Abstract C115: Anticancer mechanism of Rg3-NPs nanoparticles in primary cancer cells and embryonal carcinoma.
Authors: Bie Li , Zhao Gang , Ju Yan , Pork Steffen 
Published: June 2012

Ginsenoside Rg3[20(R)-Ginsenoside Rg3] is a natural active ingredient that is extracted from Korean red ginseng root. Ginsenoside Rg3 elevates therapeutic effect of radiotherapy and chemotherapy. The use of Rg3 as a potential anti-cancer durg has been addressed in some papers, but Pang et al found that the application of ginsenoside Rg3 is heavily limited by its low bioavailability and poor absorption via oral administration. To overcome these problems, a new microencapsulated drug delivery system is needed that can control drug delivery and extend the drug circulation time in blood. In the present study, Rg3-loaded PEG-PLGA-NPs (Rg3-NPs) were prepared by the modified spontaneous emulsification solvent diffusion (SESD) method, and the physicochemical characteristics of Rg3-NPs were investigated. We treated primary glioblastoma, hepatocellular carcinoma and human embryonic carcinoma cells (NCCIT) with 50μM Rg3-NPs for 48h. We then used gene expression arrays (Illumina) for genome-wide expression analysis and validated the results for genes of interest by means of Real-Time PCR. Functional annotations were then performed using the DAVID and KEGG online tools. We compared the expression profiles of NCCIT cells with that of the cancer cell lines in order to identify common Rg3-NPs -dependent transcriptional changes and accompanying signaling cascades. The results show that the Rg3-NPs are slick and uniform, the average diameter of nanopartical is between 75–90nm, and entrapment efficiency is (89.7×1.7)%. MTT shows that the growth of cells can be significantly inhibited by Rg3-NPs in a dose-dependence manner. FCM test shows Rg3-NPs can be released from the conjugate nanopartical and react with the genes in the cell nuclei causing changes in the gene molecules. We also found that cancer cells treated with Rg3-NPs undergo cell-cycle arrest at different checkpoints. This arrest was associated with a decrease in the mRNA levels of core regulatory genes, BUB1, CDC20, TTKand CENPE, as determined by microarray-analysis and verified by RealTime PCR. In contrast, human NCCIT cells showed over-expression of GADD45 A and G (growth arrest- and DNA-damage-inducible proteins 45A and G), as well as down-regulation of OCT4, and NANOG protein. Furthermore, Rg3-NPs induced the expression of apoptotic and anti-migratory proteins p53 in all cell lines. Rg3-NPs also up-regulated steady-state levels of both cyclin A and B.

The results of the present study, together with the results of earlier studies show that Rg3-NPs targets genes involved in the progression of the M-phase of the cell cycle. It is associated with several important pathway, which include apoptosis (p53) and motility (p38; MAPK). Rg3-NPs may be a potent cell-cycle regulation drug targeting the M-phase, both in cell lines and primary patient-derived cancer cells from various tumor entities.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C115.