Background
Breast tumor heterogeneity leads to phenotypic diversity, such as tumor-initiating and metastatic properties and drug sensitivity. Materials and
Conclusion
SFCs enrich drug-resistant subpopulations even in vitro and might reflect the highly plastic nature of breast cancer cells even in vitro.
Methods
We found that a self-floating cell (SFC) culture enriches a drug-resistant subpopulation in a HER2-positive breast cancer cell line. SFCs were analyzed for cancer stem cell markers, gene expression profiles, and sensitivity for anticancer drugs.
Results
SFCs expressed cancer stem cell markers, such as aldehyde dehydrogenase (ALDH) activity and elevated HER2 autophosphorylation. Gene expression profiles of SFCs showed a dramatic difference compared to those of parental or forced floating cells. SFCs also expressed CD133, a marker of drug resistance, and resisted cytotoxic drugs by drug efflux transporters. In contrast, HER2 kinase inhibitors efficiently reduced SFC viability.