A Naturally-Derived Small Molecule Disrupts Ligand-Dependent and Ligand-Independent Androgen Receptor Signaling in Human Prostate Cancer Cells
Menée in vitro, cette étude met en évidence des mécanismes par lesquels, en perturbant la signalisation du récepteur des androgènes, la mahanine (alcaloïde dérivé des feuilles d'un arbre asiatique, le kaloupilé) inhibe la croissance de cellules de cancer de la prostate
Continued reliance on androgen receptor (AR) signaling is a hallmark of prostate cancer, including the development of castration-resistant prostate cancer (CRPC), making it an attractive therapeutic target for prostate cancer treatment. Mahanine is a novel carbazole alkaloid derived from the leaves of Murraya koenigii, commonly known as the curry leaf plant, which grows widely across East Asia. We show here that mahanine possesses the ability to inhibit ligand-dependent and ligand-independent AR transactivation, leading to a prominent decline in AR target gene expression. Mahanine treatment causes a time- and dose- dependent decline in AR protein levels, including truncated AR splice variants, in a panel of androgen-responsive and androgen-independent prostate cancer cells. The decrease in AR levels induced by mahanine occurs post-translationally by proteasomal degradation, without any change in AR gene expression. Mahanine treatment induces an outward movement of the AR from the nucleus to the cytoplasm, leading to an initial rise in cytoplasmic AR levels, followed by a gradual decline in the AR levels in both cellular compartments. Ligand-induced AR phosphorylation at Ser-81, a phospho-site associated with prostate cancer cell growth and AR transactivity, is greatly diminished in the presence of mahanine. The decline in AR phosphorylation at Ser-81 by mahanine occurs via the inactivation of mitotic kinase, CDK1. Collectively, our data demonstrate that mahanine strongly disrupts androgen receptor signaling and inhibits the growth of androgen-dependent and -independent prostate cancer cells, thereby implicating a therapeutic role for mahanine in prostate cancer treatment.
http://mct.aacrjournals.org/content/early/2013/11/20/1535-7163.MCT-13-0478.abstract