Abstract
Benign prostatic hyperplasia (BPH) is a common disease that occurs mainly in older men. The pathogenesis of BPH is complex and patients face a prolonged treatment course, and novel drugs with better selectivity and lower toxicity are required. Incaspitolide A (compound TMJ-12) is a germacrane-type sesquiterpenoid compound extracted from the plant Carpesium carnuum. Extracts of C. carnuum are known to exert suppressive effects on BPH-1 cells. In the present study, we investigated the molecular mechanisms underlying the suppressive effect of TMJ-12 specifically on BPH-1 cells. A cytotoxicity assay indicated that TMJ-12 inhibited BPH-1 cell proliferation, while flow cytometry assays showed that TMJ-12 induced G2/M phase cell cycle arrest and the apoptosis of BPH-1 cells. TMJ-12 was also shown to regulate the expression of several apoptosis- and cell cycle-related proteins, namely Bcl-2, Bax, Bad, Caspase-9, Caspase-3, cyclin-dependent kinase 1 (CDK1), Cyclin B1, CDC25C, and c-Myc, among others. Collapse of the mitochondrial membrane potential (ΔΨm) following exposure to TMJ-12 was detected with the JC-1 staining assay. Further investigation revealed that treatment with TMJ-12 inhibited the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway by increasing the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Taken together, the results suggest that TMJ-12 prevents BPH-1 cell proliferation via the PI3K/AKT pathway by inducing apoptosis and cell cycle arrest.