Kaehler Meike, Ruemenapp Johanna, Gonnermann Daniel, Nagel Inga, Bruhn Oliver, Haenisch Sierk, Ammerpohl Ole, Wesch Daniela, Cascorbi Ingolf, Bruckmueller Henrike
Institute of Experimental and Clinical Pharmacology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
Institute of Immunology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
Oncotarget. 2017 Sep 26;8(54):92018-92031. doi: 10.18632/oncotarget.21272. eCollection 2017 Nov 3.
BCR-ABL-independent resistance against tyrosine kinase inhibitor is an emerging problem in therapy of chronic myeloid leukemia. Such drug resistance can be linked to dysregulation of ATP-binding cassette (ABC)-transporters leading to increased tyrosine kinase inhibitor efflux, potentially caused by changes in microRNA expression or DNA-methylation. In an -imatinib-resistance model using K-562 cells, microRNA-212 was found to be dysregulated and inversely correlated to ABC-transporter ABCG2 expression, targeting its 3'-UTR. However, the functional impact on drug sensitivity remained unknown. Therefore, we performed transfection experiments using microRNA-mimics and -inhibitors and investigated their effect on imatinib-susceptibility in sensitive and resistant leukemic cell lines. Under imatinib-treatment, miR-212 inhibition led to enhanced cell viability ( = 0.01), reduced apoptosis ( = 0.01) and cytotoxicity ( = 0.03). These effects were limited to treatment-naïve cells and were not observed in cells, which were resistant to various imatinib-concentrations (0.1 μM to 2 μM). Further analysis in treatment-naïve cells revealed that miR-212 inhibition resulted in ABCG2 upregulation and increased ABCG2-dependent efflux. Furthermore, we observed promoter hypermethylation in 0.5 and 2 μM IM-resistant sublines, whereas methylation status was not altered. Taken together, the miR-212/ABCG2-axis influences imatinib-susceptibility contributing to development of imatinib-resistance. Our data reveal new insights into mechanisms initiating imatinib-resistance in leukemic cells.
对酪氨酸激酶抑制剂的BCR-ABL非依赖性耐药是慢性髓性白血病治疗中一个新出现的问题。这种耐药性可能与ATP结合盒（ABC）转运蛋白的失调有关，导致酪氨酸激酶抑制剂外排增加，这可能是由微小RNA表达或DNA甲基化的变化引起的。在一个使用K-562细胞的伊马替尼耐药模型中，发现微小RNA-212失调，并且与ABC转运蛋白ABCG2的表达呈负相关，靶向其3'-非翻译区。然而，其对药物敏感性的功能影响仍不清楚。因此，我们使用微小RNA模拟物和抑制剂进行了转染实验，并研究了它们对敏感和耐药白血病细胞系中伊马替尼敏感性的影响。在伊马替尼治疗下，miR-212抑制导致细胞活力增强（P = 0.01）、凋亡减少（P = 0.01）和细胞毒性降低（P = 0.03）。这些作用仅限于未接受过治疗的细胞，在对不同伊马替尼浓度（0.1 μM至2 μM）耐药的细胞中未观察到。对未接受过治疗的细胞的进一步分析表明，miR-212抑制导致ABCG2上调和ABCG2依赖性外排增加。此外，我们观察到在0.5 μM和2 μM伊马替尼耐药亚系中ABCG2启动子高甲基化，而ABCC1甲基化状态未改变。综上所述，miR-212/ABCG2轴影响伊马替尼敏感性，促成伊马替尼耐药的发生。我们的数据揭示了白血病细胞中引发伊马替尼耐药机制的新见解。
