Modulation of Mitochondrial and Epigenetic Targets by Polyphenols-rich Extract from Araucaria angustifolia in Larynx Carcinoma.

Araucaria angustifolia extract (AAE) is a polyphenol-rich extract that has gained interest as a natural anticancer agent. Recent work suggests that AAE induces oxidative damage and apoptosis through its action on decreasing complex I activity of the mitochondrial electron transport chain (ETC). In the present study, we aimed to further examine the specific targets by which AAE exerts pro-apoptotic effects in HEp-2 cancer cells. Specifically, the effect of AAE on the: 1) levels of pyruvate dehydrogenase was assessed by ELISA assay; 2) levels of mitochondrial ETC complexes, focusing on complex I at the gene transcript and protein level relevant to ROS generation was evaluated by multiplex ELISA followed by qRT-PCR and immunoblotting; 3) mitochondrial membrane potential (ΔΨm) was assessed by MitoTracker Red CMXRos; and 4) chemical variations on DNA was evaluated by dot-blotting in HEp-2 cells. Results demonstrated that AAE increased protein levels of PDH, switching energy metabolism to oxidative metabolism. Protein expression levels of complex I and III were found decreased in AAE-treated HEp-2 cells. Analyzing the subunits of complex I, changes in protein and gene transcript levels of NDUFS7 and NDUFV2 were found. AAE was able to induced a loss of ΔΨm, along with DNA hypomethylation and decreased DNA (cytosine-5)-methyltransferase 1 activity. Our data demonstrate for the first time that AAE alters expression of NDUFS7 and NDUFV2 mitochondrial subunits and induce epigenetic changes in HEp-2 cancer cells leading to a possible suppression of oncogenes.