[Reverse effect of genetically modified adenovirus H101 on drug-resistance of A549/DDP cells to cisplatin]

Abstract

Background & objective: Multidrug resistance is one of the main causes of treatment failure of chemotherapy. Reversal agents may be used to reverse drug-resistance. To date, no appropriate reversal agent is used clinically. This study was to evaluate reverse effect of genetically modified adenovirus H101 on drug-resistance of A549/DDP cells to cisplatin (DDP), and to explore its mechanisms.

Methods: Lung adenocarcinoma cell line A549 and its DDP-resistant cell line A549/DDP were treated with DDP and H101. Reverse effect of H101 on drug-resistance of A549/DDP to DDP was tested by MTT assay. The levels of cellular multidrug resistant protein 1 (MRP1), glutathione-S-transferase (GST), and topoisomerase-II (TOPO-II) were detected by flow cytometry (FCM). The level of intracellular glutathione (GSH) was measured by fluorescence-Coomassie light blue method. The intracellular concentration of platinum was measured by atomic absorption spectrometry.

Results: The resistance index of A549/DDP cells to DDP was 14.3. After infection of H101, the 50% inhibitory concentration (IC(50)) of DDP to A549/DDP cells reduced from 352.4 micromol/L to 61.6 micromol/L by 5.7 folds. Protein levels of GST and TOPO-II were higher in A549/DDP cells than in A549 cells, which were markedly decreased in A549/DDP cells after infection of H101. No MRP1 protein was detected in both A549 cells and A549/DDP cells. Intracellular amount of GSH in A549/DDP cells was 2 times higher than that in A549 cells, which was significantly decreased after infection of H101. The concentration of platinum in A549 cells was 3 times higher than that in A549/DDP cells. After infection of H101, the concentration of platinum in A549 cells had no significant change, but that in A549/DDP cells was significantly increased.

Conclusion: H101 may reverse drug-resistance of A549/DDP cells to DDP through down-regulating GST and TOPO-IIand increasing intracellular cumulation of platinum.