Silver nanoparticles induces apoptosis of cancer stem cells in head and neck cancer

Abstract

Background: Several nano formulations of silver nanoparticles with bioconjugates, herbal extracts and anti-cancerous drug coating have been vividly studied to target cancer. Despite of such extensive studies, AgNPs (silver nanoparticles) have not reached the stage of clinical use. Out of all possible reasons for this failure, the unexplored effect on Cancer Stem Cell (CSC) population and mechanism of action of AgNPs, are the most plausible ones and are worked upon in this study. Methods: AgNPs were synthesized by chemical reduction method using sodium citrate and characterized by UV, FTIR, XRD and electron microscopy. CSC population was isolated from Cal33 cell line by MACS technique. MTT assay, trypan blue exclusion assay, Annexin V and PI based apoptosis assay and cell cycle assay were performed. Results: The results showed that synthesized AgNPs have cytotoxic activity on all cancer cell lines tested with the IC50 value of a wide range (1.5–49.21 µg/ml for cell lines and 0.0643–0.1211 µg/ml for splenocytes and thymocytes). CSCs Cal33 showed higher resistance to AgNP treatment and arrest in G1/G0 phase upon cell cycle analysis. Conclusion: AgNPs as an anti-cancer agent although have great potential but is limited by its off-target effects on normal cells and less effective on cancer stem cells at lower concentrations.

Keywords

• AgNPs
• CSCs
• Cell Cycle
• Apoptosis
• Anti-cancer
• Cell viability