STAT3 has been recognized as an efficacious
drug target for
prostate cancer because of its constitutive activation in this fatal disease. We recently identified the root bark of Morus alba Linn. as a potential STAT3 inhibitor among 33 phytomedicines traditionally used in Korea.
Morusin, an active compound isolated from the root bark of Morus alba, has shown
anti-oxidant and anti-inflammatory effects. In the present study, we examined whether
morusin has a potential as an anti-
cancer agent in
prostate cancer. We found that
morusin suppressed viability of
prostate cancer cells, but little effect in normal human prostate epithelial cells.
Morusin also reduced STAT3 activity by inhibiting its phosphorylation, nuclear accumulation, and
DNA binding activity. In addition,
morusin down-regulated expression of STAT3 target genes encoding Bcl-xL, Bcl-2,
Survivin, c-Myc and
Cyclin D1, which are involved in regulation of apoptosis and cell cycle. Furthermore,
morusin induced apoptosis in human
prostate cancer cells by reducing STAT3 activity. Taken together, these results suggest that
morusin could be a potentially therapeutic agent for
prostate cancer by reducing STAT3 activity and inducing apoptosis.