Cell experiment:

LAPC4 (wild-functional AR/ADPC); LNCaP (mutant-functional AR/ADPC); 22Rν1 (mutant-functional AR/androgen-independent but responsive); C4-2b cells (mutant-functional AR/CRPC) and PC-3 and DU-145 (lack of endogenous AR) are grown under standard cell culture conditions at 37℃ and 5% CO2 environment. The cells (60-70% confluent) are treated with Lupeol (10-50 μM) for 48 h in complete growth medium. For combination set of experiments, cells are treated with either agonistic androgen-analogue R1881 (1 nM), or antagonist Bicalutamide (10 μM), and/or combination (R1881+Lupeol) for 48 h. After incubation for specified times at 37℃, MTT assay is performed. For sensitization studies, hormone refractory C4-2b cells are treated with Lupeol for 24 h. After 24 h, cells are incubated with Bicalutamide (10 μM) for further 24 h. Cells are assessed for viability[1].

Animal experiment:

Mice[1] Tumor studies are conducted in athymic nude mice and two cohorts of animals are created. 3×106 of cells are injected subcutaneously in the right flanks of each mouse. Each cohort receive a specific cell type either LNCaP or C4-2b. One week post-implantation, twenty mice (with visible tumors) in each cohort are randomly divided into two groups, with 10 animals in each group. The first group of animals receive intraperitoneal (i.p.) administration of corn oil (100 μL) and served as control. The second group of animals receive i.p. administration of Lupeol (40 mg/kg in 100 μL of corn oil) three times/week. Body weights and tumor volumes are recorded. All animals of group 1 and group 2 are sacrificed when tumors cross a pre-set endpoint volume of 1,000 mm3.

Lupeol is a novel androgen receptor inhibitor.

Lupeol, an effective AR inhibitor, can be developed as a potential agent to treat human prostate cancer (CaP). Lupeol (10–50 μM) treatment for 48 h results in a dose-dependent growth inhibition of androgen-dependent phenotype (ADPC) cells viz., LAPC4 and LNCaP cells with an IC50 of 15.9 and 17.3 μM, respectively. Lupeol also inhibits the growth of 22Rν_1 with an IC50 of 19.1 μM. Further, Lupeol inhibits the growth of C4-2b cells with an IC50 of 25 μM. Lupeol has the potential to inhibit the growth of CaP cells of both ADPC and CRPC phenotype. Androgens by activating AR are known to drive the growth of CaP cells[1].

Lupeol is an effective agent that has the potential to inhibit the tumorigenicity of CaP cells in vivo. At the conclusion of the study on day 56, the total circulating serum-PSA levels (secreted by the implanted tumor cells) are measured. At 56thday post-implantation, PSA levels are observed between 11.95-12.79 ng/mL in control animals with LNCaP-tumors and C4-2b-tumors, respectively. However, Lupeol-treated counterpart animals exhibits reduced serum-PSA levels in a range of 4.25-7.09 ng/mL. Tumor tissues of animals receiving Lupeol treatment exhibits reduced serum-PSA levels as compared to control[1].

References:
[1]. Siddique HR, et al. Lupeol, a novel androgen receptor inhibitor: implications in prostate cancer therapy. Clin Cancer Res. 2011 Aug 15;17(16):5379-91.