Background: Breast Cancer Stem Cells (BCSCs) possess the ability of self-renewal and cellular
heterogeneity, and therefore, play a key role in the initiation, propagation and clinical outcome of breast cancer.
It has been shown that ferrocene complexes have remarkable potential as anticancer drugs.
Objective: The present study was conducted to investigate the effects of a novel ferrocene complex, 1-
ferrocenyl-3-(4-methylsulfonylphenyl)propen-1-one (FMSP) on MCF-7 breast cancer cell line and its derived
mammospheres with cancer stem cell properties.
Methods: Mammospheres were developed from MCF-7 cells and validated by the evaluation of CD44 and
CD24 cell surface markers by flow cytometry as well as of the expression of genes that are associated with stem
cell properties by real-time PCR. Cells viability was assessed by a soluble tetrazolium salt (MTS) after the
treatment of cells with various concentrations of FMSP. Apoptosis was evaluated by flow cytometry analysis of
annexin V and PI labeling of cells. Reactive Oxygen Species (ROS) production was measured using a cellpermeable,
oxidant-sensitive fluorescence probe (carboxy-H2DCFDA). The involvement of the JAK2/STAT3
pathway was also investigated by western blotting.
Results: FMSP could successfully prevent mammosphere formation from differentiated MCF-7 cells and significantly
down-regulated the expression of genes involved in the production of the stem cell properties including
Wnt1, Notch1, β -catenin, SOX2, CXCR4 and ALDH1A1. FMSP decreased cell viability in both MCF-7
cells and spheroid cells, although MCF-10A cells were unaffected by this compound. Apoptosis was also dramatically
induced by FMSP, via ROS production but independent of CD95 activation. Phosphorylation levels of
JAK2 and STAT3 were also found to be significantly attenuated even in the presence of IL-6, the putative activator
of the JAK/STAT pathway.
Conclusion: FMSP can effectively target BCSCs via ROS production and modulation of major signaling pathways
that contribute to the stemness of breast cancer cells, and therefore, might be considered a promising anticancer
agent after in vivo studies.