Fig. 2.

Autophagic response induced by melatonin 2 mM in HepG2 cells is essential for cell survival. Silencing of ATG5 for 24 hours reduces ATG5 mRNA levels and autophagy induced by melatonin 2 mM treatment for 8 hours (A and B). Representative immunoblots showed not increased levels of Atg5 and LC3, as well as p62 accumulation. After 48 hours, MTT assays revealed lower viability of ATG5-silenced cells in presence of melatonin in a dose-dependent manner (C). Autophagy blocks the increased apoptotic response to melatonin 2 mM treatment. Representative immunoblots of cleaved-PARP, a marker of apoptosis, showed that ATG5-silenced cells are more susceptible to apoptosis in presence of melatonin (D). Images of immunoblots are representative for experiments performed in triplicate. Data are expressed as a percentage of mean values ± SEM of three independent experiments. *P < 0.05 significant differences vs non-silenced cells **P < 0.05 significant differences between treated and untreated silenced cells #P < 0.05 significant differences between control-treated cells and silenced-treated cells cells.