Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: Bursa Uludağ Üniversitesi, FEN-EDEBİYAT FAKÜLTESİ, BİYOLOJİ, Türkiye
Tezin Onay Tarihi: 2017
Tezin Dili: Türkçe
Öğrenci: NAZLIHAN AZTOPAL
Danışman: Egemen Dere
Özet:
Epigenetic changes play a critical role in the regulation of cancer stem cell (CSC) properties and the development of drug resistance. CSCs are responsible for apoptosis resistance induced by chemotherapy and the Wnt signaling which is associated with cell survival/self-renewal and differentiation, is re-activated in these cells. For this reason, a possible cytotoxic/apoptotic effect of the combination of niclozamide (Wnt/β-katenin pathway inhibitor) and Valproic acid (VPA, histone deacetylase inhibitor) on breast CSCs was investigated. Successful enrichment of the CSC population from parental MCF-7 cells has been shown by western blotting. The effects of niclozamide and VPA combination on the viability of MCF-7s cells were demonstrated by the ATP assay. The effect that is observed at selected doses for the combination was then confirmed by flow cytometry. The levels of acetylated histone H3 and the inhibition of histone deacetylases were assessed by ELISA and western blotting. Protein levels associated with the Wnt/β-catenin signaling pathway, stemness, epithelial mesenchymal transformation and histone modifications, which were changed by combination therapy, were shown by western blotting. Apoptosis was assessed by Hoechst 33342/PI double staining, M30 ELISA and flow cytometry. Gene and protein expressions related to autophagy and apoptosis were determined by real-time PCR and western blotting. As a result, in breast CSCs, the combination of Niclozamide and VPA showed a marked decrease in cell viability by inducing apoptosis with increased histone H3 acetylation and stronger Wnt inhibition compared with the single use of each agent. It has been concluded that the future success of this combination therapy in targeting CSCs should be used as a new and promising treatment option and assumed to warrant further in vivo investigation.
Keywords: Cancer Stem Cell, Wnt/β-catenin Pathway, Histone Modifications, Apoptosis