Cowie F J, Pritchard-Jones K, Renshaw J, Pinkerton C R
Children's Department, The Royal Marsden NHS Trust, Downs Road, Sutton, Surrey SM2 5PT, UK.
Int J Oncol. 1998 May;12(5):1143-9. doi: 10.3892/ijo.12.5.1143.
Four rhabdomyosarcoma and three neuroblastoma cell lines were characterised for the presence of P-glycoprotein and MDR-1 expression using immunohistochemistry, northern analysis, RT-PCR and in situ mRNA hybridisation. None of the rhabdomyosarcoma lines were unequivocally positive in contrast to all three neuroblastoma lines. Chemosensitivity to cytotoxic agents was determined using the MTT assay and chemosensitisation by cyclosporin and verapamil was evaluated. In a single rhabdomyosarcoma line (HX 170) there was sensitisation to etoposide using verapamil but not to other drugs or using cyclosporin A. In contrast, in all three neuroblastoma lines both cyclosporin and verapamil sensitised to vincristine and doxorubicin. No evidence of sensitisation to etoposide was apparent. The sensitisation was most marked for vincristine, using either modulator and therefore the influence of modulator scheduling was evaluated with this drug in the neuroblastoma line SK N BE. Prolonged pre-exposure to modulator did not appear necessary and maximum sensitisation was apparent where either cyclosporin or verapamil was added 1-3 h prior to and post vincristine. Continuity of exposure was important and even a break of 30 min appeared to reduce sensitisation. These data confirm the potential for chemosensitisation in MDR-1 positive neuroblastoma cell lines and provide some basis for rational schedule design in clinical practice. Because of the probability that vincristine resistance is predominantly related to MDR-1 and less multifactorial than for other drugs such as doxorubicin or etoposide, this agent should be considered for inclusion in any clinical evaluation of MDR reversal strategies.
利用免疫组织化学、Northern印迹分析、逆转录聚合酶链反应（RT-PCR）和原位mRNA杂交技术，对4种横纹肌肉瘤细胞系和3种神经母细胞瘤细胞系进行了P-糖蛋白和多药耐药基因1（MDR-1）表达的鉴定。与所有3种神经母细胞瘤细胞系不同，没有一种横纹肌肉瘤细胞系呈明确阳性。采用MTT法测定对细胞毒性药物的化学敏感性，并评估环孢素和维拉帕米的化学增敏作用。在一个横纹肌肉瘤细胞系（HX 170）中，维拉帕米可使细胞对依托泊苷敏感，但对其他药物或环孢素A不敏感。相比之下，在所有3种神经母细胞瘤细胞系中，环孢素和维拉帕米均可使细胞对长春新碱和阿霉素敏感。未发现对依托泊苷有增敏作用的证据。使用任何一种调节剂时，对长春新碱的增敏作用最为明显，因此在神经母细胞瘤细胞系SK N BE中，用该药物评估了调节剂给药方案的影响。似乎没有必要长时间预先接触调节剂，在长春新碱给药前和给药后1 - 3小时添加环孢素或维拉帕米时，可出现最大增敏作用。持续接触很重要，即使中断30分钟似乎也会降低增敏作用。这些数据证实了MDR-1阳性神经母细胞瘤细胞系存在化学增敏的可能性，并为临床实践中的合理给药方案设计提供了一些依据。由于长春新碱耐药可能主要与MDR-1相关，且比阿霉素或依托泊苷等其他药物的多因素耐药性更低，因此在任何MDR逆转策略的临床评估中都应考虑使用该药物。
