Demonstration of specifically sensitized lymphocytes in patients treated with an aqueous mistletoe extract (Viscum album L.)

Cancer and apoptosis: The apoptotic activity of plant and marine natural products and their potential as targeted cancer therapeutics

Cancer is a multifactorial, multi-stage disease, including complex cascades of signaling pathways—the cell growth governed by dysregulated and abrupt cell division. Due to the complexity and multi-regulatory cancer progression, cancer is still a challenging disease to treat and survive. The screening of extracts and fractions from plants and marine species might lead to the discovery of more effective compounds for cancer therapeutics. The isolated compounds and reformed analogs were known as future prospective contenders for anti-cancer chemotherapy. For example, Taxol, a potent mitotic inhibitor discovered from Taxus brevifolia, suppresses cell growth and arrest, induces apoptosis, and inhibits proliferation. Similarly, marine sponges show remarkable tumor chemo preventive and chemotherapeutic potential. However, there is limited research to date. Several plants and marine-derived anti-cancer compounds having the property to induce apoptosis have been approved for clinical trials. The anti-cancer activity kills the cell and slows the growth of cancer cells. Among cell death mechanisms, apoptosis induction is a more profound mechanism of cell death triggered by naturally isolated anti-cancer agents. Evading apoptosis is the major hurdle in killing cancer cells, a mechanism mainly regulated as intrinsic and extrinsic. However, it is possible to modify the apoptosis-resistant phenotype of the cell by altering many of these mechanisms. Various extracts and fractions successfully induce apoptosis, cell-cycle modulation, apoptosis, and anti-proliferative activity. Therefore, there is a pressing need to develop new anti-cancer drugs of natural origins to reduce the effects on normal cells. Here, we’ve emphasized the most critical elements: i) A better understanding of cancer progression and development and its origins, ii) Molecular strategies to inhibit the cell proliferation/Carcino-genesis, iii) Critical regulators of cancer cell proliferation and development, iv) Signaling Pathways in Apoptosis: Potential Targets for targeted therapeutics, v) Why Apoptosis induction is mandatory for effective chemotherapy, vi) Plants extracts/fractions as potential apoptotic inducers, vii) Marine extracts as Apoptotic inducers, viii) Marine isolated Targeted compounds as Apoptotic inducers (FDA Approved/treatment Phase). This study provides a potential therapeutic option for cancer, although more clinical studies are needed to verify its efficacy in cancer chemotherapy.

Synergistic anticancer effects of lectin and doxorubicin in breast cancer cells

We studied the effects, either combined or alone, of lectin from Korean mistletoe (Viscum album var. coloratum agglutinin, VCA) and doxorubicin (DOX) in MCF-7 (estrogen receptor-positive) and MDA-MB231 (estrogen receptor-negative) human breast cancer cells. When VCA and DOX were combined, a strong synergistic effect was shown in cell growth inhibition, compared to VCA or DOX treatment alone. In quantitative apoptosis studies analyzed by flow cytometry, a combination of two agents showed an increase in apoptosis in both cells, compared to agents alone. Also, pro-apoptotic proteins including Bax, Bik, and Puma were increased in both cells, and the survival factor Bcl-2 was inhibited in MCF-7 cells when drugs were combined. Furthermore, VCA combined with DOX mediated S phase arrest, accompanied with a decrease of cell number at G0/G1 phase. This suggests that VCA and DOX combination may possibly lead to a novel strategy for the treatment of breast cancer.

Mistletoe lectin (Viscum album coloratum) modulates proliferation and cytokine expressions in murine splenocytes

It is well documented that an extract of European mistletoe has a variety of biological effects, such as the stimulation of cytokine production from immune cells, and additional immunoadjuvant activities. While the European mistletoe has been studied intensively, we know less about Korean mistletoe as a therapeutic plant, especially as a possible immunomodulating drug. This study will investigated the effects of Korean mistletoe lectin (Viscum album L. var. coloratum agglutinin, VCA) on murine splenocytes to investigate whether VCA acts as an immunomodulator, which could lead to improved immune responses in these cells. The results showed that VCA inhibited cell proliferation at higher concentrations (at 1-8 ng/ml) and enhanced cell proliferation at lower concentrations (at 4-32 pg/ml). Further studies were carried out to determine if the proproliferative or anti-proliferative activity exhibited by VCA was correlated with cytokine secretion. Consequently, interferon (IFN)-gamma secretion was decreased in concanavalin A (ConA)-stimulated murine splenocytes by VCA (4-64 ng/ml), but there was no change in IL-4 levels. This suggests that VCA has the ability to modulate murine splenocyte proliferation and can possibly act on the balance of Th1/Th2 cellular immune responses.

Phase II study of viscum fraxini-2 in patients with advanced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Although a wide range of therapeutic options is available, the efficacy of these methods and the prognosis of patients with HCC remain very poor. This study was conducted to evaluate the efficacy and safety of viscum fraxini-2 in patients with chemotherapy–naïve, advanced hepatocellular carcinoma. 23 patients with unrespectable HCC who had received no prior systemic chemotherapy with objectively measurable tumors were enrolled on this study. The mistletoe preparation for the study is an aqueous injectable solution. It contains one milliliter of viscum fraxini in dilution stage–2 (15 mg extract of 20 mg mistletoe herb from ash tree, diluted in di-natrium-mono-hydrogen phosphate, ascorbic acid and water) which is equivalent to 10 000 ng/ml injection ampoules. 2 ampoules of viscum fraxini–2 were administered subcutaneously once weekly. As assessed by conventional imaging criteria, 3 (13.1%) patients have achieved complete response, 2 (8.1%) patients have achieved a partial response. 9 (39.1%) had progressive disease while 9 (39.1%) patients didn't have evaluation of response due to early death. The median overall survival time for all patients was 5 months (range 2–38 months), for those who achieved a CR was 29 months (range 12–38 months) and, for those who achieved a PR was 6.5 months (range 6–7 months). The median progression free survival for all patients was 2 months (range 1–38 months), for those who achieved a CR, it was 29 months (range 8–38 months) and for those who achieved a partial response, it was 5 months (range 4–6 months). No hematologic toxicity has been encountered. The spectrum of non-hematologic toxicity was mild. The WHO toxicity criteria grade 3–4 were 34.8% drug related fever, 13.1% erthyma at injection site and 17.4% pain at the site of injection. No drug related discontinuation or toxic deaths have occurred. Viscum fraxini-2 seems to be particularly promising in patients with advanced HCC, it shows antitumor activity and low toxicity profile. Further studies in combination with other active agents are clearly warranted.

Natural product inhibitors of ovarian neoplasia

The present work constitutes a review of the literature on natural products with potential antitumor activity against ovarian neoplasias. The review refers to five plant extracts and sixty-nine compounds isolated from higher plants and microorganisms, which are classified in appropriate chemical groups and model tested, and cites their activity. Some aspects of recent research with natural products directed to ward producing drugs which are inhibitors of ovarian neoplasia are discussed.

Effects of a lectin- and a viscotoxin-rich mistletoe preparation on clinical and hematologic parameters: a placebo-controlled evaluation in healthy subjects

BACKGROUND AND OBJECTIVES

Mistletoe preparations, which are widely used among patients with cancer in Germany, have immunomodulating properties in vitro and in vivo. The aim of this evaluation was to determine and compare the effects of a lectin-rich (Iscador Qu [IQ] special, Weleda Company, Schwäbisch, Gmünd, Germany.) and a lectin-poor but viscotoxin-rich (Iscador Pini [IP] Weleda Company) mistletoe preparation on clinical and hematologic parameters in healthy subjects.

DESIGN

In a double-blinded study, 48 volunteers were randomized to one of three groups: 16 received IQ or IP in increasing doses or placebo twice per week subcutaneously for 12 weeks. The differential blood count and the acute phase markers haptoglobin and C-reactive protein were examined weekly and the symptoms were scored using standardized questionnaires.

RESULTS

IQ resulted in significant eosinophilia (315 +/- 109) beginning at week 5 (until week 12) compared to IP (183 +/- 120) or placebo (200 +/- 179). Furthermore, the acute phase marker haptoglobin was significantly increased in the IQ group during week 4. Dose-dependent local reactions (LRs) at the injection site occurred in all subjects who received mistletoe preparations but were stronger in the IQ-treated subjects than in the IP-treated group. The LRs observed in the IQ-treated group were characterized by stronger itching and longer latency than LRs in the IP-treated group (p < 0.05). Severe side-effects did not occur in any of the probands.

CONCLUSIONS

IQ but not IP can induce eosinophilia in healthy individuals, and this may be related to its content of mistletoe lectins. In contrast, exposure to the viscotoxin-enriched extract IP did not result in specific changes of hematologic parameters. Furthermore, intensity and time course of local reactions seemed to depend on the concentration of mistletoe lectins in those extracts.

Complementary and alternative medicine: opportunities and challenges for cancer management and research

Given the widespread use of diverse complementary and alternative medicine (CAM) approaches by cancer patients, research to establish their safety and efficacy is critical as is improved patient-physician communication about their possible risks and benefits. The mission of the National Center for Complementary and Alternative Medicine (NCCAM) is to support exacting research and disseminate clear and compelling information on CAM. Although many of the challenges facing such research are not unique to CAM, these approaches do present unique challenges, but the opportunities are many for prevention, palliation, and even treatment. Using the current research portfolio of NCCAM to illustrate how the field may mature, this report summarizes the challenges facing CAM investigators, the most fruitful areas for exploration, and existing information resources.

Comparative study of Korean (Viscum album var. coloratum) and European mistletoes (Viscum album)

A lectin (agglutinin, VCA) from Korean mistletoe (Viscum album L. coloratum) was isolated by affinity chromatograpy on a asialofetuin-Sepharose 4B. The molecular weights of A- and B-chains of VCA were differenf from those of VAAS. The VCA recognized the antibody of VAAs in the Western blot analysis and ELLA system. We also investigated the synergistic effects of the components in mistletoe by dividing the extract into different molecular weight fractions.

Characterisation of granulocyte stimulation by thionins from European mistletoe and from wheat

Thionins are small basic peptides found in different plant species, which are known to exert cytotoxic properties. In addition, previous data indicated an activation of human granulocytes by thionins from European mistletoe (viscotoxins, VT). To extend these latter findings, we investigated the influence of VT and from thionins from wheat flour (purothionin) on human granulocytes by flow cytometry and tried to characterise the involved molecular structures and mechanisms. Phagocytosis was determined by incorporation of FITC-labelled Escherichia coli and respiratory burst by oxidation of dihydrorhodamine 123 to rhodamine 123. VT and purothionin significantly enhanced E. coli-stimulated phagocytosis and respiratory burst at 25 and 250 microgram/ml. Phagocytosis of damaged lymphocytes by granulocytes was detected by electron microscopy in the VT-stimulated (100 microgram/ml) but not in the control cultures. The poly-cationic structure of the intact molecule seems to be crucial, as evidenced by comparison of the burst and phagocytosis-enhancing effects induced by other poly-cationic (protamine sulphate, histone, poly-l-arginine, poly-l-lysine) and poly-anionic (poly-l-glutamic acid) peptides, while pore forming due to amphipathic properties seems to be less important. Ca2+ and Mg2+ could not inhibit VT-enhanced phagocytosis and, thus, could not inhibit binding of VT to granulocytes. In addition, verapamil at low concentrations inhibited VT activity, suggesting the involvement of Ca2+ channels for granulocyte activation by the VT. Similarly, thionins and histones in contrast to protamine sulphate induced cell death of granulocytes at 250 microgram/ml as demonstrated by an enhanced release of reactive oxygen intermediates in unstimulated granulocytes. From these data one may suggest that activity of VT is induced by strong unspecific ionic binding, probably followed by specific receptor binding, and thionins exhibit stimulatory and cytotoxic effects on immune cells, which have to be further characterised.

Isolation and characterization of beta-galactoside specific lectin from Korean mistletoe (Viscum album var. coloratum) with lactose-BSA-sepharose 4B and changes of lectin conformation

Lectins and its A- and B-chains from Korean mistletoe (Viscum album var. coloratum) were isolated by affinity chromatography on the Sepharose 4B modified by lactose-BSA conjugate synthesized by reductive amination of ligand (lactose) to epsilon-amino groups of lysine residues of spacer (BSA) after reduction by NaCNBH3. The lactose-BSA conjugate was coupled to Sepharose 4B activated by cyanogen bromide. The molecular weight determined by SDS-PAGE were a 31 kD of A-chain and a 35 kD of B-chain. Amino acid analysis and N-terminal sequencing were performed. The effects of pH, temperature and guanidine chloride on the conformation of the lectin were investigated by measuring its intrinsic fluorescence and compared with its hemagglutinating activities. Blue shift was detected on the acidic pH and there was a close relationship between activities and conformation of the lectin. Under denaturing conditions, the tryptophan emission profile of lectin showed typical denaturational red shift which also correspond to the conformations and activity of lectin.

Flow cytometric analyses of the specific activation of peripheral blood mononuclear cells from healthy donors after in vitro stimulation with a fermented mistletoe extract and mistletoe lectins

Immunostimulatory properties of mistletoe extracts derived from Viscum album L. (VAL) are well described, demonstrating activation especially of T, T-helper cells and monocytes/macrophages. In order to characterise in detail the communication between different cell populations, we studied mistletoe-induced expression of co-stimulatory signals and their ligands by flow cytometry. Peripheral blood mononuclear cells (PBMC) from 15 healthy controls were incubated for 7 days with a fermented VAL extract. VAL significantly upregulated the expression of the co-stimulatory molecule B7.1 (CD80) on monocytes/macrophages, but not B7.2 (CD86). No significant changes in the expression of either molecules on B cells could be found, suggesting that only monocytes/macrophages act as antigen presenting cells (APCs) in this in vitro system. Purified mistletoe lectins, components of most VAL extracts were also analysed, but did not induce similar responses of monocytes/macrophages. The receptor for B7 molecules, CD28, but not CTLA-4 (CD152), was also found to be significantly enhanced on CD4+ cells after VAL simulation. There was no evidence for activation of a B cell response via the CD40/CD40L pathway. Our data support the concept that stimulation by VAL extracts induces a specific T-helper cell reaction with monocytes/macrophages acting as APCs and purified lectins do not exert the same effects.

Induction of apoptosis in human lymphocytes treated with Viscum album L. is mediated by the mistletoe lectins

Viscum album L. (VAL) is a phytopreparation used in adjuvant cancer therapy with both immunostimulatory and DNA stabilizing properties at low drug concentrations and cytostatic/cytotoxic properties at higher concentrations. The present work examines the cytotoxic effects of VAL extracts produced from mistletoes grown on different host trees and of purified toxic proteins from VAL, such as the D-galactose-specific lectin I (ML I), the N-acetyl-D-galactosamine-specific ML II and ML III, and crude viscotoxins towards cultured human lymphocytes. The decrease in the number of cultured lymphocytes and blast cells treated with whole plant extracts from VAL was host tree-specific. Nevertheless, there was no close correlation to the content of MLs or viscotoxins. Using the purified proteins, it became obvious that the cell killing was mediated by the induction of apoptosis, as measured by the appearance of a hypodiploid DNA peak using flow cytometry. ML III was the most effective to induce apoptosis, followed by ML II and ML I, while the viscotoxins and oligosaccharides from VAL did not. By measuring the surface expression of IL-2R alpha chains, transferrin receptors and APO-1/Fas molecules on non-apoptotic T cells, no significant changes were observed at low ML concentrations (1 ng/ml), but their decrease at higher ones. Our findings suggest that there might be at least two different ways of cell killing operative in VAL-mediated cytotoxicity: (a) the typical apoptotic cell death with the appearance of hypo-diploid nuclei, and (b) a direct or indirect killing by damaging the cell membrane with subsequent influx of Ca2+ and of the DNA intercalating dye propidium iodide and cell shrinkage. These effects might not be exclusive, as they probably occur simultaneously.

Effects of Viscum album L. on cyclophosphamide-treated peripheral blood mononuclear cells in vitro: sister chromatid exchanges and activation/proliferation marker expression

Based on recently published data, Viscum album L. (VAL) extracts have been shown to provide a DNA stabilizing effect which seems to be restricted to the peripheral blood mononuclear cells (PBMC). We have now investigated whether VAL exerts effects of cellular protection for phytohemagglutinin-activated PBMC treated with cyclophosphamdie (CP) in vitro. The addition of VAL resulted in a slight reduction of CP-induced sister chromatid exchanges of cultured PBMC from healthy individuals. The incubation with CP significantly reduced the expression of the low affinity interleukin-2 receptor (IL-2R alpha chain) and of transferrin receptor (TfR) on PHA-stimulated T lymphocytes. The addition of 10 micrograms/ml VAL was protective against the CP-induced depression of IL-2R alpha chain and TfR expression on these cells. The simultaneous addition of CP and purified VAL components, such as ML I, ML II/III, and viscotoxins did not significantly change expression of IL-2R alpha chain and TfR on T cells. Thus, so far undefined VAL components might be responsible for the observed protection effects of the whole plant extract. The results presented here should encourage investigation of this drug, which might become an interesting adjuvant in cancer therapy.

Non-lectin component in a fermented extract from Viscum album L. grown on pines induces proliferation of lymphocytes from healthy and allergic individuals in vitro

Mistletoe preparations have been shown to express immunomodulatory properties. In order to evaluate the stimulatory potency of different mistletoe extracts, peripheral blood mononuclear cells (PBMC) from healthy and allergic/atopic individuals were exposed to aqueous or fermented extracts derived from Viscum album L. grown on apple trees (Mali-extracts) or on pines (Pini-extracts). None of them had received any mistletoe treatment. Iscador Pini was the only extract which strongly induced proliferation of PBMC in contrast to the other five preparations. On testing these extracts by Western blotting with anti-mistletoe lectin-1 (ML-1) antibody positive sera from mistletoe-treated patients, it became evident that Iscador Pini was almost devoid of lectins. The stimulatory potency of Iscador Pini for PBMC from three different groups was examined: PBMC from 35 normal controls (Group I), 23 patients with drug-induced adverse effects (Group II) and 16 individuals with allergic manifestations (Group III). Cells were exposed in 7-day cultures to the extract at concentrations between 1 and 10,000 micrograms/ml. PBMC from 63% of Group III individuals showed strong stimulation (SI varying from 6 to 97) in contrast to only 9% from Group I and 22% from Group II individuals. Anti-ML-1 antibodies were detected in 5% and anti-IP antibodies in 11% of subjects in the three groups. They were either of the IgA or IgM type but not of the IgG type. Our findings strongly imply that a non-lectin associated antigen from Iscador Pini is able to activate PBMC from healthy and allergic/atopic individuals, thereby demonstrating sensitization to probably highly conserved plant antigens.