Dataset Information

Hypermethylation of MAPK13 Promoter in Oesophageal Squamous Cell Carcinoma Is Associated with Loss of p38? MAPK Expression.

ABSTRACT: The loss of tumour suppressor gene function is a hallmark of malignant transformation and can occur by a variety of genetic and/or epigenetic alterations. We have previously characterised p38? mitogen-activated protein kinase (MAPK) as a tumour suppressor in oesophageal squamous cell carcinoma (OESCC) and outlined how loss of p38? MAPK expression promotes increased proliferation and migration, as well as reduced chemosensitivity. Our aim was to investigate the underlying molecular causes of loss of p38? MAPK expression in OESCC. Sequence analysis of DNA from p38? MAPK positive and p38? MAPK negative OESCC cell lines was used to investigate potential loss of function causing mutations. Epigenetic control of p38? expression in OESCC was examined using methylation-specific PCR and sequencing of bisulfite-converted DNA. We did not identify any mutations in the MAPK13 sequence in OESCC cell lines which lack p38? MAPK expression. However, we identified a differential pattern of methylation between p38? MAPK positive and p38? MAPK negative cell lines. We outline here for the first time differential MAPK13 promoter methylation in OESCC. Our results suggest that epigenetic alterations are responsible, in part, for the suppression of p38? MAPK expression and promotion of tumourigenesis in OESCC.

SUBMITTER: O' Callaghan C

PROVIDER: S-EPMC4695881 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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Hypermethylation of MAPK13 Promoter in Oesophageal Squamous Cell Carcinoma Is Associated with Loss of p38δ MAPK Expression.

O' Callaghan Carol C Fanning Liam J LJ Barry Orla P OP

Cancers 20151023 4

The loss of tumour suppressor gene function is a hallmark of malignant transformation and can occur by a variety of genetic and/or epigenetic alterations. We have previously characterised p38δ mitogen-activated protein kinase (MAPK) as a tumour suppressor in oesophageal squamous cell carcinoma (OESCC) and outlined how loss of p38δ MAPK expression promotes increased proliferation and migration, as well as reduced chemosensitivity. Our aim was to investigate the underlying molecular causes of loss ...[more]

PMID: 26512696

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Project description:BACKGROUND: MYCT1, previously named MTLC, is a novel candidate tumor suppressor gene. MYCT1 was cloned from laryngeal squamous cell cancer (LSCC) and has been found to be down-regulated in LSCC; however, the regulatory details have not been fully elucidated. METHODS: Here, we sought to investigate the methylation status of the CpG islands of MYCT1 and mRNA levels by bisulfite-specific PCR (BSP) based on sequencing restriction enzyme digestion, reverse transcription and real-time quantitative polymerase chain reaction (RQ-PCR). The function of specific sites in the proximal promoter of MYCT1 in LSCC was measured by transient transfection, luciferase assays, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation assay (ChIP). RESULTS: The results suggested hypermethylation of 12 CpG sites of the promoter in both laryngeal cancer tissues and the laryngeal cancer line Hep-2 cell. The hypermethylation of the site CGCG (-695 to -692), which has been identified as the c-Myc binding site, was identified in laryngeal cancer tissues (59/73) compared to paired mucosa (13/73); in addition, statistical analysis revealed that the methylation status of this site significantly correlated with cancer cell differentiation(p?<?0.01). The mRNA level of MYCT1 increased in Hep-2 cells treated with 5-aza-C (p?<?0.01). The luciferase activity from mutant transfectants pGL3-MYCT1m (-852/+12, mut-695-C?>?A, mut-693-C?>?G) was significantly reduced compared with the wild type pGL3-MYCT1 (-852/+12), while the luciferase activity from wild transfectants pGL3-MYCT1 (-852/+12) rose after 5-aza treatment in Hep-2 cells. Finally, EMSA and ChIP confirmed that the methylation of the CGCG (-695 to -692) site prevented c-Myc from binding of the site and demethylation treatment of the 5' flanking region of MYCT1 by 5-aza induced the increased occupation of the core promoter by c-Myc (p?<?0.01). CONCLUSION: In summary, this study concluded that hypermethylation contributed to the transcriptional down-regulation of MYCT1 and could inhibit cancer cell differentiation in LSCC. DNA methylation of the CGCG site (-695 to -692) of MYCT1 altered the promoter activity by interfering with its binding to c-Myc in LSCC. Epigenetic therapy of reactivating MYCT1 by 5-aza should be further evaluated in clinical trails of LSCC.

Project description:BackgroundOesophageal cancer is one of the most common malignancies worldwide,and oesophageal squamous cell carcinoma (ESCC) is the predominant histological type both globally and in China. Collagen triple helix repeat containing 1 (CTHRC1) has been found to be upregulated in ESCC. However, its role in tumourigenesis and progression of ESCC remains unclear.MethodsUsing our previous ESCC mRNA profiling data, we screened upregulated genes to identify those required for proliferation. Immunohistochemistry was performed to determine the level of CTHRC1 protein expression in 204 ESCC patients. Correlations between CTHRC1 expression and clinicopathological characteristics were assessed. In addition, pyrosequencing and 5-aza-dC treatment were performed to evaluate methylation status of CTHRC1 promoter. In vitro and in vivo analyses were also conducted to determine the role of CTHRC1 in ESCC cell proliferation, migration and invasion, and RNA sequencing and molecular experiments were performed to study the underlying mechanisms.ResultsBased on mRNA profiling data, CTHRC1 was identified as one of the most significantly upregulated genes in ESCC tissues (n = 119, fold change = 20.5, P = 2.12E-66). RNA interference screening also showed that CTHRC1 was required for cell proliferation. Immunohistochemistry confirmed markedly high CTHRC1 protein expression in tumour tissues, and high CTHRC1 expression was positively correlated with advanced T stage (P = 0.043), lymph node metastasis (P = 0.023), TNM stage (P = 0.024) and poor overall survival (P = 0.020). Promoter hypomethylation at cg07757887 may contribute to increased CTHRC1 expression in ESCC cells and tumours. Forced overexpression of CTHRC1 significantly enhanced cell proliferation, migration and invasion, whereas depletion of CTHRC1 suppressed these cellular functions in three ESCC cell lines and xenografts. CTHRC1 was found to activate FRA-1 (Fos-related antigen 1, also known as FOSL1) through the MAPK/MEK/ERK cascade, which led to upregulation of cyclin D1 and thus promoted cell proliferation. FRA-1 also induced snail1-mediated MMP14 (matrix metallopeptidase 14, also known as MT1-MMP) expression to facilitate ESCC cell invasion, migration, and metastasis.ConclusionsOur data suggest that CTHRC1 may act as an oncogenic driver in progression and metastasis of ESCC, and may serve as a potential biomarker for prognosis and personalized therapy.

Dataset Information

Hypermethylation of MAPK13 Promoter in Oesophageal Squamous Cell Carcinoma Is Associated with Loss of p38? MAPK Expression.

Publications

Hypermethylation of MAPK13 Promoter in Oesophageal Squamous Cell Carcinoma Is Associated with Loss of p38δ MAPK Expression.

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