Cell surface glycolipids and glycoproteins in malignant transformation

Biochemical and molecular aspects of 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis: a review

1,2-dimethylhydrazine (DMH) is a member in the class of hydrazines, strong DNA alkylating agent, naturally present in cycads. DMH is widely used as a carcinogen to induce colon cancer in animal models. Exploration of DMH-induced colon carcinogenesis in rodent models provides the knowledge to perceive the biochemical, molecular, and histological mechanisms of different stages of colon carcinogenesis. The procarcinogen DMH, after a series of metabolic reactions, finally reaches the colon, there produces the ultimate carcinogen and reactive oxygen species (ROS), which further alkylate the DNA and initiate the development of colon carcinogenesis. The preneolpastic lesions and histopathological observations of DMH-induced colon tumors may provide typical understanding about the disease in rodents and humans. In addition, this review discusses about the action of biotransformation and antioxidant enzymes involved in DMH intoxication. This understanding is essential to accurately identify and interpret alterations that occur in the colonic mucosa when evaluating natural or pharmacological compounds in DMH-induced animal colon carcinogenesis.

Elevated Serum Sialic Acid Levels Predict Prostate Cancer As Well As Bone Metastases

Objective: To evaluate the value of serum sialic acid (SA) in diagnosis of benign prostatic hyperplasia (BPH), prostate cancer (PCa), and bone metastases in PCa patients. Materials and Methods: Data from 540 patients who were newly diagnosed with PCa or BPH between November 2014 and March 2018 were retrospectively collected and analyzed. Pretreatment SA levels were compared across various groups, then, associations between SA levels and clinic parameters of patients were analyzed as well. Univariate and multivariate logistic regression analyses were further used to identify independent associations. Results: The mean SA levels in patients with PCa were significantly higher than with BPH (p = 0.013). Furthermore, PCa patients with bone metastases showed elevated SA levels compared with PCa without bone metastases (p < 0.001). A multivariate logistic regression model showed that: SA level > 52.35 mg/dL was identified to be independently associated with the diagnosis of PCa (HR = 1.645, p = 0.036), and SA level > 59 mg/dL was identified to be independent association with the presence of bone metastases in PCa patients (HR = 6.421, p = 0.012). Conclusions: Elevated SA level is an independent predictor of prostate cancer as well as its bone metastases. Therefore, SA level may be a promising diagnostic and prognostic biomarker for prostate cancer and bone metastases.

Usefulness and Potential Pitfalls of Sialic Acid Determination in Sera of Patients with Ovarian Tumors

Increasing evidence in the literature indicates that serum sialic acid is increased in cancer patients suggesting a possible usefulness of its determination as a tumor marker. However there are many discrepancies in the data reported, probably due to methodological errors, mainly in lipid bound sialic measurement.

In this paper we illustrate the results obtained when we applied a method worked out in our laboratory for the determination of total and fractionated sialic acid (lipid and protein bound) to the analysis of sera from patients with ovarian tumors and the preliminary data on the follow up of selected cases. The potential pitfalls in using this relatively new tumor marker will be critically evaluated.

Total Sialic Acid as a Tumor Marker for Oral Cancer

Serum sialic acid levels were measured in 80 healthy subjects, in 60 patiens with benign tumors and in 110 patients with oral cancer. It was shown that these levels were significantly elevated in oral cancer patients compared to healthy controls and patients with benign tumors (p < 0.01); they were higher in patients with stage III and stage IV disease than in those with stage I and II disease (p < 0.01). However, no difference was observed between healthy controls and stage I and II cancer patients. The results of this study suggest that the determination of sialic acid levels may be of value in the diagnosis of oral cancer, but its usefulness as an adjunct in clinical staging is limited.

Tumor Markers in Leukemia: Evaluation of Serum Levels of Different Forms of Sialic Acid, Regan Isoenzyme and Lactate Dehydrogenase

A sensitive and specific serum marker can greatly help in the early diagnosis of malignancy as well as in monitoring the treatment of cancer patients. The present work was initiated for determining serum levels of Total Sialic Acid (TSA), Lipid Bound Sialic Acid (LSA), Free Sialic Acid (FSA), Regan Isoenzyme (RI) and Lactate Dehydrogenase (LDH), so as to evaluate their value as potential tumor markers. Fifty patients with anemia and 78 patients with leukemia were studied. The leukemia group consisted of 32 cases of Acute Myeloid Leukemia (AML), 29 cases of Chronic Myeloid Leukemia (CML) and 17 cases of Acute Lymphatic Leukemia (ALL). The levels were compared with the values obtained from 88 healthy individuals. Compared to the healthy controls, all the biomarkers were significantly elevated in patients with anemia as well as in those with leukemia. However, in leukemia patients significantly higher levels of TSA, LSA, FSA and LDH were observed compared to anemia patients. TSA levels were significantly higher in AML patients compared to CML and ALL patients. LSA levels were also significantly higher in AML patients compared to ALL patients. LSA was the most sensitive (84.6%) while FSA and RI levels were the most specific (78.0%) markers for leukemia. The combined use of the markers showed increased sensitivity and specificity (100.0% and 98.0%, respectively). The study suggested that the biomarkers investigated might be used for differentiating anemic from leukemic conditions, however, more in-depth studies are indicated to assess their utility in classifying various leukemias.

A New Procedure for Gangliosidic N-Acetylneuraminic Acid Analysis in Serum

In this paper a method is presented which is suitable for the extraction, purification and analysis of serum gangliosides. The advantage in comparison with other previously published procedures is the complete extraction of sialoglycolipids without contamination of sialoglycoproteins and/or sialoglycopeptides. The method could be used as a second-level test for the diagnosis and follow-up of cancer patients, and also could be potentially used for pharmaco-kinetic studies after ganglioside treatment.

Glycosylation Changes in Brain Cancer

Protein glycosylation is a posttranslational modification that affects more than half of all known proteins. Glycans covalently bound to biomolecules modulate their functions by both direct interactions, such as the recognition of glycan structures by binding partners, and indirect mechanisms that contribute to the control of protein conformation, stability, and turnover. The focus of this Review is the discussion of aberrant glycosylation related to brain cancer. Altered sialylation and fucosylation of N- and O-glycans play a role in the development and progression of brain cancer. Additionally, aberrant O-glycan expression has been implicated in brain cancer. This Review also addresses the clinical potential and applications of aberrant glycosylation for the detection and treatment of brain cancer. The viable roles glycans may play in the development of brain cancer therapeutics are addressed as well as cancer-glycoproteomics and personalized medicine. Glycoprotein alterations are considered as a hallmark of cancer while high expression in body fluids represents an opportunity for cancer assessment.

Glycosylation alterations in lung and brain cancer

Alterations in glycosylation are common in cancer and are thought to contribute to disease. Lung cancer and primary malignant brain cancer, most commonly glioblastoma, are genetically heterogeneous diseases with extremely poor prognoses. In this review, we summarize the data demonstrating that glycosylation is altered in lung and brain cancer. We then use specific examples to highlight the diverse roles of glycosylation in these two deadly diseases and illustrate shared mechanisms of oncogenesis. In addition to alterations in glycoconjugate biosynthesis, we also discuss mechanisms of postsynthetic glycan modification in cancer. We suggest that alterations in glycosylation in lung and brain cancer provide novel tumor biomarkers and therapeutic targets.

Production and characterization of monoclonal antibodies specific to lactotriaosylceramide

We have established hybridoma cell lines producing monoclonal antibodies (mAbs) directed to N-acetylglucosaminylβ1-3galactose (GlcNAcβ1-3Gal) residue by immunizing BALB/c mice with lactotriaosylceramide (Lc(3)Cer). These obtained hybridoma cells, specific to Lc(3)Cer, were dual immunoglobulin (Ig)-producing cells which secreted both IgM and IgG molecules as antibodies. The established mAbs are able to react with not only Lc(3)Cer but also GlcNAcβ1-3-terminal glycosphingolipids (GSLs) despite branching or lactosamine chain lengths and human transferrin with terminal GlcNAc residues. Comparison of the variable regions of the cloned IgM and IgG by reversed transcription-polymerase chain reaction analysis confirmed that the variable regions determine the specificity, the other amino acids are conserved, and these mAbs are encoded by J558 and Vκ-21family genes. Furthermore, we have analyzed the expression of GSLs with GlcNAcβ1-3 epitope in acute leukemia cell lines and mouse fetal tissues using these mAbs, in which antigens were distributed comparatively. These mAbs are useful for studying the precise distribution of GlcNAcβ1-3Gal-terminating GSL expression in tissues as well as for detecting GSLs carrying terminal GlcNAcβ1-3Gal carbohydrate structure.

Sialyltransferases of marine bacteria efficiently utilize glycosphingolipid substrates

Bacterial sialyltransferases (STs) from marine sources were characterized using glycosphingolipids (GSLs). Bacterial STs were found to be beta-galacotoside STs. There were two types of STs: (1) ST obtained from strains such as ishi-224, 05JTC1 (#1), ishi-467, 05JTD2 (#2), and faj-16, 05JTE1 (#3), which form alpha2-3 sialic acid (Sia) linkages, named alpha2-3ST, (2) ST obtained from strains such as ISH-224, N1C0 (#4), pda-rec, 05JTB2 (#5), and pda-0160, 05JTA2 (#6), which form alpha2-6 Sia linkages, named alpha2-6ST. All STs showed affinity to neolacto- and lacto-series GSLs, particularly in neolactotetraosyl ceramide (nLc(4)Cer). No large differences were observed in the pH and temperature profiles of enzyme activities. Kinetic parameters obtained by Lineweaver-Burk plot analysis showed that #3 and #4 STs had practical synthetic activity and thus it became easily possible to achieve large-scale ganglioside synthesis (100-300 muM) using these recombinant enzymes. Gangliosides synthesized from nLc(4)Cer by alpha2-3 and alpha2-6STs were structurally characterized by several analytical and immunological methods, and they were identified as IV(3)alphaNeuAc-nLc(4)Cer(S2-3PG) and IV(6)alphaNeuAc-nLc(4)Cer (S2-6PG), respectively. Further characterization of these STs using lactotetraosylceramide (Lc(4)Cer), neolactohexaosylceramide (i antigen), and IV(6)kladoLc(8)Cer (I antigen) showed the synthesis of corresponding gangliosides as well. Synthesized gangliosides showed binding activity to the influenza A virus [A/panama/2007/99 (H3N2)] at a similar level to purified S2-3PG and S2-6PG from mammalian sources. The above evidence suggests that these STs have unique features, including substrate specificities restricted to lacto- and neolactoseries GSLs, as well as catalytic potentials for ganglioside synthesis. This demonstrates that efficient in vitro ganglioside synthesis could be a valuable tool for selectively synthesizing Sias modifications, thereby permitting the exploration of unknown functions.

Erythrocyte and platelet phospholipid fatty acids as markers of advanced non-small cell lung cancer: comparison with serum levels of sialic acid, TPS and Cyfra 21-1

The phospholipid fatty acid profiles of erythrocytes and platelets from fifty patients with advanced non-small cell lung cancer were investigated using gas chromatography/mass spectrometry, followed by "ROC" curves analysis to gain novel biomarker information. Sialic acid and cytokeratins were also examined. Potentially useful fatty acid markers: Erythrocytes: phosphatidylcholine, 18:2n6 and 20:4n6; phosphatidylethanolamine, 22:4n6 and 22:6n3 + 24:1n9. Platelets: phosphatidylcholine, 22.0; phosphatidylethanolamine, 22:5n3 + 24:0. At the cut-off value to obtain maximum accuracy, the best biomarkers were found in platelets: phosphatidylserine + phosphatidylinositol (PS + PI), 21:0; sphyngomyelin: 20:1n9 and 22:1n9. All these fatty acids showed similar/higher diagnostic yields than the commonly used markers sialic acid or cytokeratins.

Adherence, anti-adherence, and oligosaccharides preventing pathogens from sticking to the host

For many pathogenic bacteria, infections are initiated only after the organism has first adhered to the host cell surface. If adherence can be inhibited, then the subsequent infection can also be inhibited. This approach forms the basis of anti-adherence strategies, which have been devised to prevent a variety of bacterial infections. In this chapter, the molecular basis by which respiratory, urinary, and gastrointestinal tract pathogens adhere to host cells will be described. The five general types of anti-adherence agents will also be reviewed. The most well-studied are the receptor analogs, which include oligosaccharides produced synthetically or derived from natural sources, including milk, berries, and other plants. Their ability to inhibit pathogen adherence may lead to development of novel, food-grade anti-infective agents that are inexpensive and safe.

Potential sialyltransferase inhibitors based on neuraminyl substitution by hetaryl rings

Replacement of the neuraminyl residue by a wide range of aryl rings in transition-state analogs of CMP-Neu5Ac led to readily accessible and potent inhibitors of alpha-(2-->6)- and alpha-(2-->3)-sialyltransferases. The synthesis of a series of potential sialyltransferase inhibitors in which the neuraminyl residue is replaced by hetaryl methylphosphonate residues (thiazole, benzothiazole, benzoxazole, benzothiophene and thiophene) is described in this paper.

Tumor galectinology: insights into the complex network of a family of endogenous lectins

Beta-Galactosides of cell surface glycoconjugates are docking sites for endogenous lectins of the galectin family. In cancer cells, primarily galectins-1 and -3 have been studied to date. With the emergence of insights into their role in growth control, resistance to or induction of apoptosis and invasive behavior the notion is supported that they can be considered as functional tumor markers. In principle, the same might hold true for the other members of the galectin family. But their expression in tumors has hitherto been a subject of attention only to a very limited extent. Pursuing our concept to define the complexity of the galectin network in cancer cells and the degree of functional overlap/divergence with diagnostic/therapeutic implications, we have introduced comprehensive RT-PCR monitoring to map their galectin gene expression. The data on so far less appreciated galectins in this context such as galectins-4 and -8 vindicate this approach. They, too, attach value to extend the immunohistochemical panel accordingly. Our initial histopathological and cell biological studies, for example on colon cancer progression, prove the merit of this procedure. Aside from the detection of gene expression profiles by RT-PCR, the detailed molecular biological monitoring yielded further important information. We describe different levels of regulation of galectin production in colon cancer cells in the cases of the tandem-repeat-type galectins-8 and -9. Isoforms for them are present with insertions into the peptide linker sequence attributed to alternative splicing. Furthermore, variants with distinct amino acid substitutions (galectin-8, Po66-CBP, PCTA-1, CocaI/II and galectin-9/ecalectin) and generation of multiple mRNA species, notably those coding for truncated galectin-8 and -9 versions with only one lectin site, justify to portray these two family members not as distinct individuals but as groups. In aggregate, the ongoing work to thoroughly chart the galectin network and to disentangle the individual functional contributions is expected to make its mark on our understanding of the malignant phenotype in certain tumor types.

A monoclonal antibody to a carbohydrate epitope expressed on glycolipid and on alpha3beta1 integrin on human esophageal carcinoma

A mouse monoclonal antibody (MAb-9) produced by immunization with a human esophageal carcinoma cell line, TE-2 (derived from undifferentiated squamous cell carcinoma) reacted specifically with about 30% of esophageal carcinoma cell lines and tissue sections from clinical samples. MAb-9 showed minimal reactivity with normal esophageal tissue. (125)I, fluorescent or gold particle labeled MAb-9 bound to TE-2 cell surfaces. (125)I-radiolabeled MAb-9 was used to detect reactive material from cell extracts in Western blot. Treatment of TE-2 membrane proteins with neuraminidase, N-glycanase or O-glycanase reduced antigen detection. Treatment of cells with periodic acid destroyed antibody binding in ELISA. Lipid extracts from cell membranes, containing glycolipids, also reacted with MAb-9. MAb-9 was used to purify target antigen from detergent solubilized membrane proteins and the prominent bands from subsequent gel electrophoresis were trypsin digested and analyzed by mass spectrometry. Peptides from alpha(3) and beta(1) integrin chains were identified. These data indicate that alpha3beta1integrin is prominently expressed on certain esophageal carcinomas and that a specific carbohydrate unit is selectively displayed on the alpha(3) integrin subunit as well as on glycolipid on the cell surface. The alpha3beta1 integrin expressed on A-431 carcinoma cells does not display this carbohydrate epitope and is not detected by MAb-9. Thus, expression of the carbohydrate epitope is the basis for the tumor selective reaction of MAb-9 with a subset of esophageal carcinomas.

Ganglioside GM3 inhibits matrix metalloproteinase-9 activation and disrupts its association with integrin

Gangliosides GM3 and GT1b both inhibit epithelial cell adhesion and migration on fibronectin. GT1b binds to integrin alpha5beta1 and blocks the integrin-fibronectin interaction; GM3 does not interact with integrin, and its effect is poorly understood. We evaluated the effects of endogenous modulation of GM3 expression on epithelial cell motility on several matrices and the mechanism of these effects. Endogenous accumulation of GM3 decreased cell migration on fibronectin, types I, IV, and VII collagen matrices; depletion of GM3 dramatically increased cell migration, regardless of matrix. GM3 overexpression and depletion in vitro correlated inversely with the expression and activity of matrix metalloproteinase-9; consistently, the cell migration stimulated by GM3 depletion is reversed by inhibition of matrix metalloproteinase-9 activity. Accumulation and depletion of GM3 in epithelial cells grown on fibronectin also correlated inversely with epidermal growth factor receptor and mitogen activated protein kinase phosphorylation and with Jun expression. Ganglioside depletion facilitated the co-immunoprecipitation of matrix metal-loproteinase-9 and integrin alpha5beta1, while endogenous accumulation of GM3, but not GT1b, blocked the co-immunoprecipitation. These data suggest modulation of epidermal growth factor receptor signaling and dissociation of integrin/matrix metalloproteinase-9 as mechanisms for the GM3-induced effects on matrix metalloproteinase-9 function.

Prognostic values of galectin-3 and the macrophage migration inhibitory factor (MIF) in human colorectal cancers

This study aims to investigate whether the immunohistochemical levels of expression of galectin-3 and the macrophage migration inhibitory factor (MIF) are associated with prognostic values in human colorectal tumors. This was performed on 99 specimens including 69 colorectal tumors (17 Dukes A, 19 Dukes B, 15 Dukes C and 18 metastatic tumors that we labeled as D), 10 hepatic metastases from colorectal cancers and 20 normal specimens (biopsies). The immunohistochemical levels of expression of MIF and galectin-3 were quantified on routine histological slides by means of computer-assisted microscopy. Separate analyses were performed on epithelial and connective tissue. The levels of expression of both MIF and galectin-3 were very significantly higher in epithelial tumor tissue when compared with normal epithelial specimens. A positive and significant correlation between MIF and galectin-3 expression was evidenced in connective tumor tissue, and in particular in the cases associated with short survival periods (less than 5 years). In the case of the Dukes A or B tumors, we established two new prognostic groups (labeled I and II) on the basis of the levels of galectin-3 expression measured in the tumor epithelium. In the case of the Dukes C or D tumors, we established two other prognostic groups (labeled III and IV) on the basis of the levels of MIF expression measured in the connective tissue. Kaplan-Meyer analyses confirmed the additional prognostic values (as compared with conventional clinical staging) given by this new classification (groups I to IV). They show that the Dukes A or B tumors characterized by low levels of galectin-3 expression in the tumor epithelium are associated with significantly better prognoses than those characterized by high levels. In addition, the Dukes C or D tumors characterized by high levels of MIF expression in the connective tumor tissue are associated with significantly better prognoses than those characterized by low levels. In conclusions, MIF and galectin-3 expression levels in colorectal tumors are related to their levels of biological aggressiveness. These markers could be used to identify patients at risk, for whom more aggressive adjuvant therapy seems to be indicated.

Clinical use of tumor markers in childhood malignancies

Tumor markers are developmentally regulated proteins or carbohydrate molecules, which are expressed in specific tissues in the fetus during certain developmental periods. With malignant transformation, these molecules are reexpressed in neoplastic tissues. Some developmental or metabolic disorders can also lead to the expression of tumor marker genes, hereditary tyrosinaemia and ataxia teleangiectasia associating with elevated serum alpha-fetoprotein are examples of such conditions. In pediatric malignancies, the most common markers in clinical use are alpha-fetoprotein in liver and yolk sac tumors, chorionic gonadotropin in germ cell tumors, and catecholamines and neuron specific enolase in neuroblastoma. Several other molecules including carbohydrate antigens CA 19-9 and CA 125 may also have a role in the diagnosis and follow-up of distinct types of childhood malignancies. The non-specificity of several markers, such as tissue polypeptide antigen and sialic acid, greatly hampers their clinical use. In this review we will discuss the biology and current knowledge on the use of serum and urine tumor markers. We also highlight the putative future use of these molecules in cancer diagnosis and therapy, including the use of monoclonal antibodies directed against these antigens.

Developmental changes in the fine structure and histochemical properties of mucous cells in the parotid gland of the infant Japanese macaque

Mucous cells have been known to occur in the terminal portions of the parotid gland in a few species of mammals during a limited period of their development. The aim of this study was to examine the occurrence and features of mucous cells in the parotid gland of the infant Japanese macaque. Light microscopy revealed that mucous cells in the macaque parotid gland were present in the terminal clusters and acini at postnatal day 15, were less prevalent at day 30, and continued to decrease in number over 3 months. Mucous cells were no longer recognized in the parotid gland in 6-month-old macaques. Electron microscopy showed that the mucous cells contained electron-lucent secretory granules and bipartite or tripartite secretory granules. By 3 months of age, there was a scarcity of mucous cells and a concomitant increase in transitional cells. These transitional cells were intermediate in structure between mucous and serous cells, and contained three types of granules: electron-lucent, bipartite or tripartite, and electron-dense. None of the cells showed apoptotic figures. Lectin histochemistry indicated that the mucous cells in the early postnatal period had sugar residues identical in nature to those seen in the granules from mature serous cells in the glands of 3-month-old macaques. Immunohistochemistry using an antibody against human alpha-amylase showed a weakly positive reactivity in the secretory granules of the mucous cells, starting from day 15. In the transitional cells, the electron-dense granules showed a stronger immunoreactivity than either the electron-lucent granules or the heterogeneously structured granules. These results suggest that the secretory granules of mucous cells have characteristics in common with those of serous cells, and that during the transitional period the mucous granules change from the initial electron-lucent to hetorogenous forms, finally becoming the electron-dense granules. The mucous cells in the parotid gland of the juvenile Japanese macaque are therefore suggested to be converted into serous cells.

Ganglioside composition and histology of a spontaneous metastatic brain tumour in the VM mouse

Glycosphingolipid abnormalities have long been implicated in tumour malignancy and metastasis. Gangliosides are a family of sialic acid-containing glycosphingolipids that modulate cell-cell and cell-matrix interactions. Histology and ganglioside composition were examined in a natural brain tumour of the VM mouse strain. The tumour is distinguished from other metastatic tumour models because it arose spontaneously and metastasizes to several organs including brain and spinal cord after subcutaneous inoculation of tumour tissue in the flank. By electron microscopy, the tumour consisted of cells (15 to 20 microm in diameter) that had slightly indented nuclei and scant cytoplasm. The presence of smooth membranes with an absence of junctional complexes was a characteristic ultrastructural feature. No positive immunostaining was found for glial or neuronal markers. The total ganglioside sialic acid content of the subcutaneously grown tumour was low (12.6 +/- 0.9 microg per 100 mg dry wt, n = 6 separate tumours) and about 70% of this was in the form of N-glycolylneuraminic acid. In contrast, the ganglioside content of the cultured VM tumour cells was high (248.4 +/- 4.4 microg, n = 3) and consisted almost exclusively of N-acetylneuraminic acid. The ganglioside pattern of the tumour grown subcutaneously was complex, while GM3, GM2, GM1, and GD1a were the major gangliosides in the cultured tumour cells. This tumour will be a useful natural model for evaluating the role of gangliosides and other glycolipids in tumour cell invasion and metastasis.

An olefin metathesis route for the preparation of (1-->6)-linked C-disaccharide glycals. A convergent and flexible approach to C-saccharide synthesis

A convergent route to a variety of C-1-disaccharide glycals based on the olefin metathesis reaction of enol ethers and alkenes is described. The DCC-mediated coupling reaction of a variety of pentose enitols (1a-c) with a number of C-5- and C-6-monosaccharide carboxylic acids (2a-e) gave the corresponding esters 3a-l in good yield. Methylenation of these compounds was followed by ring-closing metathesis, mediated by the Schrock molybdenum catalyst 8 in warm toluene, to provide the target C-disaccharide glycals 5a-l. The formed enol ether double bond in 5a was then transformed, via standard manipulations, into a variety of C-disaccharide derivatives 21-25.

Role of natural killer cells in iscador mediated inhibition of metastasis by adoptive immunotherapy

Iscador activated (in vivo and in vitro) splenocytes were found to inhibit metastatic tumour growth in C57BL/6 mice. In order to check whether NK cells are involved in the antimetastatic activity of Iscador activated splenocytes ,animals were depleted of NK cells using antiasialo GMI antibodies. When spleen cells activated in vivo with Iscador were injected into animals pretreated with Antiasialo GM I antibodies, there was an average of 44.6 tumour nodules on 21st day indicating that stimulation of NK cell activity produced by the Iscador compensate for the NK cell depletion by Antiasialo GM I antibody. Animals treated with Iscador activated splenocytes showed an average survival period of 68 days whereas that of control tumour bearing animals treated with Ab the average survival was 19.3 days. The lung collagen hydroxyproline content, serum sialic acid levels, markers of metastasis were also significantly (P<0.001) lowered in these animals compared to those of the untreated tumour bearing animals. gamma-glutamyl transpeptidase a marker of neoplastic growth, was also significantly reduced (P<0.001) in animals treated with activated splenocytes.

Clinical correlations of alpha2,6-sialyltransferase expression in colorectal cancer patients

We have previously demonstrated a link between alpha2,6-Sialyltransferase (alpha2,6-ST; E.C. 2.4.99.1) expression and differentiation of colon tumors. So far, information is not available relative to the expression of alpha2,6-ST in tumors and the survival of patients with colorectal cancer. We have examined the expression of alpha2,6-ST in a variety of colorectal adenocarcinomas (n = 46) at different stages of differentiation (G1 to G3) by immunoperoxidase assay using monoclonal antibody (MAb) 6B9. Clinical outcome of the patients in a 5-year follow-up study has been correlated with the expression of alpha2,6-ST in tumors surgically removed from the same patients. No significant difference in the alpha2,6-ST expression was noted when age, sex, and tumor locations (colon, rectum) were included as parameters. However, 52% of the moderate (G2) and well-differentiated (G1) adenocarcinomas showed stronger alpha2,6-ST expression compared with poorly differentiated (G3) adenocarcinomas. Notably, absence to moderate levels of tumor alpha2,6-ST expression was correlated with 100% survival in patients with stage I and II tumors compared with 64% survival in patients with strong tumor alpha2,6-ST expression (p < 0.01). These studies suggest a negative correlation between the expression of alpha2,6-ST in tumors and a good clinical outcome in colorectal cancer patients.

CDw60: an antigen expressed in many normal tissues and in some tumours

CDw60 is a recently described T-cell antigen, which functionally delivers a costimulatory signal in T-cell activation. In addition, CDw60 has been regarded as a melanoma-associated antigen. To date, only limited information exists on the distribution of CDw60 in other normal and pathologically altered tissues in human. In the present study, the expression of CDw60 was analysed immunohistologically in a large panel of formalin-fixed and paraffin-embedded normal and pathological human tissues. The antigen was detected in several normal tissues, such as epithelia of the reproductive system, exocrine and endocrine glands, glial cells and neurons of the central and peripheral nervous systems, and lymphoid cells. These showed different subcellular distribution patterns, i.e. (1) cell surface labelling of peripheral lymphocytes and lymphocytes of the lymph node and thymus, (2) diffuse cytosolic staining in lymphocytes, subpial glial processes, and the outer plexiform layer of the retina, (3) granular cytoplasmic staining associated with the Golgi apparatus in epithelial cells of certain endocrine and exocrine glands, of the ductus epididymis and deferens, neurons of the peripheral and central nervous system, and lymphocytes and megakaryocytes of the bone marrow. In exocrine glands, e.g. of the prostate and uterine corpus, CDw60-positive Golgi fields were located in the juxtaluminal cell compartment, thus reflecting a polarized distribution. In some malignant tumours, the neoplastic cells contained CDw60-immunolabelled Golgi complexes, which were disorderly distributed throughout the cytoplasm, thus reflecting a loss of epithelial polarity. Only in mammary carcinomas was abnormal cell surface labelling detected. A putative de novo expression of CDw60 was observed in pleomorphic adenoma and mucoepidermoid carcinoma of the parotid gland, seminoma, embryonal and teratocarcinoma of the testis, small cell carcinoma of the lung, and malignant melanoma. These results define the CDw60 determinant as a broadly distributed antigen within a large panel of normal human tissues. The antigen is also detectable in some previously undescribed benign and malignant tumours, which may give importance to CDw60 as a possible diagnostic marker.

Alterations of endothelial nucleotide levels by mycophenolic acid result in changes of membrane glycosylation and E-selectin expression

The effect of the inhibitor of inosine-5'-monophosphate dehydrogenase (IMPDH), mycophenolic acid, on intracellular nucleotides and the synthesis of cellular glycoproteins was evaluated in human umbilical vein endothelial cells. A clinically attainable concentration (10 micromol/l) of mycophenolic acid decreased guanosine-5'-triphosphate (GTP) levels significantly and led to a strong elevation of uridine-5'-triphosphate (UTP), whereas intracellular adenosine-5'-triphosphate (ATP) pools remained unaffected. The staining of the endothelial cell membranes with lectins specific for fucose and mannose (Ulex europaeus- and Galanthus nivalis agglutinin, respectively) was reduced, reflecting an inhibition of fucose and mannose incorporation into endothelial glycoproteins. The surface expression of E-selectin, an important determinant for leuko-endothelial interactions decreased significantly. Guanine and guanosine prevented the actions of mycophenolic acid and reversed the drug-induced decrease in GTP and its associated effects. The findings that mycophenolic acid produces alterations in the formation of glycoproteins and in the membrane architecture are indicative of metabolic lesions induced by an agent that depresses guanine nucleotide synthesis through inhibition of IMPDH. The pronounced reduction of E-selectin surface expression on endothelial cells accompanied by changes of endothelial cell fucosylation, a prerequisite for the contact with lymphocytic L-selectin, indicates an inhibitory effect of mycophenolic acid in the rolling phase of leukocyte recruitment and strongly implies a new and additional immunosuppressive mechanism of this agent.

Inhibition of lung metastasis by adoptive immunotherapy using Iscador

Adoptive immunotherapy using spleen cells activated with Iscador was found to inhibit tumour growth significantly (P<0.001). Metastatic B16F10 tumour bearing animals treated with a single dose of spleen cells activated with Iscador (in vitro) showed 100% inhibition of tumour nodule formation on 21st day. Single injection of splenocytes isolated from mice treated with Iscador inhibited the tumour nodule formation by 93.8%. Animals treated with in vivo and in vitro activated spleen cells along with Iscador had an increase in life span of 119% and 81% respectively. Treatment of animals with low dose of Iscador after adoptive immunotherapy further augmented the life span. Animals which underwent adoptive immunotherapy showed significantly reduced lung collagen hydroxyproline (9.8 microg/mg protein) and serum sialic acid (24.61 micro/ml serum) levels compared to control tumour bearing animals with increased levels of lung hydroxyproline (26.95 microg/mg protein) and serum sialic acid levels (151.3 microg/ml serum). Serum gamma -glutamyl transpeptidase levels were found to be significantly reduced in the group of animals treated with Iscador and Iscador activated splenocytes (16.6+/-2.3 nmol P-nitroaniline released /ml serum) Group of animals treated with Iscador activated splenocytes alone also showed significantly reduced serum gamma - glutamyl transpeptidase levels (17.3+/-10 nmol P-nitroaniline released /ml serum) compared to control tumour bearing animals (91+/-12 nmol P-nitroaniline released /ml serum).

The salubrious effect of tamoxifen [correction of Tamaxifen] on serum marker enzymes, glycoproteins, and lysosomal enzymes level in breast cancer woman

Tumour markers correlate strongly with prognosis based on tumour burden and surgical resectability. If chemotherapy is extremely effective in certain stage of the disease, the sensitive marker may be of great use in monitoring disease response and drug treatment. Hence, this study was launched to evaluate the changes in tumour marker enzymes like lactate dehydrogenase (LDH), glutamate oxaloacetate transaminase (SGOT), glutamate pyruvate transaminase (SGPT), alkaline phosphatase, and acid phosphatase in before and after 3 and 6 months tamoxifen treated breast cancer patients. In addition, the changes in serum glycoproteins viz., hexose, hexosamine, and sialic acid and lysosomal enzymes such as N-acetyl-beta-D-glucosaminidase, beta-D-galactosidase, and beta-D-glucuronidase were analysed in these patients. These values were compared with their age matched healthy control subjects. At 6 months evaluation, the tamoxifen treated postmenopausal breast cancer women showed a statistically significant decreased (p < 0.001, 0.05 respectively) levels of LDH, SGOT, SGPT, alkaline and acid phosphatases than their baseline values. Similarly, the levels of hexose, hexosamine, and sialic acid and N-acetyl-beta-D-glucosaminidase, beta-D-galactosidase, and beta-D-glucuronidase were decreased significantly (p < 0.001) in tamoxifen received postmenopausal women. The result of this study suggested that tamoxifen potentially retard the metastasis of breast cancer as well as the bone demineralisation in postmenopausal breast cancer women. Thus, tamoxifen may also have its antitumour activity through its beneficial effects on tumour marker enzymes and serum proteins in breast cancer women.

Circulating levels in serum of total sialic acid, lipid-associated sialic acid, and fucose in precancerous lesion and cancer of the oral cavity

Total sialic acid (TSA), lipid-associated sialic acid (LASA), and fucose were estimated in sera of 35 patients with precancerous lesion of the oral cavity, 68 patients with cancer of the oral cavity, and 25 age- and sex-matched non-chewers of both tobacco and betal nut and nonsmokers as controls. Significant elevation in the serum levels of TSA and LASA were observed in patients with the precancerous and cancer lesions when compared with the controls. Serum TSA levels were elevated significantly in patients with cancer when compared with those with precancerous lesions. Circulating TSA and LASA levels were found to reflect tumor burden and correlated well with stage of the disease. However, serum fucose levels did not show an increase corresponding to stage of the disease. The results suggests that combined evaluation of these markers may be useful in predicting early malignant change and also in assessing the spread and invasiveness of the disease in cancer of the oral cavity.

Seromucoid fraction: a useful biomarker for patients with breast cancer

Seromucoid fraction was measured in terms of mucoid proteins (MP) and hexose content from sera of 1) 47 healthy women, 2) 48 women who had benign breast diseases, 3) 151 untreated patients with breast cancer, and 4) 245 follow-up samples collected from the same breast cancer patients. Mucoid proteins and hexose levels were found to be significantly elevated in untreated patients with breast cancer when compared with the healthy participants (p < 0.001) and patients who had benign breast diseases (p < 0.02 and p < 0.05, respectively). Receiver operating characteristic (ROC) curve analysis revealed potential diagnostic application of both markers for breast cancer. A good correlation was observed between favorable treatment response and decline in serum-marker levels. The markers in patients who did not respond to anticancer therapy remained stable or increased during follow-up. These data indicate that seromucoid fraction can be an useful biochemical marker for breast cancer patients.

Lectin histochemistry of laryngeal squamous cell carcinomas

A panel of five biotinylated lectins was applied to study the presence and distribution of membrane carbohydrate residues in the normal laryngeal epithelium and in laryngeal squamous cell carcinomas (SCCs) of 86 patients with the avidin-biotin peroxidase complex technique. The lectin-binding pattern of well-differentiated SCCs was comparable to that of the spinous cells of the normal laryngeal epithelium. In the less differentiated SCCs, staining of the keratinocyte plasma membrane with lectins was either reduced or absent, indicating a decline in the glycosylation of cell surface glycoconjugates. The lectins applied here could be used in the rapid assessment of less-differentiated areas within a laryngeal SCC, but they cannot be regarded as reliable markers of laryngeal keratinocytes undergoing malignant transformation.

Quantitative analysis of mRNA encoding MUC1, MUC2, and MUC5AC genes: a correlation between specific mucin gene expression and sialomucin expression in non-small cell lung cancer

The expression of mucins is important for tumor invasiveness and metastasis. In our previous report (Am. J. Respir. Crit. Care Med. 1997; 155:1419-1427), non-small cell lung cancers bearing sialomucin expression tended to relapse earlier than those without sialomucin. However, it remained unclear whether the expression of sialomucin in lung cancer is caused by an abnormal glycosylation process or by the expression of a specific mucin gene product. To address this problem, we established a modified quantitative competitive polymerase chain reaction (QC-PCR) analysis. RNA internal standards of MUC1, MUC2, and MUC5AC non-tandem repeat sequences were constructed, and known copy numbers of mucin RNA internal standards were introduced into reverse transcription-polymerase chain reactions (RT-PCR) for each mucin gene in order to compete with native mucin gene RNA during the reaction. The RNA of Gbeta-like gene (a housekeeping gene) was used as internal control for the RNA analysis. Twenty-five lung cancer tissues (13 adenocarcinomas and 12 squamous cell carcinomas) were used for analysis. Mann-Whitney rank sum test was applied to compare the expression amounts of different mucin genes in tissues. The results revealed that adenocarcinoma expressed higher amounts of MUC5AC gene than did squamous cell carcinoma (P = 0.03). The expression amount of MUC5AC correlated positively with the expression status of sialomucin (P = 0.012). Further studies are anticipated to elucidate the underlying mechanism contributing to this phenomenon.

Differential expression of alpha2,6-sialyltransferase in colon tumors recognized by a monoclonal antibody

It has been reported that alpha2,6-sialyltransferase (alpha2,6-ST; E.C. 2.4.99.1) activity is associated with cellular differentiation. To define its role in colon carcinoma differentiation, we have generated murine monoclonal antibodies (MAb) against alpha2,6-sialyltransferase. The MAb, designated 6B9 of IgM isotype, showed strong reactivity with the purified and crude alpha2,6-ST by ELISA and dot blot assays. Western blotting with MAb 6B9 identified purified alpha2,6-ST of MW 47 kDa and the same MW protein from rat and human liver extracts. The MAb also reacted with two other liver proteins of approximate MW 65 and 100 kDa. Immunoperoxidase studies with formalin-fixed paraffin-embedded tissues showed that MAb 6B9 reacts with liver tissues, the staining of hepatocytes was granular and cytoplasmic. There was a distinct pattern of zonal distribution of this enzyme in hepatocytes located particularly in the portal areas of the liver corresponding to zone 1. Normal colon (100%) and hyperplastic polyps (100%) showed very weak to no reactivity. Adenomas (100%) demonstrated moderate reactivity, while the poor (33%), moderate (100%) and well-differentiated (80%) colon adenocarcinomas showed strong reactivity. Results suggest that alpha2,6-ST is associated with the differentiation state of colon tumors.

A new histobiochemical method to analyze sialylation on cell-surface glycoproteins of head and neck squamous-cell carcinomas

Oncogenic transformation is often accompanied by alterations of glycosylation on a tumor cell's surface, which may contribute to uncontrolled cell growth. The sialoglycans and degree of sialylation on the cell surface are of increasing interest because of their possible role in metastasis and tissue invasion. Since primary tumors and metastases may differ in the degree of sialylation, we examined the expression of sialic acid as a terminal constituent of lactosaminyl glycans on the cell surfaces of 30 cervical lymph-node metastases and 30 squamous-cell carcinomas of the oropharynx and oral cavity. Cell-surface sialylation was determined by a new histobiochemical assay on cryostat sections and was based on the enzymatic introduction of a fluorescence-labelled sialic acid into lactosaminyl type (Gal-beta 1-4 GlcNAc) oligosaccharide chains of cell-surface-expressed glycoproteins. To this end, tissues were incubated in the presence of 5-acetamido-9-deoxy-9-fluoresceinyl-thioureido neuraminic acid (CMP-9-fluoresceinyl-NeuAc) and alpha-2,6-sialyltransferase. In order to compare the degree of sialylation with the potential total amount of sialylation sites, pretreatment with sialidase for desialylation was required. We observed a significantly higher amount of lactosaminyl-type binding sites for sialic acid on metastases compared to the primary tumors (P = 0.001), indicating a lower degree of sialylation in metastases. In primary tumors no correlation was seen between the amount of binding sites and tumor localization, TNM stage or histologic grading. Pretreatment of specimens with sialidase demonstrated a significant degree of sialylation on both primary tumors and lymph-node metastases, but no difference between primary tumors and metastases. When tumor stroma of primary tumors and metastases was compared, tumor cells showed a higher degree of free binding sites for sialic acid, but a low degree of sialylation. Our results suggest that differences in the degree of sialylation of glycoconjugates on a tumor cell's surface may play an important role in the process of cell metastasis. Our histobiochemical method turned out to be very reliable, effective and readily performed.

A study of glycoconjugates in nasopharyngeal carcinoma with correlation to clinical transformation

Little is known about the glycoconjugate changes in human nasopharyngeal epithelium following neoplastic changes. Glycoconjugate histochemistry (Glycine maximus (SBA), Griffonia simplicifolia II (GSA-II), Ulex europaeus (UEA-I), Arachis hypogaea (PNA) and Canavalia ensiformis (ConA)) were performed on the following nasopharyngeal biopsies: 10 adenoid tissues (benign controls), 10 chronic inflammation, 20 squamous metaplasia, 20 undifferentiated carcinoma and 5 squamous cell carcinoma. These results were correlated with the clinical transformations findings. Strong ConA and PNA staining (after neuraminidase treatment (NA)) characterized a subpopulation of squamous metaplasia subjects who later transformed to nasopharyngeal carcinoma. Strong ConA and PNA (before and after NA) depicted the majority of undifferentiated carcinoma subjects having local recurrence following irradiation therapy. In squamous metaplasia, ConA and PNA (after NA) staining may serve as a warning sign for neoplastic changes. Strong stainings for ConA and PNA (before and after NA) in undifferentiated carcinoma subjects may predict a risk for local recurrence.

Increased sialyl Lewis A expression and fucosyltransferase activity with acquisition of a high metastatic capacity in a colon cancer cell line

A human colon cancer cell line, OCUC-LM1(LM), was established from a liver metastasis in our laboratory. Intrasplenic injection of LM into nude mice was repeated three and five times, and the daughter cell lines were designated as LM-H3 and LM-H5 respectively. The level of sialyl Lewis A (SLA) in the supernatant of LM-H3 and LM-H5 was 3 and 4.5 times higher than that of LM respectively. Flow cytometric analysis of SLA expression showed that the peak channel for LM was 113; for LM-H3, 126; and for LM-H5, 146. The mean fluorescence intensity of LM was 102.3 +/- 43.5; for LM-H3, 126.2 +/- 28.4; and for LM-H5, 144.8 +/- 23.4. In endothelial cell adhesion assays, the percentages of adherent LM-H3 and LM-H5 cells were significantly higher than for LM. The activity of alpha1-->4 fucosyltransferase was higher in LM-H3 and LM-H5 than in LM, but there was no difference in alpha2-->3 sialyltransferase activities for type 1 chain among the cell lines. Our results suggest that SLA expression is associated with acquisition of a high capacity for liver metastasis of colon cancer; increased SLA expression is due mainly to increased fucosyltransferase activity.

Studies on the inhibition of sialyl- and galactosyltransferases

The inhibition of the alpha-2,6-sialyltransferase from rat liver, the alpha-2,3-sialyltransferase from porcine submandibular gland and of the galactosyltransferase from human milk were studied using monosaccharide-, nucleoside- and nucleotide-derivatives of their naturally occurring donor substrates cytidine 5'-monophosphate-N-acetylneuraminic acid and uridine 5'-diphosphate-galactose, respectively. Only the corresponding nucleosides/nucleotides showed inhibitory activity. Periodate oxidation of CMP or CMP-Neu5Ac and of UMP or UDP-Gal led to reduced inhibitory efficiency with the respective transferase. The type and reversibility of the inhibition of some of these compounds, as well as the corresponding Ki values were determined.

The loss of lectin reactivity from human endometrium is a feature of malignant change

Changes in the cell surface glycoproteins were investigated in endometrial adenocarcinomas using eight biotin-labelled lectins (Con A, LCA, WGA, e-PHA, l-PHA, SBA, PNA, LTA) which select for the major classes of N-linked and O-linked oligosaccharides. The tissues studied were 14 normal endometria, 20 cases of simple hyperplasia and 30 endometrial adenocarcinomas. Sections were cut at 5 microns from formalin fixed paraffin embedded blocks and were stained with an avidin-peroxidase method. All normal and hyperplastic endometria contained the full range of expected saccharides (positive staining for Con A, LCA, WGA, SBA, PNA, LTA, e-PHA and l-PHA). By contrast, over half of the endometrial adenocarcinomas exhibited a loss of galactosamine (56.7%) and over a third of them failed to reveal galactose (36.7%) and fucose (30.0%) (negative staining for SBA, PNA and LTA, respectively). Interestingly, following neuraminidase treatment, galactose was identified in all adenocarcinomas studied, but the expression of galactosamine and fucose was unaffected. There was a discrete linear staining at the level of the basement membranes in a proportion of endometrial glands treated with e-PHA, l-PHA and LCA; this was continuous in normal and hyperplastic endometria, while it was fragmentary in endometrial adenocarcinomas. The loss of galactosamine reactivity from endometrial adenocarcinomas was significantly correlated with high grade differentiation, and also with the more frequent occurrence of a poor oestrogen (ER) and progesterone (PR) receptor status and with an unfavourable 5-year survival. No relationship was found between fucose reactivity and tumour differentiation, stage of disease, hormone receptor status or prognosis. It is concluded that galactosamine loss, together with reduced fucose expression, is a common feature of endometrial malignancy, and that galactosamine deficient tumours may reflect a more aggressive biological behaviour.

Lectin histochemistry of oral premalignant and malignant lesions: correlation of JFL and PNA binding pattern with tumour progression

The expression of glycoconjugates specific to Jack fruit lectin (JFL) and peanut agglutinin (PNA) in various clinicopathological stages of tumour progression in the oral mucosa were studied. These included various clinical forms of dysplastic and non-dysplastic oral leucoplakias, carcinomas, normal keratinising (gingiva) and non-keratinising (buccal mucosa) epithelia. It was seen that the binding patterns of PNA and JFL in the epithelial cells of various types of oral lesions were more or less similar. Normal non-keratinising epithelium showed mild membrane staining only in the spinal layers, while normal keratinising epithelium showed a moderate membrane staining and mild cytoplasmic staining in all layers. Moderate membrane and mild cytoplasmic staining were observed in leucoplakias, irrespective of various clinical or histological types. In carcinomas, the intensity of lectin binding was high, particularly in the membrane of differentiated cells. Correlation analysis of the binding pattern of PNA and JFL showed significant correlation in the membrane and cytoplasm of all layers with histological stages of tumour progression. The present study thus showed that PNA and JFL may be used as cytochemical probes in differentiating malignancy from benign lesions of the oral mucosa.

Expression of sulfomucins in normal mucosae, colorectal adenocarcinomas, and metastases

We have examined the expression of specific mucin antigens in tissue sections from 92 cases of colorectal carcinoma, using sulfomucin-specific monoclonal antibody (MAb) 91.9H. The expression of sulfomucins was high in normal mucosae and much lower in primary colorectal carcinoma, in metastatic lesions in lymph nodes or in liver. The intracellular localization of sulfomucins was also different among these tissues. In normal mucosae, MAb 91.9H binding was seen in the supranuclear area, presumably Golgi complexes, the luminal surface, and secretory products. In primary colorectal carcinomas and in their metastatic lesions, MAb 91.9H was preferentially localized in the cell surface and substances attached to the luminal surface of glandular structures. Analysis of the lysates of normal and tumor tissues showed that very-high-molecular-weight components contained the antigenic epitopes. The intensity of MAb 91.9H binding was lower in tumors at advanced stages than in tumors at early stages. These high-molecular-weight components were apparently reactive with MAb FH6 specific for sialyl-Le(X) (s-Le(X) structures. Histological specimens with low levels of MAb 91.9H reactivity often exhibited relatively high levels of MAb FH6 reactivity. These two mucins may have reversed expression during carcinogenesis and carcinoma progression, and this change may be related to metastatic potential.

Role of SPan-1 antigen in adhesion of human colon cancer cells to vascular endothelium

Recently E-selectin (ELAM-1, endothelial leukocyte adhesion molecule-1) was shown to recognize not only sialyl Lewis X but also sialyl Lewis A, and these carbohydrate antigens may be involved in the process of the adhesion between cancer cells and endothelial cells in cancer metastasis. To investigate the contribution of sialylated carbohydrate antigen, SPan-1, and sialic acid to the adhesion of human colon cancer cells to endothelial cells, adhesion assay using HUVECs (human umbilical vein endothelial cells) was performed. The adhesion was significantly inhibited by pretreatment with anti-E-selectin antibody, indicating that this adhesion was thought to be mediated by E-selectin. When these cancer cells were pretreated with SPan-1 antibody, the adhesion was significantly inhibited in a concentration-dependent manner. The adhesion was also inhibited by pretreatment with neuraminidase. These findings suggest that the SPan-1 antigen plays a significant role in the adhesion of human colon cancer cells to endothelial cells, and sialylation of the terminal structure of carbohydrate antigens is important in this adhesion.

Use of lectins as diagnostic and therapeutic tools for cancer

Within the past few years, lectins have become a well-established means for understanding varied aspects of cancer and metastasis. Evidence is now emerging that lectins are dynamic contributors to tumor cell recognition (surface markers), cell adhesion and localization, signal transduction across membranes, mitogenic stimulation, augmentation of host immune defense, cytotoxicity, and apoptosis. To advance understanding of these lectin-dependent processes, attempts are being made to discover new lectins that have one or more of these functions and to develop lectin- (or glycoconjugate-) based tools that could be used to home in on tumor cells. This review will summarize current research on the lectins and recent advances in the development of lectin-based diagnostic and therapeutic tools for cancer. Additionally, the future potential of lectin-based diagnosis and therapy is discussed.