Serra M, Reverter-Branchat G, Maurici D, Benini S, Shen J-N, Chano T, Hattinger C-M, Manara M-C, Pasello M, Scotlandi K, Picci P
Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
Ann Oncol. 2004 Jan;15(1):151-60. doi: 10.1093/annonc/mdh004.
To evaluate the impact of dihydrofolate reductase (DHFR) and reduced folate carrier (RFC) genes on methotrexate (MTX) resistance in osteosarcoma cells in relation to retinoblastoma (RB1) gene status.
A series of human osteosarcoma cell lines-either sensitive or resistant to MTX-and 16 osteosarcoma tumour samples were used in this study.
In U-2OS MTX-resistant variants, and in other RB1-positive cell lines, MTX resistance was associated with increased levels of DHFR and with a slight decrease of RFC gene expression. In Saos-2 MTX-resistant variants, and in another RB1-negative cell line, development of MTX resistance was associated with a decrease in expression of RFC, without any significant involvement of DHFR. In osteosarcoma clinical samples, amplification of the DHFR gene at clinical onset appeared to be more frequent in RB1-positive compared with RB1-negative tumours.
Amplification of the DHFR gene may occur more frequently in the presence of RB1-mediated negative regulation of its activity and can be present at clinical onset in osteosarcoma patients. Simultaneous evaluation of RFC, DHFR and RB1 gene status at the time of diagnosis may become the basis for the identification of potentially MTX-unresponsive osteosarcoma patients, who could benefit from treatment protocols with alternative antifolate drugs.
评估二氢叶酸还原酶（DHFR）和还原型叶酸载体（RFC）基因对骨肉瘤细胞中甲氨蝶呤（MTX）耐药性的影响，并探讨其与视网膜母细胞瘤（RB1）基因状态的关系。
本研究使用了一系列对MTX敏感或耐药的人骨肉瘤细胞系以及16例骨肉瘤肿瘤样本。
在U-2OS MTX耐药变异体以及其他RB1阳性细胞系中，MTX耐药与DHFR水平升高以及RFC基因表达略有下降有关。在Saos-2 MTX耐药变异体以及另一个RB1阴性细胞系中，MTX耐药的发生与RFC表达降低有关，而DHFR无明显参与。在骨肉瘤临床样本中，与RB1阴性肿瘤相比，RB1阳性肿瘤在临床发病时DHFR基因扩增似乎更频繁。
在存在RB1介导的对其活性的负调控时，DHFR基因扩增可能更频繁发生，并且可在骨肉瘤患者临床发病时出现。在诊断时同时评估RFC、DHFR和RB1基因状态可能成为识别潜在MTX无反应性骨肉瘤患者的基础，这些患者可能从使用替代抗叶酸药物的治疗方案中获益。
