Oh Seon-Hee, Lee Sook-Young, Choi Cheol-Hee, Lee Song-Hee, Lim Sung-Chul
Research Center for Resistant Cells, Chosun University, Gwangju 501-759, Korea.
Arch Pharm Res. 2009 Jun;32(6):883-91. doi: 10.1007/s12272-009-1610-6. Epub 2009 Jun 26.
To elucidate the mechanisms involved in adaptation of lung epithelial cells to cadmium (Cd), we established a cell line that exhibits Cd-resistance (RWI38). RWI38 showed approximately 5-fold greater Cd-resistance (MTT assays) than WI38 cells, and cross-resistance to Zn and cisplatin. RWI38 cells also demonstrated an upregulated level of multidrug resistance-associated protein (MRP) and metallothionein (MT) (as shown by Western blot analysis and RT-PCR studies). The protein level of MRP decreased after Cd exposure in WI38 cells, but was sustained at high levels in RWI38 cells, leading led to enhanced calcein efflux. Cd induced Akt phosphorylation in RWI38 but not WI38 cells; this was prevented by probenecid or siRNA for MRP, both of which led to enhanced cell death, as demonstrated by capsase-3 activation and decreased cell viability. These results suggest a functional role for MRP in the regulation of the Akt pathway as well in the efflux pumping of drugs, thereby contributing toward the adaptation of cells to Cd toxicity. The findings of this study could be potentially beneficial in the design of therapeutic targets for Cd-induced tumor progression.
为了阐明肺上皮细胞适应镉（Cd）的相关机制，我们建立了一种具有镉抗性的细胞系（RWI38）。与WI38细胞相比，RWI38在MTT试验中显示出约5倍的更高镉抗性，并且对锌和顺铂具有交叉抗性。RWI38细胞还表现出多药耐药相关蛋白（MRP）和金属硫蛋白（MT）水平上调（如蛋白质印迹分析和逆转录-聚合酶链反应研究所显示）。WI38细胞在镉暴露后MRP蛋白水平下降，但在RWI38细胞中维持在高水平，导致钙黄绿素外排增强。镉诱导RWI38细胞而非WI38细胞中的Akt磷酸化；丙磺舒或MRP的小干扰RNA可阻止这种磷酸化，二者均导致细胞死亡增强，如半胱天冬酶-3激活和细胞活力降低所证实。这些结果表明MRP在Akt途径调节以及药物外排泵中具有功能作用，从而有助于细胞适应镉毒性。本研究结果可能对镉诱导的肿瘤进展治疗靶点的设计具有潜在益处。
