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An In Vitro Protocol for Evaluating MicroRNA Levels, Functions, and Associated Target Genes in Tumor Cells
Published on: May 21, 2019
MicroRNA-137 targets carboxyl-terminal binding protein 1 in melanoma cell lines
1Laboratory of Signal Transduction & Molecular Targeted Therapy, State Key Laboratory of Biotherapy/ Department of Medical Oncology, West China Hospital, Sichuan University, Chengdu, Sichuan Province 610041, China.
Abstract:
Carboxyl-terminal binding protein 1 (CtBP1) is a transcriptional co-repressor that represses expression of various tumor suppressor genes. In the present study, we identified miR-137 as a potential regulator of CtBP1 expression in melanoma cells. Expression of miR-137 in melanoma cell lines was found to inversely correlate with CtBP1 levels. Target Scan predicted a putative site for miR-137 within the CtBP1 3' untranslated region (3'UTR) at nt 710-716, which is highly conserved across species. To explore the mechanism of miR-137 targeting CtBP1, we performed an Argonaute 2 (Ago2)-pull down assay, and miR-137 was identified in complex with CtBP1 mRNA. miR-137 suppressed CtBP1 3' UTR luciferase-reporter activity, and this effect was lost with deletion of the putative 3' UTR target-site. Consistent with the results of the reporter assay, ectopic expression of miR-137 reduced expression levels of CtBP1. Furthermore, expression of miR-137 increased the immediate downstream effectors of CtBP1, such as E-cadherin and Bax. The human miR-137 gene is located at chromosome 1p22, which has previously been determined to be a susceptive region for melanoma. This study suggests miR-137 may act as a tumor suppressor by directly targeting CtBP1 to inhibit epithelial-mesenchymal transition (EMT) and inducing apoptosis of melanoma cells, thus illustrating a functional link between miR-137 and CtBP1 in melanoma development.
Insights
MicroRNA-137 (miR-137) suppresses melanoma by targeting Carboxyl-terminal binding protein 1 (CtBP1). This interaction inhibits tumor suppressor gene repression, potentially blocking melanoma cell growth and metastasis.
Area of Science:
- Molecular Biology
- Genetics
- Oncology
Background:
- Carboxyl-terminal binding protein 1 (CtBP1) acts as a transcriptional co-repressor, inhibiting tumor suppressor genes.
- Melanoma is a significant health concern, and understanding its molecular underpinnings is crucial for developing effective therapies.
Purpose of the Study:
- To investigate the regulatory role of microRNA-137 (miR-137) in the expression of CtBP1 in melanoma cells.
- To elucidate the functional consequences of the miR-137/CtBP1 interaction in melanoma development.
Main Methods:
- Correlation analysis of miR-137 and CtBP1 expression in melanoma cell lines.
- Bioinformatic prediction and experimental validation of miR-137 binding site in CtBP1 3' UTR.
- Argonaute 2 (Ago2)-pull down assays to confirm complex formation.
- Luciferase reporter assays to assess miR-137's regulatory activity.
- Analysis of downstream target gene expression (E-cadherin, Bax) following miR-137 modulation.
Main Results:
- miR-137 expression inversely correlated with CtBP1 levels in melanoma cells.
- miR-137 directly targets the 3' UTR of CtBP1 mRNA, suppressing its expression.
- Ectopic miR-137 expression reduced CtBP1 levels and increased expression of CtBP1's downstream effectors, E-cadherin and Bax.
- The miR-137 gene locus at chromosome 1p22 is a known melanoma susceptibility region.
Conclusions:
- miR-137 functions as a tumor suppressor in melanoma by directly targeting and downregulating CtBP1.
- This interaction may inhibit epithelial-mesenchymal transition (EMT) and promote apoptosis in melanoma cells.
- A functional link between miR-137 and CtBP1 is established, offering potential therapeutic targets for melanoma treatment.
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