Baicalin enhances chemosensitivity to doxorubicin in breast cancer cells via upregulation of oxidative stress-mediated mitochondria-dependent apoptosis

Doxorubicin (Dox) is an effective anthracycline anticancer drug. However, recent studies have revealed that Dox resistance is a highly critical issue, and a significant reason for treatment failure. Baicalin is a flavonoid component in the roots of Scutellaria baicalensis Georgi; however, whether baicalin can increase chemosensitivity in breast cancers is still unclear. In this study, we found that cellular apoptosis occurs when excessive intracellular ROS is generated, triggered by the dual intervention of baicalin and doxorubicin, which increases intracellular calcium [Ca²⁺]_i concentrations. Increased [Ca²⁺]_i concentrations decrease the mitochondrial membrane potential (△Ψ_m), thereby causing cellular apoptosis. Pretreatment with NAC (ROS inhibitor) or BATBA (Ca²⁺ chelator) reduces baicalin-induced chemosensitivity. The findings of this study demonstrate that the effect of baicalin on Dox treatment could enhance cytotoxicity toward breast cancer cells via the ROS/[Ca²⁺]_i-mediated intrinsic apoptosis pathway—thus potentially lessening the required dosage of doxorubicin, and further exploring associated mechanisms in combined treatments for breast cancer clinical interventions in the future.