title: Quercetin-induced apoptotic cascade in cancer cells: antioxidant versus estrogen receptor alpha-dependent mechanisms.
abstract: The flavonol quercetin, especially abundant in apple, wine, and onions, is reported to have anti-proliferative effects in many cancer cell lines. Antioxidant or pro-oxidant activities and kinase inhibition have been proposed as molecular mechanisms for these effects. In addition, an estrogenic activity has been observed but, at the present, it is poorly understood whether this latter activity plays a role in the quercetin-induced anti-proliferative effects. Here, we studied the molecular mechanisms of quercetin committed to the generation of an apoptotic cascade in cancer cells devoid or containing transfected estrogen receptor alpha (ERalpha; i.e., human cervix epitheloid carcinoma HeLa cells). Although none of tested quercetin concentrations increase reactive oxygen species (ROS) generation in HeLa cells, quercetin stimulation prevents the H(2)O(2)-induced ROS production both in the presence and in the absence of ERalpha. However, this flavonoid induces the activation of p38/MAPK, leading to the pro-apoptotic caspase-3 activation and to the poly(ADP-ribose) polymerase cleavage only in the presence of ERalpha. Notably, no down-regulation of survival kinases (i.e., AKT and ERK) was reported. Taken together, these findings suggest that quercetin results in HeLa cell death through an ERalpha-dependent mechanism involving caspase- and p38 kinase activation. These findings indicate new potential chemopreventive actions of flavonoids on cancer growth.
authors.affiliation: Department of Biology, University Roma Tre, Rome, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Galluzzo
authors.forename: Chiara
authors.initials: C
authors.lastname: Martini
authors.forename: Pamela
authors.initials: P
authors.lastname: Bulzomi
authors.forename: Stefano
authors.initials: S
authors.lastname: Leone
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bolli
authors.forename: Valentina
authors.initials: V
authors.lastname: Pallottini
authors.forename: Maria
authors.initials: M
authors.lastname: Marino
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D047628:Estrogen Receptor alpha / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D020935:MAP Kinase Signaling System; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011794:Quercetin / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
chemical_list: D016588:Anticarcinogenic Agents; D000975:Antioxidants; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D005419:Flavonoids; D047428:Protein Kinase Inhibitors; D011794:Quercetin; D048051:p38 Mitogen-Activated Protein Kinases