Grape seed extract (GSE) from Italia, Palieri and Red Globe cultivars inhibits cell growth and induces apoptosis in Caco-2 human colon cancer cells in a dose-dependent manner. In order to investigate the mechanism(s) supporting the apoptotic process, we analysed reactive oxygen species (ROS) production, intracellular Ca2+ handling and extracellular signal-regulated kinase (ERK) activation. Upon exposure to GSE, ROS and intracellular Ca2+ levels increased in Caco-2 cells, concomitantly with ERK inactivation. As ERK activity is thought to be essential for promoting survival pathways, inhibition of this kinase is likely to play a relevant role in GSE-mediated anticancer effects. Indeed, pretreatment with N-acetyl cysteine, a ROS scavenger, reversed GSE-induced apoptosis, and promoted ERK phosphorylation. This effect was strengthened by ethylene glycol tetraacetic acid-mediated inhibition of extracellular Ca2+ influx. ROS and Ca2+ influx inhibition, in turn, increased ERK phosphorylation, and hence almost entirely suppressed GSE-mediated apoptosis. These data suggested that GSE triggers a previously unrecognised ERK-based mechanism, involving both ROS production and intracellular Ca2+ increase, eventually leading to apoptosis in cancer cells.
Dinicola S, Mariggiò MA, Morabito C, Guarnieri S, Cucina A, Pasqualato A, D'Anselmi F, Proietti S, Coluccia P, Bizzarri M. Grape seed extract triggers apoptosis in Caco-2 human colon cancer cells through reactive oxygen species and calcium increase: extracellular signal-regulated kinase involvement. British Journal of Nutrition 2013 September Department of Clinical and Molecular Medicine, Piazza Sassari 3, La Sapienza University, 00161 Rome, Italy.