Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Biotechnology

This study aimed to appraise the activity of Jania rubens, Petrocladia capillacea, Corallina officinalis, Colpomenia sinuosa, Sargassum asperifolium and Sargassum dentifolium polysaccharides against breast cancer stem cells (BCSCs) in MDA-MB-231 and MCF-7 cell lines. These compounds were characterized to be sulfated polysaccharide-protein complexes. Cytotoxicity of the polysaccharides against MDA-MB-231, MCF-7 breast cancer cell lines and normal Vero E6 cells was assessed by MTT (3-(4,5-dimethylthiazol-2-yl)- 2,5- diphenyltetrazolium bromide) assay, and their impact on CD44+/CD24{u2212} and aldehyde dehydrogenase 1(ALDH1) positive BCSC population was determined by flow cytometry. Their effect on the gene expression of CSC markers, Wnt/Ý- catenin and Notch signaling pathways was evaluated by quantitative real-time PCR. All tested polysaccharides inhibited the growth of breast cancer cells with a more prominent action against MDA-MB-231 than MCF-7 cells at most time intervals along with their weaker cytotoxicity against Vero E6 cells, and reduced BCSC subpopulation. P. capillacea polysaccharides down-regulated the expression levels of OCT4, SOX2 and ALDH1A3 genes in MDA-MB-231 as well as in MCF-7 cells. C. officinalis polysaccharides exhibited similar effects on SOX2 and ALDH1A3 genes

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