[Inhibition of PRDX1 protein expression and promotion of apoptosis of colorectal cancer cells by furanodienone via inducing ROS generation from NOX4-derived mitochondria].

This study explored the generation site and regulation mechanism of reactive oxygen species(ROS) in the apoptosis of colorectal cancer cells induced by furanodienone(Fur). RKO cells were treated with 200 μmol·L~(-1) of Fur, and the changes in intracellular nicotinamide adenine dinucleotide phosphate oxidase(NOX) activity were detected by the NOX activity detection method. The control group, Fur group, diphenyleneiodonium(DPI) inhibitor group for general NOX, mitochondrial-targeted antioxidant(MitoTEMPO) group, Fur+DPI group, Fur+MitoTEMPO group, and H_2O_2 positive control group were set up. Intracellular ROS levels were detected by the ROS fluorescent staining method, and NOX1-NOX5 protein expressions were detected by Western blot. The NOX1-specific inhibitor ML171 and NOX4-specific inhibitor(GLX351322) were further introduced, and the cell activity was determined by cell counting kit-8(CCK-8) assay. The effects of ROS level change on the protein expressions of NOX4 and peroxiredoxin 1(PRDX1) were measured by Western blot. BAY11-7082, which is an inhibitor of the inhibitor of nuclear factor κB protein α(IκBα), was used to explore the effect of the expression of phosphorylated nuclear factor κB(p-NF-κB) in the nucleus after the Fur treatment on the NOX4 protein level. The lentiviral plasmid and empty plasmid for PRDX1 gene silencing were constructed to transfect RKO cells, and stably transfected strains were screened. The impact of PRDX1 gene knockout on Fur-induced apoptosis was further analyzed using the flow cytometry assay. The findings demonstrate a considerable increase in mitochondrial ROS level in response to Fur treatment, with an increase in intracellular NOX activity. However, the mitochondrial ROS level is significantly reduced in the Fur+DPI group. The results from Western blot and CCK-8 analysis suggest that intracellular NOX1 and NOX4 protein expressions are elevated by Fur treatment, and GLX351322 effectively reverses the pro-apoptotic effect of Fur, while ML171 has a minimal impact on apoptosis rate. Meanwhile, Fur significantly boosts the level of p-NF-κB in the nucleus, whereas the protein levels of p-NF-κB and NOX4 are reduced after the BAY treatment. The regulation of Fur on NOX4 and PRDX1 protein expressions is negatively correlated. In the stably transfected cell strain with PRDX1 gene knockout, the apoptosis rate is considerably higher than that of the negative control group after Fur treatment. The above results indicate that Fur can induce the apoptosis of colorectal cancer cells by promoting the signal transduction of NF-κB in the nucleus and increasing the generation of mitochondrial ROS derived from NOX4 to inhibit the PRDX1 protein expression.