Antiandrogen-induced cell death in LNCaP human prostate cancer cells

Abstract

Antiandrogens such as Casodex (Bicalutamide) are designed to treat advance stage prostate cancer by interfering with androgen receptor-mediated cell survival and by initiating cell death. Treatment of androgen sensitive, non-metastatic LNCaP human prostate cancer cells with 0-100 μM Casodex or 0-10 ng/ml TNF-α induces cell death in 20-60% of the cells by 48 h in a dose-dependent manner. In cells treated with TNF-α, this is accompanied by the loss of mitochondrial membrane potential (ΔΨm) and cell adhesion. In contrast, cells treated with Casodex display loss of cell adhesion, but sustained mitochondrial dehydrogenase activity. Overexpression of Bcl-2 in LNCaP cells attenuates the induction of cell death by TNF-α but not Casodex, suggesting that mitochondria depolarization is not required for the induction of cell death by Casodex. While both TNF-α and Casodex-induced release of cytochrome c in LNCaP cell is predominantely associated with the translocation and cleavage of Bax, our data also suggest that Casodex induces cell death by acting on components downstream of decline of ΔΨm and upstream of cytochrome c release. Furthermore, while induction of both caspase-3 and caspase-8 activities are observed in TNF-α and Casodex-treated cells, a novel cleavage product of procaspase-8 is seen in Casodex-treated cells. Taken together, these data support the hypothesis that Casodex induces cell death by a pathway that is independent of changes in ΔΨm and Bcl-2 actions and results in an extended lag phase of cell survival that may promote the induction of an invasive phenotype after treatment.