Therapeutic potential of MicroRNAs in targeting breast cancer stem cells: A systematic review

BACKGROUND: A distinct subpopulation of tumour cells, known as breast cancer stem cells (BCSCs), plays a critical role in driving poor therapeutic outcomes due to its high proliferative capacity, metastatic potential and resistance to treatment. MicroRNAs (miRNAs) have emerged as a promising focus of research owing to their stability and ability to modulate tumour biology. However, the role of miRNAs in regulating BCSC characteristics remains insufficiently understood. This systematic review aims to synthesise evidence from in vitro and in vivo studies to evaluate the potential of miRNA-based strategies in targeting BCSCs to suppress their proliferation, metastasis potential, and treatment resistance. METHODS: A systematic search of major scientific databases was conducted for studies published from 2015 to 2024. Studies investigating the effects of microRNAs on BCSCs were screened based on predefined inclusion criteria. KEY FINDINGS: Twenty studies met the inclusion criteria, identifying 16 miRNAs with reported regulatory effects on BCSCs. Most miRNAs demonstrated tumour-suppressive functions by reducing proliferation, stemness marker expression, metastatic potential, or treatment resistance, whereas a smaller subset displayed oncogenic activity. miR-7 was the most consistently studied tumour-suppressive miRNA and exhibited multifunctional inhibitory effects. CONCLUSION: miRNAs represent promising therapeutic candidates for targeting BCSCs through coordinated regulation of proliferation, resistance, and metastatic behaviour. However, the translational advancement of miRNA-based strategies requires more standardized experimental frameworks, expanded in vivo studies, and deeper mechanistic investigation to ensure safety and efficacy across breast cancer subtypes.