Omeprazole reverses the drug resistance in cisplatin-resistant human lung adenocarcinoma cell line A549/DDP

Objective:To study the effects of omeprazole(OME),a nonspecific inhibitor of vacuolar(H+)-ATPase,in reversing the cisplatin resistance of human lung adenocarcinoma cell line A549/DDP and elucidate the possible mechanism.Methods:A549/DDP were pretreated with OME at non-toxic concentration of 4 μg/mL for 24 h and then incubated with cisplatin(DDP) 2 μg/mL.Cell proliferation was measured with MTT assays.The intracellular pH was detected using laser scanning confocal microscopy(LSCM).The intracellular Bcl-2 and PTEN protein expressions were measured using flow cytometry(FCM).The mRNA expressions of V-ATPase,Bcl-2,and PTEN were detected using semi-quantitative reverse transcription polymerase chain reaction(RT-PCR).Results:OME reversed the drug resistance of A549/DDP cells.The reversal multiple was 1.45(P0.01).LSCM indirectly showed that the intracellular pH was decreased after OME pretreatment.The expression of Bcl-2 in A549/DDP cells was decreased(P0.01),but the expression of PTEN was increased(P0.01).The relative expressions of V-ATPase mRNA were 0.88±0.00 and 0.99±0.00 in A549 and A549/DDP cells,respectively(P0.01).The relative expressions of V-ATPase mRNA of A549/DDP cells were 1.09±0.00 and 1.05±0.02 in OME-treated group and OME-untreated group.RT-PCR assay showed that pretreatment with OME for 24 h inhibited the relative expressions of Bcl-2 mRNA in A549/DDP cells and increased the PTEN mRNA expression(P0.01).Conclusion:The V-ATPase mRNA is over-expressed in A549/DDP cells.OME partly reverses the drug resistance of A549/DDP cells.The action mechanism may be related with up-regulation of PTEN expression and down-regulation of Bcl-2 expression.