Abstract:

Objective To explore the inhibition effects of epidermal growth factor receptor (EGFR) antagonist monoclonal antibody cetuximab (C225) on breast cancer stem cells in human breast cancer cell line MCF-7. Methods The effects of C225 on the proliferation of breast cancer cell line MCF-7 were detected by MTT assay. MCF-7 cells were cultured to generate primary mammospheres, and were divided into control group, C225 group, epidermal growth factor (EGF) group and EGF+C225 group according to whether or not the culture media contained exogenous EGF and C225. Thirteen days after culture, the volume and number of mammospheres of these four groups were observed, and mammosphere-forming efficiency (MFE) was calculated. The percentages of CD44⁺CD24^- cells in mammospheres of these four groups and in routinely cultured MCF-7 cells were determined by flow cytometry. Results The inhibition rate on MCF-7 cells increased with the concentration of C225. Compared with control group, the volume of mammospheres in C225 group significantly decreased, and MFE and percentages of CD44⁺CD24^- cells in mammospheres significantly decreased [(0.61±0.04)% vs (1.44±0.09)%, P<0.01; (3.50±0.29)% vs (9.07±0.52)%, P<0.01]. Compared with EGF group, the volume of mammospheres in EGF+C225 group significantly decreased, and MFE and percentages of CD44⁺CD24^- cells in mammospheres significantly decreased [(0.68±0.04)% vs (1.61±0.05)%, P<0.01; (4.00±0.58)% vs (10.47±0.79)%, P<0.01]. The percentage of CD44⁺CD24^- cells in routinely cultured MCF-7 cells was (2.03±0.15)%, and was significantly different from those in EGF group and control group (P<0.01). There was no significant difference in volume of mammospheres, MFE and percentage of CD44⁺CD24^- cells in mammospheres between EGF group and control group (P>0.05). Conclusion C225 has significant inhibition effects on CD44⁺CD24^- cells in MCF cells.

Key words: breast cancer, stem cells, mammoshpere, epidermal growth factor receptor, monoclonal antibody, C225