Brefeldin A induced apoptosis in prostatic cancer DU-145 cells: a possiblep53-independent death pathway

Objective To investigate the growth inhibitory mechanism of brefeldin A (BF A), an antiviral antibiotic, in androgen-independent prostatic cancer DU-14 5 cells. Materials and methods The inhibitory effects of BFA (30 ng/mL) on cell grow th were monitored by cell counting and Viability tests after specified expo sures. Flow cytometry and western immunoblot analysis were performed to exa mine the effects of BFA on the cell cycle and on specific growth regulators . The possible induction of apoptosis by BFA was further assessed by in sit u hybridization (ISH) assay and by qualitative DNA analysis using agarose-g el electrophoresis. Results Cell growth was completely inhibited with BFA (30 ng/mL), accompani ed by 40-50% cell death. Cell cycle analysis revealed that this growth inhi bition coincided with an 85% reduction in the S-phase cell population. West ern blots showed that the expression of cell cycle-dependent kinases (cdk2 and cdk4), cyclin D-1 and p53 was significantly reduced, while WAF1 was inc reased, after BFA treatment. Apoptosis was confirmed by both the ISH assay, which showed the characteristic brownish staining of BFA-treated cells, an d by DNA analysis, which revealed the internucleosomal DNA ladder. Conclusion BFA-induced growth inhibition in DU-145 cells is primarily due t o the modulation of specific G(1) cell-cycle regulators, blocking the G(1)- S phase progression. Such a growth arrest ultimately results in apoptosis, presumably through a p53-independent pathway.