体外诱导K562细胞伊马替尼耐药及其机理的初步探讨

目的 体外诱导K562细胞伊马替尼(imatinib)耐药并对其耐药性进行检测.方法 以浓度递增的方法诱导K562对伊马替尼产生耐药, MTT法确定其耐药性.RT-PCR方法半定量测定耐药细胞中BCR/ABL基因水平,并进行BCR/ABL基因序列测定.流式细胞术测定P-gp表达.高效液相色谱仪(HPLC)测定耐药细胞内药物浓度.结论 ①浓度递增法成功诱导K562细胞伊马替尼耐药(K562R),K562R细胞能长期在含5.0 μmol/L的伊马替尼的培养液中生长.②细胞生长曲线显示5.0 μmol/L伊马替尼作用于K562R细胞120 h,其活细胞数量与0 h无明显差别.6个浓度梯度的伊马替尼(0、0.25、0.50、0.75、1.00、2.00 μmol/L)作用于K562细胞24 h,发现所有浓度(除0 μmol/L外)伊马替尼均可抑制K562细胞的生长,24 h细胞活力几乎为零.③MTT法抑制率测定K562细胞半数抑制浓度约为0.75 μmol/L,K562R细胞约为7.5 μmol/L,耐药倍数约为10倍.④HPLC细胞内药物浓度测定显示K562R胞内伊马替尼药物浓度低于K562细胞(P＜0.01),流式细胞检测未发现P-gp表达.⑤374 bp的BCR/ABL基因序列分析未发现常规热点区域基因突变.结论 体外成功诱导出伊马替尼耐药细胞--K562R细胞.K562R耐药主要环节为胞内药物浓度降低,而胞内药物浓度降低与P-gp无关.耐药机理需要进一步研究.

Establishment of an Imatinib Resistance Cell Line K562R and Its Resistant Principia

OBJECTIVE: To establish an imatinib resistance cell line and to study its resistant principia. METHODS: K562 cells were cultured in imatinib at gradually increased concentrations to generate their resistance cell line. MTT assay, RT-PCR, flow cytometry and HPLC were used to clarify the possible mechanisms of the resistance. RESULTS: (1) Imatinib resistance cell line K562R was successfully induced by continuous culture in the presence of gradually increasing doses of imatinib up to 5 micromol/L. K562R cells were maintained in the media containing 5 micromol/L imatinib. (2) Proliferation data showed that cell growth of K562R was not inhibited in 5 micromol/ L imatinib, whereas the parental sensitive cell was significantly inhibited by up to 2.0 micromol/L imatinib. (3) The IC50 of K562R was about 7.5 micromol/L which was ten times higher than that of the parental cell. (4) HPLC revealed that the intracellular imatinib concentration of K562R was strikingly lower than that of the parental cells (up to 27. 8-fold). By flow cytometry, P-gp was not detected on K562R cell, indicating that low intracellular imatinib concentration may not be due to P-gp mediated efflux. (5) Sequence analysis of the 374 bp ABL kinase domain showed no mutation in K562R cell. CONCLUSION: An imatinib resistance cell line K562R has been successfully established. Low intracellular imatinib concentration is a key link in the chain of cell resistance.