Aberrant Methylation-Mediated Silencing of lncRNA MEG3 Functions as a ceRNA in Esophageal Cancer

Area of Science:

• Oncology
• Molecular Biology
• Epigenetics

Background:

• Maternally expressed gene 3 (MEG3), a long non-coding RNA (lncRNA), exhibits tumor-suppressive functions but its role in esophageal squamous cell carcinoma (ESCC) is unclear.
• Loss of MEG3 expression is observed in various human cancers, necessitating investigation into its specific involvement in ESCC pathogenesis.

Purpose of the Study:

• To elucidate the role and methylation status of MEG3 in esophageal cancer cells and clinical ESCC specimens.
• To investigate the competing endogenous RNA (ceRNA) activity of MEG3 in ESCC development.
• To assess the potential of MEG3 as a biomarker for ESCC patient prognosis.

Main Methods:

• Quantitative analysis of MEG3 expression in esophageal cancer cells and ESCC tissues.
• Treatment of cancer cells with 5-aza-dC (a DNA methyltransferase inhibitor) to assess MEG3 expression changes.
• Functional assays to evaluate the impact of MEG3 upregulation on cancer cell proliferation and invasion.
• Analysis of MEG3 promoter methylation status.
• Investigation of MEG3's ceRNA activity by examining its interaction with hsa-miR-9 and downstream targets (E-cadherin, FOXO1).
• Correlation analysis between MEG3 expression/methylation and ESCC patient survival.

Main Results:

• MEG3 was significantly downregulated in esophageal cancer cells and ESCC tissues.
• MEG3 expression increased after treatment with 5-aza-dC, indicating promoter hypermethylation contributes to its silencing.
• Upregulation of MEG3 suppressed cancer cell proliferation and invasion.
• MEG3 functions as a ceRNA, regulating E-cadherin and FOXO1 by sponging hsa-miR-9, which was upregulated in ESCC.
• Downregulation and hypermethylation of MEG3 correlated with poorer survival in ESCC patients.

Conclusions:

• MEG3 acts as a tumor-suppressive lncRNA in ESCC, with aberrant promoter hypermethylation leading to its silencing.
• MEG3's ceRNA activity, involving the miR-9/E-cadherin/FOXO1 axis, plays a role in ESCC pathogenesis.
• MEG3 holds potential as a predictive biomarker for ESCC progression and patient prognosis.