Natural product ginsenoside 25-OCH3-PPD inhibits breast cancer growth and metastasis through down-regulating MDM2.

Although ginseng and related herbs have a long history of utility for various health benefits, their application in cancer therapy and underlying mechanisms of action are not fully understood. Our recent work has shown that 20(S)-25-methoxyl-dammarane-3β, 12β, 20-triol (25-OCH(3)-PPD), a newly identified ginsenoside from Panax notoginseng, exerts activities against a variety of cancer cells in vitro and in vivo. This study was designed to investigate its anti-breast cancer activity and the underlying mechanisms of action. We observed that 25-OCH(3)-PPD decreased the survival of breast cancer cells by induction of apoptosis and G1 phase arrest and inhibited the growth of breast cancer xenografts in vivo. We further demonstrated that, in a dose- and time-dependent manner, 25-OCH(3)-PPD inhibited MDM2 expression at both transcriptional and post-translational levels in human breast cancer cells with various p53 statuses (wild type and mutant). Moreover, 25-OCH(3)-PPD inhibited in vitro cell migration, reduced the expression of epithelial-to-mesenchymal transition (EMT) markers, and prevented in vivo metastasis of breast cancer. In summary, 25-OCH(3)-PPD is a potential therapeutic and anti-metastatic agent for human breast cancer through down-regulating MDM2. Further preclinical and clinical development of this agent is warranted

MDM2 overexpression reduces cell response to 25-OCH₃-PPD treatment.

<p>MCF7 MDM2-inducible cells were incubated with (Tet+) or without tetracycline (Tet-) for 12 h, followed by exposure to various concentrations of 25-OCH₃-PPD for various times: (A) 72 h for analysis of cell viability using MTT assay; (B) 24 h for analysis of cell proliferation using BrdUrd assay; (C) 48 h for apoptosis analysis using Flow Cytometry; and (D) 24 h for cell cycle analysis. (E) 25-OCH₃-PPD inhibits MDM2 expression in MCF7 inducible cells without tetracycline. MDM2 overexpression was confirmed in MCF7 inducible cell line treated with tetracycline, which reversed the effect of 25-OCH₃-PPD.</p

25-OCH₃-PPD inhibits MDM2 transcription.

<p>(A) MCF7 cells were treated with various concentrations of 25-OCH₃-PPD for 24 h. MDM2 mRNA was co-amplified with β-actin mRNA. The relative levels of MDM2 were normalized to that of β-actin. (B) MCF7 cells were co-transfected with full-length MDM2 P2 promoter luciferase vectors and a Renilla luciferase reporter, followed by incubation with 25-OCH₃-PPD for 24 h. The MDM2 luciferase activity was detected using the Dual-Luciferase Reporter Assay System. All the analyses were performed in triplicate. (C) Structures of full-length and deleted MDM2 P2 promoter. (D) The effects of 25-OCH₃-PPD (10 µM) on the activity of various MDM2 luciferase reporters were analyzed using the same procedure as above (B). Luciferase activities were plotted as percentages of the control. * P<0.01.</p

MDM2 knockdown reduces cell response to 25-OCH₃-PPD treatment.

<p>MCF7 MDM2-inducible cells were incubated with (Tet+) or without tetracycline (Tet-) for 12 h, followed by exposure to various concentrations of 25-OCH₃-PPD for various times: (A) 72 h for analysis of cell viability using MTT assay; (B) 24 h for analysis of cell proliferation using BrdUrd assay; (C) 48 h for apoptosis analysis using Flow Cytometry; and (D) 24 h for cell cycle analysis. (E) 25-OCH₃-PPD inhibits MDM2 expression in MCF7 inducible cells with or without tetracycline. MDM2 knockdown was confirmed in MCF7 inducible cell line treated with tetracycline, which reversed the effect of 25-OCH₃-PPD.</p

25-OCH₃-PPD inhibits the growth of breast cancer xenograft tumors.

<p>25-OCH₃-PPD was administered by i.p. injection at doses of 5 or 20 mg/kg/d, 5 days/wk for 6 (MCF7 (A)) or 4 weeks (MDA-MB-468 (B)). The growth of tumors was monitored. The body weights of animals were also monitored as a surrogate marker for toxicity in MCF7 (C) and MDA-MB-468 (D) xenograft models.</p

25-OCH₃-PPD decreases MDM2 expression in a dose- and time-dependent manner in human breast cancer cells.

<p>MCF7 (p53 wild type) and MDA-MB-468 (p53 mutant) cells were treated with various concentrations of 25-OCH₃-PPD for 24 h (A) or with 25 µM 25-OCH₃-PPD for various periods (B). (C) 25-OCH₃-PPD also inhibits MDM2 expression <i>in vivo</i>. The tumor-bearing animals were treated with 25-OCH₃-PPD (20 mg/kg/d, 5 days/wk) and tumors were removed at indicated times. The protein levels of MDM2, p53, and p21 in tumor tissue homogenates were analyzed by Western blotting.</p

KCN1, a novel synthetic sulfonamide anticancer agent: in vitro and in vivo anti-pancreatic cancer activities and preclinical pharmacology.

The purpose of the present study was to determine the in vitro and in vivo anti-cancer activity and pharmacological properties of 3,4-dimethoxy-N-[(2,2-dimethyl-2H-chromen-6-yl)methyl]-N-phenylbenzenesulfonamide, KCN1. In the present study, we investigated the in vitro activity of KCN1 on cell proliferation and cell cycle distribution of pancreatic cancer cells, using the MTT and BrdUrd assays, and flow cytometry. The in vivo anti-cancer effects of KCN1 were evaluated in two distinct xenograft models of pancreatic cancer. We also developed an HPLC method for the quantitation of the compound, and examined its stability in mouse plasma, plasma protein binding, and degradation by mouse S9 microsomal enzymes. Furthermore, we examined the pharmacokinetics of KCN1 following intravenous or intraperitoneal injection in mice. Results showed that, in a dose-dependent manner, KCN1 inhibited cell growth and induced cell cycle arrest in human pancreatic cancer cells in vitro, and showed in vivo anticancer efficacy in mice bearing Panc-1 or Mia Paca-2 tumor xenografts. The HPLC method provided linear detection of KCN1 in all of the matrices in the range from 0.1 to 100 µM, and had a lower limit of detection of 0.085 µM in mouse plasma. KCN1 was very stable in mouse plasma, extensively plasma bound, and metabolized by S9 microsomal enzymes. The pharmacokinetic studies indicated that KCN1 could be detected in all of the tissues examined, most for at least 24 h. In conclusion, our preclinical data indicate that KCN1 is a potential therapeutic agent for pancreatic cancer, providing a basis for its future development

25-OCH₃-PPD inhibits cell migration <i>in vitro</i> and metastasis <i>in vivo</i>.

<p>(A) Wound healing assay in MDA-MB-231 cells. After cell growth reached confluence, a scratch was made, and then the cells were incubated with various concentrations of 25-OCH₃-PPD for indicated times. The closure of the scratch was imaged. (B) Effects of 25-OCH₃-PPD on the expression of EMT markers in human breast cancer cells. Cells were treated with various concentrations of 25-OCH₃-PPD for 48 h. The expression of EMT markers was analyzed by Western blotting. (C) <i>In vivo</i> metastasis assay. 1×10⁶ of MDA-MB-231-Luc cells were intravenously injected into a tail vein of nude mice. 25-OCH₃-PPD was administered by i.p. injection at a dose of 10 mg/kg/d, 5 days/wk for 2 weeks. The luciferase signals were determined and photographed using IVIS <i>in vivo</i> image system on Days 1, 8, and 15.</p

25-OCH₃-PPD destabilizes MDM2 protein.

<p>(A) MCF7 and MDA-MB-468 cells were treated with DMSO or 25-OCH₃-PPD (25 µM) followed by exposure to protein synthesis inhibitor cycloheximide (CHX, 10 µg/mL). MDM2 levels were detected by Western blotting at indicated times after exposure to CHX. (B) MCF7 cells were transfected with MDM2 and ubiquitin plasmids followed by treatment with various concentrations of 25-OCH₃-PPD for 24 h. Cells were harvested (left panel) or exposed to proteasome inhibitor MG132 (25 μM) for additional 6 h (right panel). Ubiquitinated MDM2 was detected by immunoblotting. (C) The cell lysates of MCF7 cells treated as above were immunoprecipitated with anti-MDM2 antibody. The ubiquitinated MDM2 was detected using anti-ubiquitin antibody.</p

Tetracycline treatment does not affect parent MCF7 cells.

<p>MCF7 cells were incubated with (Tet+) or without tetracycline (Tet-) for 12 h, followed by exposure to 25-OCH₃-PPD (25 µM) for various times: (A) 72 h for analysis of cell viability using MTT assay; (B) 24 h for analysis of cell proliferation using BrdUrd assay; (C) 48 h for apoptosis analysis using Flow Cytometry; and (D) 24 h for cell cycle analysis. (E) 25-OCH₃-PPD inhibits MDM2 expression in MCF7 cells with or without tetracycline.</p