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Deregulated expression of the 14q32 miRNA cluster in clear cell renal cancer cells
Ravneet Chhabra1, Jennifer Guergues1, Jessica Wohlfahrt1
1Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL, United States.
Abstract:
Clear cell renal cell carcinomas (ccRCC) are characterized by arm-wide chromosomal alterations. Loss at 14q is associated with disease aggressiveness in ccRCC, which responds poorly to chemotherapeutics. The 14q locus contains one of the largest miRNA clusters in the human genome; however, little is known about the contribution of these miRNAs to ccRCC pathogenesis. In this regard, we investigated the expression pattern of selected miRNAs at the 14q32 locus in TCGA kidney tumors and in ccRCC cell lines. We demonstrated that the miRNA cluster is downregulated in ccRCC (and cell lines) as well as in papillary kidney tumors relative to normal kidney tissues (and primary renal proximal tubule epithelial (RPTEC) cells). We demonstrated that agents modulating expression of DNMT1 (e.g., 5-Aza-deoxycytidine) could modulate 14q32 miRNA expression in ccRCC cell lines. Lysophosphatidic acid (LPA, a lysophospholipid mediator elevated in ccRCC) not only increased labile iron content but also modulated expression of a 14q32 miRNA. Through an overexpression approach targeting a subset of 14q32 miRNAs (specifically at subcluster A: miR-431-5p, miR-432-5p, miR-127-3p, and miR-433-3p) in 769-P cells, we uncovered changes in cellular viability and claudin-1, a tight junction marker. A global proteomic approach was implemented using these miRNA overexpressing cell lines which uncovered ATXN2 as a highly downregulated target. Collectively, these findings support a contribution of miRNAs at 14q32 in ccRCC pathogenesis.
Insights
MicroRNAs at the 14q32 locus are downregulated in kidney cancer, impacting cell viability and potentially serving as therapeutic targets for clear cell renal cell carcinoma (ccRCC).
Area of Science:
- Genomics and Molecular Biology
- Oncology
- Epigenetics
Background:
- Clear cell renal cell carcinoma (ccRCC) exhibits chromosomal abnormalities, with 14q loss linked to aggressive disease.
- The 14q32 locus hosts a significant miRNA cluster, yet its role in ccRCC pathogenesis is largely unexplored.
- Understanding miRNA dysregulation in ccRCC is crucial for identifying novel therapeutic strategies.
Purpose of the Study:
- To investigate the expression of 14q32 miRNAs in kidney tumors and ccRCC cell lines.
- To explore the regulatory mechanisms influencing 14q32 miRNA expression, including epigenetic factors and signaling pathways.
- To determine the functional impact of specific 14q32 miRNAs on ccRCC cell behavior and identify downstream targets.
Main Methods:
- Quantitative analysis of miRNA expression in TCGA kidney tumors and ccRCC cell lines.
- Treatment of ccRCC cell lines with DNMT1 inhibitors (e.g., 5-Aza-deoxycytidine) and lysophosphatidic acid (LPA).
- Overexpression of specific 14q32 miRNAs (miR-431-5p, miR-432-5p, miR-127-3p, miR-433-3p) in 769-P cells, followed by proteomic analysis.
Main Results:
- The 14q32 miRNA cluster is significantly downregulated in ccRCC and papillary kidney tumors compared to normal kidney tissues.
- DNMT1 modulators and LPA affect 14q32 miRNA expression in ccRCC cell lines.
- Overexpression of selected 14q32 miRNAs alters cellular viability, affects claudin-1 expression, and downregulates ATXN2.
Conclusions:
- The 14q32 miRNA cluster plays a role in ccRCC pathogenesis.
- Epigenetic modifications and cellular mediators like LPA contribute to the dysregulation of these miRNAs.
- These findings highlight the potential of 14q32 miRNAs as biomarkers or therapeutic targets in ccRCC.
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