Won-Bong Park

Inhibition of tumor growth and metastasis by Korean mistletoe lectin is associated with apoptosis and antiangiogenesis

The mistletoe lectins are major active components in the extract of European mistletoes that have been widely used in adjuvant chemotherapy of cancer. This study was performed to investigate the mechanism of anticancer and antimetastatic activity of the purified Korean mistletoe lectin (Viscum album L. coloratum agglutinin, VCA). C57BL6 mice inoculated with B16-BL6 melanoma cells and treated with VCA were assessed for survival and metastasis. The induction of apoptosis of B16-BL6 cells by VCA was investigated by morphological changes, DNA fragmentation characteristics, and cell cycle analysis. The antiangiogenic activity of VCA was also measured by the CAM (choriallantoic membrane) assay. Length of survival of mice was increased and lung metastasis was inhibited by VCA. Treatment of cells with VCA resulted in growth suppression, nuclear morphological changes, DNA fragmentation, and an increased fraction of cells in sub-G1 consistent with apoptosis. Antiangiogenesis of VCA was assessed by CAM assay, where vessel growth induced by fat emulsion was decreased. These results suggest that VCA inhibits tumor growth and metastasis by increasing apoptosis and inhibiting angiogenesis.

Isolation and characterization of lectins from stem and leaves of Korean mistletoe (Viscum album var.coloratum) by affinity chromatography.

We attempted to isolate and characterize the lectins from stem and leaves of Korean mistletoe (Viscum album var.coloratum) by affinity chromatography. Lectin I was isolated only from stem. Lectin II was not isolated from Korean mistletoe, whereas lectin III was isolated from the stem and leaves. The hemagglutinating activity of lectin I was 16HU and inhibited by D-galactose, lactose, and N-acetyl-D-galactosamine. The lectin I has molecular weight of 60,000D being composed of two basic subunits with molecular weights of 32,000 D and 28,000 D which are linked by a disufide bond. The lectin III from stem has molecular weight of 66,000D being two basic subunits which have molecular weights of 34,000D and 29,000D and are linked by a disufide bond. The activity of lectin I was stable at the pH range of 4.00∼8.50, and at a wide range of temperature (0∼42°C). The lectin I showed more potent mitogenic activity to murine lymphocytes than concanavalin A.

Characterization of an alkali-extracted peptidoglycan from KoreanGanoderma lucidum

The biologically active peptidoglycan was purified from the alkali fraction of the fruiting bodies ofGanoderma lucidum and the composition of the peptidoglycan was investigated by conventional analyses. The alkali-extracted peptidoglycan showed differences in chemical compositions from the water-extracted. The alkali-extracted peptidoglycan contained 6.9% protein and 75.9% carbohydrates composed mainly of β-glucose, mannose, and α-glucose. The molecular weight range of the peptidoglycan was determined as 2,000 kDa-1 7 kDa. The peptidoglycan is considered to be a hybrid molecule of polysaccharide chains covalently bound as a side chain to the polypeptide core.

Mistletoe lectin modulates intestinal epithelial cell-derived cytokines and B cell IgA secretion

A galactose- and N-acetyl-D-galactosamine-specific lectin (Viscum album L. var. coloratum agglutinin, VCA), which is known for its anti-cancer activity, was isolated from Korean mistletoe. In this study, IEC-6 rat intestinal epithelial cells and IM-9 human B-cells were cultured to determine the effect of VCA on cytokine and immunoglobulin (Ig) secretion. In lipopolysaccharide (LPS)-stimulated IEC-6 cells, VCA significantly shifted the interleukin (IL)-2, IL-5, IL-6, and tumor necrosis factor-alpha (TNF-α) secretion toward a more immunostimulatory response. Since intestinal epithelial cell-derived secretions may be capable of affecting local B cell Ig production in a variety of ways, we mimicked this condition by deriving a 2-day culture supernatant from IEC-6 cell line which was treated VCA in the presence or absence of LPS, and adding these supernatants to cultures of IM-9 human B cells. As a result, IgA secretion was significantly enhanced at in the presence of VCA at 10−8–10–4 μg/mL. This study suggests that cytokines derived from IEC by VCA may create an environment which may contribute to the enhancement of IgA secretion seen in mucosal tissues. Overall, the induction of cytokines in intestinal epithelial cells, and IgA in B cells by Korean mistletoe lectin could indicate an enhanced immunosurveillance to prevent intestinal infections or other intestinal pathologies.

Korean mistletoe lectin regulates self-renewal of placenta-derived mesenchymal stem cells via autophagic mechanisms

The balance between survival and death is a key point for regulation of physiology of stem cells. Recently, applications of natural products to enhance efficiencies in culturing and differentiation of stem cells are increasing. Korean mistletoe lectin (Viscum album L. var. coloratum agglutinin, VCA) has been known to be toxic to some cancer cells, but it is still unclear whether VCA has a cytotoxic or indeed a proliferative effect on mesenchymal stem cells (MSCs). Here, we have compared effects of VCA in naïve placenta‐derived stem cells (PDSCs), immortalized PDSCs and cancer cells (HepG2), and analysed their mechanisms.

Transport of mistletoe lectin by M cells in human intestinal follicle-associated epithelium (FAE) In vitro

Purified mistletoe lectins are known to have cytotoxic and stimulating activities in the immune system. Mistletoe extract has been given subcutaneously because of its unstablity and poor absorption in the Gastrointestinal (GI) tract. A hallmark of M cells is their capacity to internalize material from the lumen and to transfer it efficiently to the underlying lymphoid cells. Although lectins are the prime candidates for oral vaccine delivery, the mechanisms whereby lectins are taken up, transported by M cells, and affect underlying immune cells remain poorly understood. In this study, uptake mechanism of Korean mistletoe lectin (Viscum album L. var. coloratum aggulutinin, VCA) across the human FAE (follicle associated epithelium) was investigated. An inverted FAE model of co-culture was obtained by a co-culture system of Caco-2 cells and human Raji B lymphocytes, and VCA transport across the in vitro model of human FAE was investigated. There was a greater transport of VCA across FAE monolayer cells than that of Caco-2 monolayer cells. These observations will be useful to assess the transport of other orally administered material in the GI tract.

Korean mistletoe lectin promotes proliferation and invasion of trophoblast cells through regulation of Akt signaling

Recently, Viscum album var. coloratum agglutinin (VCA) was shown to have various effects on cancer cells. However, most researchers are focused on high concentrations (1-1000 ng/ml) of VCA and its anti-cancer effects. Therefore, we wanted to know whether low concentrations of VCA have an effect on proliferation and invasion of human trophoblast cells (HTR-8/SVneo cell line). Cell proliferations at low concentration of VCA (1-10 pg/ml) were increased over 2-fold relative to the control. Also, gelatinolytic activities of matrix metalloproteinase-2 were increased after VCA treatment, while TIMP-1 expression was reduced. Furthermore, the expression of integrin subunits α5 and β1 were increased 1.5-fold when cells were treated with low dose of VCA (10 pg/ml). Lastly, VCA was able to promote trophoblast invasion through activation of the Akt signaling pathway. In conclusion, low concentrations of VCA can stimulate the ability of trophoblast cells to invade through the extracellular matrix in vitro.

Mistletoe lectin transport by M-cells in follicle-associated epithelium (FAE) and IL-12 secretion in dendritic cells situated below FAE In Vitro

A galactose- and N-acetyl-D-galactosamine-specific lectin (Viscum album L. var. coloratum agglutinin, VCA), which is known for its anti-tumor activity, was isolated from Korean mistletoe. Mistletoe preparations have been given subcutaneously because of the unstability and poor absorption in the GI tract. In this study, we investigated the effect of incubation time and glucose on the VCA transport across the in vitro model of human FAE (follicle-associated epithelium) by two different cell models: Caco-2 cell monolayers mimicking human enterocytes and a model of the human FAE which is mainly composed of M-cells and enterocytes. As a result, the VCA transport across the FAE monolayer cells was higher and faster than the transport across the Caco-2 monolayer cells, and glucose increased VCA transport across both monolayer cells. In addition, IL-12 was secreted from myeloid DC1 and lymphoid DC2.4 cells which were co-treated simultaneously with LPS and VCA. Furthermore, the FAE model associated with underlying immune cells was established and VCA was added to the inserts apically. There was a greater IL-12 secretion in dendritic cells situated below FAE monolayer than Caco-2 monolayer. The results from this study provide important insight into the possible oral application of mistletoe on anti-tumor therapeutics.

Gene network analysis on the effect of Viscum album var. coloratum in T cells stimulated with anti-CD3/CD28 antibodies

A galactose- and N-acetyl-D-galactosamine-specific lectin (Viscum album L. var. coloratum agglutinin, VCA), which is known for its anticancer activity, was isolated from Korean mistletoe. This study reports a microarray analysis of the effects of VCA on an activated human T cells under various times and concentrations. A total of over 3000 genes were identified whose expression levels were significantly altered against controls after treatment with VCA and anti-CD3/CD28 antibody stimulation on human T-cells over an 8 h period. An analysis of the gene expression profile induced by VCA following incubation in human T cells revealed the activation and inhibition of genes involved in a wide range of immune functions in line with the broad mechanisms of action of VCA. These functions include cytokine gene expression, cell adhesion, cell motility, cell growth and maintenance, cell death, and the response to stress and to external stimulus. This report is aimed at providing the mistletoe research community with a robust database on which further studies could be built.

Conversion of water-insoluble components of the basidiocarps ofGanoderma lucidum to water-soluble components by hydrolyzing with chitinase

We investigated the optimum conditions for conversion of water-insoluble components of basidiocarps ofGanoderma lucidum to water-soluble components by hydrolyzing with chitinase. We also tried it withGanoderma lucidum residue remaining after extracting hot water-soluble components ofGanoderma lucidum. After hydrolyzing under optimum conditions (20 ppm chitinase, 2%Ganoderma lucidum or 6%Ganoderma lucidum residue, at pH 3 and at 35°C), the contents of total water-soluble components (polysaccharide or protein) were measured, and it was found that the contents of water-soluble components increased to 1.5∼2.7 fold. Michaelis constant, Km and maximum rate, Vmax calculated by Lineweaver-Burk plot for hydrolysis ofGanoderma lucidum were 1.75% and 0.02%/min respectively and those for hydrolysis ofGanoderma lucidum residue were 53.15% and 0.53%/min respectively. The protein-bound polysaccharide was isolated after hydrolysis and molecular weights were measured by Sepharose CL-4B gel filtration and compared with the molecular weights of polysaccharide before hydrolysis.