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 a 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 their derived mammospheres with cancer stem cell properties.
Methods: Mammospheres were developed from MCF-7 cells and validated by evaluation of CD44 and CD24 cell surface markers by flow cytometry as well as 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 treatment of cells with various concentrations of FMSP. Apoptosis was evaluated by flow cytometry analysis of annexin V and PI labeling of cells. ROS production was measured using a cell permeable, oxidant-sensitive fluorescence probe (carboxy-H2DCFDA). Involvement of 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 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 significantly attenuated even in the presence of IL-6, the putative activator of 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.