Effect of intraperitoneally administered plant lectins on leukocyte diapedesis and visceral organ weight in rats and mice

The effects of intraperitoneally administered plant lectins were examined in rats and mice. Intraperitoneally injected ConA transiently decreased the leukocyte count in the peritoneal cavity, due to the agglutination and attachment of cells to the peritoneal lining. Subsequently the total cell count was increased for hours, exceeding initial values. Peritoneal fluid aspartate transaminase (AST) concentration showed little change during the accumulation of ascitic fluid. The most marked histological alterations were found when wheat germ lectin was injected ip. (WGA, 10 mg/kg, 6 h). Neutrophil granulocytes migrated across the wall of both arterioles and venules, but the response was highly variable among adjacent vessels. The wall of the arterioles may have impeded the migration of neutrophil granulocytes, resulting in their accumulation in the muscular layer. Granulocyte accumulation was also observed in patches under the mesothelium and in other sites of the interstitium. Marked dilatation and thrombosis of a few venules were also observed. Kidney bean lectin (PHA) induced similar but less pronounced changes. The neutrophil diapedesis suggests the release of mediator(s) from mesothelial cells and/or peritoneal white cells. The cytokine-induced neutrophil chemoattractant CINC-1, injected as control, resulted in the diapedesis of predominantly mononuclear cells in the omentum within 40 minutes. In rats ip. injected ConA increased the wet weight of spleen and liver within 6 and 10 h, respectively, but kidney weight did not change. Intravascular clumping of red blood cells, thrombosis and organ weight changes also suggest the absorption of ConA into the circulation. The experiments show that plant lectins, used as models of bacterial lectins, can reproduce some aspects of peritonitis.     

Binding of lectins to human mammary tumors: Ultrastructural study

Summary The site of several lectin receptors in human mammary tumors and stroma was studied with the electron microscope. The advantage of the ultrastructural over light microscopic study was that lectin receptors could be localized with precision on the different cell types of the tumor and stroma. Eighteen human mammary carcinomas were incubated with three peroxidase-labeled lectins: peanut agglutinin (PNA),Helix pomatia, andUlex europaeus I (UEA). These lectins reacted in a selective way; some tumors were negative and others showed reaction in some areas of the tumor and/or the stroma. No correlation was found, however, between the presence of these lectin receptors on the tumor cells and either hormone receptors or histological type of the tumors. These results show that the value of the presence of lectin receptors in human mammary tumors as markers for evaluation of mammary lesions is more complex than thought up to now. The most relevant observations on the stroma cells and inflammatory infiltrates were: (A) Some lymphocytes were positive with PNA, probably representing sessile T cells. In two carcinomas, abundant plasma cells were present in the infiltrates, always with PNA receptors. (B) In all mammary tumors where blood vessels were present in the sections, these were always stained with UEA. This supports the use of UEA as a marker for human endothelial cells even in pathologically altered tissues.     

Plant lectins: Potential antineoplastic drugs from bench to clinic

Plant lectins, carbohydrate-binding proteins distributed widely in a variety of plant species, have drawn a rising attention for cancer biologists due to their remarkable anti-tumour properties. In this review, we present a brief outline of the up-to-date advances of plant lectins in elucidating their complex anti-cancer mechanisms implicated in apoptosis and autophagy. In addition, we further discuss the pre-clinical and clinical studies of plant lectins for their potential therapeutic applications. In conclusion, these inspiring findings would open a new perspective for plant lectins as potential antineoplastic drugs from bench to clinic.     

The application of lectins to the characterization and isolation of mammalian cell populations

Mammalian cells invariably contain a vast array of glycosylated moieties, both inside the cell and on the cell surface. There is an increasing awareness of the utility of these carbohydrates in delineating the phenotype or function of many populations of cells. To this end lectins are extremely useful reagents. Lectins are carbohydrate-binding proteins and glycoproteins of non-immune origin derived from numerous plants and animals. A wide variety of lectins with many distinct carbohydrate specificities have been isolated. Historically the most common laboratory techniques utilizing lectins have been agglutination, mitogen stimulation, and fluorescence techniques. Recent advances in the development and conjugation procedures for labels and matrices have led to the creation of numerous novel lectin-based assays. Lectins are currently used not only to identify cells with specified carbohydrate groups, but also to quantitate the carbohydrate groups or to isolate the carbohydrate-bearing cells or structures     

Cancer of the gastrointestinal tract and exposure to asbestos in drinking water among lighthouse keepers (Norway)

Objective Previous studies of predominantly ecological design have indicated a possible elevation of gastrointestinal cancer risk in population groups exposed to drinking water contaminated with asbestos from natural sources or asbestos–cement containing water pipes. In the present study the possible effect of ingested asbestos fibers on gastrointestinal cancer risk was investigated in an occupational group where a proportion of the employees was exposed to asbestos in their drinking water.Method A cohort of 726 lighthouse keepers first employed between 1917 and 1967 were followed up for cancer incidence from 1960 to 2002. The standardized incidence ratio (SIR) was calculated as the number of new cancer cases divided by the expected number based on five-year age and sex specific incidence rates in the general rural population of Norway. A 95% confidence interval (CI) was calculated for all SIR values assuming a Poisson distribution of the cancer cases.Results Risk of stomach cancer was elevated in the whole cohort (SIR: 1.6, CI: 1.0–2.3), in the subgroup with definite asbestos exposure (SIR: 2.5, CI: 0.9–5.5), and when the group was followed for 20 years and more after first possible exposure (SIR: 1.7, CI: 1.1–2.7). Less consistent results were found for colon cancer; SIR was 1.5 (CI: 0.9–2.2) overall, 0.8 (CI: 0.1–2.9) among the exposed, and 1.6 (CI: 1.0–2.5) twenty years and more after first possible exposure.Conclusion The results support the hypothesis of an association between ingested asbestos and gastrointestinal cancer risk in general and stomach cancer risk specifically.     

Binding of peanut lectin to breast epithelium, human carcinomas, and a cultured rat mammary stem cell: use of the lectin as a marker of mammary differentiation.

We investigated the binding of fluorescence-labeled peanut agglutinin (PNA) to breast epithelium. Specific binding of PNA to the mammary glands of female Sprague-Dawley rats increased as the gland matured. Sexually immature rats showed relatively little fluorescence, but this increased in mature and pregnant animals. A maximum was reached in lactating rats in which significant labeling of material within the lumen was observed. PNA was bound exclusively to the epithelial and not the myoepithelial or mesenchymal cells. In tissue culture, a rat mammary epithelial stem cell line, which can be stimulated to differentiate to alveolus-like secretory or myoepithelial cells, showed evidence of PNA binding only on the secretory cells and not on unstimulated or myoepithelial cells. Fibroblast cultures also failed to show significant binding of PNA. Receptor sites on the secretory cells were masked mainly by sialic acid. Human breast sections, like those of the rat, showed fluorescent labeling at the apical region of the epithelial cells; this labeling increased if the tissue had prior treatment with neuraminidase. Breast carcinomas that were morphologically differentiated showed more labeling with PNA than did undifferentiated tumors, which often had weak or sometimes negative labeling. When significant fluorescence was observed, it was localized mainly in the cytoplasm. By contrast, labeling was restricted to the cell periphery in differentiated carcinomas. The use of PNA as a marker for breast epithelial cell differentiation is therefore proposed.     

Binding of [14C]azaserine to DNA and protein in the rat and hamster

The binding of [¹⁴C]azaserine or its metabolites to DNA and protein in the organs of rats and hamsters was determined at various times after treatment with [¹⁴C]azaserine. The specific activity of ¹⁴C labelling of DNA and protein was determined. Rat liver DNA and protein were most extensively labelled at 90 min post-injection, but by 24 h the specific activity decreased to the levels found in pancreas and kidney. Thymus contained negligible amounts of radioactivity at all time-points. DNA and protein from hamster pancreas contained more label than did DNA and protein from rat pancreas. The results suggest that factors other than DNA binding play a role in determining the species and organ specificity of azaserine.     

Response of the 9L rat brain tumor to combination treatment with radiation and bleomycin

The therapeutic efficacy of combined modality treatment with radiation therapy and bleomycin was investigated in rats burdened with the intracerebral 9L gliosarcoma. Both radiation (single or fractionated exposures) and bleomycin (injected intracerebrally directly into the tumor region) are effective in prolonging survival when used as single agents. Bleomcyin (1.0 mg/kg/week) combined with low-dose radiation therapy (15.3 Gy in 6 fractions in 2 weeks) prolonged survival over that of radiation alone, but not to the extent of high-dose radiation therapy (30.6 Gy in the same schedule). Bleomycin was effective whether given simultaneously or following fractionated radiation therapy-the important factor being delivery of radiation therapy early in the disease process. The greatest enhancement in survival caused by combination therapy compared to that by single agent therapy was observed when single exposure radiation therapy (20 Gy) followed single bleomycin administration by 4 hr. These results suggest the possibility of using bleomycin as an adjunct to radiation therapy for the treatment of patients with malignant brain tumors.     

Studies on estrogen induced pituitary tumor in the rat with special reference to the relationship of the tuberoinfundibular dopamine neuron system

Pituitary tumors were experimentally induced in female Wistar rats by repeated injections of estradiol dipropionate. The hypothalamus and pituitary tumors were studied simultaneously by fluorescence histochemistry and immunohistochemistry. The pituitary gland became larger with a concomitant increase of serum prolactin in proportion to the dose of estrogen. Estrogen-induced pituitary tumor exhibited a proliferating prolactin cells by the peroxidase immunohistochemical method. Ultramicroscopical findings showed that these tumor cells were in an extremely hyperfunctional state. The dopamine neuronal perikarya in the hypothalamic arcuate nucleus and their terminals in the external layer of the median eminence were examined by fluorescence histochemistry in the rats bearing estrogen induced pituitary tumor and it was concluded that in our experimental conditions, estrogen effected directly on pituitary rather than on the hypothalamus and consequently dopamine synthesis in the arcuate neurons and its release into portal capillaries were accerelated simultaneously in order to inhibit prolactin secretion from tumor cells.     

L-DOPA preloading increases the uptake of borophenylalanine in C6 glioma rat model: a new strategy to improve BNCT efficacy

PURPOSE: Boron neutron capture therapy (BNCT) is a radiotherapeutic modality based on (10)B(n,alpha)(7)Li reaction, for the treatment of malignant gliomas. One of the main limitations for BNCT effectiveness is the insufficient intake of (10)B nuclei in the tumor cells. This work was aimed at investigating the use of L-DOPA as a putative enhancer for (10)B-drug 4-dihydroxy-borylphenylalanine (BPA) uptake in the C6-glioma model. The investigation was first performed in vitro and then extended to the animal model. METHODS AND MATERIALS: BPA accumulation in C6-glioma cells was assessed using radiowave dielectric spectroscopy, with and without L-DOPA preloading. Two L-DOPA incubation times (2 and 4 hours) were investigated, and the corresponding effects on BPA accumulation were quantified. C6-glioma cells were also implanted in the brain of 32 rats, and tumor growth was monitored by magnetic resonance imaging. Rats were assigned to two experimental branches: (1) BPA administration; (2) BPA administration after pretreatment with L-DOPA. All animals were sacrificed, and assessments of BPA concentrations in tumor tissue, normal brain, and blood samples were performed using high-performance liquid chromatography. RESULTS: L-DOPA preloading induced a massive increase of BPA concentration in C6-glioma cells only after a 4-hour incubation. In the animal model, L-DOPA pretreatment produced a significantly higher accumulation of BPA in tumor tissue but not in normal brain and blood samples. CONCLUSIONS: This study suggests the potential use of L-DOPA as enhancer for BPA accumulation in malignant gliomas eligible for BNCT. L-DOPA preloading effect is discussed in terms of membrane transport mechanisms.     

An antigen related to the phenotype of multi-drug resistance can be induced in vivo and used as a target for immunotherapy of rat leukemia

Several laboratories have reported that new plasma membrane peptides appear in rodent and human cells after induction of in-vitro resistance to vinca alkaloids, anthracyclines and other anti-neoplastic drugs. Recently, murine monoclonal antibodies have been produced that recognize surface components of such drug-resistant cells. The work presented here describes the development of an in-vivo animal model of this phenomenon using a rat myeloid leukemia. Brown Norway rats were made leukemic with promyelocytes of the BNML line and subsequently were treated with 7.7 mg kg-1 of daunorubicin. After eight cycles of passage-treatment-regrowth, the resulting cells reacted with this antibody in immunofluorescence and cytotoxicity assays. Animals injected with cells that had been pre-incubated with antibody in the absence of complement survived significantly longer than did the controls. Further prolongation of survival occurred when the cells were treated with a second antibody of a different specificity. These results demonstrate that some of the changes associated with in-vitro drug resistance occur also in vivo and potentially may be exploited as a focus for immunotherapy.     

Characterization of a rat model with site-specific bone metastasis induced by MDA-MB-231 breast cancer cells and its application to the effects of an antibody against bone sialoprotein

Metastasis into the skeleton is a serious complication of certain neoplastic diseases such as breast, prostate and lung cancer, but the reasons for this osteotropism are poorly understood. Our aim was to establish a physiologically relevant animal model that is characterized by osteolytic lesions confined to the hind leg of nude rats. For this purpose, we injected 1x10(5) MDA-MB-231 human breast cancer cells transfected with GFP into the superficial epigastric artery, which is an anastomosing vessel between the femoral and iliac arteries. As assessed with the aid of X-rays, computed tomography and immunohistochemisty, osteolytic lesions occurred exclusively in the femur, tibia and fibula of the animals. The tumor take rate was 93% in a series of 96 rats and the increase in lesion size was observed up to 110 days after tumor cell inoculation. When applying this animal model to the effects of an antibody against bone sialoprotein (BSP), a significantly reduced osteolytic lesion size was observed after preincubation of cells (2 hr, 600 microg/ml anti-BSP) prior to intra-arterial tumor cell injection resulting in 19 T/C% at day 60 after tumor implantation (p < 0.05). In addition, the osteolytic lesion size was also significantly reduced after s.c. treatment of the animals with the antibody (20 mg/kg anti-BSPx3 within 5 days after tumor implantation), resulting in 30 T/C% at day 60 after tumor cell implantation (p < 0.05). In conclusion, the novel rat model for site-specific osteolytic lesions provides in vivo evidence that preincubation of MDA-MB-231GFP cells and treatment of rats after tumor implantation with an antibody against BSP significantly reduces the size of lytic lesions in bone.