Human breast cancer MCF-7 cells: SN38-selected cells

Transcriptional profiling of human breast cancer MCF-7 cells comparing control untreated cells with cells exposed to step-wise increasing doses of SN38, an active metabolite of irinotecan. MCF-7 cell clones were established by a limiting dilution method. SN38-sensitive MCF-7 clone (Clone 3) was used for further analyses. MCF-7/SNR cells were established by continuously exposing this clone to SN38 with stepwise increasing concentrations ranging from 0.5 ng/mL to 50 ng/mL over a period of six months. MCF-7/SNR cells were maintained in the presence of 50 ng/mL SN38 until 24 h prior to any experiment. Total RNA was extracted from MCF-7 and MCF-7/SNR cells for cDNA microarray analysis.