Targeting the miR-325-3p/GSTP1 axis overcomes paclitaxel resistance in triple-negative breast cancer by inducing ferroptosis.

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subtype with limited treatment options, and paclitaxel resistance remains a major therapeutic challenge. Ferroptosis, an iron-dependent cell death mechanism, and microRNAs (miRNAs) like miR-325-3p have emerged as potential regulators of chemoresistance, but their roles in TNBC are poorly understood.

OBJECTIVE

This study aimed to investigate whether ferroptosis and miR-325-3p modulate paclitaxel resistance in TNBC and to identify the underlying molecular mechanisms.

METHODS

Paclitaxel-resistant TNBC cell lines (MDA-MB-231/Pac, SUM159PT/Pac) were established and treated with ferroptosis modulators. miR-325-3p expression was assessed in resistant vs. sensitive TNBC tissues and cells. Functional assays (CCK-8, EdU, flow cytometry, TBARS, FerroOrange) evaluated cell viability, proliferation, apoptosis, and ferroptosis markers. GSTP1 was validated as a miR-325-3p target via dual-luciferase reporter assays and rescue experiments. In vivo xenograft models tested the therapeutic potential of miR-325-3p overexpression with/without GSTP1 restoration.

RESULTS

Ferroptosis inducers (erastin, RSL3) sensitized resistant TNBC cells to paclitaxel, while inhibitors (deferiprone, NAC) attenuated this effect. MiR-325-3p was downregulated in paclitaxel-resistant tissues and cells. Its overexpression restored paclitaxel sensitivity by promoting apoptosis and ferroptosis (↑iron accumulation, ↑lipid peroxidation). GSTP1 was identified as a direct target of miR-325-3p. Rescue experiments confirmed that GSTP1 restoration partially reversed miR-325-3p-mediated ferroptosis and paclitaxel sensitization. In vivo, miR-325-3p overexpression suppressed tumor growth, while GSTP1 co-expression mitigated this effect.

CONCLUSION

The miR-325-3p/GSTP1 axis regulates paclitaxel resistance in TNBC by modulating ferroptosis. Targeting this axis represents a promising strategy to overcome chemoresistance.