Institute of Medical and Molecular Toxicology, Chung Shan Medical University, Taichung City 402, Taiwan.
Toxicol Lett. 2010 Feb 15;192(3):408-18. doi: 10.1016/j.toxlet.2009.11.018. Epub 2009 Nov 26.
Multidrug resistance (MDR) of cancer cells to cytotoxic drugs significantly impedes chemotherapeutic treatment. The purpose of this study is to characterize docetaxel (DOC) or vincristine (VCR) selected A549 and H1299 non-small cell lung cancer (NSCLC) sublines that exhibit MDR phenotypes and followed by re-sensitization study. Although all drug resistant sublines showed cross-resistance to DOC, VCR, and doxorubicin (DXR), the expression of ATP-binding cassette (ABC) transporter B1 (ABCB1) gene was found to be strongly induced in DOC but not in VCR resistant A549 sublines by quantitative reverse transcription real-time polymerase chain reaction (qRT-PCR). In DOC and VCR resistant H1299 sublines, moderate expression of ABCB1 was detected. The levels of ABCB1 protein and efflux activities were further examined by immunoblotting and rhodamin-123 staining assay. The results showed that both ABC and non-ABC mediated MDR are existed. Furthermore, verapamil (VER), an inhibitor of ABCB1 and an L-type calcium channel blocker, is capable of reversing the resistance in all drug-resistant sublines independent of ABCB1 expression. Importantly, VER only sensitizes resistant sublines but has no effect on parental cancer cells. Other L-type calcium channel blockers, such as diltiazem (DIL) and nifedipine (NIF), also sensitize MDR sublines without interfering with ABCB1 activity but with lower efficacy than VER. Our data showed that in addition to ABCB1, calcium channel activity may play a crucial role in DOC- and VCR-acquired MDR. Therefore, inhibition of calcium influx may provide a new target to modulate MDR in chemotherapy.
癌细胞对细胞毒性药物的多药耐药（MDR）显著阻碍了化疗治疗。本研究的目的是表征表现出 MDR 表型的多西紫杉醇（DOC）或长春新碱（VCR）选择的 A549 和 H1299 非小细胞肺癌（NSCLC）亚系，然后进行再敏化研究。尽管所有耐药亚系均表现出对 DOC、VCR 和阿霉素（DXR）的交叉耐药性，但通过定量逆转录实时聚合酶链反应（qRT-PCR）发现，DOC 耐药 A549 亚系中 ABC 转运蛋白 B1（ABCB1）基因的表达被强烈诱导，但在 VCR 耐药亚系中则没有。在 DOC 和 VCR 耐药 H1299 亚系中，检测到 ABCB1 的中度表达。通过免疫印迹和罗丹明-123 染色测定进一步检查 ABCB1 蛋白和外排活性。结果表明，存在 ABC 和非-ABC 介导的 MDR。此外，维拉帕米（VER），一种 ABCB1 的抑制剂和 L 型钙通道阻滞剂，能够独立于 ABCB1 表达逆转所有耐药亚系的耐药性。重要的是，VER 仅使耐药亚系敏感，但对亲本癌细胞没有影响。其他 L 型钙通道阻滞剂，如地尔硫卓（DIL）和硝苯地平（NIF），也可使 MDR 亚系敏感，而不干扰 ABCB1 活性，但效果低于 VER。我们的数据表明，除了 ABCB1 之外，钙通道活性可能在 DOC 和 VCR 获得的 MDR 中起关键作用。因此，抑制钙内流可能为调节化疗中的 MDR 提供新的靶标。
