Inhibition of triple-negative breast cancer growth via delphinidin-mediated suppression of the JAK2/STAT3/PD-L1 pathway.

BACKGROUND

Breast cancer is a leading cause of cancer-related mortality among women globally, with triple-negative breast cancer (TNBC) being particularly aggressive. Delphinidin (Dp), an anthocyanin monomer, has shown promising health benefits.

OBJECTIVE

This study investigates the effects of Dp on TNBC and aims to elucidate its specific mechanisms of action.

DESIGN

We utilized cell counting kit-8 (CCK-8) assays, colony formation assays, and scratch assays to evaluate the influence of Dp on the proliferation and migration of TNBC cells. Flow cytometry was employed to analyze programmed cell death-ligand 1 (PD-L1) and Cluster of Differentiation 69 expression, while Western blotting assessed the levels of PD-L1, Janus Kinase 2 (JAK2), Signal Transducer and Activator of Transcription 3 (STAT3), p-JAK2, p-STAT3, and exosomal marker proteins. Additionally, enzyme-linked immunosorbent assay (ELISA) was conducted to measure concentrations of PD-L1, interferon-γ (IFN-γ), and tumor necrosis factor-β (TNF-β).

RESULTS

Dp effectively inhibited TNBC cell proliferation and migration, as evidenced by CCK-8, colony formation, and scratch assays. Flow cytometry and Western blot analysis indicated a reduction in PD-L1 expression in TNBC cells. Meanwhile, we successfully isolated TNBC cell-derived exosomes, with ELISA experiments showing a decrease in PD-L1 expression in these exosomes following Dp treatment. In a co-culture system with TNBC and Jurkat cells, Dp enhanced Cluster of Differentiation 69 expression and reactivated Jurkat cells, resulting in increased secretion of IFN-γ and TNF-β. Additionally, Dp significantly reduced the p-JAK2/JAK2 and p-STAT3/STAT3 ratios in TNBC cells.

CONCLUSION

Dp may exert its anti-TNBC effects by downregulating PD-L1 expression in TNBC cells and exosomes through the JAK2/STAT3 signaling pathway, potentially restoring T cell activity and modifying the tumor microenvironment.