Molecular studies into the role of CD44 variants in metastasis in gastric cancer

Understanding Hyaluronan Receptor (CD44) Interaction, HA-CD44 Activated Potential Targets in Cancer Therapeutics

Cancer is a complex mechanism involving a series of cellular events. The glycoproteins such as hyaluronan (HA) are a significant element of extracellular matrix (ECM), involve in the onset of cancer developmental process. The pivotal roles of HA in cancer progression depend on dysregulated expression in various cancer. HA, also gain attention due to consideration as a primary ligand of CD44 receptor. The CD44, complex transmembrane receptor protein, due to alternative splicing in the transcription process, various CD44 isoforms predominantly exist. The overexpression of distinct CD44 isoforms (CD44v) standard (CD44s) depends on the tumour type and stage. The receptor proteins, CD44 engage in a variety of biological processes, including cell growth, apoptosis, migration, and angiogenesis. HA-CD44 interaction trigger survival pathways that result in cell proliferation, invasion ultimately complex metastasis. The interaction and binding of ligand-receptor HA-CD44 regulate the downstream cytoskeleton pathways involve in cell survival or cell death. Thus, targeting HA, CD44 (variant and standard) isoform, and HA-CD44 binding consider as an attractive and useful approach towards cancer therapeutics. The use of various inhibitors of HA, hyaluronidases (HYALs), and utilizing targeted Nano-delivery of anticancer agents and antibodies against CD44, peptides gives promising results in vitro and in vivo. However, they are in clinical trials with favourable and unfavourable outcomes, which reflects the need for various modifications in targeting agents and a better understanding of potential targets in tumour progression pathways.

Molecular weight of surface immobilized hyaluronic acid influences CD44-mediated binding of gastric cancer cells

The physiological importance of the interactions between hyaluronic acid (HA) and its main membrane receptor, CD44, in pathological processes, e.g. cancer, is well recognized. However, these interactions are mainly studied in solution, whereas HA in the extracellular matrix (ECM) is partially immobilized via its interactions with other ECM components. We therefore, developed substrates in which HA is presented in an ECM-relevant manner. We immobilized HA with different molecular weights (Mw) in a Layer-by-Layer (LbL) fashion and studied the interactions of the substrates with CD44 and two human gastric cancer cell lines that overexpress this receptor, namely AGS and MKN45. We demonstrate that MKN45 cells are more sensitive to the LbL substrates as compared with AGS. This difference is due to different CD44 expression: while CD44 is detected mainly in the cytoplasm of AGS, MKN45 express CD44 predominantly at the cell membrane where it is involved in the recognition and binding of HA. The invasiveness of the studied cell lines was also evaluated as a function of HA Mw. Invasive profile characterized by low cell adhesion, high cell motility, high expression of cortactin, formation of invadopodia and cell clusters was observed for MKN45 cells when they are in contact with substrates presenting HA of high Mw.

Alternative Pre-mRNA Splicing in Mammals and Teleost Fish: A Effective Strategy for the Regulation of Immune Responses Against Pathogen Infection

Pre-mRNA splicing is the process by which introns are removed and the protein coding elements assembled into mature mRNAs. Alternative pre-mRNA splicing provides an important source of transcriptome and proteome complexity through selectively joining different coding elements to form mRNAs, which encode proteins with similar or distinct functions. In mammals, previous studies have shown the role of alternative splicing in regulating the function of the immune system, especially in the regulation of T-cell activation and function. As lower vertebrates, teleost fish mainly rely on a large family of pattern recognition receptors (PRRs) to recognize pathogen-associated molecular patterns (PAMPs) from various invading pathogens. In this review, we summarize recent advances in our understanding of alternative splicing of piscine PRRs including peptidoglycan recognition proteins (PGRPs), nucleotide binding and oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) and their downstream signaling molecules, compared to splicing in mammals. We also discuss what is known and unknown about the function of splicing isoforms in the innate immune responses against pathogens infection in mammals and teleost fish. Finally, we highlight the consequences of alternative splicing in the innate immune system and give our view of important directions for future studies.

Mucin-Type O-Glycosylation in Gastric Carcinogenesis

Mucin-type O-glycosylation plays a crucial role in several physiological and pathological processes of the gastric tissue. Modifications in enzymes responsible for key glycosylation steps and the consequent abnormal biosynthesis and expression of their glycan products constitute well-established molecular hallmarks of disease state. This review addresses the major role played by mucins and associated O-glycan structures in Helicobacter pylori adhesion to the gastric mucosa and the subsequent establishment of a chronic infection, with concomitant drastic alterations of the gastric epithelium glycophenotype. Furthermore, alterations of mucin expression pattern and glycan signatures occurring in preneoplastic lesions and in gastric carcinoma are also described, as well as their impact throughout the gastric carcinogenesis cascade and in cancer progression. Altogether, mucin-type O-glycosylation alterations may represent promising biomarkers with potential screening and prognostic applications, as well as predictors of cancer patients' response to therapy.

Utilization of Glycosaminoglycans/Proteoglycans as Carriers for Targeted Therapy Delivery

The outcome of patients with cancer has improved significantly in the past decade with the incorporation of drugs targeting cell surface adhesive receptors, receptor tyrosine kinases, and modulation of several molecules of extracellular matrices (ECMs), the complex composite of collagens, glycoproteins, proteoglycans, and glycosaminoglycans that dictates tissue architecture. Cancer tissue invasive processes progress by various oncogenic strategies, including interfering with ECM molecules and their interactions with invasive cells. In this review, we describe how the ECM components, proteoglycans and glycosaminoglycans, influence tumor cell signaling. In particular this review describes how the glycosaminoglycan hyaluronan (HA) and its major receptor CD44 impact invasive behavior of tumor cells, and provides useful insight when designing new therapeutic strategies in the treatment of cancer.

Low-dose interleukin-8 induces the adhesion, migration and invasion of the gastric cancer SGC-7901 cell line

Interleukin-8 (IL-8), an important inflammatory cytokine, is strongly associated with gastric cancer development and metastasis. High-dose (>1 ng/ml) IL-8 has been revealed to promote the adhesion, migration and invasion of human gastric cancer SGC-7901 cells in a dose-dependent manner. However, the IL-8 level produced by gastric cells is marginal, at even less than 1 ng/ml. It is unclear whether low-dose IL-8 also induces these capacities. In the present study, the effect of low-dose IL-8 on the adhesion, migration and invasion of the SGC-7901 cell line and the underlying molecular mechanism with regard to cluster of differentiation 44 (CD44) were investigated. The SGC-7901 cells were exposed to various concentrations of IL-8 (0, 0.2, 0.5, 0.8 and 1 ng/ml) in vitro. The adhesion of the SGC-7901 cells to fibronectin, an extracellular matrix component, was then detected by cell counting kit 8 assay. Migration and invasion abilities were evaluated by wound scratch and Transwell chamber assays. In addition, protein and mRNA levels of CD44 were measured using immunofluorescence and western blotting, and quantitative polymerase chain reaction, respectively, in cells cultured for 72 h. Following the exposure of the SGC-7901 cells to the various low doses of IL-8, the cell adhesion, migration and invasion capacities were promoted by IL-8, but not in a significant dose-dependent manner. Low-dose IL-8 upregulated the protein and mRNA expression of CD44. In conclusion, low-dose IL-8 potently induces the adhesion, migration and invasion of SGC-7901 cells, and the regulation of CD44 expression is one of the potential molecular mechanisms involved.

Interactions between Hyaluronan and Its Receptors (CD44, RHAMM) Regulate the Activities of Inflammation and Cancer

The glycosaminoglycan hyaluronan (HA), a major component of extracellular matrices, and cell surface receptors of HA have been proposed to have pivotal roles in cell proliferation, migration, and invasion, which are necessary for inflammation and cancer progression. CD44 and receptor for HA-mediated motility (RHAMM) are the two main HA-receptors whose biological functions in human and murine inflammations and tumor cells have been investigated comprehensively. HA was initially considered to be only an inert component of connective tissues, but is now known as a “dynamic” molecule with a constant turnover in many tissues through rapid metabolism that involves HA molecules of various sizes: high molecular weight HA (HMW HA), low molecular weight HA, and oligosaccharides. The intracellular signaling pathways initiated by HA interactions with CD44 and RHAMM that lead to inflammatory and tumorigenic responses are complex. Interestingly, these molecules have dual functions in inflammations and tumorigenesis. For example, the presence of CD44 is involved in initiation of arthritis, while the absence of CD44 by genetic deletion in an arthritis mouse model increases rather than decreases disease severity. Similar dual functions of CD44 exist in initiation and progression of cancer. RHAMM overexpression is most commonly linked to cancer progression, whereas loss of RHAMM is associated with malignant peripheral nerve sheath tumor growth. HA may similarly perform dual functions. An abundance of HMW HA can promote malignant cell proliferation and development of cancer, whereas antagonists to HA-CD44 signaling inhibit tumor cell growth in vitro and in vivo by interfering with HMW HA-CD44 interaction. This review describes the roles of HA interactions with CD44 and RHAMM in inflammatory responses and tumor development/progression, and how therapeutic strategies that block these key inflammatory/tumorigenic processes may be developed in rodent and human diseases.

CD44 family proteins in gastric cancer: a meta-analysis and narrative review

With a meta-analysis and narrative review, we evaluated the clinical and prognostic role of all CD44 family proteins in gastric cancer (GC). Literatures published up to August 2014 were searched on PubMed. Among the 37 eligible studies (6606 patients), 34 were included in meta-analysis, and 10 were subjected to narrative review. With meta-analysis, standard CD44 (CD44s) was demonstrated to predict reduced overall survival (OS) (HR = 1.93, 95% CI: 1.58-2.34, PHR = 0.0222) and disease free survival (HR = 3.13, 95% CI: 1.02-9.68, PHR = 0.0469), advanced N-stage (RR = 1.12, 95% CI: 1.04-1.21, PRR = 0.0019), and distant metastasis (RR = 2.14, 95% CI: 1.46-3.14, PRR < 0.0001) of GC. CD44 variant 6 (CD44v6) in GC might influence OS (5 studies; HR = 1.27, 95% CI: 0.75-2.14, PHR = 0.3783; 4 studies; HR = 1.52, 95% CI: 1.09-2.14, PHR = 0.0139), while significantly associated with N-stage (RR = 1.23, 95% CI: 1.03-1.48, PRR = 0.0240), M-stage (RR = 2.54, 95% CI: 1.08-6.00, PRR = 0.0333), TNM-stage (RR = 1.72, 95% CI: 1.18-2.50, PRR = 0.0045), Lauren type (RR = 0.67, 95% CI: 0.50-0.91, PRR = 0.0106), lymphatic invasion (RR = 1.13, 95% CI: 1.04-1.23, PRR = 0.0057), and liver metastasis (RR = 3.20, 95% CI: 1.94-5.27, PRR < 0.0001) of the disease. Moreover, a narrative review was performed for CD44 isoforms, such as v3, v5, v7, v8-10, and v9, in GC. In conclusion, CD44s and CD44v6 as evaluated by immunohistochemistry, respectively, predicts the prognosis and disease severity of GC.

Metastasis review: from bench to bedside

Cancer is the final result of uninhibited cell growth that involves an enormous group of associated diseases. One major aspect of cancer is when cells attack adjacent components of the body and spread to other organs, named metastasis, which is the major cause of cancer-related mortality. In developing this process, metastatic cells must successfully negotiate a series of complex steps, including dissociation, invasion, intravasation, extravasation, and dormancy regulated by various signaling pathways. In this review, we will focus on the recent studies and collect a comprehensive encyclopedia in molecular basis of metastasis, and then we will discuss some new potential therapeutics which target the metastasis pathways. Understanding the new aspects on molecular mechanisms and signaling pathways controlling tumor cell metastasis is critical for the development of therapeutic strategies for cancer patients that would be valuable for researchers in both fields of molecular and clinical oncology.

CD44v/CD44s expression patterns are associated with the survival of pancreatic carcinoma patients

Background and purpose

CD44 variants have been associated with tumor invasion and metastasis, but CD44 expression patterns have not been systematically investigated in pancreatic carcinoma. This study systematically investigated whether CD44 expression patterns are involved in pancreatic carcinoma metastasis and prognosis.

Methods

We applied primers specific for all CD44 variants and CD44s to analyze the expression patterns of CD44 (CD44v2-CD44v10 and CD44s) using quantitative real-time PCR (qRT-PCR). We then further evaluated their roles in pancreatic carcinoma metastasis and prognosis using clinical survival analysis.

Results

Increased CD44v expression and decreased CD44s expression were found in metastatic pancreatic carcinoma in three different cell lines and in human tumor tissue. Clinical analysis showed that CD44v6⁺ and CD44v9⁺ were correlated with lymph node metastasis, liver metastasis and TNM stage. However, CD44s⁻ was associated with liver metastasis, tumor differentiation and TNM stage. Survival analysis showed that patients with CD44v6⁺/CD44s⁻ or CD44v6⁺/CD44s⁻ had lower overall survival (OS) rates, although the individual expression of CD44v6, CD44v9 and CD44s was also related to decreased OS rates. Univariate analysis showed that lymph node metastasis; vessel invasion; hepatic metastases; TNM stage; and individual or co-expression of CD44v6, CD44v9 and CD44s were risk factors affecting survival. Multivariate analysis showed that CD44v6⁺/CD44s⁻ was an independent predictor of survival.

Conclusions

We found that CD44v6⁺, CD44v9⁺ and CD44s⁻ were associated with pancreatic carcinoma metastasis and progression and that CD44v6⁺/CD44s⁻ was an independent risk factor affecting survival in pancreatic carcinoma. Therefore, the different expression patterns of CD44v/CD44s may determine pancreatic carcinoma prognosis.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1579257224116287.

Immunohistochemical Analysis of p53, Ki-67, CD44, HER-2/neu Expression Patterns in Gastric Cancer, and Their Association with One Year Survival in North-West of Iran

INTRODUCTION

Gastric cancer remains the second most common cause of cancer-related deaths worldwide. In many malignancies like, lung and breast, multiple prognostic factors are known, such as mutations in Ki-67, HER-2/neu, p53. In this study, we evaluated immunohistochemical protein expression patterns of cell-cycle-regulators p53, proliferation marker Ki-67, surface expression of CD44, HER-2/neu oncogene proposed as useful prognostic factors.

METHODS

In this descriptive-analytic study, we evaluate 100 patients with gastric cancer who were referred to Shahid Ghazi Hospital or other oncology clinics of Tabriz University of Medical Sciences in 2005-2010. Patients with pathologic confirmation of gastric cancer were selected. Expression of p53, ki-67, CD-44, HER-2/neu were detected by immunohistochemical staining.

RESULTS

In this study, 100 patients with gastric cancer participated. 76(76%) were men and 24(24%) were women with mean age of 64.02(8.05) years. Seventy two samples were intestinal type and 28 were diffuse type. CD44 was positive in 27(27%) patients. P53 was positive in 35(35%) patients. Ki-67 was positive in 53(53%) patients. HER-2/neu was positive in 51(51%) patients.

CONCLUSION

The frequency of positive p53, Ki-67, CD44 and HER-2/neu varied in different studies. Positive Ki-67 and HER-2/neu were not associated with changes in survival but positive p53 and CD44 were significantly associated with improved survival.

Cancer-Associated Perturbations in Alternative Pre-messenger RNA Splicing

For most of our 25,000 genes, the removal of introns by pre-messenger RNA (pre-mRNA) splicing represents an essential step toward the production of functional messenger RNAs (mRNAs). Alternative splicing of a single pre-mRNA results in the production of different mRNAs. Although complex organisms use alternative splicing to expand protein function and phenotypic diversity, patterns of alternative splicing are often altered in cancer cells. Alternative splicing contributes to tumorigenesis by producing splice isoforms that can stimulate cell proliferation and cell migration or induce resistance to apoptosis and anticancer agents. Cancer-specific changes in splicing profiles can occur through mutations that are affecting splice sites and splicing control elements, and also by alterations in the expression of proteins that control splicing decisions. Recent progress in global approaches that interrogate splicing diversity should help to obtain specific splicing signatures for cancer types. The development of innovative approaches for annotating and reprogramming splicing events will more fully establish the essential contribution of alternative splicing to the biology of cancer and will hopefully provide novel targets and anticancer strategies. Metazoan genes are usually made up of several exons interrupted by introns. The introns are removed from the pre-mRNA by RNA splicing. In conjunction with other maturation steps, such as capping and polyadenylation, the spliced mRNA is then transported to the cytoplasm to be translated into a functional protein. The basic mechanism of splicing requires accurate recognition of each extremity of each intron by the spliceosome. Introns are identified by the binding of U1 snRNP to the 5' splice site and the U2AF65/U2AF35 complex to the 3' splice site. Following these interactions, other proteins and snRNPs are recruited to generate the complete spliceosomal complex needed to excise the intron. While many introns are constitutively removed by the spliceosome, other splice junctions are not used systematically, generating the phenomenon of alternative splicing. Alternative splicing is therefore the process by which a single species of pre-mRNA can be matured to produce different mRNA molecules (Fig. 1). Depending on the number and types of alternative splicing events, a pre-mRNA can generate from two to several thousands different mRNAs leading to the production of a corresponding number of proteins. It is now believed that the expression of at least 70 % of human genes is subjected to alternative splicing, implying an enormous contribution to proteomic diversity, and by extension, to the development and the evolution of complex animals. Defects in splicing have been associated with human diseases (Caceres and Kornblihtt, Trends Genet 18(4):186-93, 2002, Cartegni et al., Nat Rev Genet 3(4):285-98, 2002, Pagani and Baralle, Nat Rev Genet 5(5):389-96, 2004), including cancer (Brinkman, Clin Biochem 37(7):584-94, 2004, Venables, Bioessays 28(4):378-86, 2006, Srebrow and Kornblihtt, J Cell Sci 119(Pt 13):2635-2641, 2006, Revil et al., Bull Cancer 93(9):909-919, 2006, Venables, Transworld Res Network, 2006, Pajares et al., Lancet Oncol 8(4):349-57, 2007, Skotheim and Nees, Int J Biochem Cell Biol 39:1432-1449, 2007). Numerous studies have now confirmed the existence of specific differences in the alternative splicing profiles between normal and cancer tissues. Although there are a few cases where specific mutations are the primary cause for these changes, global alterations in alternative splicing in cancer cells may be primarily derived from changes in the expression of RNA-binding proteins that control splice site selection. Overall, these cancer-specific differences in alternative splicing offer an immense potential to improve the diagnosis and the prognosis of cancer. This review will focus on the functional impact of cancer-associated alternative splicing variants, the molecular determinants that alter the splicing decisions in cancer cells, and future therapeutic strategies.

Secreted 70kDa lumican stimulates growth and inhibits invasion of human pancreatic cancer

Lumican expression in the stromal tissues of pancreatic ductal adenocarcinoma (PDAC) correlates with tumor invasion, and tends to correlate with poor prognosis. We used gene transfection techniques to examine the biological roles of lumican secreted from PDAC cells. Lumican-transfected PANC-1 cells secreted a 70-kDa lumican protein and had an active ERK pathway. Transfection stimulated PANC-1 cell growth, increased cell adhesion to laminin, inhibited cell invasion, and decreased active matrix metalloproteinase-9. Down-regulation of lumican using siRNA resulted in opposite cell behavior. Thus, the 70-kDa lumican secreted by PDAC cells plays important roles in cell growth and invasion.

The Role of CD44 in the Pathogenesis, Diagnosis, and Therapy of Gastric Cancer

CD44 is a transmembrane glycoprotein and surface receptor for hyaluronan that is involved in the response of cells to their microenvironment. CD44 splice variants play roles in carcinogenesis, differentiation, and lymph node metastasis and are predictive of the prognosis for various carcinomas, including gastric cancer. Current data suggest that gastric tissue stem cells and gastric cancer stem cells both express the splice variant, CD44v9. Overall, the data regarding the alterations that occur in CD44 and its splice variants in response to acute and chronic infection with Helicobacter pylori are scant and poorly elucidated in terms of possible changes in expression that occur in gastric cancer precursor lesions, such as chronic atrophic gastritis, pyloric metaplasia and intestinal metaplasia. In this study, we discuss the available data and suggest which new data would likely be useful in clinical practice. We also discuss the potential for CD44-targeted therapeutic strategies in gastric cancer. CD44 and its splice variants are positively associated with the initiation and progression of gastric cancer and may also play important roles in diagnosis, therapy and prognosis. CD44 research has been active but fragmented, and it may offer new therapeutic approaches to gastric cancer.

The Role of CD44 in the Pathogenesis, Diagnosis, and Therapy of Gastric Cancer

CD44 is a transmembrane glycoprotein and surface receptor for hyaluronan that is involved in the response of cells to their microenvironment. CD44 splice variants play roles in carcinogenesis, differentiation, and lymph node metastasis and are predictive of the prognosis for various carcinomas, including gastric cancer. Current data suggest that gastric tissue stem cells and gastric cancer stem cells both express the splice variant, CD44v9. Overall, the data regarding the alterations that occur in CD44 and its splice variants in response to acute and chronic infection with Helicobacter pylori are scant and poorly elucidated in terms of possible changes in expression that occur in gastric cancer precursor lesions, such as chronic atrophic gastritis, pyloric metaplasia and intestinal metaplasia. In this study, we discuss the available data and suggest which new data would likely be useful in clinical practice. We also discuss the potential for CD44-targeted therapeutic strategies in gastric cancer. CD44 and its splice variants are positively associated with the initiation and progression of gastric cancer and may also play important roles in diagnosis, therapy and prognosis. CD44 research has been active but fragmented, and it may offer new therapeutic approaches to gastric cancer.

Nuclear translocation of β-catenin correlates with CD44 upregulation in Helicobacter pylori-infected gastric carcinoma

Infection with Helicobacter pylori CagA-positive strains is associated with gastric adenocarcinoma. CagA H. pylori activates the β-catenin signal by translocation into nucleus which promotes carcinogenesis. Deregulated accumulation of nuclear β-catenin enhances transcription of β-catenin target genes including CD44 and promotes malignant transformation. The aim of this study was to investigate whether nuclear translocation of β-catenin correlates with CD44 expression in CagA H. pylori-infected gastric carcinoma. To address these issues, we examined 140 gastric biopsy specimens by using immunohistochemical and immunofluorescence staining, Western blot, and mutational analysis of the exon 3 β-catenin gene. The nuclear localization of β-catenin was significantly (χ(2) = 21.175; P < 0.001) increased in advanced gastric carcinoma and also correlated (χ(2) = 22.857; P < 0.001) with the CagA H. pylori positive specimens. We also observed that tyrosine-phosphorylated β-catenin was significantly (χ(2) = 14.207; P < 0.001) increased in samples showing nuclear localization of β-catenin and also it correlated (χ(2) = 43.69; P < 0.03) with the CagA H. pylori positive specimens. Exon 3 β-catenin gene mutation was not detected in H. pylori-infected gastric carcinoma. CD44 up regulation was significantly associated with tyrosine-phosphorylated β-catenin (χ(2) = 22.5; P < 0.001), and this change was closely associated with nuclear translocation of β-catenin (χ(2) = 13.393; P < 0.001) in CagA H. pylori-infected gastric carcinoma. In conclusion, our data suggest that CagA H. pylori infection is responsible for the tyrosine phosphorylation of β-catenin and its nuclear translocation, which upregulates β-catenin target gene CD44 in gastric carcinoma.

EpCAM: a potential antimetastatic target for gastric cancer

PURPOSE

Epithelial cellular adhesion molecule (EpCAM) is an attractive immunotherapeutic target to overcome metastasis of a variety of epithelium-oriented cancers. Edrecolomab, one kind of EpCAM monoclonal antibody (Panorex), has been approved for clinical application as postoperative adjuvant therapy in breast and colorectal cancer. However, the role of EpCAM in gastric cancer metastasis remains unclear.

RESULTS

EpCAM was found to be more highly overexpressed in metastatic gastric cancer than in nonmetastatic samples by immunohistochemistry staining. The expression level of EpCAM in gastric cancer cell lines was determined by reverse-transcription polymerase chain reaction (RT-PCR) and Western blotting, respectively. Downregulation of EpCAM by small interfering RNA (siRNA) significantly suppressed in vitro adhesive, invasive, and migratory and in vivo metastatic abilities of gastric cancer cells.

CONCLUSION

We provide first evidence that EpCAM contributes to the migration of gastric cancer, suggesting that EpCAM-targeted therapy might be a promising strategy in metastatic gastric cancer.

CD44, a therapeutic target for metastasising tumours

Members of the CD44 family of transmembrane glycoproteins, in particular CD44v6 isoforms, were shown to be metastatic determinants of rat pancreatic tumour cells back in the early 1990s. Furthermore, the expression of several CD44 proteins correlates with aggressive stages of various human cancers. Because of the frequent and homogeneous expression of CD44v6 isoforms in squamous cell carcinoma, antibodies recognising these proteins were used in clinical trials for patients suffering from head and neck squamous cell carcinoma (HNSCC). Although the phase I clinical trials looked promising, the studies were abruptly ended after the death of a patient. Despite the termination of the trials, CD44 certainly remains a valid target for anti-cancer therapy. In this review, alternative strategies targeting CD44 functions are presented. These functions include the binding to hyaluronan (HA), the collaboration with osteopontin and the contribution of CD44 isoforms to receptor tyrosine kinase (RTKs) activation. These new attempts led to the development of peptides that interfere for example with HA binding and that might be used to induce apoptosis in mammary carcinoma or to prevent homing of leukaemia stem cells. Other peptides block RTK activation and thereby inhibit tumour angiogenesis and metastatic spread.

Altered expression of glycan genes in cancers induced by epigenetic silencing and tumor hypoxia: clues in the ongoing search for new tumor markers

The glycan molecules that preferentially appear in cancers are clinically utilized as serum tumor markers. The exact reason, however, why glycans are useful as tumor markers remain elusive. Here, we will summarize lessons learned from well-established cancer-associated glycans, and propose strategies to develop new cancer markers. Our recent results on cancer-associated glycans, sialyl Lewis A and sialyl Lewis X, indicated that the repressed transcription of some glycan genes by epigenetic silencing during early carcinogenesis, and the transcriptional induction of some other glycan genes by tumor hypoxia accompanying cancer progression at locally advanced stages, are two major factors determining cancer-associated glycan expression. Multiple genes are involved in glycan synthesis, and epigenetic silencing of a part of such genes leads to accumulation of glycans having truncated incomplete structures, which are readily detected by specific antibodies. Glycans are very unique and advantageous as marker molecules because they are capable of reflecting epigenetic silencing in their structures. Transcriptional induction of some glycan genes by tumor hypoxia at the later stages produces further glycan modifications, such as an unusual increase of the N-glycolyl sialic acid residues in the glycan molecules. The entire process of malignant transformation thus creates abnormal glycans, whose structures reveal the effects of both epigenetic silencing and tumor hypoxia. The second advantage of a glycan marker over a proteinous marker is that they can reflect the plurality of genetic anomalies in a singular molecule, as it is synthesized by the cooperative action of multiple genes. Glycans are sometimes covalently bound to well-known cancer-associated proteins, such as CD44v, and this eventually contributes to a high cancer specificity and functional relevancy in cancer progression.

Expression of cell adhesion molecule CD44 in gastric adenocarcinoma and its prognostic importance

AIM: To evaluate the relation of cluster of differentiation 44 (CD44) expression with clinicopathological features of gastric adenocarcinoma, and also its effect on prognosis with an emphasis on the differences between intestinal and diffuse types.

METHODS: From 2000 to 2006, 100 patients with gastric adenocarcinoma, who had undergone total or subtotal gastrectomy without any prior treatment, were studied. Haematoxylin & eosin (HE) staining was used for histological evaluation, including the type (Lauren’s classification) and grading of the tumor. The expression of CD44 in the gastric adenocarcinoma mucosa and the adjacent mucosa were determined by immunohistochemistry. The survival analysis was obtained using the Kaplan-Meier test.

RESULTS: Of 100 patients, 74 (74%) patients were male. The tumors were categorized as intestinal type (78%) or diffuse type (22%). Sixty-five percent of patients were CD44-positive. CD44 expression was not detected in normal gastric mucosa. Rather, CD44 was more commonly expressed in the intestinal subtype (P = 0.002). A significant relation was seen between the grade of tumor and the expression of CD44 (P = 0.014). The survival analysis showed a poor prognosis of patients with CD44-positive tumors (P = 0.008); and this was more prominent in the intestinal (P = 0.001) rather than diffuse type.

CONCLUSION: Cell adhesion molecule CD44 is highly expressed in gastric adenocarcinoma. CD44 expression is correlated with a poor prognosis in patients with the intestinal type of gastric adenocarcinoma. CD44 can, therefore, be utilized as a prognostic marker for this group of patients.

Genetic and phenotypic heterogeneity in the PTEN hamartoma tumour syndrome

Germline PTEN (Phosphatase and TENsin homologue deleted on chromosome TEN) mutations predispose to phenotypically diverse disorders that share several overlapping clinical features: Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome, Proteus syndrome and Proteus-like syndrome, collectively classified as PTEN hamartoma tumour syndrome (PHTS). The meticulous acquisition and documentation of PHTS phenotypic data at different levels and the profiling of the plethora of genetic changes in PTEN and other genes within the same or related pathways are important in resolving the challenge of discriminating heritable cancers from sporadic PHTS-mimicking clinical features. The characterization of PTEN and PTEN-related pathways from a multidisciplinary perspective underscores the importance of incorporating data from different -omics, which is crucial for the advancement of personalized medicine.

Expression of seven gastric cancer-associated genes and its relevance for Wnt, NF-kappaB and Stat3 signaling

The aim of the current study was to profile c-Myc, standard CD44 (CD44s), CD44v6, cyclin D1, survivin, MMP-7 and VEGF expression patterns in different gastric samples and to elucidate their relevance for Wnt, NF-kappaB and/or Stat3 activation using multiple experimental approaches. The results revealed that 87.1% (27/31) of gastric cancers and 8.7% (2/23) of noncancerous lesions (chronic gastritis and intestinal metaplasia) showed Wnt activation (Wnt(+)) that was closely related to the expression of the seven genes. Some Wnt(-) noncancerous lesions also expressed the above-mentioned genes, higher frequencies of survivin (7/8), VEGF (7/8), cyclin D1 (6/8) and c-Myc (5/8) but not CD44s (2/8), CD44v6 (3/8) and MMP-7 (2/8) being detected in the NF-kappaB(+) samples. Stat3 was activated in 37/54 gastric tissues, and in 3/4 VEGF, 4/6 c-Myc, 4/8 survivin, 2/4 MMP-7, 1/2 CD44v6, and 4/9 cyclin D1(+) but Wnt(-)/NF-kappaB(-) samples. These findings showed a close correlation in GCs between Wnt, NF-kappaB and Stat3 signaling and expression of the seven genes, the importance of NF-kappaB and Stat3 activation in regulating c-Myc, survivin, cyclin D1 and VEGF in noncancerous lesions, and the potential coordinative effects of these three signalings on GC formation presumably by promoting the transcription of their common target genes.

Distinct expression profiles for PTEN transcript and its splice variants in Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome

Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba syndrome (BRRS) are autosomal dominant hamartoma syndromes. Germline PTEN mutations have been associated with 85% of CS cases and 65% of BRRS cases and also with other disorders, which are collectively referred to as the "PTEN hamartoma tumor syndrome." The human PTEN gene has been previously found to express two naturally occurring splice variants (SVs). Recently, we identified eight novel naturally occurring PTEN SVs that result in different downstream signaling effects: SV3a, SV3b, SV3c (inclusion of various lengths of intron 3 3' of exon 3), SV5a, SV5b, SV5c, SV5d (inclusion of various lengths of intron 5 3' of exon 5), and SV Delta Ex6 (deletion of exon 6). We therefore sought to characterize the relative expression of 5', middle, and 3' full-length PTEN mRNA (FL-PTEN) and also of these eight PTEN SVs in 85 (65 female and 20 male) patients with CS/BRRS (with or without PTEN mutations) compared with 27 controls, using a SYBR green quantitative polymerase chain reaction method. Significantly reduced FL-PTEN levels were found in the probands, compared with those of controls (P < .01). Apart from FL-PTEN, SV3a is the most consistently relatively underexpressed in patients compared with controls. The patients showed relative underexpression of SV3a and SV3b and overexpression of SV5b (P = .005, P = .02, and P = .04, respectively). Indeed, there appears to be an SV expressional genotype-phenotype correlation in which the SV expressional profiles are distinct among CS, CS-like, and BRRS. The reduced FL-PTEN transcript expression, associated with differential expression of PTEN SVs, regardless of PTEN mutation status, supports the concept that modulation of PTEN inactivation may also occur at the transcription level influencing the specific phenotypes seen in these syndromes.

Gene expression profiling in intestinal-type gastric carcinoma by cDNA microarray

AIM: To identify a set of genes involved in the development of intestinal-type gastric carcinoma.

METHODS: Pure mRNAs from 6 cases of intestinal-type gastric carcinoma and corresponding noncancerous mucosae were reversely transcribed into cDNAs labeled with Cy5 and Cy3 dyes for probes, then mixed and hybridized with the cDNA microarray consisting of 4 096 genes, and the fluorescent signals were scanned.

RESULTS: Among total genes, 333 were up-regulated and 333 down-regulated in intestinal-type gastric cancer tissues. Within altered expression of those genes, cell-cycle regulators and growth factors were up-regulated, and the promoter genes of apoptosis were down-regulated; Oncogenes and cell-adhesion molecules were more up-regulated; The cancer progression genes were up-regulated, while the anti-cancer progression genes were down-regulated.

CONCLUSION: The quick and high-throughout method of gene expression profile by cDNA array provides us with an overview of gene changes that may involved in intestinal-type gastric cancer development, and will open up new possibilities to identify novel molecular targets for diagnosis and therapy. Several genes are altered in intestinal-type gastric cancer, which need to be further investigated.

Effect of P-selectin monoclonal antibody on metastasis of gastric cancer and immune function

AIM: To investigate the effect of cell adhesion molecule P-selectin monoclonal antibody (Mab) on metastasis and immune function of mice orthototopically implanted with human gastric cancer tissue.

METHODS: SCID mice were implanted orthotopically with SGC-7901 human gastric carcinoma tissue. Starting from day 3 after operation, animals were given intravenously PBS or P-selectin Mab (100 μg/injection) (for both normal mice and tumor-implanted mice with tumors), twice weekly for 3 wk. Two animals in each group were sacrificed randomly at the 1st, 2nd, 4th week and 6th week. While T cell and B cell transformation indices were determined with the ³H TdR infiltration method, the NK cell activity was detected by the LDH release method.

RESULTS: The metastatic rate in the P-selectin Mab treated group was lower than that in the PBS treated group (with tumors). The NK activity of normal mice increased over time. The immune functions (T, B cell function, NK activity) of the tumor group in the 6th week were significantly lower than those in the 4th week, but the change was attenuated by P-selectin Mab.

CONCLUSION: P-selectin Mab could suppress the metastasis of gastric cancer with no adverse effect on host immune function.

Prognostic significance of CD44v5 expression in human thymic epithelial neoplasms

BACKGROUND

Cell surface glycoproteins of the CD44 family play roles in cell-cell and cell-matrix interactions. Their aberrant expression has been implicated in tumor invasion and metastasis of a variety of neoplasms, but not, to date, of thymic epithelial tumors.

METHODS

To investigate the expression of CD44 molecules, immunohistochemical staining using monoclonal antibodies against human CD44 standard form (CD44 s) and two common splicing variant (CD44v) isoforms, CD44v5 and CD44v6, was performed on 64 resected thymomas and 20 normal thymuses. These tumors were categorized histologically according to the World Health Organization (WHO) histologic classification, and the pathologic staging was classified according to the definitions of Masaoka.

RESULTS

The positive expression rates in these patients were as follows: CD44 s (normal thymuses, 10%; thymomas, 22%), CD44v5 (normal thymuses, 0%; thymomas, 67%), and CD44v6 (normal thymuses, 0%; thymomas, 26%). CD44 s and CD44v5 immunoreactivity showed a positive correlation with tumor stages (p = 0.034 and 0.027, respectively). The CD44v5 expression of neoplastic cells in tumor capsules has significant correlation with tumor stages (II, 5%; III, 70%; IVA, 100%; p < 0.001). On the basis of univariate survival analysis, the Masaoka staging system, WHO histologic classification, and CD44v5 expression showed a statistically significant positive relation to survival (p < 0.001, 0.002, 0.011, respectively). Using Cox's regression model, increasing CD44v5 expression, the Masaoka staging, and the WHO classification system were found to be significant independent prognostic factors.

CONCLUSIONS

CD44v5 expression is independently positively correlated with the aggressiveness of thymic epithelial tumors. The expression of CD44v5 may be a potential trigger of tumor invasion in thymomas.

A gene encoding an apurinic/apyrimidinic endonuclease-like protein is up-regulated in human gastric cancer

AIM: To identify the gene that may predispose to human gastric cancer and to analyze its expression in gastric cancer and non-tumorous gastric mucosa.

METHODS: Cancer, para-tumor, and non-tumor gastric tissues were studied for gene expression profile using fluorescent differential display reverse transcription polymerase chain reaction (DDRT-PCR). The differentially expressed bands of interest were analyzed by cloning, Northern blotting, and sequencing. The sequencing results were compared with the GenBank database for homology and conserved domain analysis. In situ hybridization with DIG-labeled cRNA probes was used to detect the expression of gene in paraffin embedded gastric adenocarcinoma and non-cancerous tissues.

RESULTS: A gene expressed higher in tumor and para-tumor tissues than in their non-tumor counterparts of all 7 tested gastric adenocarcinoma patients was identified by means of DDRT-PCR analysis. It was named GCRG213 (gastric cancer related gene 213). Northern blot confirmed the differential expression. GCRG213 (GenBank No. AY053451) consisted of 1094 base pairs with an open reading frame (ORF) which encoded 142 amino acids. The deduced amino acid sequence contained a putative conserved domain, apurinic/apyrimidinic endonuclease (APE). In situ hybridization analysis showed that GCRG213 was expressed higher in gastric cancer tissues than in their corresponding non-tumor ones. Precancerous leisions of gastric adenocarcinoma showed a high GCRG213 expression, too. No difference of the expression patterns was found between the early and advanced gastric cancer.

CONCLUSION: A gene named GCRG213 was identified in human gastric adenocarcinoma. It encoded an APE-like protein which was probably a new member of the APE family. GCRG213 was over-expressed not only in gastric cancer, but also in its precancerous leisions. The role of GCRG213 expression in carcinogenesis needs further study.

Differential gene expression profiles of gastric cancer cells established from primary tumour and malignant ascites

Advanced gastric cancer is often accompanied by metastasis to the peritoneum, resulting in a high mortality rate. Mechanisms involved in gastric cancer metastasis have not been fully clarified because metastasis involves multiple steps and requires a combination of altered expressions of many different genes. Thus, independent analysis of any single gene would be insufficient to understand all of the aspects of gastric cancer peritoneal dissemination. In this study, we performed a global analysis of the differential gene expression of a gastric cancer cell line established from a primary main tumour (SNU-1) and of other cell lines established from the metastasis to the peritoneal cavity (SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB). The application of a high-density cDNA microarray method made it possible to analyse the expression of approximately 21 168 genes. Our examinations of SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB showed that 24 genes were up-regulated and 17 genes down-regulated besides expression sequence tags. The analysis revealed the following altered expression such as: (a) up-regulation of CD44 (cell adhesion), keratins 7, 8, and 14 (epitherial marker), aldehyde dehydrogenase (drug metabolism), CD9 and IP3 receptor type3 (signal transduction); (b) down-regulation of IL2 receptor gamma, IL4-Stat (immune response), p27 (cell cycle) and integrin beta4 (adhesion) in gastric cancer cells from malignant ascites. We then analysed eight gastric cancer cell lines with Northern blot and observed preferential up-regulation and down-regulation of these selected genes in cells prone to peritoneal dissemination. Reverse transcriptase-polymerase chain reaction confirmed that several genes selected by DNA microarray were also overexpressed in clinical samples of malignant ascites. It is therefore considered that these genes may be related to the peritoneal dissemination of gastric cancers. The results of this global gene expression analysis of gastric cancer cells with peritoneal dissemination, promise to provide a new insight into the study of human gastric cancer peritoneal dissemination.

[Relationship between lymphatic metastasis in breast and cervix cancers and the level of CD44-H expression evaluated by an immunohistochemical method]

Immunohistochemistry has been used to evaluate the relationship between the rate of CD44-H antigen expression in breast invasive intracanalicuar and cervical epidermoïd carcinomas and the presence of node metastasis. A total of 36 cases of breast carcinoma and 20 cases of cervical carcinoma was examined. For the two types of carcinoma, the CD44-H molecule was highly expressed in cases with node metastasis; with 50% and 75% median value of CD44-H positive tumor cells respectively for the breast (p < 0.02) and for the uterine cervix (p < 0.05) compared to respectively 10% and 37.5% in the cases without node metastasis. The expression of this molecule increases with invasive potential of tumor cells and the use of this antigen for prognostic ends may be possible.

Proteolysis-inducing factor regulates hepatic gene expression via the transcription factors NF-(kappa)B and STAT3

A novel protein, proteolysis-inducing factor (PIF), has been isolated from the urine of patients with pancreatic cancer and is capable of inducing muscle proteolysis in vitro. Only adult skeletal muscle and liver exhibit substantial binding of PIF. We have investigated the effect of PIF on hepatic gene expression. Primary cultures of human hepatocytes and the human cell line HepG2 were incubated in the presence of PIF to assess its effects on hepatic transcription factors, proinflammatory cytokine production, and acute phase proteins. PIF activates both the transcription factors NF-kB and STAT3, which result in the increased production of IL-8, IL-6, and C-reactive protein and the decreased production of transferrin. The function of PIF, beyond muscle degradation, is unknown but here we show that it is involved in hepatic gene expression, and is thus likely to be involved in the proinflammatory response observed in cachexia. These results may also suggest a potential role for PIF during embryonic development. The expression of PIF peaks during the embryonic period E8 to E9, a stage that is crucial in the development of skeletal muscle and liver and during which both NF-kB and STAT3 activation can also be observed.