Synergistic Effect of Baicalin and Adriamycin in Resistant HL-60/ADM Leukaemia Cells
Background/Aims: The present study was designed to investigate the expression of multidrug resistance (MDR)-related genes, verify the synergistic effects of baicalin and Adriamycin (ADM) and investigate the related mechanisms in ADM-resistant leukaemic HL-60/ADM cells. Methods: We used a HL-60/ADM cell line. Cytotoxicity and flow cytometry assays were employed to verify the cytotoxic effects of baicalin. Real-time polymerase chain reaction and Western blotting assays were used to assess the expression of MDR-related genes and the changes in gene expression (both MDR-related and PI3K/Akt pathway-related) induced by administration of baicalin. Results: We found that only multidrug resistance protein 1 (MRP1), lung resistance-related protein (LRP) and Bcl-2 genes were expressed in both HL-60 and HL-60/ADM cells. HL-60/ADM cells exhibited significantly higher expression (p < 0.05). We also observed that low-dose baicalin (5 and 10 µmol/L) can induce growth inhibition and apoptotic effects on HL-60/ADM cells by increasing the intracellular accumulation of ADM. The synergistic effect of baicalin and ADM was verified. Concerning the potential mechanisms involved in this process, we showed that baicalin down-regulated the expression of several MDR-related and PI3K/Akt pathway-related genes. Conclusions: We confirmed the increased expression of MRP1, LRP and Bcl-2 genes in HL-60/ADM cells compared to regular HL-60 cells, which are recommended for future investigation on MDR. The present study provided evidence of the synergistic effect of baicalin and ADM in HL-60/ADM cells. Therefore, baicalin may be considered as a potential therapeutic agent against resistant leukaemia. Suppression of the PI3K/Akt signalling pathway, followed by inhibition of the expression of MDR-related genes may be a common mechanism in combination treatments with ADM for the reduction of resistance to ADM.