Elucidation of Selective Apoptosis of Breast Cancer Cells Induced by Panax ginseng-Derived Exosomes via Regulation of Bax/Bcl-2 Ratio and AMPK-α Signaling

This study evaluated the anticancer potential of Panax ginseng-derived exosomes (PGEs) against MDA-MB-231 breast cancer cells, focusing on AMP-activated protein kinase (AMPK)-mediated apoptosis and tumor cell selectivity. PGE was isolated using size-exclusion chromatography and exhibited a mean particle size of 163.4 nm with a concentration of 1.2 × 1010 particles/mL. The exosomal identity was verified by elevated expression levels of CD9 (91.4%), CD63 (96.8%), and TET-8 (127.2%). Treatment with PGE caused a dose-dependent decline in the viability of MDA-MB-231 cells (87.2% at 0.38 × 1010 particles/mL), while normal human mammary epithelial cells (HMECs) maintained 90.1% viability even at 3.0 × 1010 particles/mL, indicating selective induction of apoptosis. In scratch assays, PGE suppressed MDA-MB-231 migration by up to 29.8% but enhanced HMEC proliferation and migration by 88.5%, demonstrating selective anti-invasive effects. Molecular analysis showed increased expression of AMPK-α, Bax, caspase-3, and caspase-9, coupled with downregulation of Bcl-2 and vascular endothelial growth factor, thereby validating mitochondrial apoptosis as the underlying mechanism. Flow cytometry further revealed a dose-dependent increase in early and late apoptosis in MDA-MB-231 cells (total apoptosis: 17.7%-32.9%), while HMEC displayed only minimal apoptotic response (< 7.6%). Immunofluorescence analysis also indicated chromatin condensation, ZO-1 disruption, and F-actin reorganization in MDA-MB-231, whereas HMEC preserved structural integrity with enhanced ZO-1 and F-actin intensity. LC-MS/MS profiling identified ginsenosides Rf, Rh1, and Rb1 as principal bioactive constituents of PGE, implicating them in AMPK-dependent apoptosis. Taken together, these results demonstrated that PGE selectively triggers apoptosis in breast cancer cells while maintaining normal cell viability, highlighting its potential as a natural exosome-based anticancer therapeutic with strong biocompatibility and translational potential.