The growth of an established murine non-Hodgkin lymphoma tumour is limited by switching to a phytohaemagglutinin-containing diet

Recombinant Phaseolus vulgaris phytohemagglutinin L-form expressed in the Bacillus brevis exerts in vitro and in vivo anti-tumor activity through potentiation of apoptosis and immunomodulation

Leukocyte phytohemagglutinin (PHA-L) is a tetrameric isomer of phytohemagglutinin (PHA) purified from the red kidney bean (Phaseolus vulgaris) and is a well-known human lymphocyte mitogen. Due to its antitumor and immunomodulatory effects, PHA-L may serve as a potential antineoplastic agent in future cancer therapeutics. However, various negative consequences of PHA have been reported in the literature as a result of the restricted acquisition methods, including oral toxicity, hemagglutinating activity, and immunogenicity. There is a critical need to explore a new method to obtain PHA-L with high purity, high activity and low toxicity. In this report active recombinant PHA-L protein was successfully prepared by Bacillus brevius expression system, and the antitumor and immunomodulatory activities of recombinant PHA-L were characterized by in vitro and in vivo experiments. The results showed that recombinant PHA-L protein had stronger antitumor effect, and its anti-tumor mechanism was realized through direct cytotoxicity and immune regulation. Importantly, compared with natural PHA-L, the recombinant PHA-L protein showed the lower erythrocyte agglutination toxicity in vitro and immunogenicity in mice. Altogether, our study provides a new strategy and important experimental basis for the development of drugs with dual effects of immune regulation and direct antitumor activity.

3'-Sulfo-TF Antigen Determined by GAL3ST2/ST3GAL1 Is Essential for Antitumor Activity of Fungal Galectin AAL/AAGL

Many lectins have been reported to have antitumor activities; identifying the glycan ligands in tumor cells of lectins is crucial for lectin clinical application. An edible mushroom galectin, Agrocybe aegerita lectin (AAL/AAGL), that has a high antitumor activity has been reported. In this paper, based on the glycan array data, it is showed that the Thomsen-Friedenreich antigen (TF antigen)-related O-glycans were found to be highly correlated with the antitumor activity of AAL/AAGL. Further glycosyltransferase quantification suggested that the ratio between GAL3ST2 and ST3GAL1 (GAL3ST2/ST3GAL1), which determined the 3'-sulfo-TF expression level, was highly correlated with the antitumor activity of AAL/AAGL. Overexpressing the enzyme of GAL3ST2 in HL60 and HeLa cell lines could increase the growth inhibition ratio of AAL/AAGL from 22.7 to 43.9% and 27.8 to 39.1%, respectively. However, ST3GAL1 in Jurkat cells could decrease the growth inhibition ratio from 44.7 to 35.6%. All the data suggested that the 3'-sulfo-TF antigen is one of the main glycan ligands that AAL/AAGL recognizes in tumor cells. AAL/AAGL may potentially serve as a reagent for cancer diagnosis and a targeted therapy for the 3'-sulfo-TF antigen.

Functional Component Isolated from Phaseolus vulgaris Lectin Exerts In Vitro and In Vivo Anti-Tumor Activity Through Potentiation of Apoptosis and Immunomodulation

Phytohemagglutinin (PHA), the lectin purified from red kidney bean (Phaseolus vulgaris), is a well-known mitogen for human lymphocyte. Because it has obvious anti-proliferative and anti-tumor activity, PHA may serve as a potential antineoplastic drug in future cancer therapeutics. However, the literature is also replete with data on detrimental effects of PHA including oral toxicity, hemagglutinating activity, and immunogenicity. There is a critical need to evaluate the functional as well as the toxic components of PHAs to assist the rational designs of treatment with it. In this report, we performed SDS-PAGE to identify components of PHA-L, the tetrameric isomer of PHA with four identical L-type subunits, and then characterized biological function or toxicity of the major protein bands through in vitro experiments. It was found that the protein appearing as a 130 kD band in SDS-PAGE gel run under the condition of removal of β-mercaptoethanol from the sample buffer together with omission of a heating step could inhibit tumor cell growth and stimulate lymphocyte proliferation, while most of the 35 kD proteins are likely non-functional impurity proteins and 15 kD protein may be related to hemolytic effect. Importantly, the 130 kD functional protein exhibits promising in vivo anti-tumor activity in B16-F10 melanoma C57 BL/6 mouse models, which may be achieved through potentiation of apoptosis and immunomodulation. Altogether, our results suggest that PHA-L prepared from crude extracts of red kidney bean by standard strategies is a mixture of many ingredients, and a 130 kD protein of PHA-L was purified and identified as the major functional component. Our study may pave the way for PHA-L as a potential anticancer drug.

Plant lectins in cancer therapeutics: Targeting apoptosis and autophagy-dependent cell death

Plant lectins are non-immunoglobin in nature and bind to the carbohydrate moiety of the glycoconjugates without altering any of the recognized glycosyl ligands. Plant lectins have found applications as cancer biomarkers for recognizing the malignant tumor cells for the diagnosis and prognosis of cancer. Interestingly, plant lectins contribute to inducing cell death through autophagy and apoptosis, indicating their potential implication in cancer inhibitory mechanism. In the present review, anticancer activities of major plant lectins have been documented, with a detailed focus on the signaling circuit for the possible molecular targeted cancer therapy. In this context, several lectins have exhibited preclinical and clinical significance, driving toward therapeutic potential in cancer treatment. Moreover, several plant lectins induce immunomodulatory activities, and therefore, novel strategies have been established from preclinical and clinical investigations for the development of combinatorial treatment consisting of immunotherapy along with other anticancer therapies. Although the application of plant lectins in cancer is still in very preliminary stage, advanced high-throughput technology could pave the way for the development of lectin-based complimentary medicine for cancer treatment.

Plant lectin can target receptors containing sialic acid, exemplified by podoplanin, to inhibit transformed cell growth and migration

Cancer is a leading cause of death of men and women worldwide. Tumor cell motility contributes to metastatic invasion that causes the vast majority of cancer deaths. Extracellular receptors modified by α2,3-sialic acids that promote this motility can serve as ideal chemotherapeutic targets. For example, the extracellular domain of the mucin receptor podoplanin (PDPN) is highly O-glycosylated with α2,3-sialic acid linked to galactose. PDPN is activated by endogenous ligands to induce tumor cell motility and metastasis. Dietary lectins that target proteins containing α2,3-sialic acid inhibit tumor cell growth. However, anti-cancer lectins that have been examined thus far target receptors that have not been identified. We report here that a lectin from the seeds of Maackia amurensis (MASL) with affinity for O-linked carbohydrate chains containing sialic acid targets PDPN to inhibit transformed cell growth and motility at nanomolar concentrations. Interestingly, the biological activity of this lectin survives gastrointestinal proteolysis and enters the cardiovascular system to inhibit melanoma cell growth, migration, and tumorigenesis. These studies demonstrate how lectins may be used to help develop dietary agents that target specific receptors to combat malignant cell growth.

Phytohemagglutinin Inhibits Lymphoid Tumor GrowthIn VitroandIn Vivo

Cure rates for a variety of leukemias and lymphomas have improved dramatically over the past several decades, but relapsed disease continues to account for thousands of deaths per year. Viable treatment options for relapsed disease are few, encouraging the development of novel therapies. In the present paper, we describe phytohemagglutinin (PHA), a standard T cell mitogen, as an inhibitor of both T- and B-cell tumors. In vitro studies show that PHA can inhibit incorporation of 3H-thymidine and mediate apoptosis of B- and T-cell tumor lines. The inhibitory effects are enhanced when PHA is used in conjunction with the cell cycle directed drug 5-fluorouracil (5-FU). Phytohemagglutinin treatments can also impede tumor growth in mice while showing no toxic side effects in this animal model.

Autophagy Induction in T Cell-Independent Acute Hepatitis Induced by Concanavalin a in SCID/NOD Mice

Concanavalin A (Con A) is known to induce acute hepatitis that is mediated by activation of NKT- and T-cell and cytokine production in immunocompetent mice. The observation of Con A-induced autophagic cell death of hepatoma cells via a Bcl-2/adenovirus E1B 19 kDa-interacting protein 3 mediated autophagic pathway made us re-evaluate the effect of Con A-induced hepatitis in mice. Con A was administrated intravenously to BABL/c, SCID, or SCID/NOD mice at doses of 20, 30 or 40 mg/kg, respectively, to induce acute hepatitis. The levels of hepatitis and autophagy induction were both analyzed. We found that Con A can induce acute hepatitis in SCID or SCID/NOD mice with a kinetics similar to that of BALB/c, but requiring a higher dose of Con A. No lymphocyte infiltrations were found in SCID or SCID/NOD mice, and the cytokine productions were different. An autophagy with microtubule-associated protein light chain 3-II conversion was demonstrated in the liver post-Con A injection in SCID/NOD mice. Due to the mannose/glucose-specific binding on cell membrane, Con A can induce a T-cell-independent acute hepatitis with autophagy in SCID/NOD mice.

Grain legume proteins and nutraceutical properties

Grain legumes are a valuable source of food proteins. Their exploitation is expected to grow in relation of a growing world's food needs. Moreover, it is currently taking place a reappraisal of the beneficial effects of legume seed dietary intake, which are the basis for various health claims. Proteins and peptides concur to the observed biological activities of legume seeds, but their effect(s) has(ve) not completely been disclosed. Aims of this review are: to report the most relevant putative positive effects of grain legumes on human health and to give an account of the current knowledge on the demonstrated legume seed protein biological activities. Specific effects on the prevention and treatment of various diseases, mostly of which are typical of the affluent countries, are reported. Examples of studies at molecular level aimed at elucidating of the underlying mechanism(s) are given. The prospects on targeted legume protein exploitation in the nutraceutical area, including the biotechnological approaches, are also considered.

Lectins as Bioactive Plant Proteins: A Potential in Cancer Treatment

Plant lectins, a unique group of proteins and glycoproteins with potent biological activity, occur in foods like wheat, corn, tomato, peanut, kidney bean, banana, pea, lentil, soybean, mushroom, rice, and potato. Thus, dietary intakes by humans can be significant. Many lectins resist digestion, survive gut passage, and bind to gastrointestinal cells and/or enter the circulation intact, maintaining full biological activity. Several lectins have been found to possess anticancer properties in vitro, in vivo, and in human case studies; they are used as therapeutic agents, preferentially binding to cancer cell membranes or their receptors, causing cytotoxicity, apoptosis, and inhibition of tumor growth. These compounds can become internalized into cells, causing cancer cell agglutination and/or aggregation. Ingestion of lectins also sequesters the available body pool of polyamines, thereby thwarting cancer cell growth. They also affect the immune system by altering the production of various interleukins, or by activating certain protein kinases. Lectins can bind to ribosomes and inhibit protein synthesis. They also modify the cell cycle by inducing non-apoptotic G1-phase accumulation mechanisms, G2/M phase cell cycle arrest and apoptosis, and can activate the caspase cascade. Lectins can also downregulate telomerase activity and inhibit angiogenesis. Although lectins seem to have great potential as anticancer agents, further research is still needed and should include a genomic and proteomic approach.

A mistletoe lectin (ML-1)-containing diet reduces the viability of a murine non-Hodgkin lymphoma tumor

In this study we show that the characteristics of non-Hodgkin lymphoma (NHL) tumors in female Naval Medical Research Institute (NMRI, USA) mice fed mistletoe lectin (ML)-containing diets were different from those in mice fed control diet. The non-Hodgkin lymphoma tumor was originally established from a spontaneous tumor which developed in the inguinal region of a male mouse. Mice (five animals per group) were fed a lactalbumin (LA)-based control diet or a diet which provided up to 10 mg lectin per day. At the highest daily intake (10 mg lectin) the degree of mitotic activity in tumors was reduced by 75% and the nuclear area had diminished by 21%. The overall level of lymphocyte infiltration (CD3 positive cells) in tumors from mistletoe lectin fed mice was increased by a factor of two. Other morphological studies showed a high incidence of apoptotic bodies in non-Hodgkin lymphoma tumors obtained from mice fed mistletoe lectin diets. The feeding of such diets thus produced several identifiable changes in the morphology of non-Hodgkin lymphoma tumors. These were consistent with the observed reduction in tumor mass. In 4/15 mice fed a mistletoe lectin diet for 11 days there was no longer evidence of viable tumor. The results show that this lectin exerts powerful anti-tumor effects when provided by the oral route.

Effect of cultivar and growing location on the trypsin inhibitors, tannins, and lectins of common beans (Phaseolus vulgaris L.) grown in the semiarid highlands of Mexico

Trypsin inhibitors (TI), tannins, and lectins appear to have a role in preventing chronic diseases in humans. The genetic variability of these traits in common bean needs to be ascertained in order to increase levels through breeding. The variability of TI, tannin, and lectins was determined in five bean cultivars grown at five locations in Mexico. TI and tannins contents in colored beans that belong to the Jalisco race were higher (11.1-11.9 trypsin units inhibited (TUI)/mg and 29.0-38.1 mg catechin equivalent (CE)/g, respectively) than cultivars of the Durango race (7.9-8.3 TUI/mg and 16.8-19.9 CE/mg, respectively). Bayo Victoria, a Durango race cultivar, had three times more lectins than levels reported for soybean. Cultivar influenced TI and tannins contents (p < 0.001), whereas site affected lectins (p < 0.001). An increase in levels of TI and tannins could be enhanced through breeding.

Customized mitogen or antibody treatments enhance the sensitivity of lymphoid tumors to 5-fluorouracil in vitro and in vivo

Despite impressive cure rates for certain leukemias and lymphomas, lymphoid tumors are responsible for thousands of deaths per year. Refractory disease remains difficult to control, encouraging the development of new treatment options. 5-fluorouracil (5-FU) has been successfully used to control (or cure) a variety of tumors, but has been only rarely applied to tumors of the lymphoid lineage. Here we demonstrate that the effects of 5-FU on lymphoid tumors can be enhanced by the concomitant binding of cellular membrane molecules with mitogen or antibody. When used in combination with 5-FU, mitogen treatments: (i) enhance the association of drug with cells, (ii) reduce cell proliferation in vitro and (iii) inhibit cell growth in a mouse B-cell tumor model.

Local (gut) and systemic metabolism of rats is altered by consumption of raw bean (Phaseolus vulgaris L var athropurpurea)

The composition of the raw legume Phaseolus vulgaris L. var. athropurpurea (PhVa) and its effects on the metabolism of young growing rats have been evaluated. The levels of protein, unsaturated fatty acids, carbohydrate, fibre and bioactive factors present in PhVa were comparable with those in other Phaseolus vulgaris varieties. However, the lectins of PhVa were predominantly of the leucoagglutinating type, and concentrated in the albumin protein fraction. Rats fed a diet (110 g total protein, 16.0 MJ/kg) in which PhVa meal provided about half of the protein excreted high levels of N in faeces and urine, and grew more slowly, than rats fed a high-quality control diet (ad libitum or pair-fed). Small intestine, large intestine and pancreas weights were increased (by almost 100 %, P<0.05), whilst skeletal muscle, thymus and spleen weights were reduced. Blood insulin (16.20 v. 0.50 mU/l, P<0.05, thyroxine, glucose, protein (60.5 v. 48.3 g/l, P<0.05) and LDL-cholesterol were lowered, whilst glucagon (155.3 v. 185.4 ng/l, P<0.05), triiodothyronine and urea were elevated, as were urinary urea, creatinine and glucose. These changes in the local (gut) and systemic metabolism of rats were probably mediated primarily by lectins in PhVa, which were concentrated in the albumin protein fraction, whereas in many other Phaseolus vulgaris lines they are distributed across the globulin and albumin fractions.

Non-nutrient bioactive substances of pulses

Pulses supply many bioactive substances found in minor amounts in food, but which may have significant metabolic and/or physiological effects. These compounds have long been classified as antinutritional factors, but many studies have reconsidered their impact on health. Some could play a role in the prevention of the major diseases of affluent societies. As these compounds can be beneficial or adverse, depending on conditions, an assessment of their various physiological effects is necessary to determine whether they should be preserved or eliminated in each main nutritional situation.

Anti-cancer therapy: diversion of polyamines in the gut

The growth of a murine non-Hodgkin lymphoma (NHL) tumour, either as an intraperitoneal ascites tumour or as a solid subcutaneous tumour, has been shown to be greatly reduced by including phytohaemagglutinin (PHA), a lectin present in raw kidney bean (Phaseolus vulgaris) in the diet. The reduced rate of growth occurred in a dose-dependent manner. Based on the experimental observations it has been suggested that a competition occurs between the gut tissue undergoing hyperplasia and the developing tumour for nutrients (including polyamines) from a common body pool. This may be an important factor with regard to the observed initial low level of tumour growth following the feeding of a PHA-containing diet. Results showing that the level of hyperplasia of the small intestine in response to feeding the PHA diets was higher in non-injected mice compared to those which had been injected with tumour cells substantiated the concept of competition between gut and tumour for nutrients etc. required for growth. The observations suggest that lectins, which exhibit growth-promoting effects on the gut, may have interesting applications in the formulation of new approaches with respect to cancer treatment.