Anticancer activity of biogenerated silver nanoparticles: an integrated proteomic investigation

// Miriam Buttacavoli 1, * , Nadia Ninfa Albanese 1, * , Gianluca Di Cara 2 , Rosa Alduina 1 , Claudia Faleri 3 , Michele Gallo 4 , Giuseppe Pizzolanti 5, 6 , Giuseppe Gallo 1, 6 , Salvatore Feo 1, 6 , Franco Baldi 4 and Patrizia Cancemi 1, 2, 6 1 Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Palermo, Italy 2 Center of Experimental Oncobiology (C.OB.S.), La Maddalena Hospital III Level Oncological Dept., Palermo, Italy 3 Department of Life Science, University of Siena, Siena, Italy 4 Department of Molecular Science and Nanosystems, Ca Foscari University of Venice, Venice, Italy 5 Biomedical Department of Internal and Specialist Medicine (DIBIMIS), Section of Endocrinology, University of Palermo, Palermo, Italy 6 Advanced Technologies Network Center (ATeN), University of Palermo, Palermo, Italy * These authors contributed equally to this work Correspondence to: Patrizia Cancemi, email: patrizia.cancemi@unipa.it Keywords: silver nanoparticles (AgNPs); bacteria; breast cancer cells; anticancer activity; proteomics Received: May 27, 2017      Accepted: October 30, 2017      Published: December 23, 2017 ABSTRACT Silver nanoparticles (AgNPs), embedded into a specific polysaccharide (EPS), were biogenerated by Klebsiella oxytoca DSM 29614 under aerobic (AgNPs-EPS aer ) and anaerobic conditions (AgNPs-EPS anaer ). Both AgNPs-EPS matrices were tested by MTT assay for cytotoxic activity against human breast (SKBR3 and 8701-BC) and colon (HT-29, HCT 116 and Caco-2) cancer cell lines, revealing AgNPs-EPS aer as the most active, in terms of IC50, with a more pronounced efficacy against breast cancer cell lines. Therefore, colony forming capability, morphological changes, generation of reactive oxygen species (ROS), induction of apoptosis and autophagy, inhibition of migratory and invasive capabilities and proteomic changes were investigated using SKBR3 breast cancer cells with the aim to elucidate AgNPs-EPS aer mode of action. In particular, AgNPs-EPS aer induced a significant decrease of cell motility and MMP-2 and MMP-9 activity and a significant increase of ROS generation, which, in turn, supported cell death mainly through autophagy and in a minor extend through apoptosis. Consistently, TEM micrographs and the determination of total silver in subcellular fractions indicated that the Ag + accumulated preferentially in mitochondria and in smaller concentrations in nucleus, where interact with DNA. Interestingly, these evidences were confirmed by a differential proteomic analysis that highlighted important pathways involved in AgNPs-EPS aer toxicity, including endoplasmic reticulum stress, oxidative stress and mitochondrial impairment triggering cell death trough apoptosis and/or autophagy activation.