Potent inhibitory effect of terpenoids from Acanthopanax trifoliatus on growth of PC-3 prostate cancer cells in vitro and in vivo is associated with suppression of NF-κB and STAT3 signalling

Five terpenoids (1-. 5) from a vegetable plant Acanthopanax trifoliatus (L.) Merr. were investigated for their effects on human prostate cancer cells. The diterpenoid (3) and triterpenoids (4 and 5) were found to inhibit the growth and stimulate apoptosis in PC-3 cells. The effects of these terpenoids on PC-3 cells were associated with strong suppression of nuclear factor-κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3). These terpenoids also inhibited the expression of survivin, a downstream target of NF-κB and STAT3. The in vivo study using a xenograft mouse model showed that 5 strongly inhibited the formation and growth of PC-3 tumours. Moreover, treatment with 5 strongly decreased the expression of phospho-STAT3 and survivin in PC-3 tumours. Our results indicate that 5 has preventive efficacy on the development of PC-3 xenograft tumours. This terpenoid may serve as a candidate for future development as a novel agent for prostate cancer prevention.