Abstract
Background: The therapeutic potential of epidermal growth factor receptor (EGFR) targeting in colorectal cancer (CRC) is hindered by the presence of KRAS codon 12 activating mutations, prevalent in approximately 25% of advanced CRC cases. This study investigates the role of reactive oxygen species (ROS) in conferring resistance to anti-EGFR monoclonal antibodies in KRAS mutant CRC cells, focusing on ROS-mediated apoptosis induction using cetuximab-PEGylated silica-coated magnetic nanoparticles (MNPs).
Methods: MNPs were synthesized and surface-coated with silica, followed by functionalization and stabilization with polyethylene glycol (PEG). Cetuximab (Cet) was covalently conjugated to generate EMNP-PEG-Cet. Structural and compositional analyses were performed using scanning electron microscopy (SEM), dynamic light scattering (DLS), UV-vis spectroscopy, and Fourier transform infrared (FTIR) analysis. Apoptosis induction, chromatin condensation, and ROS production were evaluated in KRAS mutant SW-480 CRC cells.
Results: Successful synthesis of EMNP-PEG-Cet was confirmed, revealing a particle size of 67 nm and a surface charge of -8.3 mV. The conjugate exhibited significant cytotoxicity against CRC cells, with notable apoptosis induction and ROS generation in EGFR-positive/KRAS mutant SW-480 cells, surpassing the effects observed with bare Cet and EMNP-PEG controls. The nuclear factor erythroid 2-related factor 2/Kelch-like ECH-related protein 1 (Nrf2-Kaep1) gene expression analysis by real-time PCR showed that cells treated with EMNP-PEG-Cet exhibited a noteworthy decrease in Nrf2 expression and a simultaneous increase in Keap1 expression compared to those treated with free Cet.
Conclusion: These findings highlight the potential of ROS-mediated apoptosis induction to enhance the cytotoxicity of Cet in EGFR-positive/KRAS mutant CRC cells, offering new avenues for overcoming drug resistance mechanisms in metastatic CRC.