Establishment Of K562/G01 Resistant Model And The Overcoming Of The Resistance And Its Molecular Mechanisms

AIM: This Study is to establish a BCR/ABL+cell line with resistance to STI571, investigate possible mechanisms of acquired resistance to STI571 and study the stragey to confer the resistance.METHODS: Human leukemia K562 cells were cultured in gradually increasing concentrations of STI571 over a period of several months to generate resistant line. MTT assay, RT-PCR analysis, Western blotting assay, and FISH analysis were used to study the possible molecular mechanisms of the resistance.RESULTS: A resistant cell line, K562/G01, was selected with more than 11-fold resistant to STI571 compared with the parental sensitive cell line. Apart from DOX, the cross-resistance to a broad spectrum of other anticancer agents was failed to be observed in the resistant cell line. Apart from the diameter, there was no difference between the two cell lines in terms of the cell shape. K562/G01 cells showed more active proliferation, increased levels of BCR/ABL, mdrl mRNA and their coding proteins and the increased tyrosion kinase activity. No point mutation in the BCR/ABL ATP-binding site from K562/G01 was detected. The copies of BCR/ABL fusion gene were increased in K562/G01 cells. Two lead compounds with novel structures discovered by virtual screening found to be effective against resistant cell line. Combination using STI571 with VPL, PND or anti-cancer drugs could significantly overcome the drug resistance in K562/G01 cells.CONCLUSION: A STI571-resistant human leukemia cell line, K562/G01, was established. The mechanisms of resistance of K562/G01 cells to STI571 involved increased expression of BCR/ABL and mdrl/Pgp, amplification of BCR/ABL fusion gene, and increased activity of BCR/ABL. Using new BCR/ABL inhibitors or STI571 combined with either Pgp inhibitors or anticancer drugs should be effctive in overcoming resistance.