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

(Sialyl)Lewis Antigen Expression on Glycosphingolipids, N-, and O-Glycans in Colorectal Cancer Cell Lines is Linked to a Colon-Like Differentiation Program

Alterations in the glycomic profile are a hallmark of cancer, including colorectal cancer (CRC). While, the glycosylation of glycoproteins and glycolipids has been widely studied for CRC cell lines and tissues, a comprehensive overview of CRC glycomics is still lacking due to the usage of different samples and analytical methods. In this study, we compared glycosylation features of N-, O-glycans, and glycosphingolipid glycans for a set of 22 CRC cell lines, all measured by porous graphitized carbon nano-liquid chromatography-tandem mass spectrometry. An overall, high abundance of (sialyl)Lewis antigens for colon-like cell lines was found, while undifferentiated cell lines showed high expression of H blood group antigens and α2-3/6 sialylation. Moreover, significant associations of glycosylation features were found between the three classes of glycans, such as (sialyl)Lewis and H blood group antigens. Integration of the datasets with transcriptomics data revealed positive correlations between (sialyl)Lewis antigens, the corresponding glycosyltransferase FUT3 and transcription factors CDX1, ETS, HNF1/4A, MECOM, and MYB. This indicates a possible role of these transcription factors in the upregulation of (sialyl)Lewis antigens, particularly on glycosphingolipid glycans, via FUT3/4 expression in colon-like cell lines. In conclusion, our study provides insights into the possible regulation of glycans in CRC and can serve as a guide for the development of diagnostic and therapeutic biomarkers.

Characterization of N-glycome profile in mouse brain tissue regions by MALDI-TOF/MS

Glycosylation is one of the most common types of post-translational modifications in mammals. It is well known that N-glycans play a key role in cell adhesion, differentiation, synapsis, and myelination during the development of the mammalian central nervous system (CNS). Neuropathological symptoms (such as epilepsy and Alzheimer's disease) are usually accompanied by N-glycosylation changes. In this study, we extracted N-glycan chains from eight regions of the mouse brain, and combined high-throughput, high-resolution matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) with the Fmoc N-hydroxysuccinimide ester (Fmoc-OSU) derivatization method to improve the sensitivity of glycan detection to characterize the total N-glycans in the mouse brain. A total of 96 N-glycan moieties were detected. An exhaustive examination of the relative abundance of N-glycans, coupled with a comparative analysis of differences, has uncovered discernible variations of statistical significance, including high mannose, fucosylated, sialylated, and galactosylated N-glycans. According to our investigations, a thorough and regionally specific cartography of glycans within the brain can facilitate the investigation of glycan-mediated mechanisms related to both the developmental trajectory and functional output of the brain. Additionally, this approach may serve as a basis for identifying potential biomarkers that are relevant to various brain-associated pathologies.

Glycosylation as a regulator of site-specific metastasis

Metastasis is considered to be responsible for 90% of cancer-related deaths. Although it is clinically evident that metastatic patterns vary by primary tumor type, the molecular mechanisms underlying the site-specific nature of metastasis are an area of active investigation. One mechanism that has emerged as an important player in this process is glycosylation, or the addition of sugar moieties onto protein and lipid substrates. Glycosylation is the most common post-translational modification, occurring on more than 50% of translated proteins. Many of those proteins are either secreted or expressed on the cell membrane, thereby making glycosylation an important mediator of cell-cell interactions, including tumor-microenvironment interactions. It has been recently discovered that alteration of glycosylation patterns influences cancer metastasis, both globally and in a site-specific manner. This review will summarize the current knowledge regarding the role of glycosylation in the tropism of cancer cells for several common metastatic sites, including the bone, lung, brain, and lymph nodes.

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.

Amigo2-upregulation in Tumour Cells Facilitates Their Attachment to Liver Endothelial Cells Resulting in Liver Metastases

Since liver metastasis is the main cause of death in cancer patients, we attempted to identify the driver gene involved. QRsP-11 fibrosarcoma cells were injected into the spleens of syngeneic mice to isolate tumour sub-populations that colonize the liver. Cells from liver metastatic nodules were established and subsequently injected intrasplenically for selection. After 12 cycles, the cell subline LV12 was obtained. Intravenous injection of LV12 cells produced more liver metastases than QRsP-11 cells, whereas the incidence of lung metastases was similar to that of QRsP-11 cells. LV12 cells adhered to liver-derived but not to lung-derived endothelial cells. DNA chip analysis showed that amphoterin-induced gene and open reading frame 2 (Amigo2) was overexpressed in LV12 cells. siRNA-mediated knockdown of Amigo2 expression in LV12 cells attenuated liver endothelial cell adhesion. Ex vivo imaging showed that suppression of Amigo2 in luciferase-expressing LV12 cells reduced attachment/metastasis to liver to the same level as that observed with QRsP-11 cells. Forced expression of Amigo2 in QRsP-11 cells increased liver endothelial cell adhesion and liver metastasis. Additionally, Amigo2 expression in human cancers was higher in liver metastatic lesions than in primary lesions. Thus, Amigo2 regulated tumour cell adhesion to liver endothelial cells and formation of liver metastases.

N-glycans and metastasis in galectin-3 transgenic mice

Poly-N-acetyl-lactosamine (polyLacNAc) on N-glycans facilitate lung specific metastasis of melanoma cells by serving as high affinity ligands for galectin-3, expressed in highest amounts in the lungs, on almost all its tissue compartments including on the surface of vascular endothelium. PolyLacNAc not only aids in initial arrest on the organ endothelium but in all the events of extravasation. Inhibition of polyLacNAc synthesis, or competitive inhibition of its interaction with galectin-3 all inhibited these processes and experimental metastasis. Transgenic galectin-3 mice, viz., gal-3(+/+) (wild type), gal-3(+/-) (hemizygous) and gal-3(-/-) (null) have been used to prove that galectin-3/polyLacNAc interactions are indeed critical for lung specific metastasis. Gal-3(+/-) mice which showed <50% expression of galectin-3 on the lungs also showed proportionate decrease in the number of B16F10 melanoma metastatic colonies affirming that galectin-3 and polyLacNAc interactions are indeed key determinants of lung metastasis. However, surprisingly, the number and size of metastatic colonies in gal-3(-/-) mice was very similar as that seen in gal-3(+/+) mice. The levels of lactose binding lectins on the lungs and the transcripts of other galectins (galectin-1, -8 and -9) which are expressed on lungs and have similar sugar binding specificities as galectins-3, remain unchanged in gal-3(+/+) and gal-3(-/-) mice. Further, inhibition of N-glycosylation with Swainsonine (SW) which drastically reduces metastasis of B16F10 cells in gal-3(+/+) mice, did not affect lung metastasis when assessed in gal-3(-/-) mice. Together, these results rule out the possibility of some other galectin taking over the function of galectin-3 in gal-3(-/-) mice. Chimeric mice generated to assess if absence of any effect on metastasis is due to compromised tumor immunity by replacing bone marrow of gal-3(-/-) mice with that from gal-3(+/+) mice, also failed to impact melanoma metastasis. As galectin-3 regulates several immune functions including maturation of different immune cells, compromised tumor immunity could be the major determinant of melanoma metastasis in gal-3(-/-) mice and warrants thorough investigation.

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.

Recent advances toward the development of inhibitors to attenuate tumor metastasis via the interruption of lectin-ligand interactions

Aberrant glycosylation is a well-recognized phenomenon that occurs on the surface of tumor cells, and the overexpression of a number of ligands (such as TF, sialyl Tn, and sialyl Lewis X) has been correlated to a worse prognosis for the patient. These unique carbohydrate structures play an integral role in cell-cell communication and have also been associated with more metastatic cancer phenotypes, which can result from binding to lectins present on cell surfaces. The most well studied metastasis-associated lectins are the galectins and selectins, which have been correlated to adhesion, neoangiogenesis, and immune-cell evasion processes. In order to slow the rate of metastatic lesion formation, a number of approaches have been successfully developed which involve interfering with the tumor lectin-substrate binding event. Through the generation of inhibitors, or by attenuating lectin and/or carbohydrate expression, promising results have been observed both in vitro and in vivo. This article briefly summarizes the involvement of lectins in the metastatic process and also describes different approaches used to prevent these undesirable carbohydrate-lectin binding events, which should ultimately lead to improvement in current cancer therapies.

Regulation of the metastatic cell phenotype by sialylated glycans

Tumor cells exhibit striking changes in cell surface glycosylation as a consequence of dysregulated glycosyltransferases and glycosidases. In particular, an increase in the expression of certain sialylated glycans is a prominent feature of many transformed cells. Altered sialylation has long been associated with metastatic cell behaviors including invasion and enhanced cell survival; however, there is limited information regarding the molecular details of how distinct sialylated structures or sialylated carrier proteins regulate cell signaling to control responses such as adhesion/migration or resistance to specific apoptotic pathways. The goal of this review is to highlight selected examples of sialylated glycans for which there is some knowledge of molecular mechanisms linking aberrant sialylation to critical processes involved in metastasis.

Immunology in the clinic review series; focus on cancer: glycolipids as targets for tumour immunotherapy

Research into aberrant glycosylation and over-expression of glycolipids on the surface of the majority of cancers, coupled with a knowledge of glycolipids as functional molecules involved in a number of cellular physiological pathways, has provided a novel area of targets for cancer immunotherapy. This has resulted in the development of a number of vaccines and monoclonal antibodies that are showing promising results in recent clinical trials.

Rac1-regulated endothelial radiation response stimulates extravasation and metastasis that can be blocked by HMG-CoA reductase inhibitors

Radiotherapy (RT) plays a key role in cancer treatment. Although the benefit of ionizing radiation (IR) is well established, some findings raise the possibility that irradiation of the primary tumor not only triggers a killing response but also increases the metastatic potential of surviving tumor cells. Here we addressed the question of whether irradiation of normal cells outside of the primary tumor augments metastasis by stimulating the extravasation of circulating tumor cells. We show that IR exposure of human endothelial cells (EC), tumor cells (TC) or both increases TC-EC adhesion in vitro. IR-stimulated TC-EC adhesion was blocked by the HMG-CoA reductase inhibitor lovastatin. Glycyrrhizic acid from liquorice root, which acts as a Sialyl-Lewis X mimetic drug, and the Rac1 inhibitor NSC23766 also reduced TC-EC adhesion. To examine the in vivo relevance of these findings, tumorigenic cells were injected into the tail vein of immunodeficient mice followed by total body irradiation (TBI). The data obtained show that TBI dramatically enhances tumor cell extravasation and lung metastasis. This pro-metastatic radiation effect was blocked by pre-treating mice with lovastatin, glycyrrhizic acid or NSC23766. TBI of mice prior to tumor cell transplantation also stimulated metastasis, which was again blocked by lovastatin. The data point to a pro-metastatic trans-effect of RT, which likely rests on the endothelial radiation response promoting the extravasation of circulating tumor cells. Administration of the widely used lipid-lowering drug lovastatin prior to irradiation counteracts this process, likely by suppressing Rac1-regulated E-selectin expression following irradiation. The data support the concern that radiation exposure might increase the extravasation of circulating tumor cells and recommend co-administration of lipid-lowering drugs to avoid this adverse effect of ionizing radiation.

E-selectin rs5361 and FCGR2A rs1801274 variants were associated with increased risk of gastric cancer in a Chinese population

Host immune responses are critical steps for carcinogenesis. Single nucleotide polymorphisms (SNPs) in immunoregulatory genes may influence gastric cancer risk. We performed a genotyping analysis for immunoregulatory genes in 311 gastric cancer cases and 425 controls from a Chinese population. We found that there were significant differences of E-selectin variant rs5361 (A>C) and FCGR2A variant rs1801274 (T>C) between cases and controls (P = 0.022 and P = 0.0001, respectively). Logistic regression analysis indicated that genotype of E-selectin rs5361AC increased the risk of gastric cancer significantly (P = 0.026, adjusted Odds ratio (OR) = 2.84, 95% confidence interval (CI) = 1.13-7.12). C allele of E-selectin rs5361 showed a significant increased frequency in cases (P = 0.023). However, the E-selectin variant did not affect the protein expression. E-selectin protein was observed not only in tumor interstitial vascular endothelial cells, but also in gastric cancer cells at primary and metastatic sites. The protein was associated with clinicopathological characteristics of gastric cancer, such as age (P = 0.008), tumor size (P = 0.027), differentiation (P = 0.000), and tumor-node-metastasis (TNM) stage (P = 0.006). CT and CC + CT genotypes of FCGR2A variant rs1801274 increased gastric cancer risk (P = 0.000, adjusted OR = 1.92, 95%CI = 1.36-2.72; P = 0.003, adjusted OR = 1.68, 95%CI = 1.20-2.35, respectively). Interleukin-4 receptor (IL-4R) variant rs2107356 presented negative correlations to E-selectin variant rs5361 and FCGR2A variant rs1801274 (P = 0.035 and P = 0.023) in conferring susceptibility to gastric cancer. We concluded E-selectin variant rs5361 and FCGR2A variant rs1801274 were significantly associated with gastric cancer risk. Expression of E-selectin protein would promote progression of gastric cancer.

The engagement of selectins and their ligands in colorectal cancer liver metastases

The colonization of the liver by colorectal cancer (CRC) cells is a complicated process which includes many stages, until macrometastases occur. The entrapment of malignant cells within the hepatic sinusoids and their interactions with resident non-parenchymal cells are considered very important for the whole metastatic sequence. In the sinusoids, cell connection and signalling is mediated by multiple cell adhesion molecules, such as the selectins. The three members of the selectin family, E-, P- and L-selectin, in conjunction with sialylated Lewis ligands and CD44 variants, regulate colorectal cell communication and adhesion with platelets, leucocytes, sinusoidal endothelial cells and stellate cells. Their role in CRC liver metastases has been investigated in animal models and human tissue, in vivo and in vitro, in static and shear flow conditions, and their key-function in several molecular pathways has been displayed. Therefore, trials have already commenced aiming to exploit selectins and their ligands in the treatment of benign and malignant diseases. Multiple pharmacological agents have been developed that are being tested for potential therapeutic applications.

An easy colorimetric assay for glycosyltransferases

Glycosyltransferases are involved in biosynthesis of both protein-bound and non-bound glycans that have multiple and important biological functions in all species. A variety of methods for assaying glycosyltransferase activity have been developed driven by the specific interests and type of information required by researchers. In this work, a novel colorimetric assay for the glycosyltransferase-catalyzed reaction was established. Compared with measuring the newly formed product, which might not exhibit visible absorption, the unreacted acceptor could be readily detected by measuring the visible absorption of the hydrolysis product. In the assay, 4-nitrophenyl-beta-D-glycoside (glycosyl-beta-pNP) is used as the glycosyl acceptor, which can be hydrolyzed by a special exoglycosidase to release the p-nitrophenol before glycosylation reactions. Absorbance change of the p-nitrophenolate corresponds to unreacted glycosyl acceptor that accompanied the glycosyl transfer. The assay is demonstrated to be useful in the initial characterization of recombinant glycosyltransferases for their kinetic parameters, optimal metal cofactor, and pH value. It provides a simple, sensitive, and quantitative method for assessing glycosyltransferase activity and is thus expected to have broad applications including automated high-throughput screening.

Analysis of E-Selectin S128R gene polymorphism in pancreatic cancer

BACKGROUND

E-selectin, an intercellular adhesion molecule that plays important roles in metastasis of tumor cells, has a polymorphism in exon 4 that results in the substitution of a serine by an arginine within the extracellular domain of the receptor, which increases its affinity for ligands. No evidence exist on the role of E-selectin polymorphism in pancreatic cancer.

METHODS

Eighty pancreatic cancer patients and 160 cases of normal healthy control subjects were investigated for genotype and allelic frequencies of S128R polymorphism of E-selectin gene by PCR-RFLPs.

RESULTS

The frequencies for "AA," "CA," and "CC" genotypes were 46.25%, 50%, and 3.75% in patients, and 63.75%, 26.9%, and 9.4% in healthy subjects, respectively. The "C" carriers group of patients ("CA + CC" genotype) and the "C" allele were over-represented among the pancreatic cancer cases (P = 0.012 and 0.096, respectively). Advanced T stage, the presence of lymph node and other adverse pathologic characteristics were not significantly correlated with either the "CA + CC" genotype group of patients or the presence of "C" allele.

CONCLUSIONS

E-selectin S128R "C" allele may confer an increased susceptibility to pancreatic cancer development, while its carriage status does not appear to be related to the aggressive features of this malignancy.

Increased levels of both carbohydrate antigen 19-9 and duke pancreatic monoclonal antigen type 2 reflect postoperative prognosis in patients with pancreatic carcinoma

OBJECTIVES

It is important to identify useful tumor markers for the prediction of postoperative outcomes in patients with pancreatic carcinoma (PC).

METHODS

A retrospective study was performed in 87 patients who underwent surgical resection for PC. Preoperative levels of tumor markers such as carbohydrate antigen 19-9 (CA19-9) and duke pancreatic monoclonal antigen type 2 (DUPAN-2) were estimated and analyzed in relation to disease-specific survival (DSS).

RESULTS

The CA19-9 level did not correlate with the DUPAN-2 level (R=-0.057). Prognosis correlated with CA19-9 levels, and patients with 185 U/mL or lower CA19-9 level showed significantly better DSS than patients with 186-U/mL or higher CA19-9 level (P=0.015). Patients with 151- to 800-U/mL DUPAN-2 level showed significantly worse DSS than patients with 801-U/mL or higher DUPAN-2 level (P=0.0023), so the prognosis was reversely related to the DUPAN-2 level. Patients with increased levels of both CA19-9 and DUPAN-2 showed significantly worse DSS than the patients without elevated levels (P<or=0.0023). The independent predictors of poor DSS (hazards ratio, 95% confidence interval) were the following: non-well-differentiated adenocarcinoma (2.35, 1.28-4.53), invasion of the portal vein (2.57, 1.47-4.47), and increased levels of both CA19-9 and DUPAN-2 (3.01, 1.72-5.32).

CONCLUSIONS

The increased levels of both CA19-9 and DUPAN-2 closely reflect prognosis in patients with PC.

E-selectin gene S128R polymorphism is associated with poor prognosis in patients with stage II or III colorectal cancer

Some host-related factors may predict the risk of metastasis after surgery of colorectal cancer (CRC). The endothelial adhesion molecule E-selectin is implicated in the metastatic spread of CRC. We postulated that some polymorphisms within the E-selectin gene, especially the S128R polymorphism, may increase the risk of metastases by facilitating adhesion of tumour cells to the endothelium. We collected blood samples for DNA extraction from 264 patients treated for stage II or III CRC and from 310 healthy controls in order to assess three polymorphisms within the E-selectin gene (S128R, G98T and L554F) and one within the P-selectin gene (V640L). Genotypes were analysed by the allelic discrimination TaqMan real-time PCR assay. The S128R polymorphism was detected in 59 patients (22.3%) and was strictly correlated with the G98T polymorphism. In multivariate analysis, the S128R polymorphism was associated with shorter event-free survival (EFS) and overall survival (OS) in the whole population (EFS: P=.003, HR 1.82, 95% CI 1.23-2.70; OS: P<10(-4), HR 4.31, 95% CI 2.46-10.99), in patients with stage II CRC(EFS: P=.04, HR 1.92, 95% CI 1.02-3.60; OS: P=.02, HR 4.44, 95% CI 1.16-17.03), and in patients with stage III CRC (EFS: P=.04, HR 1.68, 95% CI 1.01-2.80; OS: P=.001, HR 4.04, 95% CI 1.73-9.46). L554F and V640L polymorphisms had no prognostic value. The S128R polymorphism is a constitutional factor associated with a higher risk of relapse and death in patients treated for CRC. This polymorphism detection may permit better selection of patients suitable for adjuvant therapy, especially among those with stage II disease.

Identification of the expression profile of apoptotic esophageal cancer cells by adenoviral-fragile histidine triad treatment

BACKGROUND

The fragile histidine triad (FHIT) functions as a tumor suppressor, and giving adenoviral-FHIT (Ad-FHIT) is thus expected to be clinically beneficial. Much attention has recently been focused on which genes are commonly regulated by Ad-FHIT, and which genes are dominant in Ad-FHIT-induced apoptotic cells.

METHODS

Ad-FHIT apoptosis-induced cells (H1299 and TE4) and non-apoptosis-induced cells (TE2) were used in the current experiments. The total RNA extracted from Ad-FHIT or control was labeled with Cy3-dCTP or Cy5-dCTP and hybridized with 19,192 genes on a chip. A microarray analysis for each gene was carried out with high reproducibility provided by seven independent experiments and duplicated oligos on a chip.

RESULTS

We listed the upregulated genes based on the TE4:TE2 expression ratio, such as c-Src, Jak-1, and sialyltransferase, which are expected to be target pathways as well as the downregulated genes, including CASP8 and CASP10, after Ad-FHIT treatment in esophageal cancer.

CONCLUSIONS

The current microarray analysis indicated that the apoptosis of esophageal cancer observed after giving Ad-FHIT was possibly induced by activation of the c-Src gene and inactivation of the CASP8 gene.

The Potentials of Glycomics in Biomarker Discovery

Introduction

Glycans have unique characteristics that are significantly different from nucleic acids and proteins in terms of biosynthesis, structures, and functions. Moreover, their isomeric nature and the complex linkages between residues have made glycan analysis a challenging task. Disease development and progression are usually associated with alternations in glycosylation on tissue proteins and/or blood proteins. Glycans released from tissue/blood proteins hence provide a valuable source of biomarkers. In this postgenome era, glycomics is an emerging research field. Glycome refers to a repertoire of glycans in a tissue/cell type, while glycomics is the study of glycome. In the past few years, attempts have been made to develop novel methodologies for quantitative glycomic profiling and to identify potential glycobiomarkers. It can be foreseen that glycomics holds the promise for biomarker discovery. This review provides an overview of the unique features of glycans and the historical applications of such features to biomarker discovery.

Future Prospective

The concept of glycomics and its recent advancement and future prospective in biomarker research are reviewed. Above all, there is no doubt that glycomics is gaining momentum in biomarker research.

Biological modulation by lectins and their ligands in tumor progression and metastasis

Lectins are a group of specific proteins that preferentially bind to carbohydrates inside and outside cells. To date, an increasing number of animal lectins have been found and categorized into several families in terms of the significant primary structural homology, while the classification is not always straightforward. These lectins can exert immense biological functions mainly through their specific carbohydrate-protein interactions in a variety of situations. In cancer biology, aberrant glycosylation changes on many glycoproteins and glycolipids are often observed and numerous experimental evidences have revealed that these structural changes are related to tumor malignancy. Galectins, which are broadly expressed animal lectins, can play crucial biological roles in tumor cell-cell or cell-matrix interactions through their binding activities to the tumor cell surface carbohydrate determinants. Certain galectin family proteins have also shown to affect tumor cell survival, signal transduction, and proliferation mainly inside the cell. Selectins, which are one of the C-type lectins and expressed leukocytes and/or vascular endothelium, can also play an immense role in tumor cell adhesion and invasion. In addition, certain annexin family proteins, which are originally known as phospholipid binding proteins, have been revealed to possess the carbohydrate binding activity, and these novel functions in tumors are being unveiled. Understanding how carbohydrate-protein interactions function in tumor cells will be one of the important goals in cancer research. This review focuses on the role of these lectins and their ligands in cancer progression and metastasis.

A novel angiogenesis inhibitor, Ki23057, is useful for preventing the progression of colon cancer and the spreading of cancer cells to the liver

Ki23057 is a new, small synthetic tyrosine kinase inhibitor that blocks autophosphorylation of the VEGF receptor2 (VEGFR2). To determine the effect of Ki23057 as an anti-angiogenic agent, we studied the effect of Ki23057 for colon cancer and vascular endothelial cells in vitro and in vivo. Ki23057 inhibited VEGF-induced proliferation of human umbilical vein endothelial cells (HUVECs), whereas no inhibitory effect of Ki23057 on the proliferation of three colon cancer cells (LM-H3, LoVo and LS174T) was observed by means of the cell count assay. Ki23057 inhibited tube formation of HUVECs. Immunoprecipitation demonstrated that Ki23057 inhibited tyrosine phosphorylation of VEGFR2 in HUVECs. Ki23057 exhibited a significant inhibitory effect on the growth of the xenografted LM-H3 tumours and the spreading of cancer cells to the liver. Anti-CD31 antibody stained significantly fewer microvessels in the xenografted tumours treated with Ki23057 compared with controls. Ki23057 may be a promising new antiangiogenic agent for colon cancer.

A new approach for mapping sialylated N-glycosites in serum proteomes

A new approach for proteome-wide analysis of sialylated N-glycopeptides based on the diagonal chromatographic COFRADIC technology is presented here. The use of alpha(2-3,6,8,9) neuraminidase is central to isolate sialylated N-glycopeptides out of a complex peptide mixture. Two different COFRADIC techniques are introduced here, either without or with post-metabolic oxygen-18 labeling (direct versus indirect sorting), and when applied to immuno-depleted mouse serum, we herewith identified 93 sialylated glycosylation sites in 53 serum proteins.

The host inflammatory response promotes liver metastasis by increasing tumor cell arrest and extravasation

Inflammation can play a regulatory role in cancer progression and metastasis. Previously, we have shown that metastatic tumor cells entering the liver trigger a proinflammatory response involving Kupffer cell-mediated release of tumor necrosis factor-alpha and the up-regulation of vascular endothelial cell adhesion receptors, such as E-selectin. Here, we analyzed spatio-temporal aspects of the ensuing tumor-endothelial cell interaction using human colorectal carcinoma CX-1 and murine carcinoma H-59 cells and a combination of immunohistochemistry, confocal microscopy, and three-dimensional reconstruction. E-selectin expression was evident mainly on sinusoidal vessels by 6 and 10 hours, respectively, following H-59 and CX-1 inoculation, and this corresponded to a stabilization of the number of tumor cells within the sinuses. Tumor cells arrested in E-selectin(+) vessels and appeared to flatten and traverse the vessel lining, away from sites of intense E-selectin staining. This process was evident by 8 (H-59) and 12 (CX-1) hours after inoculation, coincided with increased endothelial vascular cell adhesion molecule-1 expression, and involved tumor cell attachment in areas of intense vascular cell adhesion molecule-1 and platelet endothelial cell adhesion molecule-1 expression. Nonmetastatic (human) MIP-101 and (murine) M-27 cells induced a weaker response and could not be seen to extravasate. The results show that metastatic tumor cells can alter the hepatic microvasculature and use newly expressed endothelial cell receptors to arrest and extravasate.

Role of S128R polymorphism of E-selectin in colon metastasis formation

The extravasation of cancer cells is a key step of the metastatic cascade. Polymorphisms in genes encoding adhesion molecules can facilitate metastasis by increasing the strength of interaction between tumor and endothelial cells as well as impacting other properties of cancer cells. We investigated the Ser128Arg (a561c at the nucleotide level) polymorphism in the E-selectin gene in patients with metastatic colon cancer and its functional significance. Genotyping for a561c polymorphism was performed on 172 cancer patients and on an age-matched control population. The colon cancer group was divided into groups with (M(+)) and without observable metastasis (M(-)). For in vitro functional assays, Huvec transfected cells expressing wild-type (WT) or the S128R variant of E-selectin were established to study in vitro binding ability and signal transduction processes of T84 colon cancer cell line. Our results demonstrated that the Arginine(128) allele was more prevalent in the M(+) group than in the M(-) group or normal controls (p < 0.005; odds ratio, 1.56; 95% confidence interval (CI) 1.16-1.92; p < 0.001, odds ratio = 1.65; CI = 1.24-1.99, respectively). In vitro, S128R E-selectin transfected Huvec cells, supported increased adhesion as well as increased cellular signaling of T84 cancer cells compared to WT E-selectin and mock-transfected Huvec cells. These findings suggest that the E-selectin S128R polymorphism can functionally affect tumor-endothelial interactions as well as motility and signaling properties of neoplastic cells that may modulate the metastatic phenotype.

Circulating KL-6/MUC1 mucin carrying sialyl Lewisa oligosaccharide is an independent prognostic factor in patients with lung adenocarcinoma

MUC1 mucin is frequently observed in adenocarcinomas, and its association with metastasis has been postulated through the interaction between sialyl Lewis oligosaccharides present on this glycoprotein and selectins. Levels of soluble MUC1 recognized by anti-KL-6 monoclonal antibody were also frequently elevated in the sera of lung adenocarcinoma patients. The aim of this study was to demonstrate the presence of KL-6/MUC1 carrying sialyl Lewis(a) oligosaccharide, designated as SLAK, and subsequently evaluate the clinical significance of circulating SLAK in patients with lung adenocarcinoma. We developed a sandwich ELISA system using anti-sialyl Lewis(a) and anti-KL-6 antibodies to detect SLAK, and also measured circulating SLAK levels in 97 healthy controls and 103 patients with lung adenocarcinoma. Circulating SLAK levels were measured in the sera taken before treatment and then were evaluated to clarify whether such levels were related to the clinical outcomes. Levels of circulating SLAK were significantly higher in lung adenocarcinoma patients than in healthy subjects, and a higher serum SLAK level was correlated with the presence of distant metastasis. The overall survival rate for patients with high serum SLAK levels was significantly poorer than that of patients with low serum SLAK levels. The survival analysis restricted to the patients with distant metastasis also showed the same trend. In a multivariate survival analysis in lung adenocarcinoma patients, a high serum SLAK level was indicated as an independent prognostic factor. In conclusion, the circulating SLAK level at diagnosis is useful for predicting a poor prognosis in patients with lung adenocarcinoma.

Promoter analysis of the human alpha1,3/4-fucosyltransferase gene (FUT III)

alpha1,3/4-Fucosyltransferase (FUT3) is involved in the synthesis of sialyl Le(a) tetrasaccharide, a tumor-associated carbohydrate antigen. Fucosyltransferases are thought to be important regulatory enzymes in the synthesis of fucosylated structures. However, there are conflicting data on the role of FUT3 in the synthesis of this carbohydrate structure and more studies on the regulation of FUT III gene expression are needed. Therefore, as first step, the promoter of FUT III gene was cloned and characterized. Sequencing data showed the absence of TATA, CAAT, and GC boxes, but many binding sites for transcription factors, previously described in colon cancer cells, were identified. Analysis of enhancer and silencing elements of deletion mutants revealed the presence of basal promoter elements of the FUT III gene in the region -636 to -674 bp from the translation initiation site, and positive and negative regulatory elements within the -674 bp to -854 bp and -854 to -1220 regions, respectively. 5'-RACE analysis showed the presence of two transcripts with 5'-ends localized within the exon A. The 5'-end of the longer transcript extended -229 nucleotides from the translation start codon and contained a sequence corresponding to an Inr element, localizing the putative transcription initiation site within this sequence. The strong correlation between the promoter activity of the FUT III gene and the high expression of sialyl Le(a) observed in different colon carcinoma cell lines seem to confirm the important regulatory role of FUT3 in the synthesis of sialyl Le(a).

Up regulation of ICAM-1 gene expression inhibits tumour growth and liver metastasis in colorectal carcinoma

We have previously reported that decreased intercellular adhesion molecule-1 (ICAM-1) expression in cancer cells is associated with liver metastasis of colorectal cancer. In this study, we have investigated the effect of ICAM-1 gene transfection into the human colorectal cancer cell line LM-H3 on cell adhesiveness and cytotoxicity of peripheral blood mononuclear cells (PBMC) to cancer cells. Furthermore, we have investigated the effects of this gene transfer on subcutaneous tumour and liver metastases of LM-H3 in nude mice. More PBMC adhered to ICAM-1 transfected LM-H3 cells, LM-H3/ICAM-1, than to non-transfected LM-H3 cells and control LM-H3/Vector. Lysis of LM-H3/ICAM-1 cells by PBMC was significantly increased compared with LM-H3/Vector. Liver metastases with LM-H3/ICAM-1 cells were fewer in number and smaller than metastases with LM-H3/Vector. Intra-tumoural injection of ICAM-1 adenoviral vector significantly inhibited the growth of subcutaneous LM-H3 tumour. In conclusion ICAM-1 gene transfection using adenovirus vector might be an effective therapy for liver metastasis of colorectal carcinoma.

Role of tumor cell adhesion and migration in organ-specific metastasis formation

To form clinically evident metastases--the main cause of death in cancer patients--, tumor cells (TC) must complete a highly complex series of steps called the metastatic cascade, including local invasiveness, intravasation, circulation, adhesion and extravasation, survival, proliferation and angiogenesis. Since failure of any one of these steps results in metastatic failure, understanding the metastatic cascade may guide us to new therapeutic concepts. Here we review the role of specific TC adhesion and migration processes for organ-selective metastasis formation. TC adhesion in the microvasculature of host organs is a specific and highly regulated process mainly mediated by selectins for TC/endothelial cell binding and by integrins for TC/extracellular matrix interactions. Defined expression of the adhesion molecules and their corresponding ligands in the host organs and on the TC governs organ-selective non-random TC arrest. TC motility and subsequent chemotactically guided extravasation of adherent cells is the second rate-limiting step in organ-specific metastasis formation. Only if cells have completed adhesion and extravasation the growth of micrometastases and finally clinically evident metastases can occur.

Lovastatin inhibits Rho-regulated expression of E-selectin by TNFalpha and attenuates tumor cell adhesion

E-selectin mediated cell-cell adhesion plays an important role in inflammatory processes and extravasation of tumor cells. Tumor necrosis factor-alpha (TNF-alpha) induces E-selectin gene and protein expression in primary human endothelial cells (HUVEC) and in an endothelial cell line (EA.hy-926). As shown by ELISA and FACS analyses, HMG-CoA reductase inhibitors (e.g., lovastatin) impair the TNF-alpha stimulated increase in E-selectin protein expression. Similar results were obtained for E-selectin mRNA expression and promoter activity, indicating that the effect of lovastatin is based on inhibition of gene expression. The effective inhibitory concentration of lovastatin was in a physiologically relevant range (IC50<0.1 microM). Lovastatin-mediated block of TNF-alpha induced E-selectin expression is due to inhibition of protein geranylgeranylation rather than farnesylation. Down-regulation of Rho signaling by coexpression of dominant-negative Rho mutants (i.e RhoA, RhoB and Rac) impaired TNF-alpha driven E-selectin gene expression, indicating Rho signaling to be essential for transcriptional activation of the E-selectin gene. Inhibition of E-selectin expression by lovastatin gives rise to a significant reduction in TNF-alpha stimulated adhesion of colon carcinoma cells to HUVEC. Furthermore, low concentration of lovastatin (i.e., < or =1 microM) attenuated TNF-alpha induced tumor cell invasion in vitro. The data support the view that statins might be clinically useful in protection against E-selectin mediated metastasis.

Usefulness of CA19-9 versus CA125 for the diagnosis of endometriosis

OBJECTIVE

To investigate the clinical value of the serum CA19-9 level in comparison with the serum CA125 level for diagnosing and determining the severity of endometriosis.

DESIGN

Retrospective study.

SETTING

Department of Comprehensive Reproductive Medicine in a university hospital.

PATIENT(S)

One hundred one women with endometriosis and 22 without endometriosis participated in this study.

INTERVENTION(S)

Blood samples were collected before the operation (laparoscopy, oophrectomy, cystectomy, and/or hysterectomy), and tissue samples of ovarian chocolate cysts were collected during the operation.

MAIN OUTCOME MEASURE(S)

The serum CA19-9 and CA125 levels and the localization of these antigens in ovarian chocolate cysts.

RESULT(S)

The mean serum CA19-9 levels in patients at all stages of endometriosis were significantly higher than those in patients without endometriosis, and serum CA19-9 levels significantly correlated with the Revised American Fertility Society classification scores. Intense staining of CA19-9 was observed in 15 of the 20 samples of ovarian chocolate cysts.

CONCLUSION(S)

CA19-9 is a useful marker for determining the severity of endometriosis.

Inhibitory effect of a selective cyclooxygenase-2 inhibitor on liver metastasis of colon cancer

COX-2 overexpression is recognized in various cancers, but the role of COX-2 in the progression of cancer, including the liver metastasis of colon cancer, is not clearly understood. We examined the role of COX-2 in the mechanism of liver metastasis of colon cancer, using a highly metastasizable colon carcinoma cell line, LM-H3. A COX-2 inhibitor, JTE-522, inhibited cell proliferation and invasion of LM-H3 in vitro and clearly reduced the number of metastatic nodules on the surface of nude mouse livers in vivo. We also examined the effects of JTE-522 on the production of growth factors and MMPs through the use of ELISA and gelatin zymography, respectively. JTE-522 downregulated PDGF production by LM-H3 but had no influence on VEGF production. JTE-522 also inhibited MMP-2 secretion by LM-H3. JTE-522 downregulated PGE(2) production, but the associated changes in PGE(2) did not affect PDGF and VEGF production by LM-H3. We conclude that JTE-522 downregulated the cell proliferation and invasive potential of LM-H3 by reducing the production of PDGF and MMP-2 and hypothesize that these inhibitory effects on the production of PDGF and MMP-2 can lead to inhibition of liver metastasis of colon cancer. These data indicate that the COX-2 inhibitor JTE-522 has a high potential for use as a clinical agent for the treatment of liver metastasis of colon cancer.

Expression of sialyltransferase family members in cervix squamous cell carcinoma correlates with lymph node metastasis

OBJECTIVE

Altered messenger ribonucleic acid (mRNA) expression of the four sialyltransferases (STs including ST3Gal I, ST3Gal III, ST3Gal IV, and ST6Gal I) is important in squamous cell carcinoma of the cervix. This study further investigates their changes in mRNA expression of the four STs in FIGO stage IB1 squamous cell carcinoma to assess the extent of sialylation associated with lymph node metastases.

METHODS

Alterations in ST mRNA expression in FIGO IB1 cervical squamous cell carcinomas (n = 79) were examined by semiquantitative reverse transcription-polymerase chain reaction.

RESULTS

Both ST6Gal I mRNA and ST3Gal III mRNA expressions were significantly increased in patients with lymph node metastases compared to those without lymph node metastases (P = 0.002 and P = 0.001, respectively, Mann-Whitney U test). Using receiver operating characteristic curves of ST ratio index for accuracy comparison of lymph node metastases, ST3Gal III and ST6Gal I were observed to be fairly interchangeable (area under the curve (AUC) of 3Gal I = 0.810; AUC of 6Gal I = 0.786, significance of difference between AUC = 0.810). High ST6Gal I expression was associated with other invasive properties of cervical cancer, such as deep stromal invasion and presence of lymph-vascular space involvement. ST6Gal I expression seemed to be more enhanced in bigger tumors.

CONCLUSIONS

Our results suggested that ST3Gal III and ST6Gal I were of importance for the lymph node metastases in FIGO IB1 cervical cancer patients; more specifically, overexpression of ST6Gal I was of crucial relevance for the presence of poor prognostic factors, such as deep stromal invasion and lymph-vascular space involvement and lymph node metastases.

Increased thermosensitivity of mouse colorectal carcinoma cells transfected with human FUT1 gene

The thermal responses of mouse colorectal carcinoma cells were investigated in the wild type cells and the transfected cells with human FUT1 gene which encodes alpha 1,2fucosyltransferase. The heat sensitivity was observed to increase in the FUT1 gene transfected cells and the effect of hyperthermia at 44 degrees C on these cells was demonstrated to be significant (P<0.001) to the wild type cells even though no remarkable difference in the expression of the heat shock protein, Hsp70 was found in these cells. Thus the expression of alpha 1,2fucosylated antigens seemed to increase the heat sensitivity in mouse colorectal carcinoma cells.

Comparative evaluation of the prognostic value of MUC1, MUC2, sialyl-Lewis(a) and sialyl-Lewis(x) antigens in colorectal adenocarcinoma

AIMS

The significance of MUC1, MUC2 and sialylated Lewis blood group antigens as prognostic markers in colorectal adenocarcinoma was investigated in a large series of patients because previous investigations revealed inconsistent results due to unrelated tumour samples from different patient groups and methodological differences.

METHODS AND RESULTS

Tissues from 243 patients with colorectal adenocarcinoma were stained immunohistochemically. MUC1 showed a strong immunoreactivity (in more than 35% of the tumour area) in 32.5%, MUC2 in 51.0%, sialyl-Lewis(x) in 67.9% and sialyl-Lewis(a) in 73.7% of the cases, respectively. MUC1 immunoreactivity displayed a significant correlation with tumour progression as reflected by advancing pTNM staging and poor differentiation. MUC2 expression was significantly stronger in mucinous adenocarcinomas. Sialyl-Lewis(x) immunostaining correlated with the extent of lymph node metastasis as well as low cytological differentiation. According to univariate and multivariate analysis (P < 0.0001) only MUC1 reactivity represented a marker of worse survival probability, opposed to the sialylated Lewis antigens that did not exert a predictive value.

CONCLUSIONS

According to our data, MUC1 and sialyl-Lewis(x) immunoreactivity exhibit statistically significant correlations with established markers of tumour progression. However, only MUC1 presents as an independent prognostic factor of colorectal adenocarcinoma.

Clinicopathologic evaluation of CDw75 antigen expression in colorectal adenocarcinomas

CDw75, a B lymphocyte surface antigen, is a sialylated carbohydrate epitope, which is generated by the enzyme beta galactosyl alpha 2,6 sialyltransferase (Sia-T1). In colon carcinomas, although higher levels of Sia-T1 has been described and found to be correlated with metastatic potential of tumor cells, the expression of CDw75 antigen still remains unknown. To address this issue, we investigated immunohistochemically CDw75 antigen expression in 195 colorectal adenocarcinomas and their nodal metastases. The correlation between CDw75 antigen expression with selected clinicopathologic variables was analyzed by using Chi-square and Fisher s exact tests. Positive staining was observed in 101 cases. Non-neoplastic mucosa was negative consistently. The frequency of positivity was decreased according to the degree of differentiation (p<0.001). Antigen expression was found to be associated with deeper penetration (p<0.006), positive lymph nodes (p<0.001), distant metastases (p<0.006) and advanced stage (p<0.001). Same relationships were detected in well and moderately differentiated tumors when CDw75 immunoreactivity was evaluated in each histologic grade separately. Our findings indicate that CDw75 antigen expression may be a good indicator of the biological aggressiveness of colorectal adenocarcinomas especially in tumors with well and moderately differentiated morphology.

Altered GalNAc-alpha-2,6-sialylation compartments for mucin-associated sialyl-Tn antigen in colorectal adenoma and adenocarcinoma

Sialyl-Tn (STn), a mucin-associated disaccharide antigen carried by apomucins such as MUC2, plays an important role in tumor biology. However, little is known about the subcellular localization and compartments involved in STn synthesis. In this study we used immunoelectron microscopy to localize STn and MUC2 apomucin in human colorectal tissues. MUC2 apomucin was localized predominantly in the rough endoplasmic reticulum (RER) in normal colorectal mucosa (n=6), colorectal adenoma (n=8), and colorectal adenocarcinoma (n=10). STn, recognized by monoclonal antibody TKH2, was not readily detectable in normal colorectal mucosa but becomes manifest in both trans-Golgi apparatus and mucin droplets in colorectal adenoma. In colorectal adenocarcinoma, STn was localized not only in late but also in early Golgi compartments, and particularly in some RER lumens. Furthermore, electron microscopic in situ hybridization revealed that gold particles representing MUC2 mRNA are primarily localized over the RER. Our findings indicate that in colorectal adenoma STn sialylation takes place in the trans-Golgi apparatus, whereas in colorectal cancer STn sialylation occurs in all the Golgi compartments and in the RER.

Sialyltransferases in cancer

It has long been known that cancer cells often express more heavily sialylated glycans on their surface and that this feature sometimes correlates with invasion. It is now well established that specific sialylated structures, such as the Thomsen-Friedenreich-related antigens, the sialyl Lewis antigens, the sialyl alpha2-6 lactosaminyl structure, the polysialic acid or some gangliosides, can mediate cellular interactions and are altered in cancer cells. This review summarizes the current knowledge on the cancer-associated alterations in sialyltransferase expression which are often at the basis of the deranged expression of sialylated structures.

Altered mRNA expression of sialyltransferase in squamous cell carcinomas of the cervix

OBJECTIVE

Increased sialylation has been reported in various kinds of cancers, but to date, sialylation of cervical carcinoma has never been evaluated. This study of the changes in messenger ribonucleic acid (mRNA) expression of the four sialyltransferases (ST3Gal I, ST3Gal III, ST3Gal IV, and ST6Gal I) in a normal cervix and that with FIGO stage IB1 squamous cell carcinoma was undertaken to assess the extent of sialylation associated with establishment of the carcinoma.

METHODS

Alterations in ST mRNA expression in FIGO IB1 cervical cancer (n = 30) and normal cervixes (n = 30) were examined by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

ST6Gal I expression was enhanced in squamous cell carcinoma of the cervix (P = 0.026, Mann-Whitney U test), but mRNA expression from the other three STs (ST3Gal I, ST3Gal III, and ST3Gal IV) was significantly down-expressed in squamous cell carcinoma of the cervix compared to the normal cervix (P = 0.003, P < 0.001, and P = 0.001, respectively). High ST6Gal I expression was associated with more invasive properties of cervical cancer, such as deep stromal invasion, lymph or vascular space involvement, and poor differentiation (P = 0.010, P < 0.001, P < 0.001, respectively).

CONCLUSIONS

A combination of enhanced ST6Gal I mRNA expression and decreased mRNA expression from ST3Gal I, ST3Gal III, and ST3Gal IV might be important in cervical cancer. Future studies will investigate whether RT-PCR detection of the expression of these enzymes can be helpful for prognostic purposes.

ABH and Lewis histo-blood group antigens in cancer

Antigens of the ABH and Lewis histo-blood group family can be found on many normal cells, mainly of epithelial type. In carcinomas, altered expression of the various carbohydrate epitopes of this family occur, and are often strongly associated with either a good or bad prognosis. A review of the available data on these tumor-associated markers, their biosynthesis and their prognostic value is proposed here. For a long time it has been unclear whether their presence could affect the behavior of carcinoma cells. Recent data, however, indicate that they play biological roles in the course of tumor progression. The presence of sialyl-Le(a) or sialyl-Le(x), which are ligands for selectins, promotes the metastatic process by facilitating interaction with the endothelium of distant organs. The loss of A and B antigens increases cellular motility, while the presence of H epitopes increases resistance to apoptosis by mechanisms that remain to be defined. The Le(y) antigen has procoagulant and angiogenic activities. All these observations are used to present a model that may account for the described associations between the presence or loss of these markers and the outcome of disease. Finally, their potential clinical applications as tumor-associated markers or as targets of immunotherapy are reviewed.

Introduction of antisense CD44S CDNA down-regulates expression of overall CD44 isoforms and inhibits tumor growth and metastasis in highly metastatic colon carcinoma cells

We created antisense CD44 transfectants using LS174T, a colon adenocarcinoma cell line and assessed the effects of overall CD44 down-regulation on colorectal tumor growth and metastasis. The expression of antisense CD44s (the standard form of CD44) cDNA markedly inhibited the overall expression of CD44 variants. In vitro studies showed a significantly reduced ability of the stable antisense transfectants (LS174TAS1 and LS174TAS2) to bind hyaluronate and osteopontin, ligands for CD44. These cells developed tumors more slowly than controls (parental LS174T and mock transfectants) when the cells were subcutaneously injected into SCID mice. However, in vitro proliferation assays demonstrated no significant difference between the antisense transfectants and the controls on a hyaluronate-coated surface, suggesting the participation of ligands other than hyaluronate in tumor growth in vivo. Intrasplenic injection of parental LS174T cells produced colonies in the liver in 10 of 11 mice, whereas mice injected with the antisense transfectants were completely free of metastasis. In peritoneal dissemination, the weight of nodules and amount of ascites were significantly reduced in LS174TAS1 and AS2 compared with the controls. In vitro adhesion assays between the transfectants or controls and human peritoneal mesothelial cells revealed that the binding of LS174T cells to mesothelial cells was partly mediated by CD44-hyaluronate interaction. These data suggest that CD44-hyaluronate interaction plays a crucial role in peritoneal dissemination in colorectal carcinoma. The results of our study demonstrate the possible application of antisense CD44s to the treatment of colorectal carcinoma.

Peritoneal colonization by human pancreatic cancer cells is inhibited by antisense FUT3 sequence

Several alpha(1,3/1,4) fucosyltransferases expressed in human pancreatic cancer cells can participate in the biosynthesis of cell surface sialyl-Lewis a and sialyl-Lewis x antigens that contribute to hematogenous metastatis. Previously, we observed a significant increase of the alpha(1,4) fucosyltransferase activity in tumoral pancreatic cell lines, suggesting that FUT3 could be involved in the sialyl-Lewis antigen expression. Therefore, we invalidated the expression of FUT3 by expressing FUT3 antisense sequence in the human pancreatic tumor BxPC-3 cell line, which expresses the alpha(1,4) fucosyltransferase activity and harbors the cell surface sialyl-Lewis antigens. The decrease of FUT3 transcript after transfection of antisense cDNA of FUT3 in these cells results in a substantial reduction of sialyl-Lewis antigen expression on cell surface. This decreased antigen expression was associated with an inhibition of adhesive properties to E-selectin and a decrease of metastatic power of FUT3 antisense-transfected BxPC-3 cells as tested in nude mice. Our study provides evidence that the expression level of FUT3 may regulate the expression of sialyl-Lewis a and sialyl-Lewis x surface antigens and consequently could play an important role in metastatic properties of human pancreatic cancer cells.

In vivo and in vitro interactions between human colon carcinoma cells and hepatic stellate cells

Stromal reaction is important for the growth of cancer both in primary and metastatic sites. To demonstrate this reaction during the hepatic metastasis of human colon carcinoma, we histologically investigated alterations to the distribution and phenotype of hepatic stellate cells (HSCs), the only mesenchymal cells in the liver parenchyma, using a nude mouse model. Intrasplenically injected colon carcinoma LM-H3 cells migrated into the space of Disse and underwent proliferation, in close association with hepatocytes and HSCs, at 2 days. At 14 days, HSCs were accumulated around the tumor mass and expressed alpha-smooth muscle actin, a marker for HSC activation. We next investigated in vitro the growth factors involved in the interactions between LM-H3 cells and HSCs. Conditioned medium of rat HSCs which underwent culture-induced activation contained platelet-derived growth factor (PDGF)-AB, hepatocyte growth factor (HGF) and transforming growth factor (TGF)-beta, and could augment LM-H3-cell proliferation and migration. Neutralizing antibodies against PDGF-AA and PDGF-BB and those against PDGF-BB and HGF inhibited proliferation and migration, respectively, of LM-H3 cells, whereas antibody against TGF-beta had no effect. LM-H3 cells expressed PDGF receptors-alpha and -beta and c-met. Conditioned medium of LM-H3 cells contained PDGF-AB, and could enhance HSC proliferation and migration. This augmenting effect was suppressed by treatment with anti-PDGF-AB antibody. The present study has demonstrated that bidirectional interactions involving PDGF and HGF take place in vitro between colon carcinoma cells and HSCs, raising the possibility that similar interactions might be involved in the stromal reaction during hepatic metastasis.

Ultrastructure of early phase hepatic metastasis of human colon carcinoma cells with special reference to desmosomal junctions with hepatocytes

To demonstrate ultrastructural events in the early phase of hepatic metastasis of human colon carcinoma, we intrasplenically injected a highly metastasizable, human colon carcinoma cell line LM-H3 (1 x 10(6) cells) into nude mice, and electron microscopically investigated the hepatic metastasis. At 24 h, tumor cells adhered to the endothelial wall of terminal portal venules and periportal sinusoids. At 48-72 h, after extravasation, they deeply invaded the hepatic cell plate and the interstitial tissue of the portal tract, in which they underwent proliferation and made the metastatic foci. Tumor cells were linked with each other or with surrounding hepatocytes by desmosomes. Desmosomes were maintained during the mitosis. When invading tumor cells were exposed to the bile canaliculi, they generated microvilli on the surface. Microvilli were also formed at the luminal surface of intracytoplasmic inclusions. In the interstitial tissue of the portal tract, tumor cells were closely associated with fibroblasts. However, no junctional specializations were seen between them. The present study demonstrated that human colon carcinoma cell line LM-H3 formed desmosomes with hepatocytes soon after invasion of the hepatic cell plate, suggesting the regulatory role of an interaction with hepatocytes in the growth of metastatic foci within the liver parenchyma.

Peritoneal colonization by human pancreatic cancer cells is inhibited by antisense FUT3 sequence

Several alpha(1,3/1,4) fucosyltransferases expressed in human pancreatic cancer cells can participate in the biosynthesis of cell surface sialyl-Lewis a and sialyl-Lewis x antigens that contribute to hematogenous metastatis. Previously, we observed a significant increase of the alpha(1,4) fucosyltransferase activity in tumoral pancreatic cell lines, suggesting that FUT3 could be involved in the sialyl-Lewis antigen expression. Therefore, we invalidated the expression of FUT3 by expressing FUT3 antisense sequence in the human pancreatic tumor BxPC-3 cell line, which expresses the alpha(1,4) fucosyltransferase activity and harbors the cell surface sialyl-Lewis antigens. The decrease of FUT3 transcript after transfection of antisense cDNA of FUT3 in these cells results in a substantial reduction of sialyl-Lewis antigen expression on cell surface. This decreased antigen expression was associated with an inhibition of adhesive properties to E-selectin and a decrease of metastatic power of FUT3 antisense-transfected BxPC-3 cells as tested in nude mice. Our study provides evidence that the expression level of FUT3 may regulate the expression of sialyl-Lewis a and sialyl-Lewis x surface antigens and consequently could play an important role in metastatic properties of human pancreatic cancer cells.

Molecular detection of disseminated cancer cells in the peripheral blood and expression of sialylated antigens in colon cancers

BACKGROUND AND OBJECTIVES

To improve the survival rate of patients with colon cancer, liver metastases must be eradicated in a clinically occult state. This study was designed to find a predictor for potential liver metastases or micrometastases in colon cancer.

METHODS

Peripheral blood samples and tumor specimens were obtained from 36 patients with colon cancers. The blood samples were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, and the expression of sialylated carbohydrates was also investigated in the tumors immunohistochemically.

RESULTS

A carcinoembryonic antigen (CEA)-specific signal in the blood was detected in 9 of 12 (75%) patients with liver metastasis and in 8 of 24 (33%) patients without liver metastasis, respectively (P < 0.05). The positive rates of sialyl Lewis A (sLeA) and sialyl Lewis X (sLeX) were 36.3% and 40% in tumors without liver metastasis vs. 58.3% and 100% with liver metastasis, respectively. Within a year after surgery, liver metastases became clinically evident in three of the four patients without liver metastasis who showed a CEA-positive signal in their blood preoperatively and who had tumors with a strong expression of sLeX.

CONCLUSIONS

A combination of both markers may provide prognostic information for liver metastases in colon cancer.