Aspidin PB is a
natural product extracted from Dryopteris fragrans (L.) Schott, which has been characterized for its various
biological activities. We reported that
aspidin PB induced cell cycle arrest and apoptosis through the p53/p21 and mitochondria-dependent pathways in human
osteosarcoma cells.
Aspidin PB inhibited the proliferation of Saos-2, U2OS, and HOS cells in a dose-dependent and time-dependent manner.
Aspidin PB induced changes in the cell cycle regulators (
cyclin A, pRb, CDK2, p53, and p21), which caused cell cycle arrest in the S phase. We also explored the role of
siRNA targeted to p53; it led to a dose-dependent attenuation of
aspidin PB-induced apoptosis signaling. Moreover,
after treatment with
aspidin PB, the p21-silenced cells decreased significantly at the S phase.
Aspidin PB increased the percentage of cells with mitochondrial membrane potential disruption. Western blot analysis showed that
aspidin PB inhibited Bcl-2 expression and induced Bax expression to disintegrate the outer mitochondrial membrane and caused
cytochrome C release. Mitochondrial
cytochrome C release was associated with the activation of
caspase-9 and
caspase-3 cascades. Furthermore, the double-stranded DNA breaks and
reactive oxygen species signaling were both involved in
aspidin PB-induced DNA damage. In addition,
aspidin PB inhibited
tumor growth significantly in U2OS xenografts. Above all, we conclude that
aspidin PB represents a valuable natural source and may potentially be applicable in
osteosarcoma therapy.