Impairment of electron transport chain and induction of apoptosis by chrysin nanoparticles targeting succinate-ubiquinone oxidoreductase in pancreatic and lung cancer cells.

Background: Flavonoids may help ameliorate the incidence of the major causes of tumor-related mortality, such as pancreatic ductal adenocarcinoma (PDAC) and lung cancer, which are predicted to steadily increase between 2020 to 2030. Here we compared the effect of chrysin and chrysin nanoparticles (CCNPs) with 5-fluorouracil (5-FLU) on the activity and expression of mitochondrial complex II (CII) to induce apoptosis in pancreatic (PANC-1) and lung (A549) cancer cells.

Methods: Chrysin nanoparticles (CCNPs) were synthesized and characterized, and the IC₅₀ was evaluated in normal, PANC-1, and A549 cell lines using the MTT assay. The effect of chrysin and CCNPs on CΙΙ activity, superoxide dismutase activity, and mitochondria swelling were evaluated. Apoptosis was assessed using flow cytometry, and expression of the C and D subunits of SDH, sirtuin-3 (SIRT-3), and hypoxia-inducible factor (HIF-1α) was evaluated using RT-qPCR.

Results: The IC₅₀ of CII subunit C and D binding to chrysin was determined and used to evaluate the effectiveness of treatment on the activity of SDH with ubiquinone oxidoreductase. Enzyme activity was significantly decreased (chrysin < CCNPs < 5-FLU and CCNPs < chrysin < 5-FLU, respectively), which was confirmed by the significant decrease of expression of SDH C and D, SIRT-3, and HIF-1α mRNA (CCNPs < chrysin < 5-FLU). There was also a significant increase in the apoptotic effects (CCNPs > chrysin > 5-FLU) in both PANC-1 and A549 cells and a significant increase in mitochondria swelling (CCNPs < chrysin < 5-FLU and CCNPs > chrysin > 5-FLU, respectively) than that in non-cancerous cells.

Conclusion: Treatment with CCNPs improved the effect of chrysin on succinate-ubiquinone oxidoreductase activity and expression and therefore has the potential as a more efficient formulation than chemotherapy to prevent metastasis and angiogenesis by targeting HIF-1α in PDAC and lung cancer.