Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, Campus de Montilivi, Maria Aurèlia Campmany, 69, 17071, Girona, Spain.
Invest New Drugs. 2012 Jun;30(3):880-8. doi: 10.1007/s10637-011-9636-2. Epub 2011 Feb 1.
We have previously described a cytotoxic human pancreatic-ribonuclease variant, named PE5, which is able to cleave nuclear RNA, inducing the apoptosis of cancer cells. We have investigated whether PE5 could specifically inhibit the accumulation of P-glycoprotein in multidrug-resistant cells, since P-glycoprotein overexpression is one of the most important mechanisms contributing to the multiple drug resistance phenotype. We show that PE5 is able to reduce the amount of P-glycoprotein in two different multidrug-resistant cell lines, NCI/H460-R and NCI/ADR-RES, while glutathione S-transferase-л is not affected. We also show that onconase, an amphibian ribonuclease that is undergoing phase II/III clinical trials as an antitumor drug, does not affect the expression of these proteins. The reduction of P-glycoprotein accumulation, which has been functionally confirmed by flow cytometry analysis, may be caused by the previously reported underphosphorylation of JNK induced by PE5. We also show that PE5 has synergistic cytotoxicity with doxorubicin on the NCI/ADR-RES multidrug-resistant cell line. In conclusion, PE5 is a cytotoxic ribonuclease that cleaves nuclear RNA and decreases the expression of P-glycoprotein, showing anticancer activity in multidrug-resistant cell lines.
我们之前描述了一种细胞毒性的人胰腺核糖核酸酶变体，名为 PE5，它能够切割核 RNA，诱导癌细胞凋亡。我们研究了 PE5 是否能够特异性抑制多药耐药细胞中 P-糖蛋白的积累，因为 P-糖蛋白的过度表达是导致多药耐药表型的最重要机制之一。我们表明，PE5 能够减少两种不同的多药耐药细胞系 NCI/H460-R 和 NCI/ADR-RES 中的 P-糖蛋白的量，而谷胱甘肽 S-转移酶-л 不受影响。我们还表明，蛙皮素，一种正在进行 II/III 期临床试验作为抗肿瘤药物的两栖动物核糖核酸酶，不会影响这些蛋白质的表达。通过流式细胞术分析功能证实的 P-糖蛋白积累的减少可能是由 PE5 先前报道的 JNK 磷酸化不足引起的。我们还表明，PE5 与多柔比星在 NCI/ADR-RES 多药耐药细胞系上具有协同细胞毒性。总之，PE5 是一种细胞毒性核糖核酸酶，可切割核 RNA 并降低 P-糖蛋白的表达，在多药耐药细胞系中显示出抗癌活性。
