Drug-resistant breast cancer cell line displays cancer stem cell phenotype and responds sensitively to epigenetic drug SAHA

Cancer stem cell (CSC) population in solid human breast tumor is identified by CD44(+)/CD24(-) phenotype, characterized by high tumorigenicity, invasiveness, and drug resistance. In this study, we characterized drug-resistant breast cancer cell line-MCF-7/Adr and a number of other breast cancer cell lines using flow cytometry, immunofluorescence, mammosphere formation assay, and migration assay, examining their CSC immunophenotypes, presence of CSC proteins, tumorigenicity in vitro, and migratory rates, respectively. Our results show that MCF-7/Adr cells uniformly display CSC characteristics yet retain low migratory rate. They are also able to self-renew and differentiate under floating culture conditions. Furthermore, MCF-7/Adr is selectively sensitive to epigenetic drug, suberoylanilide hydroxamic acid, losing drug resistance and changes morphology yet retaining CSC immunophenotypes. In conclusion, we show that resistant breast cancer cell line MCF-7/Adr demonstrates uniform CSC-like characteristics and are sensitive to epigenetic drug treatment.