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