In vitro effects of AGNPs exopolysaccharide from Klebsiella Oxytoca DSM29614 on breast cancer cells

Bacterial exopolysaccharides (EPSs), high-molecular-weight sugar polymers surrounding bacterial cells , have achieved considerable attention because of their potential applications in many fields, including biomedicine, exspecially as antineoplastic molecules. A Klebsiella oxytoca DSM 29614 (KO) strain, ex BAS-10, produces an EPS made of rhamnose, glucuronic acid and galactose, which shows metal-binding properties1,2. More recently, it has been reported that KO in the presence of AgNO3 is able to synthesize Ag nanoparticles (AgNPs) embedded in branched EPS (AgNPs-EPS). The AgNPs-EPS, produced under aerobic and anaerobic conditions, contain Ag+1 and Ag0 that could have different biological activity3. The present study was aimed to assess the cytotoxic effects of AgNPs-EPS, produced under aerobic and anaerobic conditions, on breast cancer cell line SK-BR3. The responses to the AgNPs-EPS treatments revealed a dose dependent behavior resulting at 5 􀀀g/ml in a inhibition of cell proliferation rate of 50% (IC50), dramatic morphological changes consistent with apoptotic features and extensive proteomic modulation . The most important effects were obtained by aerobically biosynthesized AgNPs-EPS treatment, due to the major release of Ag+1, as verified by voltammetry analysis. Proteomic analysis showed modulation of several proteins related to oxidative stress and apoptotic and mitochondrial pathways. Taken together, these results provide new important elements in support of the potential antitumoral activity of AgNPs-EPS. 1. Leone S et al. Eur J Org Chem 2007, 31:5183-5189. 2. Baldi F et al. N Biotechnol 2011, 29:74-78. 3. Battistel D et al. Talanta. 2015, 132:294-300.