HY251, a novel decahydrocyclopenta[a]indene analog, from Aralia continentalis induces apoptosis via down-regulation of AR expression in human prostate cancer LNCaP cells.

In the course of screening for a novel anticancer drug candidate, we previously isolated HY251 with the molecular structure of 3-propyl-2-vinyl-1,2,3,3a,3b,6,7,7a,8,8a-decahydrocyclopenta[a]indene-3,3a,7a,8a-tetraol from the roots of Aralia continentalis. The current study was designed to evaluate the detailed mechanisms of apoptotic induction of HY251 in androgen-sensitive prostate cancer LNCaP cells. TUNEL assay and Western blot analysis revealed an appreciable apoptotic induction in LNCaP cells treated with 95μM of HY251 for 24h. This apoptotic induction is also associated with cytochrome c release from mitochondria which, in turn, resulted in the activation of caspase-9 and -3, and the cleavage of poly(ADP-ribose) polymerase (PARP). Moreover, we found that HY251 significantly inhibited the expression levels of androgen receptor (AR) and prostate-specific antigen (PSA) in a time-dependent manner, as well as abrogated up-regulation of AR and PSA genes with and without androgen. Therefore, we suggest that HY251, a novel androgen antagonist, may be a potent cancer chemotherapeutic candidate for the treatment of both androgen-sensitive and hormone-refractory prostate cancer.