Proteoglycans Isolated from Bramble Shark Cartilage (Echinorhinus brucus) Inhibits Proliferation of MCF-7 Human Breast Cancer Cells by Inducing Apoptosis

Proteoglycans (PGs) were isolated from deep sea shark Echinorhinus brucus (bramble shark) cartilage and their anti-proliferative activity against MCF-7 cell lines was evaluated. To establish apoptosis involvement for cytotoxicity, the following assays were performed i.e., caspases 3 and 9 assay, double fluorescent staining and DNA laddering assay. PGs were isolated by DEAE-sephacel ion exchange chromatography and identification and purity confirmed by chemical composition such as total carbohydrate, total protein, hexosamine, uronic aicd, sulfated GAG, wavelength scan and modified AGE. To confirm apoptosis pathway expression of genes BAX, Bcl-2 and p53 were carried out. PGs (100 μg/mL) induced a significant rise in activity of caspase 3 and 9, major apoptotic markers. A significant rise in the expression was also observed for Bcl-2 and p53. Whereas, low BAX expression was observed for PGs (100 μg/mL) treated sample. Significant anti-proliferative effect was observed and the mechanism behind cell death was concluded to be apoptosis.