Quinacrine based gold hybrid nanoparticle caused apoptosis through modulating replication fork in oral cancer stem cells

• Published in: Molecular pharmaceutics
• Main Authors: Hembram, Krushna Chandra, Dash, Somya Ranjan, Das, Biswajit, Sethy, Chinmayee, Chatterjee, Subhajit, Bindhani, Birendra Kumar, Kundu, Chanakya Nath
• Format: Journal Article
• Language: English
• Published: United States 14.05.2020
• ISSN: 1543-8392

Presence of cancer stem cells (CSCs) in tumor micro environment is responsible for development of chemo-resistance and recurrence of cancer. Our previous investigation revealed the anti-cancer mechanism of quinacrine based silver and gold hybrid nanoparticle (QAgNP & QAuNP) in oral cancer cells. But to avoid cancer recurrence, it is important to study the effect of these nanoparticles (NPs) on CSCs. Here, we developed an In vitro CSCs model using SCC-9 oral cancer cells and validated via FACS analysis. 40-60% of cells were found CD44+/CD133+ and CD24-. QAuNP showed excellent anti-CSC growth potential against SCC-9- cancer stem like cells (IC50 0.4 µg/mL) with downregulation of representative CSC markers. Prolonged exposure of QAuNP induced S-phase arrest, caused re-replication showed by extended G2/M population and apoptosis to SCC-9- CSC like cells. Up-regulation of BAX, PARP cleavage and simultaneous down regulation of Bcl-xL in prolonged treatment to CSCs suggested that, majority of the cells have undergone apoptosis. QAuNP treatment also caused loss in DNA repair in CSCs. Mostly, the base excision repair (BER) components (Fen-1, DNA ligase-1, Pol-β, RPA, etc.) got significantly down-regulated after QAuNP treatment which suggested its action against DNA repair machinery. The replication fork maintainance related proteins, RAD 51 and BRCA-2 were also deregulated. Very surprisingly, depletion of WRN (an interacting partner for Pre-RC and Fen-1), and significant increase in expression of fork-degrading nuclease MRE-11 in 96 h treated NPs were observed. Results suggest, QAuNP treatment caused excessive DNA damage and re-replication mediated replication stress (RS) and stalling of replication fork. Inhibition of BER components hinders the Flap clearance activity of Fen-1 and it further caused RS and stops DNA synthesis. Overall, QAuNP treatment led to irreparable replication fork movement and the stalled replication fork might have degraded by MRE-11, which ultimately results in apoptosis and death of the CSCs.