| Summary: | Objective To explore the molecular mechanism by which cepharanthine (CEP) sensitizes triple-negative breast cancer cells to doxorubicin (DOX) chemotherapy. Methods The triple-negative breast cancer cell lines MDA-MB-231 and MDA-MB-468 were treated with CEP (2, 4, 6, 8, or 10 μmol/L) alone, DOX (0.2, 0.4, 0.6, 0.8, or 1.0 μmol/L) alone, or the combination of CEP (4 μmol/L) and DOX (0.5 μmol/L). MTT assay was used to test the cell viability after the treatments, and flow cytometry was used to analyze the cell apoptosis and the production of reactive oxygen species (ROS); Western blotting was performed to detect the expression of PARP-1, cleaved caspase-3 and cytochrome C in the cells. Transmission electron microscopy (TEM) was used to observe the ultrastructural changes of MDA-MB-231 cells in response to the treatments; the mitochondrial membrane potential of the cells was detected using JC-1 probe, and the mitochondrial morphology and mitophagosomes were observed with confocal laser scanning microscopy and TEM. Results Compared with CEP or DOX treatment alone, the combined treatment with CEP and DOX significantly suppressed the proliferation of both MDA-MB-231 and MDA-MB-468 cells (P < 0.01) with an obvious synergistic effect(synergy coefficient < 1). The combined treatment induced obvious apoptosis in the 2 cell lines (P < 0.01) and caused the degradation of PARP-1, activation of caspase-3, and the release of cytochrome C. The combined treatment also resulted in significantly decreased mitochondrial membrane potential, accumulation of mitophagosomes, and a massive production of ROS in MDA-MB-231 cells (P < 0.01). Conclusion CEP can sensitize triple-negative breast cancer cells to DOX chemotherapy probably by inducing the accumulation of mitophagosomes and increasing ROS production to cause mitochondrial damage and cell apoptosis.
|
|---|