# Exploring the Cytotoxic and Redox-Modulatory Effects of Nanoceria in MCF7 Breast Cancer Cells Using Integrated Molecular and Proteomic Analyses

## TL;DR

This study explores how nanoceria nanoparticles kill breast cancer cells by causing oxidative stress and mitochondrial damage.

## Contribution

The study provides new insights into the molecular and proteomic mechanisms of nanoceria-induced cytotoxicity in MCF7 breast cancer cells.

## Key findings

- Nanoceria reduced MCF7 cell viability in a dose-dependent manner, with 61% and 57% viability at 200 µg/mL and 400 µg/mL, respectively.
- Nanoceria increased ROS levels and decreased mitochondrial membrane potential, indicating oxidative stress and mitochondrial dysfunction.
- Proteomic analysis revealed over 150 altered proteins linked to redox balance, apoptosis, and cell cycle regulation.

## Abstract

Background: Cerium oxide nanoparticles (nanoceria) have attracted growing attention as promising anticancer agents due to their unique redox properties. Their selective cytotoxicity in cancer cells is thought to be mediated primarily through disruption of redox homeostasis. However, the precise molecular mechanisms underlying their action in breast cancer remain unclear. To address this gap, the present study investigates the dose-dependent cytotoxic, oxidative, and mitochondrial effects of nanoceria in MCF7 breast cancer cells, with mechanistic insights gained through gene expression and proteomic analyses. Methods: MCF7 breast cancer cells were treated with nanoceria (200 µg/mL and 400 µg/mL). Cytotoxicity, ROS levels, and mitochondrial membrane potential were assessed via MTT, DCFDA staining, and MitoTracker, respectively. Gene expression and label-free LC-MS/MS proteomics were used to evaluate molecular and pathway-level changes. Results: Nanoceria exhibited dose-dependent cytotoxicity, significantly reducing MCF7 cell viability to 61 ± 1.5% (p < 0.01) and 57 ± 1.8% (p < 0.01) at 200 µg/mL and 400 µg/mL, respectively, compared with the control. ROS levels increased 1.4-fold (p < 0.01) and 1.5-fold (p < 0.0001), accompanied by a decreased mitochondrial membrane potential by 11% (p < 0.01) and 25% (p < 0.05), indicating oxidative stress and mitochondrial dysfunction. Gene expression analysis supported activation of apoptotic pathways demonstrated by upregulation of BNIP3, the BAX/BCL-2 ratio (p < 0.05), and disruption of mitochondrial homeostasis. Proteomic profiling revealed dose-specific alterations in >150 proteins (fold change ≥ 1.5, p < 0.05) related to redox balance, mitochondrial function, apoptosis, and cell cycle regulation. Conclusions: Nanoceria induces dose-dependent oxidative stress and mitochondrial dysfunction in MCF7 breast cancer cells, triggering apoptotic pathways and widespread alterations in protein expression. These results offer valuable mechanistic insights into nanoceria’s selective anticancer activity and highlight its potential as a promising therapeutic agent for breast cancer.