Betulinic acid is a pentacyclic
triterpenoid that exhibits anticancer functions in human
cancer cells. This study provides evidence that
betulinic acid is highly effective against the human
cervical cancer cell line HeLa by inducing dose- and time-dependent apoptosis. The apoptotic process was further investigated using a proteomics approach to reveal
protein expression changes in HeLa cells following
betulinic acid treatment. Proteomic analysis revealed that there were six up- and thirty down-regulated
proteins in
betulinic acid-induced HeLa cells, and these
proteins were then subjected to functional pathway analysis using multiple analysis software.
UDP-glucose 6-dehydrogenase,
6-phosphogluconate dehydrogenase decarboxylating, chain A Horf6-a novel human
peroxidase enzyme that involved in redox process, was found to be down-regulated during the apoptosis process of the oxidative stress response pathway. Consistent with our results at the
protein level, an increase in intracellular
reactive oxygen species was observed in
betulinic acid-treated cells. The
proteins glucose-regulated
protein and
cargo-selection protein TIP47, which are involved in the endoplasmic reticulum pathway, were up-regulated by
betulinic acid treatment. Meanwhile, 14-3-3 family
proteins, including 14-3-3β and 14-3-3ε, were down-regulated in response to
betulinic acid treatment, which is consistent with the decrease in expression of the target genes 14-3-3β and 14-3-3ε. Furthermore, it was found that the antiapoptotic bcl-2 gene was down-regulated while the proapoptotic bax gene was up-regulated after
betulinic acid treatment in HeLa cells. These results suggest that
betulinic acid induces apoptosis of HeLa cells by triggering both the endoplasmic reticulum pathway and the ROS-mediated mitochondrial pathway.