In-Sung Jung

Radioprotective Effects of Ginsan, an Immunomodulator

Abstract Song, J-Y., Han, S-K., Bae, K-G., Lim, D-S., Son, S-J., Jung, I-S., Yi, S-Y. and Yun, Y-S. Radioprotective Effects of Ginsan, an Immunomodulator. Radiat. Res. 159, 768–774 (2003). We previously reported that ginsan, a purified polysaccharide isolated from Panax ginseng, had a mitogenic activity, induced LAK cells, and increased levels of several cytokines. In an effort to identify other immunostimulatory effects, we evaluated the protective effects of ginsan injected in vivo against radiation by measuring its effects on the CFU-S bone marrow cells and spleen cells. Ginsan was found to significantly increase the number of bone marrow cells, spleen cells, granulocyte-macrophage colony-forming cells (GM-CFC), and circulating neutrophils, lymphocytes and platelets in irradiated mice. In addition, ginsan induced the endogenous production of cytokines such as Il1, Il6, Ifng and Il12, which are required for hematopoietic recovery, and was able to enhance Th1 function while interfering with the Th2 response in irradiated mice. We demonstrated that pretreatment with ginsan protected mice from the lethal effects of ionizing radiation more effectively than when it was given immediately after or at various times after irradiation. A significant increase in the LD50/30 from 7.54 Gy for PBS injection to 10.93 Gy for mice pretreated with 100 mg/kg ginsan was observed. These findings indicate that ginsan may be a useful agent to reduce the time necessary for reconstituting hematopoietic cells after irradiation.

Effects of polysaccharide ginsan from Panax ginseng on liver function.

Ginsan, a polysaccharide isolated fromPanax ginseng, has been shown to be a potent immunomodulator, producing a variety of cytokines such as TNF-α, IL-1β IL-2, IL-6, IL-12, IFN-γ and GM-CSF, and stimulating lymphoid cells to proliferate. In the present study, we analyzed some immune functions 1st-5th days after ginsan i.p. injection, including the level of non-protein thiols (NPSH) as antioxidants, heme oxygenase (HO) activity as a marker of oxidative stress, zoxazolamine-induced paralysis time and level of hepatic cytochrome P-450 (CYP450) as indices of drug metabolism system, and activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin, and albumin level as indicators of hepatotoxicity. Ginsan in the dose of 100 mg/kg caused marked elevation (1.7~2 fold) of HO activity, decrease of total CYP450 level (by 20-34%), and prolongation of zoxazolamine induced paralysis time (by 65-70%), and showed some differences between male and female mice. Ginsan treatment did not seem to cause hepatic injury, since serum AST, ALT, and ALP activities and levels of total bilirubin and albumin were not changed.

Immunomodulatory Activity of Protein-Bound Polysaccharide Extracted from Chelidonium majus

In the course of searching immunomodulators from natural sources, the protein-bound polysaccharide, CM-Ala, has been isolated from the water extract ofChelidonium majus L. (Papaveraceae). The immunostimulatory characteristics have been investigated in several experiments such as generation of activated killer (AK) cells, proliferation of splenocytes, activation of macrophages and granulocyte macrophage-colony forming cell (GM-CFC) assay. Of the fractions obtained using Sephacryl S200 column chromatography, CM-Ala was the most effective fraction that augmented the cytotoxicity against Yac-1 tumor cells from 0.88% to 34.18% by culturing with splenocytes for 5 days. CM-Ala also enhanced nitric oxide production by two fold in peritoneal macrophages and exhibited antitumor activity. It showed mitogenic activity on both spleen cells and bone marrow cells. CM-Ala induced proliferation of splenocytes by 84 fold and increased GM-CFC numbers by 1.48 fold over than the non-treated. On the contrary, CM-Ala had cytotoxic activity to a diverse group of tumor cells. From the above results, we proposed that CM-Ala has a possibility of an effective antitumor immunostimulator.

Radiation Protective Effect of an Extract from Chelidonium majus

We earlier reported that CM-AIa isolated from Chelidonium majus had mitogenic activity, generated lymphokine-activated killer cells, and increased the number of granulocyte-macrophage colony-forming cells (GM-CFC). In an extended effort to search for other immunostimulatory effects, we evaluated the protective effects of in vivo injected CM-AIa against irradiation. CM-AIa was found to increase the number of bone marrow cells, spleen cells, GM-CFC, and platelets in irradiated mice. In addition, this agent induced endogenous production of cytokines such as interleukin 1 and tumor necrosis factor alpha, which are required for hematopoietic recovery. We also demonstrated that CM-AIa treatment 24 hours before irradiation protected mice with 80% survival at lethal dose 100/15. These findings indicate that CM-AIa may be a useful agent for reducing the time needed for reconstitution of hematopoietic cells after irradiation treatment.

Abstract 1355: A novel derivative of benzoxazole enhances radiosensitivity of human colon cancer cells through p53-mediated G2/M arrest and mitochondrial apoptotic pathway

The tumor suppressor p53 plays a critical role in cell cycle regulation and apoptotic cell death, and its activation can sensitize cancer cells to radio- or chemotherapy. To identify small molecules that induce apoptotic cell death via increasing p53 transcriptional activity, we designed and synthesized 44 benzoxazole derivative small molecule compounds. Using a cell-based screening with p53-responsive luciferase reporter assay system of benzoxazole derivatives, we found AU14022, which significantly increased p53 transcriptional activity in a concentration dependent manner. Treatment of AU14022 increased p53 protein expression, its phosphorylation on serine 15 and its target p21 gene/protein expression and induced apoptotic cell death measured by FACS analysis using Annexin V/PI double staining in wild-type p53 HCT116 human colon cancer cells but not in p53 knockout HCT116 cells. Furthermore, treatment of HCT116 cells with AU14022 exhibited mitochondrial dysfunction including bcl-2 family modulation and cytochrome c release. Combination treatment of AU14022 and ionizing radiation (IR) synergistically induced apoptotic cell death, compared to IR or AU14022 alone. Further investigation demonstrated that cell cycles are significantly arrested at G2/M phase, and marked inductions of p21 protein expression and phosphorylation of Chk1 protein and a decrease of cyclin B1 protein expression were observed by treatment of AU14022 alone and combination treatment with AU14022 and IR. Our findings indicate that AU14022 induced apoptosis through p53-mediated cell cycle arrest with mitochondrial dysfunction, leading to enhanced radiosensitivity of colon cancer cells. These results provide a basis for the further investigations required for its assessment as a promising anticancer agent. Citation Format: Hwani Ryu, Bitna Seo, Jooyoung Kim, In-Sung Jung, Jie-Young Song, Jiyeon Ahn. A novel derivative of benzoxazole enhances radiosensitivity of human colon cancer cells through p53-mediated G2/M arrest and mitochondrial apoptotic pathway. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1355.