Related Experiment Video
Updated: Oct 6, 2025
Clinicopathological Analysis of miRNA Expression in Breast Cancer Tissues by Using miRNA In Situ Hybridization
Published on: June 7, 2016
miR-4759 suppresses breast cancer through immune checkpoint blockade
You-Zhe Lin1, Shu-Hsuan Liu2, Wan-Rong Wu1
1Graduate Institute of Biomedical Sciences, College of Medicine, China Medical University, Taichung 40402, Taiwan.
Abstract:
Programmed cell death protein 1 (PD-1)/ programmed cell death protein ligand 1 (PD-L1) is the key immune checkpoint governing evasion of advanced cancer from immune surveillance. Immuno-oncology (IO) therapy targeting PD-1/PD-L1 with traditional antibodies is a promising approach to multiple cancer types but to which the response rate remains moderate in breast cancer, calling for the need of exploring alternative IO targeting approaches. A miRNA-gene network was integrated by a bioinformatics approach and corroborated with The Cancer Genome Atlas (TCGA) to screen miRNAs regulating immune checkpoint genes and associated with patient survival. Here we show the identification of a novel microRNA miR-4759 which repressed RNA expression of the PD-L1 gene. miR-4759 targeted the PD-L1 gene through two binding motifs in the 3' untranslated region (3'-UTR) of PD-L1. Reconstitution of miR-4759 inhibited PD-L1 expression and sensitized breast cancer cells to killing by immune cells. Treatment with miR-4759 suppressed tumor growth of orthotopic xenografts and promoted tumor infiltration of CD8+ T lymphocytes in immunocompetent mice. In contrast, miR-4759 had no effect to tumor growth in immunodeficient mice. In patients with breast cancer, expression of miR-4759 was preferentially downregulated in tumors compared to normal tissues and was associated with poor overall survival. Together, our results demonstrated miR-4759 as a novel non-coding RNA which promotes anti-tumor immunity of breast cancer.
Insights
A newly discovered microRNA, miR-4759, targets and represses PD-L1 expression, enhancing anti-tumor immunity in breast cancer. This finding offers a novel approach to improve immuno-oncology (IO) therapy effectiveness.
Area of Science:
- Immunology
- Oncology
- Molecular Biology
- Genetics
Background:
- Immune checkpoints like PD-1/PD-L1 are crucial for cancer immune evasion.
- Current immuno-oncology (IO) therapies targeting PD-1/PD-L1 show moderate efficacy in breast cancer, necessitating alternative strategies.
- MicroRNAs (miRNAs) are key regulators of gene expression and can influence immune responses.
Purpose of the Study:
- To identify novel miRNAs that regulate immune checkpoint genes, specifically PD-L1, in breast cancer.
- To investigate the therapeutic potential of targeting PD-L1 with a novel miRNA for breast cancer treatment.
- To explore the impact of miR-4759 on anti-tumor immunity and patient survival.
Main Methods:
- Bioinformatic analysis of miRNA-gene networks integrated with The Cancer Genome Atlas (TCGA) data.
- Experimental validation of miR-4759 targeting the PD-L1 gene's 3'-UTR.
- In vitro studies assessing PD-L1 expression and immune cell killing in breast cancer cells.
- In vivo studies using orthotopic xenografts in immunocompetent and immunodeficient mice.
- Analysis of miR-4759 expression levels and correlation with survival in breast cancer patients.
Main Results:
- Identified miR-4759 as a novel miRNA that directly represses PD-L1 RNA expression.
- Restoring miR-4759 inhibited PD-L1, sensitized breast cancer cells to immune cell-mediated killing, and suppressed tumor growth in vivo.
- miR-4759 promoted CD8+ T lymphocyte infiltration in tumors, demonstrating an enhancement of anti-tumor immunity.
- Downregulation of miR-4759 in breast tumors correlated with poor patient survival.
Conclusions:
- miR-4759 is a novel non-coding RNA with the potential to overcome resistance to current IO therapies.
- Targeting miR-4759 represents a promising new strategy to enhance anti-tumor immunity in breast cancer.
- miR-4759 serves as a potential biomarker for predicting patient prognosis in breast cancer.
