Resistance to chemotherapy is one of the major problems in treatment responses of lung cancer. This study explored the mechanism underlying the arsenic resistance of lung cancer. Four lung cancer cells with different proliferation activity were characterized for cytotoxicity, arsenic influx/efflux, and arsenic effects on intracellular glutathione and 8-hydroxy-2??deoxyguanosine (8-OHdG) production. Our data revealed that relative proliferation potency of these cells was H1299 > A549 > CL3 > H1355. Moreover, A549, H1299, and H1355 were markedly resistant to As2O3 with IC50 ??100 弮M, whereas CL3 was sensitive to As2O3 with IC50 ??11.8 弮M. After treatment with the respective As2O3 at IC50, arsenic influx/efflux activity in CL3 was comparable to those in the other three arsenic-resistant cells. However, differences in glutathione levels and 8-OHdG production were also detected either before or after arsenic treatment, indicating that a certain degree of variation in anti-oxidative systems and/or 8-OHdG repair activity existed in these cell lines. By transfection of an aquaglyceroporin 9 (AQP9) gene, we showed that increased AQP9 expression significantly enhanced arsenic uptake and disrupted arsenic resistance of A549. The present study strongly suggests that membrane transporters responsible for arsenic uptake, such as AQP9, may play a critical role in development of arsenic resistance in human lung cancer cells. 2008 Elsevier Ltd. All rights reserved.
