Resveratrol and propolis as necrosis or apoptosis inducers in human prostate carcinoma cells

Vegetables and fruit help the prevention and the therapy of several kinds of cancer because they contain micronutrients, a class of substances that have been shown to exhibit chemopreventive and chemotherapeutic activities. In the present study the effects of resveratrol (100 and 200 μM), a phytoalexin found in grapes, and of the ethanolic extract of propolis (50 and 100 μg/ml), a natural honeybee hive product, were tested in androgen-resistant prostate cancer cells (DU145), a cell line resembling the last stage of prostate carcinoma. A comparison between the activity of these micronutrients and vinorelbine bitartrate (Navelbine®), a semi-synthetic drug normally used in the therapy of prostate cancer, was conducted. Several biochemical parameters were tested, such as cell viability (MTT assay), cell membrane integrity (lactate dehydrogenase release), cell redox status (nitric oxide formation, reactive oxygen species production, reduced glutathione levels), genomic DNA fragmentation (COMET assay) with special attention on the presence of apoptotic DNA damage (TUNEL test), and possible mitochondrial transmembrane potential alteration (AΨ). Our results point out the anticancer activity of resveratrol and propolis extract in human prostate cancer, exerting their cytotoxicity through two different types of cell death: necrosis and apoptosis, respectively. The data obtained suggest the possible use of these micronutrients both in alternative to classic chemotherapy, and in combination with very low dosage of vinorelbine (5 μM).