Related Experiment Video
Updated: Oct 5, 2025
Clinicopathological Analysis of miRNA Expression in Breast Cancer Tissues by Using miRNA In Situ Hybridization
Published on: June 7, 2016
microRNA-221 and tamoxifen resistance in luminal-subtype breast cancer patients: A case-control study
Alfiah Amiruddin1, Muhammad Nassrum Massi2, Andi Asadul Islam3
1Doctoral Program of Biomedical Sciences, Faculty of Medicine, Hasanuddin University, Makassar, Indonesia.
Background:
Around 70% of breast cancers (BCs) are estrogen receptor-α (ERα)-positive. Adjuvant endocrine therapy is used to reduce estrogen levels and inhibit signal transduction through the ER. The anti-estrogen drugs that are most commonly used in endocrine therapy belong to the selective ER modulator (SERM) class and include tamoxifen. Although it has been used for three decades in cases of early-stage and ERα-positive BC, resistance to tamoxifen is a common problem. microRNAs (miRNAs) have a potential role in demonstrating BC resistance to tamoxifen therapy. Hence, there is a need to investigate the expression of miRNA-221 (miR-221) in luminal-subtype BC patients receiving tamoxifen therapy.
Methods:
This case-control study investigated luminal-subtype BC patients who had undergone endocrine therapy for at least 1 year. The case group comprised patients with local or metastatic recurrence, and the control group comprised patients without local or metastatic recurrence.
Results:
There was a significant difference in miR-221 expression (p = 0.005) between the case and control groups. There were no significant differences between the groups that were positive and negative for the progesterone receptor (PR) (p = 0.25), had high and low marker of proliferation Ki-67 levels (p = 0.60), were positive and negative for lymphovascular invasion (p = 0.14), and had stage 2 and stage 3 cancer (p = 0.25).
Conclusion:
miR-221 expression was higher in tamoxifen-resistant BC cases. miR-221 is a potential biomarker of tamoxifen resistance.
Insights
Higher microRNA-221 (miR-221) expression indicates tamoxifen resistance in estrogen receptor-positive breast cancer (BC). This finding suggests miR-221 may serve as a biomarker for predicting treatment outcomes in BC patients.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Estrogen receptor-alpha (ERα)-positive breast cancer (BC) accounts for approximately 70% of cases.
- Adjuvant endocrine therapy, often using selective estrogen receptor modulators (SERMs) like tamoxifen, is standard for ERα-positive BC.
- Tamoxifen resistance is a significant clinical challenge, and microRNAs (miRNAs) are implicated in its development.
Purpose of the Study:
- To investigate the expression of microRNA-221 (miR-221) in patients with luminal-subtype breast cancer receiving tamoxifen therapy.
- To determine if miR-221 expression levels correlate with tamoxifen resistance.
Main Methods:
- A case-control study design was employed.
- Luminal-subtype breast cancer patients with at least 1 year of endocrine therapy were included.
- The case group consisted of patients with recurrence (local or metastatic), while the control group had no recurrence.
Main Results:
- A statistically significant difference in miR-221 expression was observed between patients with and without recurrence (p = 0.005).
- No significant differences in miR-221 expression were found based on progesterone receptor status, Ki-67 levels, lymphovascular invasion, or cancer stage (p > 0.14 for all).
Conclusions:
- miR-221 expression levels were significantly higher in tamoxifen-resistant breast cancer cases.
- miR-221 shows potential as a predictive biomarker for tamoxifen resistance in breast cancer.
