Pakistan Journal of Pharmaceutical Sciences

Abstract: Background: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and currently lacks defined therapeutic targets. Although miR-152-3p functions as a tumor suppressor in various cancers, its specific mechanism and regulatory network in TNBC remain poorly understood. Objectives: To investigate the expression and tumor-suppressive function of miR-152-3p in TNBC cells and to elucidate its mechanism of targeting STAT3, RELA and ADCY6. Methods: miR-152-3p expression was compared between MDA-MB-231 and MCF-10A cells using qRT-PCR. MDA-MB-231 cells were transfected with miR-152-3p mimics or inhibitors and cell proliferation, apoptosis and invasion were assessed by MTT assay, flow cytometry and Transwell assay, respectively. Direct target interactions were validated by a dual-luciferase reporter assay, and protein levels of STAT3, RELA, and ADCY6 were examined by Western blot. Key findings were further validated in Hs 578T cells. Results: miR-152-3p expression was significantly downregulated in TNBC cells. Overexpression of miR-152-3p markedly inhibited proliferation and invasion while promoting apoptosis in MDA-MB-231 cells. Dual-luciferase reporter assays confirmed that miR-152-3p directly binds to the 3‘untranslated regions of STAT3, RELA and ADCY6. Overexpression of miR-152-3p significantly reduced STAT3 and RELA protein levels while upregulating ADCY6 expression. Rescue experiments demonstrated that restoration of STAT3 expression partially reversed the tumor-suppressive effects of miR-152-3p. These findings were recapitulated in Hs 578T cells, suggesting generalizability across TNBC subtypes. Conclusion: miR-152-3p suppresses TNBC progression by downregulating STAT3/RELA and upregulating ADCY6, thereby activating cAMP signaling. These findings provide a foundation for further investigation into the potential of miR-152-3p as a multi-target therapeutic strategy for TNBC.