OBJECTIVETo study the resistant related molecules of human leukemia drug resistant K562 cells (K562/HHT) induced by homoharringtonine (HHT).

METHODSGene expression profiles on K562/HHT, K562 and K562/HHT/RU486 (K562/HHT reversed by RU486) cells were detected by DNA microarray. The bone marrow tyrosine kinase gene in chromosome X (BMX) which changed dynamically among the three cells was confirmed by RT-PCR and Western blot. Then, BMX was transfected into K562 and K562/HHT cells, and the changes of daunorubicin (DNR) concentrations in these two cells were observed for BMX overexpression.

RESULTSAs compared with K562, there were changes in 117 gene expressions in K562/HHT, 57 of which were up-regulated and 60 down-regulated. The mdrl gene was significantly up-regulated. When compared with K562/HHT, 50 significantly differently expressed genes were screened out in the K562/HHT/RU486 cells, of which up- and down-regulated genes were 13 and 37 respectively. These genes involved in drug resistance, cell signaling, cell differentiation, cell proliferation, transcription regulator, ion transport and so on. Four genes [NM-001721 (BMX), NM-031459 (SESN2), NM-033642 (FGF13) and AL-049309 (SFRS12)] expressed significantly differently in the two group cells, BMX gene expression was higher in K562/HHT, than in K562, but lower than in K562/HHT/RU486 as confirmed by RT-PCR and Western blot. After the plasmid pCI-neo-BMX was transfected into K562 and K562/HHT cells, DNR concentration was significantly lower (79.28 +/- 4.04, 29.84 +/- 2.67) than those before transfection (158.52 +/- 8.08, 58.58 +/- 6.53).

CONCLUSIONBMX is associated with multi-drug resistance of K562/HHT cell line.