The effects and mechanisms of triptolide to reverse the multi-drug resistance of A549/DDP lung cancer

Object: To investigate the effects and mechanisms of triptolide to reverse the multi-drug resistance of lung cancer cell line A549/DDP. Methods: After treating A549/DDP cells with triptolide, we determined the cells proliferation inhibition ratio by MTS assay, the intracellular concentration of rhodamine-123 (Rh-123) and cells surface expression of p-glycoprotein (P-gp) by flow cytometry, the expression of multi-drug resistance protein (MDR1) and lung resistance related protein (LRP) by western blot and real time PCR, and the activity of NF-κB by report gene system. We also determined the phosphorylation of Akt by western blot. Results: Treatment with triptolide was able to increase the drug sensitivity of A549/DDP cells. After treatment with 2 or 10 μM triptolide, the reverse folds (RF) to cisplatin were 2.09and 2.93, respectively. The intracellular concentration of Rh-123 was elevated by 1.38 and 2.88 folds, and the P-gp level was 57.1% and 32.1% of the control, respectively. The expression of MDR1 and LRP was downregulated significantly. Accordingly, the mRNA level of MDR1 was 64.2% and 22.6% of control, and the mRNA level of LRP was 54.8% and 34.7% of control, respectively. Furthermore, the transcriptional activity of NF-κB was reduced to 55.6% and 23.6% of the control, and the phosphorylation of Akt was also decreased significantly. Conclusions: Triptolide was potential to reverse the multi-drug resistance of A549/DDP, increase its drug sensitivity. Triptolide could inhibit the drug efflux, downregulate the expresson of MDR1 and LRP. The possible mechanisms were inhibition of Akt phosphorylation and NF-κB activity by triptolide.