# Arsenic Nanoparticles Trigger Apoptosis via Anoikis Induction in OECM-1 Cells

## TL;DR

Arsenic nanoparticles from a Chilean bacterium induce apoptosis in oral cancer cells by triggering anoikis, a type of cell death linked to loss of cell attachment.

## Contribution

The study reveals a novel mechanism by which arsenic nanoparticles induce apoptosis via anoikis in cancer cells.

## Key findings

- AsNPs reduced OECM-1 cell viability in a concentration-dependent manner.
- AsNPs induced both extrinsic and intrinsic apoptotic pathways in OECM-1 cells.
- AsNPs triggered anoikis by potentially interacting with ECM components and reducing cell attachment.

## Abstract

Arsenic compounds have been used as therapeutic alternatives for several diseases including cancer. In the following work, we obtained arsenic nanoparticles (AsNPs) produced by an anaerobic bacterium from the Salar de Ascotán, in northern Chile, and evaluated their effects on the human oral squamous carcinoma cell line OECM-1. Resazurin reduction assays were carried out on these cells using 1–100 µM of AsNPs, finding a concentration-dependent reduction in cell viability that was not observed for the non-tumoral gastric mucosa-derived cell line GES-1. To establish if these effects were associated with apoptosis induction, markers like Bcl2, Bax, and cleaved caspase 3 were analyzed via Western blot, executor caspases 3/7 via luminometry, and DNA fragmentation was analyzed by TUNEL assay, using 100 µM cisplatin as a positive control. OECM-1 cells treated with AsNPs showed an induction of both extrinsic and intrinsic apoptotic pathways, which can be explained by a significant decrease in P-Akt/Akt and P-ERK/ERK relative protein ratios, and an increase in both PTEN and p53 mRNA levels and Bit-1 relative protein levels. These results suggest a prospective mechanism of action for AsNPs that involves a potential interaction with extracellular matrix (ECM) components that reduces cell attachment and subsequently triggers anoikis, an anchorage-dependent type of apoptosis.