protopanaxadiol and Prostatic-Neoplasms

The potential cancer preventive roles of calcitriol, the dihydroxylated metabolite of Vitamin D3, as well as 20(S)-protopanaxadiol (aPPD), the aglycone of the protopanaxadiol family of ginsenosides, have gained much attention in recent years for the prevention/treatment of prostate cancer (PCa). In the present study, we evaluated the anticancer and chemosensitization effects of calcitriol at clinically relevant concentrations and aPPD, either alone or in combination, in two well-characterized human PCa cell lines: androgen-sensitive non-metastatic LNCaP cells and androgen-independent metastatic C4-2 cells. The effects of the treatments on PCa cell viability and proliferation rates were evaluated by MTS and Brdu assays, respectively. Combination Indices (CI) and Dose Reduction Indices (DRI) were estimated to assess synergistic anticancer activity using Calcusyn software (Biosoft, Cambridge, UK). Then, we determined the potential Pharmacodynamic interaction mechanisms as follows: The protein expression levels of the genes those are known to control cell cycle (cyclin D1 and cdk2); apoptosis (Bcl-2, Bax, and Capspases 3), androgen receptor and Vitamin D receptors were examined upon combinational treatment. The cell viability assay data show that addition of 10nM calcitriol to aPPD significantly lowered its IC50 values from the range of 41-53μM to 13-23μM, in LNCaP and C4-2 prostate cancer cells. The cell proliferation rate was significantly lower for combination treatments compared to the cells treated with aPPD alone. Similarly, Western blot results indicate that aPPD significantly upregulated Vitamin D receptor (VDR) expression, while calcitriol further enhanced the ability of aPPD to induce pro-apoptotic BAX, increased cleaved caspase-3 and downregulate cdk2 protein levels. Thus, the pharmacodynamic interaction between aPPD and calcitriol in impacting growth inhibition and apoptosis appears to be synergistic in nature. In conclusion, calcitriol sensitizes PCa cells to aPPD-mediated anticancer effects by enhancing its ability to induce apoptosis and reduce cell proliferation, and this synergism may limit calcitriol toxicity by facilitating the use of lower calcitriol doses. The associated increase in VDR expression and calcitriol half-life may be mechanistically associated with this sensitization effect.

Topics: Antineoplastic Agents; Apoptosis; Calcitriol; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Synergism; Humans; Intracellular Signaling Peptides and Proteins; Kallikreins; Male; Prostate-Specific Antigen; Prostatic Neoplasms; Receptors, Androgen; Receptors, Calcitriol; Sapogenins

As a public health problem, prostate cancer engenders huge economic and life-quality burden. Developing effective chemopreventive regimens to alleviate the burden remains a major challenge. Androgen signaling is vital to the development and progression of prostate cancer. Targeting androgen signaling via blocking the production of the potent ligand dihydrotestosterone has been shown to decrease prostate cancer incidence. However, the potential of increasing the incidence of high-grade prostate cancers has been a concern. Mechanisms of disease progression after the intervention may include increased expression of androgen receptor (AR) in prostate tissue and expression of the constitutively active AR splice variants (AR-Vs) lacking the ligand-binding domain. Thus, novel agents targeting the receptor, preferentially both the full-length and AR-Vs, are urgently needed. In the present study, we show that ginsenoside 20(S)-protopanaxadiol-aglycone (PPD) effectively downregulates the expression and activity of both the full-length AR and AR-Vs. The effects of PPD on AR and AR-Vs are manifested by an immediate drop in proteins followed by a reduction in transcripts, attributed to PPD induction of proteasome-mediated degradation and inhibition of the transcription of the AR gene. We further show that although PPD inhibits the growth as well as AR expression and activity in LNCaP xenograft tumors, the morphology and AR expression in normal prostates are not affected. This study is the first to show that PPD suppresses androgen signaling through downregulating both the full-length AR and AR-Vs, and provides strong rationale for further developing PPD as a promising agent for the prevention and/or treatment of prostate cancer.

Topics: Alternative Splicing; Animals; Cell Line, Tumor; Down-Regulation; Humans; Male; Mice; Prostatic Neoplasms; Proteasome Endopeptidase Complex; Receptors, Androgen; Sapogenins

Biotransformation of 20(S)-protopanaxadiol (1) by the fungus Absidia corymbifera AS 3.3387 yielded five metabolites (2-6). On the basis of spectroscopic data analyses, the metabolites were identified as 26-hydroxyl-20(S)-protopanaxadiol (2), 23, 24-en-25-hydroxyl-20(S)-protopanaxadiol (3), 25-hydroxyl-20(S)-protopanaxadiol (4), 7β-hydroxyl-20(S)-protopanaxatriol (5), and 7-oxo-20(S)-protopanaxatriol (6), respectively. Among them, 5 and 6 are new compounds. These results indicated that A. corymbifera AS 3.3387 could catalyze the side-chain oxidation-reduction, 7β hydroxylation, and the specific C-7 dehydrogenation of derivatives of 20(S)-protopanaxadiol. The metabolites 2, 5, and 6 showed the more potent inhibitory effects against DU-145 and PC-3 cell lines than the substrate.

Topics: Absidia; Antineoplastic Agents, Phytogenic; Cell Line, Tumor; Humans; Male; Molecular Structure; Prostatic Neoplasms; Sapogenins

Microbial transformation of 20(S)-protopanaxadiol (1) by Mucor racemosus AS 3.205 yielded two novel hydroperoxylated metabolites and three known hydroxylated metabolites. The structures of the metabolites were identified as 26-hydroxyl-20(S)-protopanaxadiol (2), 23,24-en-25-hydroxyl-20(S)-protopanaxadiol (3), 25,26-en-24(R)-hydroperoxyl-20(S)-protopanaxadiol (4), 23,24-en-25-hydroperoxyl-20(S)-protopanaxadiol (5), and 25-hydroxyl-20(S)-protopanaxadiol (6). 4 and 5 are new compounds. Metabolites 2, 4, and 5 showed the more potent inhibitory effects against DU-145 and PC-3 cell lines than the substrate.

Topics: Antineoplastic Agents; Biotransformation; Cell Line, Tumor; Humans; Magnetic Resonance Spectroscopy; Male; Molecular Structure; Mucor; Prostatic Neoplasms; Sapogenins

This study focuses on determining the pharmacokinetics, biodistribution, and efficacy of the ginsenoside aglycone protopanaxadiol (aPPD) administered as a single agent in a novel oral dosage formulation. To obtain these data and to characterize the stability of aPPD, appropriate analytical assay development was carried out. The solubility and stability of aPPD were determined, and the compound was formulated for oral gavage. aPPD levels in blood and tissues following oral administration to nu/nu nude mice were determined using liquid chromatography-mass spectrometry/mass spectrometry. The efficacy of aPPD was determined upon oral administration to nu/nu nude mice bearing PC-3 human prostate cancer xenograft tumors. Immunohistochemical analysis of tumor tissues was performed to establish apoptotic indices and Ki-67 expression as markers of proliferation. The maximum solubility of aPPD in ethanol was 68.4 mg/ml. aPPD administered at a dose of 70 mg/kg yielded a T(max) of approximately 40 min and a C(max) value of 3.9 ± 1.4 μg/ml, and no toxicity was observed. aPPD accumulated largely in the stomach and small intestine and was also present in the brain. This dose engendered a significant delay in PC-3 tumor growth, an increase in apoptotic index, and a decrease in Ki-67 levels. We have shown that aPPD is a stable compound that can be formulated for oral gavage. Pharmacokinetic studies demonstrate the ability of this compound to be absorbed after oral administration. Future studies will assess the activity and pharmacokinetics of aPPD when administered in combination with standard chemotherapy.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Chemistry, Pharmaceutical; Chromatography, High Pressure Liquid; Drug Compounding; Drug Stability; Ginsenosides; Humans; Immunohistochemistry; Male; Mass Spectrometry; Maximum Tolerated Dose; Mice; Mice, Nude; Molecular Structure; Prostatic Neoplasms; Sapogenins; Solid Phase Extraction; Solubility; Tissue Distribution; Xenograft Model Antitumor Assays

We recently isolated 20(S)-25-methoxyl-dammarane-3beta, 12beta, 20-triol (25-OCH3-PPD), a natural product from Panax notoginseng, and demonstrated its cytotoxicity against a variety of cancer cells. Here we report the effects of this compound in vitro and in vivo on human prostate cancer cells, LNCaP (androgen-dependent) and PC3 (androgen-independent), in comparison with three structurally related ginsenosides, ginsenoside Rh2, ginsenoside Rg3, and 20(S)-protopanaxadiol. Of the four test compounds, 25-OCH3-PPD was most potent. It decreased survival, inhibited proliferation, induced apoptosis, and led to G1 cell cycle arrest in both cell lines. It also decreased the levels of proteins associated with cell proliferation (MDM2, E2F1, cyclin D1, and cdks 2 and 4) and increased or activated pro-apoptotic proteins (cleaved PARP, cleaved caspase-3, -8, and -9). In LNCaP cells, 25-OCH3-PPD inhibited the expression of the androgen receptor and prostate-specific antigen. Moreover, 25-OCH3-PPD inhibited the growth of prostate cancer xenograft tumours. Combining 25-OCH3-PPD with conventional chemotherapeutic agents or with radiation led to potent antitumour effects; tumour regression was almost complete following administration of 25-OCH3-PPD and either taxotere or gemcitabine. 25-OCH3-PPD also demonstrated low toxicity to noncancer cells and no observable toxicity in animals. In conclusion, our preclinical data indicate that 25-OCH3-PPD is a potential therapeutic agent against both androgen-dependent and androgen-independent prostate cancer.

Topics: Animals; Apoptosis; Biomarkers, Tumor; Cell Cycle; Cell Proliferation; Drugs, Chinese Herbal; Gene Expression Regulation, Neoplastic; Ginsenosides; Humans; In Vitro Techniques; Male; Mice; Mice, Nude; Prostate-Specific Antigen; Prostatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sapogenins; Survival Rate; Triterpenes; Tumor Cells, Cultured; Xenograft Model Antitumor Assays