Resveratrol affects undifferentiated and differentiated PC12 cells differently, particularly with respect to possible differences in mitochondrial and autophagic functions

Since resveratrol is considered to exert a unique dual effect, protective for normal cells but toxic to tumor cells, its action on undifferentiated (original) and differentiated PC12 cells was analyzed, because undifferentiated cells are tumorigenic and differentiated ones are neuronal in nature. Compared to resveratrol-untreated cells in both undifferentiated and differentiated cell groups, cells treated with different doses of resveratrol, at dosages of 1, 10 and 100 mu M, showed the following alterations. Dying/dead cells were significantly increased in a dose-dependent manner in undifferentiated cells, but they were unchanged at doses of up to 10 mu M resveratrol in differentiated cells. In living cells, neurites were short in undifferentiated cells, but drastically elongated with an increased number in differentiated cells. The expression of SIRT1 was drastically reduced in undifferentiated cells, but stable in differentiated cells. SIRT3 was significantly enhanced in a dose-dependent manner at resveratrol doses of up to 10 mu M in both cells, with reduction and more enhanced at a dosage of 100 mu M in undifferentiated and differentiated cells, respectively. Mitochondrial number and ATP synthase beta subunit expression was unaltered at doses of up to 10 mu M and were significantly reduced at doses of 100 mu M in undifferentiated cells, but they were significantly increased in a dose-dependent manner, with a slight reduction in the ATP synthase at doses of 100 mu M, in differentiated cells. In a dose-dependent manner, the number of autophagosomes and the LC3-II/LC3-I ratio were significantly less in undifferentiated cells and greater in differentiated cells. Also, in a dose-dependent manner, the expression of phosphorylated AMP-activated kinase (AMPK) was significantly less in undifferentiated cells and greater in differentiated cells. Resveratrol-induced AMPK suppression and activation, possibly through the modulation of SIRT protein activity, may thus be related to the inhibition and promotion of mitochondrial and autophagic functions, leading to cell death and survival in undifferentiated and differentiated cells, respectively. (C) 2012 Elsevier GmbH. All rights reserved.