title: Salinomycin induces selective cytotoxicity to MCF-7 mammosphere cells through targeting the Hedgehog signaling pathway.
abstract: Breast cancer stem cells (BCSCs) are believed to be responsible for tumor chemoresistance, recurrence, and metastasis formation. Salinomycin (SAL), a carboxylic polyether ionophore, has been reported to act as a selective breast CSC inhibitor. However, the molecular mechanisms underlying SAL-induced cytotoxicity on BCSCs remain unclear. The Hedgehog (Hh) signaling pathway plays an important role in CSC maintenance and carcinogenesis. Here, we investigated whether SAL induces cytotoxicity on BCSCs through targeting Hh pathway. In the present study, we cultured breast cancer MCF-7 cells in suspension in serum-free medium to obtain breast CSC-enriched MCF-7 mammospheres (MCF-7 MS). MCF-7 MS cells possessed typical BCSC properties, such as CD44+CD24-/low phenotype, high expression of OCT4 (a stem cell marker), increased colony-forming ability, strong migration and invasion capabilities, differentiation potential, and strong tumorigenicity in xenografted mice. SAL exhibited selective cytotoxicity to MCF-7 MS cells relative to MCF-7 cells. The Hh pathway was highly activated in BCSC-enriched MCF-7 MS cells and SAL inhibited Hh signaling activation by downregulating the expression of critical components of the Hh pathway such as PTCH, SMO, Gli1, and Gli2, and subsequently repressing the expression of their essential downstream targets including C-myc, Bcl-2, and Snail (but not cyclin D1). Conversely, Shh-induced Hh signaling activation could largely reverse SAL-mediated inhibitory effects. These findings suggest that SAL-induced selective cytotoxicity against MCF-7 MS cells is associated with the inhibition of Hh signaling activation and the expression of downstream targets and the Hh pathway is an important player and a possible drug target in the pathogenesis of BCSCs.
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Ying-Zi
authors.initials: YZ
authors.lastname: Fu
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Yan
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Miao
authors.initials: M
authors.lastname: He
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Qing-Huan
authors.initials: QH
authors.lastname: Xiao
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Wei-Fan
authors.initials: WF
authors.lastname: Yao
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Hui-Zhe
authors.initials: HZ
authors.lastname: Wu
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Zhao-Jin
authors.initials: ZJ
authors.lastname: Yu
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Ming-Yi
authors.initials: MY
authors.lastname: Zhou
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Mu-Tian
authors.initials: MT
authors.lastname: Lv
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Zhang
authors.affiliation: Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, P.R. China.
authors.forename: Min-Jie
authors.initials: MJ
authors.lastname: Wei
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D053823:Hedgehog Proteins / Q000378:metabolism*; D006801:Humans; D061986:MCF-7 Cells; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000187:drug effects*; D011714:Pyrans / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D023041:Xenograft Model Antitumor Assays; D000095662:Polyether Polyketides
chemical_list: D000970:Antineoplastic Agents; D053823:Hedgehog Proteins; D011714:Pyrans; C010327:salinomycin; D000095662:Polyether Polyketides