Photothermal treatment with EGFRmAb-AuNPs induces apoptosis in hypopharyngeal carcinoma cells via PI3K/AKT/mTOR and DNA damage response pathways

Hypopharyngeal carcinoma (HC) is one of the most malignant tumors in the upper aerodigestive tract. Currently, there are no effective treatments for HC. Gold nanoparticles (AuNPs) are a promising tool that can be used for plasmonic photothermal therapy (PPTT), which refers to the use of electromagnetic radiation, most often in near infrared (NIR) region, for the treatment of various medical conditions including cancer. AuNPs have been proved to be a promising tool for NIR spectroscopy-mediated photothermal therapies. In this study, we chemically conjugated AuNPs with a monoclonal antibody (mAb) targeting the epidermal growth factor receptor (EGFR), a cell-surface receptor that is overexpressed in many cancers. We then assessed the effect of NIR photothermal treatment with the EGFRmAb-AuNPs in FaDu HC cells. Our data showed that nanoparticle conjugation with the EGFRmAb improved the specific targeting towards FaDu cells and reduced cytotoxicity towards normal (293 T) cells which do not overexpress the EGFR. A significant amount of our EGFRmAb-conjugated AuNPs could enter the nucleus. Moreover, the expression levels of double strand DNA break repair proteins, including p-ATR, p-CHK1, and p-CHK2 were increased following AuNPs treatment, indicating the presence of DNA damage. These findings suggest that the AuNPs can potentially disrupt genome integrity and induce apoptosis. In addition, EGFRmAb-AuNPs+ NIR could induce FaDu cell apoptosis, accompanied by the inhibition of the PI3K/AKT/mTOR pathway and stimulation of DNA damage response. Based on these data, PPTT using the EGFRmAb-AuNPs could be a new promising treatment for HC.