A novel dietary triterpene Lupeol induces fas-mediated apoptotic death of androgen-sensitive prostate cancer cells and inhibits tumor growth in a xenograft model.
In prostate cancer, a fine balance between cell proliferation and apoptotic death is lost, resulting in increased cellular mass and tumor progression. One approach to redress this imbalance and control this malignancy is its preventive intervention through the use of dietary natural agents. Here, we investigated the growth-inhibitory effect and associated mechanisms of Lupeol, a triterpene present in fruits and vegetables, in androgen-sensitive human prostate cancer cells. Lupeol treatment resulted in significant inhibition of cell viability in a dose-dependent manner and caused apoptotic death of prostate cancer cells. Lupeol was found to induce the cleavage of poly(ADP-ribose) polymerase protein and degradation of acinus protein with a significant increase in the expression of FADD protein. Among all death receptor targets examined, Lupeol specifically caused a significant increase in the expression of Fas receptor. The small interfering RNA-mediated silencing of the Fas gene and inhibition of caspase-6, caspase-8, and caspase-9 by their specific inhibitors confirmed that Lupeol specifically activates the Fas receptor-mediated apoptotic pathway in androgen-sensitive prostate cancer cells. The treatment of cells with a combination of anti-Fas monoclonal antibody and Lupeol resulted in higher cell death compared with the additive effect of the two compounds alone, suggesting a synergistic effect. Lupeol treatment resulted in a significant inhibition in growth of tumors with concomitant reduction in prostate-specific antigen secretion in athymic nude mice implanted with CWR22Rnu1 cells. Because early clinical prostate cancer growth is an androgen-dependent response, the results of the present study suggest that Lupeol may have a potential to be an effective agent against prostate cancer.
Saleem
Mohammad
M
Department of Dermatology, University of Wisconsin, Madison, Wisconsin 53706, USA.
Kweon
Mee-Hyang
MH
Yun
Jung-Mi
JM
Adhami
Vaqar Mustafa
VM
Khan
Naghma
N
Syed
Deeba N
DN
Mukhtar
Hasan
H
D000728:Androgens / Q000502:physiology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D008928:Mitochondria / Q000378:metabolism; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy* / Q000473:pathology; D053978:Pentacyclic Triterpenes; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017430:Prostate-Specific Antigen / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D034741:RNA, Small Interfering / Q000235:genetics; D011944:Receptors, Androgen / Q000378:metabolism; D014315:Triterpenes / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays; D019014:fas Receptor / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D000094042:Lupanes
D000728:Androgens; D000911:Antibodies, Monoclonal; D061945:Caspase Inhibitors; D020169:Caspases; D053978:Pentacyclic Triterpenes; D011065:Poly(ADP-ribose) Polymerases; D017430:Prostate-Specific Antigen; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; D014315:Triterpenes; D019014:fas Receptor; C010480:lupeol; D000094042:Lupanes