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Updated: Jul 4, 2025
Clinicopathological Analysis of miRNA Expression in Breast Cancer Tissues by Using miRNA In Situ Hybridization
Published on: June 7, 2016
In vivo validation of the functional role of MicroRNA-4638-3p in breast cancer bone metastasis
R L Akshaya1, I Saranya1, G Margaret Salomi2
1Department of Biotechnology, School of Bioengineering, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu, 603 203, India.
Purpose:
Skeletal metastases are increasingly reported in metastatic triple-negative breast cancer (BC) patients. We previously reported that TGF-β1 sustains activating transcription factor 3(ATF3) expression and is required for cell proliferation, invasion, and bone metastasis genes. Increasing studies suggest the critical regulatory function of microRNAs (miRNAs) in governing BC pathogenesis. TGF-β1 downregulated the expression of miR-4638-3p, which targets ATF3 in human BC cells (MDA-MB-231). In the present study, we aimed to identify the functional role of miR-4638-3p in BC bone metastasis by the caudal artery injection of the MDA-MB-231 cells overexpressing mir-4638 in the mice.
Methods:
MDA-MB-231 cells overexpressing miR-4638 were prepared by stable transfections. Reverse transcriptase quantitative PCR was carried out to determine the expression of endogenous miR-4638-3p and bone resorption marker genes. X-ray, micro-CT, and Hematoxylin & Eosin studies were used to determine osteolytic lesions, trabecular structure, bone mineral density, and micrometastasis of cells.
Results:
The mice injected with MDA-MB-231 cells overexpressing miR-4638-3p decreased the expression of bone resorption marker genes, compared to MDA-MB-231 cells injection. Reduced osteolytic lesions and restored bone density by MDA-MB-231 cells overexpressing miR-4638-3p were observed. Similarly, the mice injected with MDA-MB-231 cells overexpressing miR-4638-3p showed a better microarchitecture of the trabecular network. A few abnormal cells seen in the femur of MDA-MB-231 cells-injected mice were not found in MDA-MB-231 cells overexpressing miR-4638.
Conclusion:
The identified functional role of ATF3 targeting miR-4638-3p in BC bone metastasis in vivo suggests its candidature as BC therapeutics in the future.
Insights
MicroRNA-4638-3p inhibits bone metastasis in triple-negative breast cancer by targeting ATF3. This finding suggests miR-4638-3p as a potential therapeutic target for breast cancer bone metastasis.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Skeletal metastases are a significant complication in metastatic triple-negative breast cancer (TNBC).
- Transforming growth factor-beta 1 (TGF-β1) sustains activating transcription factor 3 (ATF3) expression, promoting TNBC cell proliferation, invasion, and bone metastasis.
- MicroRNAs (miRNAs) are critical regulators of breast cancer (BC) pathogenesis, with TGF-β1 known to downregulate miR-4638-3p, a direct target of ATF3.
Purpose of the Study:
- To investigate the functional role of miR-4638-3p in breast cancer bone metastasis.
- To assess the therapeutic potential of miR-4638-3p in preclinical models of TNBC bone metastasis.
Main Methods:
- MDA-MB-231 cells engineered to overexpress miR-4638 were utilized for in vivo studies.
- Quantitative PCR was employed to measure miR-4638-3p and bone resorption marker gene expression.
- X-ray, micro-CT, and Hematoxylin & Eosin staining were performed to evaluate osteolytic lesions, bone density, and microarchitecture.
Main Results:
- Overexpression of miR-4638-3p in injected cells significantly reduced the expression of bone resorption markers.
- Mice receiving miR-4638-3p-overexpressing cells exhibited reduced osteolytic lesions and improved bone mineral density.
- Enhanced trabecular bone microarchitecture and absence of abnormal metastatic cells were observed in the femurs of mice treated with miR-4638-3p-overexpressing cells.
Conclusions:
- MiR-4638-3p plays a crucial inhibitory role in breast cancer bone metastasis in vivo.
- The miR-4638-3p/ATF3 axis represents a promising therapeutic target for managing bone metastasis in breast cancer.
- Further research into miR-4638-3p's role could lead to novel BC treatment strategies.
