The selective toxicity of superparamagnetic iron oxide nanoparticles (SPIONs) on oral squamous cell carcinoma (OSCC) by targeting their mitochondria.

In recent years, many researchers have made tremendous efforts into using nanotechnology in biomedical applications and science, such as magnetic resonance imaging, drug delivery, and in particular, oncological therapeutic via superparamagnetic iron oxide nanoparticles (SPIONs). Head and neck squamous cell carcinoma (HNSCC) and especially oral squamous cell carcinoma (OSCC) have been a serious and ongoing concern. There are many strong emphases on the importance of toxic mechanisms due to oxidative stress and specifically, the changed cellular response. Therefore, our study was designed to evaluate the effects of SPIONs on OSCC mitochondria because of the usefulness of the application of these nanoparticles in cancer treatment and diagnosis. An increased level of reactive oxygen species (ROS) is one of the substantial mechanisms found for SPIONs in this study, and initially originated from disruption of the electron transfer chain shown by a decrease in mitochondrial succinate dehydrogenase activity. Increased ROS formation subsequently followed a decline of mitochondrial membrane potential, the release of mitochondrial cytochrome complex, and mitochondrial swelling in the OSCC mitochondria compared with almost no effect in normal mitochondria. In addition, the SPIONs decreased cell viability and increased lipid peroxidation level and caspase-3 activity in OSCC cells. The results represented that the exposure to the SPIONs induced selective toxicity only on the OSCC but not normal mitochondria. Based on our findings, we finally concluded that the SPIONs may be considered as a potential therapeutic candidate for the treatment of OSCC.