Zusammenfassung
Fragestellung: Die Adipositas gilt als ein Risikofaktor für das Prostatakarzinom. Das Adipozytokin Leptin zeigt mitogene Effekte in vielen Zelltypen. Proliferative Effekte von Leptin auf Prostatakarzinomzellen und die Rolle von Tyrosinkinasen bei der Vermittlung dieser Aktionen wurden untersucht. Material und Methoden: Zwei humane Androgen-resistente und eine Androgen-sensible Prostatakarzinomzelllinie wurden mit Leptin (5–100 ng / ml) bis zu 48 Stunden behandelt. Die Zellproliferation wurde mit dem kolorimetrischen XTT®-Assay gemessen und die Phosphorylierung von ERK1 / 2 mittels Western-Blot evaluiert. Ein spezifischer Inhibitor der Mitogen-aktivierten Proteinkinase (MAPK)-Kaskade (PD98059, 40 µM) wurde verwendet, um die Rolle dieser Signalkaskade zu klären. Ergebnisse: Leptin induzierte eine dosisabhängige Proliferationsantwort in Androgen-resistenten Zelllinien nach einer Inkubationsdauer von 24 bzw. 48 Stunden (Prozent der Kontrolle: DU145 = 194,6 ± 5,9 %, PC-3 = 177,9 ± 6,8 %; 100 ng / ml Leptin; 48 Stunden; p < 0,001). Im Gegensatz dazu zeigten die Androgen-sensiblen Zellen eine geringere proliferative Antwort auf die Leptinbehandlung (Prozent der Kontrolle: LNCaP = 112,3 ± 6,1 %; 100 ng / ml Leptin, 48 Stunden). Leptin verursachte eine dosisabhängige ERK1 / 2-Phosphorylierung in den Androgen-resistenten Zelllinien. Die proliferativen Effekte wurden durch eine MAPK-Blockade mit PD98059 aufgehoben. Schlussfolgerung: Die Daten aus dieser In-vitro-Studie lassen ein Zusammenhang zwischen Adipositas-assoziierter Hyperleptinämie und einem erhöhten Risiko für das Prostatakarzinom vermuten. Weitere Untersuchungen sind notwendig, um zu klären, ob diese Daten eine klinische Relevanz bez. der Verwendung als prognostische Marker zur Vorhersage des Zeitpunkts haben, zu dem Androgenresistenz auftritt.
Abstract
Purpose: Obesity is considered to be a risk factor for prostate cancer. Mitogenic actions of leptin, an adipocyte-derived hormone in a variety of cancer cell types have been indentified. We have investigated the proliferative effects of leptin on human prostate cancer cells and assessed the role of tyrosine kinase signalling in mediating these actions. Materials and Methods: Two human androgen-resistant prostate cancer cell lines and one androgen-sensitive human prostate adenocarcinoma cell line were treated with leptin (5–100 ng / mL) for up to 48 hours. Under serum-free conditions, cell proliferation was measured using an enzyme-linked colorimetric assay. Furthermore, phosphorylation of a downstream component of MAPK (ERK1 / 2) was detected by Western blotting and a specific inhibitor of MAPK (PD98059; 40 µM) was used to evaluate the role of this signalling pathway. Results: Leptin dose-dependently increased the cell number in both androgen-resistant cell lines after 24 h and 48 h of incubation (percent of control: DU145 = 194.6 ± 5.9 %, PC-3 = 177.9 ± 6.8 %; 100 ng / mL leptin; 48 h; p < 0.001). Conversely, leptin’s proliferative effect on the androgen-sensitive cell line was less pronounced (percent of control: LNCaP = 112.3 ± 6.1 %; 100 ng / mL leptin; 48 h). Leptin also caused dose-dependent ERK1 / 2 phosphorylation in both androgen-resistant cell lines. In addition, pre-treatment with PD98059 inhibited these responses and attenuated leptin’s mitogenic action. Conclusions: Data from this in vitro study suggest an association between obesity-associated hyperleptinemia and an increased risk for prostate cancer. Further investigations are necessary to clarify whether these data have clinical relevance regarding the use as a prognostic marker for predicting the timing of the occurrence of androgen resistency.
Schlüsselwörter
Prostatakarzinom - Adipositas - Adipozytokine - Leptin - Tyrosinkinasen
Key words
prostate cancer - obesity - adipocytokines - leptin - tyrosine kinase
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1 Diese Studie wurde zum Teil am „Annual Meeting of American Urological Association”, AUA, 25.–30.04.2009, Chicago, IL präsentiert.
Dr. med. M. Raschid Hoda
Klinik und Poliklinik für Urologie und Nierentransplantationszentrum · Universitätsklinikum Halle / Wittenberg
Ernst-Grube-Straße 40
06120 Halle
Phone: 03 45 / 5 57 18 01
Fax: 03 45 / 5 57 46 92
Email: rhoda@ucsd.edu