Mechanisms of Naringenin-induced Apoptotic Cascade in Cancer Cells: Involvement of Estrogen Receptor a and ß Signalling

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Abstract

The flavanone naringenin (Nar), especially abundant in the Mediterranean diet, is reported to have anti-proliferative effects in many cancer cell lines. Antioxidant activities, kinase and glucose uptake inhibition have been proposed as molecular mechanisms for these effects. In addition, an anti-estrogenic activity has been observed but, at the present, it is poorly understood whether this latter activity could play a role in the Nar anti-tumoral effects. Here, we tested the ability of Nar to activate a specific, rapid signal transduction pathway committed to the generation of an apoptotic cascade in the presence of one of the two estrogen receptor (ER) isoforms (i.e., ERα or ERβ). Cancer cells containing transfected (human cervix epitheloid carcinoma HeLa cells) or endogenous ERα (human hepatoma HepG2 cells) or ERβ (human colon adenocarcinoma DLD-1 cells) were used. Our results show that Nar exerts an anti-proliferative effect only in the presence of ERα or ERβ. Moreover, Nar stimulation induces the activation of p38/MAPK leading to the pro-apoptotic caspase-3 activation and to the poly(ADP-ribose) polymerase cleavage in all cancer cell lines considered. Notably, Nar shows an anti-estrogenic effect only in ERα containing cells; whereas in ERβ containing cells, Nar mimics the 17β-estradiol effects. These findings indicate new steps in the mechanism underlying ER-dependent anti-proliferative effects of Nar suggesting new potential chemopreventive actions of flavonoids on cancer growth. IUBMB Life, 56: 491-499, 2004

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