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Aberrantly hypermethylated Homeobox A2 derepresses metalloproteinase-9 through TBP and promotes invasion in Nasopharyngeal carcinoma.

ABSTRACT: Nasopharyngeal carcinoma (NPC) is notorious for its high invasiveness and metastatic ability. In this study, we identified a differential hypermethylated transcription repressor, Homeobox A2 (HOXA2), which may render NPC cells invasive and metastatic. Aberrant hypermethylation of HOXA2 led to low RNA expression in NPC tumors and cells. Addition of methylation inhibitor 5'Aza restored HOXA2 RNA expression in NPC cells. Methylated HOXA2 promoter reduces the binding affinity of the transcriptional co-activator p300, causing transcriptional repression of HOXA2. In NPC cells, re-expression of ectopic HOXA2 was correlated with decreased invasive ability and reduced metalloproteinase MMP-9 RNA and protein expression. Promoter, ChIP and DNA-pull down assays indicated that HOXA2 competes with the transcription activator, TATA-box binding protein (TBP) for a recognition sequence near the MMP-9 transcription start site, and suppresses MMP-9 transcription. Thus, HOXA2 acts as a suppressor or TBP-antagonist to inhibit MMP-9 expression; while methylation-mediated inactivation of HOXA2 in NPC derepresses MMP-9 production and increases invasion of NPC cells. In NPC plasma samples, increased plasma EBV copy number was correlated with increased in cell-free HOXA2 hypermethylation and elevated MMP-9 levels. Plasma EBV DNA and methylated cell-free HOXA2 can be used as biomarkers for monitoring NPC treatment.

SUBMITTER: Li HP

PROVIDER: S-EPMC3875777 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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Aberrantly hypermethylated Homeobox A2 derepresses metalloproteinase-9 through TBP and promotes invasion in Nasopharyngeal carcinoma.

Li Hsin-Pai HP Peng Chen-Ching CC Chung I-Che IC Huang Mei-Yuan MY Huang Shao-Tung ST Chen Chia-Chun CC Chang Kai-Ping KP Hsu Cheng-Lung CL Chang Yu-Sun YS

Oncotarget 20131101 11

Nasopharyngeal carcinoma (NPC) is notorious for its high invasiveness and metastatic ability. In this study, we identified a differential hypermethylated transcription repressor, Homeobox A2 (HOXA2), which may render NPC cells invasive and metastatic. Aberrant hypermethylation of HOXA2 led to low RNA expression in NPC tumors and cells. Addition of methylation inhibitor 5'Aza restored HOXA2 RNA expression in NPC cells. Methylated HOXA2 promoter reduces the binding affinity of the transcriptional ...[more]

PMID: 24243817

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Project description:BackgroundOverexpression of heterogeneous nuclear ribonucleoprotein K (hnRNP K), a DNA/RNA binding protein, is associated with metastasis in nasopharyngeal carcinoma (NPC). However, the mechanisms underlying hnRNP K-mediated metastasis is unclear. The aim of the present study was to determine the role of matrix metalloproteinase (MMP) in hnRNP K-mediated metastasis in NPC.MethodsWe studied hnRNP K-regulated MMPs by analyzing the expression profiles of MMP family genes in NPC tissues and hnRNP K-knockdown NPC cells using Affymetrix microarray analysis and quantitative RT-PCR. The association of hnRNP K and MMP12 expression in 82 clinically proven NPC cases was determined by immunohistochemical analysis. The hnRNP K-mediated MMP12 regulation was determined by zymography and Western blot, as well as by promoter, DNA pull-down and chromatin immunoprecipitation (ChIP) assays. The functional role of MMP12 in cell migration and invasion was demonstrated by MMP12-knockdown and the treatment of MMP12-specific inhibitor, PF-356231.ResultsMMP12 was overexpressed in NPC tissues, and this high level of expression was significantly correlated with high-level expression of hnRNP K (P?=?0.026). The levels of mRNA, protein and enzyme activity of MMP12 were reduced in hnRNP K-knockdown NPC cells. HnRNP K interacting with the region spanning -42 to -33 bp of the transcription start site triggered transcriptional activation of the MMP12 promoter. Furthermore, inhibiting MMP12 by MMP12 knockdown and MMP12-specific inhibitor, PF-356231, significantly reduced the migration and invasion of NPC cells.ConclusionsOverexpression of MMP12 was significantly correlated with hnRNP K in NPC tissues. HnRNP K can induce MMP12 expression and enzyme activity through activating MMP12 promoter, which promotes cell migration and invasion in NPC cells. In vitro experiments suggest that NPC metastasis with high MMP12 expression may be treated with PF-356231. HnRNP K and MMP12 may be potential therapeutic markers for NPC, but additional validation studies are warranted.

Project description:BACKGROUND:Oral squamous cell carcinoma (OSCC) is a genetic and epigenetic disease. There is growing evidence to suggest that environmental factors due to epigenetic changes can be involved in the OSCC pathogenesis. Although tumor suppressor genes (TSGs) are commonly inactivated by promoter hypermethylation in human cancers, the epigenetic changes and the mechanism of TSGs in human OSCC remain unclear. We therefore assessed the methylation status of the TSGs, which are associated with epigenetic silencing in human cancers, OSCC cell lines, primary tumors, and normal oral mucosa. RESULTS:We used 14 TSGs that were originally identified in colon cancer to investigate the aberrant hypermethylation of these genes associated with transcriptional silencing in 10 OSCC cell lines. We found three TSGs, TFPI2, SOX17, and GATA4, that are robustly hypermethylated and are associated with transcriptional silencing in OSCC cell lines. The re-expression of the three genes was induced by 5-aza-2'-deoxycytidine (5-aza-dC) in cells in which these genes were not expressed or had a lack of expression. In 33 cases of primary OSCC tumors, promoter hypermethylation was detected for the TFPI2, SOX17, and GATA4 genes at (32/33) 97%, (22/33) 67%, and (11/33) 33%, respectively. Eleven normal oral mucosa samples showed no promoter hypermethylation for all three genes, which suggests that this promoter hypermethylation is cancer-specific. Bisulfite sequencing analysis confirmed the cancer-specific methylation of the TFPI2, SOX17, and GATA4 promoters in the OSCC cell lines and tumors but not in the normal oral mucosa samples. More importantly, the methylation status of TFPI2, GATA4, and SOX17 was significantly associated with OSCC patients' overall survival through TCGA DNA methylation database. CONCLUSIONS:We identified that TFPI2, SOX17, and GATA4 are frequently hypermethylated in human OSCC cells in a cancer-specific manner and that the transcriptional expression of these genes is regulated by promoter hypermethylation in OSCC. Our results highlight the great potential used as a synergistic biomarker set to improve the prognosis and therapeutic treatment for patients with OSCC.

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Aberrantly hypermethylated Homeobox A2 derepresses metalloproteinase-9 through TBP and promotes invasion in Nasopharyngeal carcinoma.

Publications

Aberrantly hypermethylated Homeobox A2 derepresses metalloproteinase-9 through TBP and promotes invasion in Nasopharyngeal carcinoma.

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