title: Addition of niclosamide to palladium(II) saccharinate complex of terpyridine results in enhanced cytotoxic activity inducing apoptosis on cancer stem cells of breast cancer.
abstract: Wnt signaling is one of the core signaling pathways of cancer stem cells (CSCs). It is re-activated in CSCs and plays essential role in the survival, self-renewal and proliferation of these cells. Therefore, we aimed to evaluate the cytotoxic effects of palladium(II) complex which is formulated as [PdCl(terpy)](sac)2H2O and its combination with niclosamide which is an inhibitor of Wnt signaling pathway associated with breast cancer stem cells. Characteristic cell surface markers (CD44(+)/CD24(-)) were determined by flow cytometry in CSCs. ATP viability assay was used to determine the cytotoxic activity. The mode of cell death was evaluated morphologically using fluorescence microscopy and biochemically using M30 ELISA assay as well as performing qPCR. Our study demonstrated that the combination of niclosamide (1.5 μM) and Pd(II) complex (12.5, 25 and 50 μM) at 48 h has enhanced cytotoxic activity resulted from the induction of apoptosis (indicated by the presence of pyknotic nuclei, increments in M30 and over expression of proapoptotic genes of TNFRSF10A and FAS). Importantly, the addition of niclosamide resulted in the suppression of autophagy (proved by the decrease in ATG5 gene levels) that might have contributed to the enhanced cytotoxicity. In conclusion, the application of this combination may be regarded as a novel and effective approach for the treatment of breast cancer due to its promising cytotoxic effect on cancer stem cells that cause recurrence of the disease.
authors.affiliation: Department of Biology, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey.
authors.forename: Didem
authors.initials: D
authors.lastname: Karakas
authors.affiliation: Department of Biology, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey.
authors.forename: Buse
authors.initials: B
authors.lastname: Cevatemre
authors.affiliation: Department of Biology, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey.
authors.forename: Nazlihan
authors.initials: N
authors.lastname: Aztopal
authors.affiliation: Department of Biology, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey.
authors.forename: Ferda
authors.initials: F
authors.lastname: Ari
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey.
authors.forename: Veysel Turan
authors.initials: VT
authors.lastname: Yilmaz
authors.affiliation: Department of Clinical Biochemistry, School of Medicine, Uludag University, 16059 Bursa, Turkey. Electronic address: eulukaya@uludag.edu.tr.
authors.forename: Engin
authors.initials: E
authors.lastname: Ulukaya
mesh_terms: D017209:Apoptosis; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D005260:Female; D006801:Humans; D014411:Neoplastic Stem Cells / Q000187:drug effects*; D009534:Niclosamide / Q000494:pharmacology*; D010165:Palladium / Q000494:pharmacology*; D060449:Wnt Signaling Pathway
chemical_list: D010165:Palladium; D009534:Niclosamide
keywords: Breast cancer stem cell; Cytotoxicity; Niclosamide; Palladium(II) complex; Targeted therapy