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Sequential emergence of MRP ‐ and MDR 1‐gene over‐expression as well as MDR 1‐gene translocation in homoharringtonine‐selected K562 human leukemia cell lines
Author(s) -
Zhou DaCheng,
Ramond Sylvie,
Viguie Franck,
Faussat AnneMarie,
Zittoun Robert,
Marie JeanPierre
Publication year - 1996
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/(sici)1097-0215(19960126)65:3<365::aid-ijc15>3.0.co;2-9
Subject(s) - homoharringtonine , chromosomal translocation , k562 cells , gene , leukemia , biology , gene expression , cancer research , genetics , microbiology and biotechnology
To investigate the mechanism of resistance to an anti‐neoplastic natural product homoharringtonine (HHT) in leukemic cells, we have established 5 sub‐lines of human myeloid leukemia K562 cells, designated as K‐H30, K‐H100, K‐H200, K‐H300 and K‐H400, which showed progressive resistance to different concentrations of HHT. These sub‐lines were cross‐resistant to daunorubicin, vincristine, etoposide and mitoxantrone, but not to melphalan. Immunofluorescence with monoclonal anti‐Pgp antibody MRK16 and Northern‐blot analysis demonstrated that resistance to HHT is related to the sequential emergence of MRP ‐ and MDR 1‐gene over‐expression. In the low‐level‐resistant K‐H30 sub‐line, the MDR 1 gene was not over‐expressed, but the MRP gene was over‐expressed 2.1‐fold. In the intermediate‐level‐resistant K‐H100 and K‐H200 sublines, both the MRP and the MDR 1 genes were over‐expressed. However, in the high‐level‐resistant K‐H300 and K‐H400 sublines, MDR 1‐gene over‐expression predominated (20‐ and 21‐fold respectively). On the other hand, GST π‐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 MDR 1 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 situ hybridization demonstrated that this HSR was translocated from chromosome 7 and consisted of the amplified MDR 1 gene, suggesting that there is a relationship between MDR 1‐gene translocation and MDR 1‐gene amplification. © 1996 Wiley‐Liss, Inc.