Involvement of HSP70 in resveratrol-induced apoptosis of human prostate cancer.
BACKGROUND
70 KDa heat shock proteins (HSPs70), either as a constitutive or inducible form, are expressed at very high levels in malignant human tumors of various origin. In different cell types, they are known to play an antiapoptotic role. Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a polyphenol present in red wine, grapes and other dietary and medicinal plants, has been shown to be active in inhibiting multistage carcinogenesis, inducing apoptotic cell death.


METHODS
With the present study, a possible relationship between HSP70 expression and cell death elicited by resveratrol in DU-145 cells, which mimic the late hormone-refractory stages of prostate carcinoma, was investigated. To this end, we treated DU-145 with different concentrations. (50, 100 and 200 microM) of resveratrol and cell viability, by tetrazolium salts assay (MTT) and membrane breakdown, by lactic dehydrogenase (LDH) release, were measured. The possible induction of oxidative stress was evidenced both by performing a fluorescent analysis of intracellular reactive oxygen species (ROS) production, or evaluating the amount of nitrite/nitrate (NO) in culture medium. In addition, the expression of HSP70 level, evaluated by immunoblotting, was examined and compared with caspase-3 activity (fluorimetrically measured) and DNA damage, determined by Single Cell Gel Electrophoresis or COMET assay.


RESULTS
Our data clearly indicate that the addition of resveratrol to DU-145 reduces cell viability and increases membrane breakdown, in a dose-dependent way, without interfering with ROS production or NO synthesis, unless 200 microM resveratrol was added. Furthermore, at low concentration (50-100 microM) resveratrol is able to raise HSP70 levels but, at high concentration (200 microM), the measured levels of protective HSP70 were unmodified with respect to that of the control values.


CONCLUSIONS
Our results confirm the ability of resveratrol to suppress the proliferation of human prostate cancer cells with a typical apoptotic feature, interfering with the expression of HSPs70.
Department of Physiological Sciences, University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy.
Venera
V
Cardile
Christian
C
Scifo
Alessandra
A
Russo
Mario
M
Falsaperla
Giuseppe
G
Morgia
Mario
M
Motta
Marcella
M
Renis
Emilio
E
Imbriani
Gianmarco
G
Silvestre
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D010636:Phenols / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D000972:Antineoplastic Agents, Phytogenic; D018840:HSP70 Heat-Shock Proteins; D010636:Phenols; D017382:Reactive Oxygen Species; D013267:Stilbenes; D000077185:Resveratrol