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Published on: February 21, 2018
The miR-203a Regulatory Network Affects the Proliferation of Chronic Myeloid Leukemia K562 Cells
Jinhua He1, Zeping Han1, Ziyi An2
1Department of Laboratory Medicine, Panyu District Central Hospital, Guangzhou, China.
Abstract:
To study the molecular mechanism by which miR-203a affects the development of CML, bioinformatics software was used to predict the upstream transcription factors and downstream target genes of miR-203a. A 5'-rapid amplification of cDNA ends assay was performed to detect gene transcription initiation sites. A chromatin immunoprecipitation assay was used to verify the binding of transcription factors and promoter regions. A double luciferase reporter gene vector was constructed to demonstrate the regulatory effect of miR-203a on target genes. Real-time PCR and western blotting were used to detect the relative expression levels of genes and proteins, respectively. The results showed that there was a binding site for the transcription factor EGR1 in the upstream promoter region of miR-203a. WT1, BMI1, and XIAP were identified as target genes regulated by miR-203a. EGR1 and miR-203a were downregulated in human peripheral blood mononuclear cells and the CML K562 cell line, while WT1, BMI1, and XIAP were upregulated. The transcription initiation site of miR-203a was identified in the upstream promoter region (G nucleotide at -339 bp), and the transcription factor EGR1 could bind to the promoter region (at -268 bp) of miR-203a and increase its expression. Over expression of miR-203a inhibited the proliferation of K562 cells. A rescue assay showed that overexpression of WT1, BMI1, and XIAP offset the antitumor effect of miR-203a. Conclusion, EGR1 positively regulated the expression of miR-203a, thus relieving the inhibition of miR-203a on the translation of its target genes (WT1, BMI1, and XIAP) and affecting the proliferation of K562 cells.
Insights
The transcription factor EGR1 promotes miR-203a expression, which inhibits chronic myeloid leukemia (CML) cell proliferation by downregulating WT1, BMI1, and XIAP. This reveals a novel regulatory pathway in CML development.
Area of Science:
- Molecular Biology
- Oncology
- Gene Regulation
Background:
- Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by specific genetic mutations.
- Understanding the molecular mechanisms underlying CML pathogenesis is crucial for developing targeted therapies.
- MicroRNAs (miRNAs) play significant roles in regulating gene expression and are implicated in various cancers, including CML.
Purpose of the Study:
- To elucidate the molecular mechanism of miR-203a in CML development.
- To identify upstream regulatory factors and downstream targets of miR-203a.
- To investigate the functional impact of the miR-203a regulatory network on CML cell proliferation.
Main Methods:
- Bioinformatic analysis for predicting transcription factors and target genes.
- 5'-rapid amplification of cDNA ends (RACE) assay to determine transcription initiation sites.
- Chromatin immunoprecipitation (ChIP) assay to confirm transcription factor binding.
- Luciferase reporter assays to validate miRNA-target interactions.
- Real-time PCR and Western blotting to quantify gene and protein expression.
- Cell proliferation assays and rescue experiments in CML cell lines.
Main Results:
- The transcription factor Early Growth Response 1 (EGR1) binds to the promoter region of miR-203a and positively regulates its expression.
- WT1, BMI1, and XIAP were identified as direct downstream target genes of miR-203a.
- EGR1 and miR-203a were downregulated, while WT1, BMI1, and XIAP were upregulated in CML cells.
- Overexpression of miR-203a inhibited K562 CML cell proliferation.
- Overexpression of WT1, BMI1, and XIAP rescued the anti-proliferative effect of miR-203a.
Conclusions:
- EGR1 acts as a positive regulator of miR-203a expression in CML.
- miR-203a exerts its tumor-suppressive function by inhibiting the translation of WT1, BMI1, and XIAP.
- The EGR1/miR-203a/WT1/BMI1/XIAP axis represents a novel regulatory pathway influencing CML cell proliferation.
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