Upregulation of stem cell genes in multidrug resistant K562 leukemia cells.

The transmembrane transporter P-glycoprotein (P-gp) encoded by ABCB1, is one major cause for multidrug resistance (MDR). We compared the genomic profile and gene expression pattern of the P-gp positive K562VCR cells with parental P-gp negative K562wt cells. In K562VCR array CGH revealed amplification of ABCB1, ABCB4, ABCB5 and SEMA3D, whereas expression microarrays demonstrated upregulation of stem cell genes (e.g. KIT and HOXB4), anti-apoptotic genes (e.g. IGF1R and CCNG1), and downregulation of pro-apoptotic genes (e.g. CASP4, 6 and 7). Thus, K562VCR cells disclose stem cell characteristics including a range of drug resistance mechanisms possibly attained as a stem cell program switched on en bloc.