Epirubicin

For proliferation assays, a CCK-8 cell counting kit (Dojindo, Kumamoto, Japan) was used to assay the cell viability. Infected cells were plated in 96-well plates with a final volume of 100 μL of growth medium and incubated overnight under 5% CO₂ at 37 °C. Ten drug concentrations were freshly prepared according to the half-log dilution method (10,000-fold range, docetaxel: 0–1 μM, epirubicin: 0–20 μM). The cells were treated with different concentrations of docetaxel (MedChemExpress, Houston, TX, USA) and epirubicin (MedChemExpress) with five replicates per condition. After 48 h, the CCK-8 assay was performed by incubating cells with a CCK-8 reagent for 2 h at 37 °C, and measuring the absorbance at 450 nm with an Infinite 200 PRO plate reader (TECAN, Männedorf, Switzerland). These data were used to calculate the cell viability at different drug concentrations. The growth and dose inhibition curves were plotted and analyzed using the GraphPad Prism 8.3.0 (GraphPad Software, Inc., San Diego, CA, USA). The IC₅₀ values were determined by nonlinear regression analysis of the plots of the percentage of growth inhibition vs. the log of inhibitor concentrations. All experiments were repeated at least three times, and data are expressed as mean ± SD.