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BACKGROUND: We have previously shown that Pterostilbene (3, 5- dimethoxy-4-hydroxystilbene), a compound found in blueberries, inhibits cell proliferation and promotes apoptosis in pancreatic cancer in vitro by induction of mitochondrial membrane depolarization and caspase 3/7 activation. To further investigate the role of mitochondria in Pterostilbene-induced apoptosis in pancreatic cancer, we examined its effects on manganese superoxide dismutase (MnSOD) activity, Cytochrome C and Smac/DIABLO release. The mitochondrial enzyme MnSOD plays a critical role in regulation of cancer cell proliferation through an unknown mechanism. Smac/DIABLO is a mitochondrial protein that potentiates apoptosis. Both Smac/DIABLO and Cytochrome C have been shown to exit mitochondria and enter the cytosol during apoptosis. We hypothesized that Pterostilbene would increase MnSOD activity and cytosolic levels of Cytochrome C and Smac/DIABLO in a dose dependent manner. METHODS: MIA and PANC-1 cell lines were treated with 25 micromolar and 50 micromolar concentrations of Pterostilbene for 48hrs and quantitative MnSOD activity was measured by superoxide dismutase ELISA assay. In separate experiments, MIA and PANC-1 cell cells were treated with 25 micromolar, 50 micromolar and 75 micromolar concentrations of Pterostilbene for 24hrs and cytosolic extracts were analyzed for Cytochrome C and Smac/DIABLO utilizing ELISA protocols. One way ANOVA and Tukey post-hoc analysis were used for statistical analysis. RESULTS: Pterostilbene increased enzymatic activity of MnSOD in both cell lines in a dose dependent manner (p <0.01). Pterostilbene treatment increased cystosolic levels of Cytochrome C in MIA cells at the 25 micromolar (p < 0.05) and 75 micromolar concentrations in PANC-1 cells (p < 0.05). Cystosolic levels of Smac/DIABLO increased in both MIA and PANC-1 cells with treatment at the 75 micromolar concentration of Pterostilbene (p <0.01). CONCLUSION: We have previously demonstrated that Pterostilbene, a natural plant-derived stilbene, inhibits pancreatic cancer in vitro through activation of the mitochondrial apoptosis pathway. MnSOD, an inducible mitochondrial enzyme that converts superoxide anion to hydrogen peroxide, has an essential role in regulation of pancreatic cancer cell proliferation. The results of our current study demonstrate for the first time that Pterostilbene increases MnSOD activity in pancreatic cancer cells. In addition, Pterostilbene increases cytosolic levels of Cytochrome C and Smac/DIABLO in both cell lines, confirming mitochondrially derived apoptotic cell death. Further studies are ongoing to elucidate the intricate relationship between intrinsic apoptosis, MnSOD activity, and pancreatic cancer cell death upon Pterostilbene treatment.