2, it is very likely that the molecular pathogenesis of both sporadic and germline schwannomas is similar. 13,34 Targeted therapeutics and rational drug targeting strategies are of great interest in the treatment of schwannoma and other tumors.…”

Rac1-Mediated DNA Damage and Inflammation Promote Nf2 Tumorigenesis but Also Limit Cell-Cycle Progression

“…Pathway profiling showed that DNA damage response (DDR) and cell death were among the top 10 pathways enriched with the DKO_Liver_Reversed gene set (Figure S4B). Interestingly, GSEA showed this set of genes also significantly associated with genes upregulated in human vestibular schwannomas (VS) (Torres-Martin et al, 2013) despite the tissue and cell type differences (Figure S4C), implying their potential relevance to NF2.…”

“…We postulated that a p53-mediated DNA damage/senescence program might also constrict the growth of human NF2 tumors. To test this hypothesis, we conducted GSEA with our HSGS on three published human schwannomas and meningiomas microarray datasets (Clark et al, 2013; Tabernero et al, 2009; Torres-Martin et al, 2013). Despite the difference in cell types, we observed significant enrichment of the Hepatocyte_Senescence_Up gene set among genes upregulated in NF2-associated schwannomas compared to normal nerves or in NF2-associated meningiomas (NF2) compared to meningiomas that do not contain NF2 mutations (nonNF2) (Figure 6A).…”