Ethanol-extracted Cameroonian propolis: Antiproliferative effects and potential mechanism of action in prostate cancer

The present study was conducted to evaluate in vitro and in vivo antiproliferative potential of the Cameroonian propolis and to elucidate its underlying mechanism. In vitro, ethanol-extracted propolis (EEP) was tested on cell growth, cell proliferation, cell cycle, cell death mechanism and cell migration. The cell cycle- and apoptosis-regulating proteins were assessed by Western blotting. In vivo the testosterone-induced benign prostatic hyperplasia (BPH) in Wistar rat was used to evaluate the antiproliferative potential of EEP. EEP reduced DU145 and PC3 cell survival with an IC₅₀ of 70 and 22 μg/ml respectively. It increased the number of late apoptotic cells, the amount of cells in G0/G1 phase in DU145 and PC3 cells at 50 µg/ml. Cell cycle proteins (cdk1, pcdk1 and their related cyclins A and B) were down-regulated in both DU145 and PC3 cells, while cdk2 and pcdk2 were down-regulated only in PC3 cells. The pro-apoptotic Bax protein was up-regulated, while the anti-apoptotic Akt and pAKT, and Bcl-2 proteins were down-regulated. It increased prostate cell adhesion and chemotaxis. EEP reduced prostate weight, volume and epithelial thickness in rats. We demonstrated for the first time that Cameroonian propolis is endowed with in vitro and in vivo antiproliferative properties in the prostate.