Sequential emergence of MRP- and MDR1-gene over-expression as well as MDR1-gene translocation in homoharringtonine-selected K562 human leukemia cell lines
✍ Scribed by Da-Cheng Zhou; Sylvie Ramond; Franck Viguie; Anne-Marie Faussat; Robert Zittoun; Jean-Pierre Marie
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- French
- Weight
- 891 KB
- Volume
- 65
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
To investigate the mechanism of resistance to an antineoplastic natural product homoharringtonine (HHT) in leukemic cells, we have established 5 sub-lines of human myeloid leukemia K562 cells, designated as K-H3O, K-H 100, K-H200, K-H300 and K-H400, which showed progressive resistance to different concentrations of HHT. These sub-lines were crossresistant to daunorubicin, vincristine, etoposide and mitoxantrone, but not to melphalan. lmmunduorescence with monoclonal anti-Pgp antibody MRKl6 and Northern-blot analysis demonstrated that resistance to HHT is related to the sequential emergence of MRP-and MDR I -gene over-expression. In the low-level-resistant K-H30 sub-line, the MDR I gene was not over-expressed, but the MRP gene was over-expressed 2. I -fold. In the intermediate-level-resistant K-H 100 and K-HZOO sublines, both the MRP and the MDR I genes were over-expressed. However, in the high-level-resistant K-H300 and K-H400 sublines, MDR I -gene over-expression predominated (20-and 2 Ifold respectively). On the other hand, GSTr-gene expression was decreased in all 5 sub-lines. Southern-blot analysis revealed no MRP-gene amplification in any of the 5 sub-lines, whereas the MDRI gene was amplified in the high-level-resistant K-H300 and K-H400 sub-lines. The most interesting observation is a homogeneously staining region (HSR) found in chromosome 2 of the K-H300 and K-H400 sub-lines. Chromosome painting and in sku hybridization demonstrated that this HSR was translocated from chromosome 7 and consisted of the amplified MDR I gene, suggesting that there is a relationship between MDRIgene translocation and MDR I -gene amplification.