Sesquiterpene lactones have long been used in traditional Chinese medicines to treat inflammatory diseases. Recently,
sesquiterpene lactone family compounds have been recognized as potential
anticancer agents. Thus, it is necessary to explore new
sesquiterpene lactones and their antitumor mechanism for
cancer treatments. In the present study, we have explored the potential anti-
cancer activity of a novel
sesquiterpene lactone compound "
santamarine" (STM) in HepG2 cells. It inhibited proliferation and induced apoptosis dose-dependently with IC50 ~ 70 μM. Induction of apoptosis was found to be linked with increased
reactive oxygen species (ROS) generation, decreased activity of
thioredoxin reductase (TrxR),
glutathione (GSH) depletion, mitochondrial membrane potential (ΔΨm) dissipation, Bcl-2 family
proteins modulation,
cytochrome c release, caspases-9, -8 and -3 activation and PARP cleavage. Further mechanistic study demonstrated that STM inhibited the constitutive and TNF-α-induced translocation of NF-кB into nucleus by decreasing phosphorylation of IkB-α. Moreover, STM inhibited STAT3 activation by decreasing phosphorylation at tyrosine705. NAC pretreatment reversed the effect of STM-mediated cell death, NF-кB inhibition and blockage of STAT3 activity, indicating the involvement of oxidative stress in STM-mediated anticancer activity. Further studies are needed to explore the exact molecular mechanism of STM-induced apoptosis to develop it into a lead for treatment of
liver cancer in future.