To investigate whether Fe@Au nanoparticles cause cytotoxicity in CRC cells via a common mechanism, we used flow cytometry to analyze the status of mitochondria in Fe@Autreated
CRC cells. Our data (Figure 6), however, revealed that Caco-2 cells showed only a minor membrane potential loss after 24-hour treatment, while HT-29 and SW480 cells displayed no loss of membrane potential at all. To further explore the underlying mechanism of the Fe@Au-induced
cytotoxicity in CRC, cells were treated with the mitochondria membrane potential transition blocker, CsA, and autophagy inhibitor, 3-MA. As shown in Figure 7, OECM1 and Caco-2 cells showed a similar response to the nanoparticle treatment. The 3-MA provided significant protection to the OECM1 and Caco-2 cells from the cytotoxicity of Fe@Au,but not to the HT-29 and SW480 cells. However, CsA was found to restore the cytotoxicity of Fe@Au in OECM1 but not in CRC cell lines, in accordance with the JC-1 staining results. This observation suggests that Fe@Au-induced cytotoxicity in HT-29 and SW480 cells occurs via an alternative pathway compared with oral cancer cells