CD44 splice variants: metastases meet lymphocytes

Circulating and disseminated tumor cells: diagnostic tools and therapeutic targets in motion

Enumeration of circulating tumor cells (CTCs) in peripheral blood with the gold standard CellSearchTM has proven prognostic value for tumor recurrence and progression of metastatic disease. Therefore, the further molecular characterization of isolated CTCs might have clinical relevance as liquid biopsy for therapeutic decision-making and to monitor disease progression. The direct analysis of systemic cancer appears particularly important in view of the known disparity in expression of therapeutic targets as well as epithelial-to-mesenchymal transition (EMT)-based heterogeneity between primary and systemic tumor cells, which all substantially complicate monitoring and therapeutic targeting at present. Since CTCs are the potential precursor cells of metastasis, their in-depth molecular profiling should also provide a useful resource for target discovery. The present review will discuss the use of systemically spread cancer cells as liquid biopsy and focus on potential target antigens.

Histomolecular Structural Aspects of High Endothelial Vessels in Lymph Node and Its Significance in Oral Cancer and Metastasis

Molecular cancer research studies focus on identifying diagnostic, screening, and metastatic indicators, and monitoring therapeutic responses. Migration of tumor cells and lymphocytes are important aspects in metastasis. High endothelial vessels are specialized histological structures identified in the blood vessels in lymphoid organs, which allow the migration of lymphocytes. In the recent decades, the role of high endothelial vessels is being addressed in cancer metastatic research. This review article is to highlight the histological and molecular structural aspects of high endothelial venules (HEVs) in the lymph node, and to demonstrate the role of HEVs in oral cancer metastasis, specifically oral and pharyngeal squamous cell carcinoma. The literature for the present paper were searched from the data sources such as Medline/PubMed, CINAHL plus, and gray literature sources from inception to May 2015. Searches were conducted using both free texts and medical subject headings related to the title of the present paper. Only the full text manuscripts of the search results that support the objective(s) of the paper and papers written in English were included. HEVs are unique structures that are identified in the lymphocytes and primarily assist in the lymphocytic migration from the blood stream into the lymph node. Understanding the histomolecular characteristics of HEV will allow researchers to develop novel therapeutic approaches in cancer tissues.

Rapid and reliable detection of CD44 variants in gastric carcinoma using a nested reverse transcription-polymerase chain reaction

The present study aimed to establish a rapid and reliable method for detecting the expression of cluster of differentiation 44 variant (CD44v) in gastric carcinoma, and to investigate the significance of CD44v in gastric carcinoma. Using a nested reverse transcription-polymerase chain reaction (RT-PCR) technique, the expression of CD44v and CD44v8-10 was analyzed in gastric cancer tissues (128 cases), precancerous lesions (19 cases of atypical hyperplasia and 6 cases of intestinal metaplasia) and corresponding adjacent non-cancerous tissues (153 cases). The tumor and non-cancerous biopsy samples of 153 patients were analyzed using nested RT-PCR. All the PCR products included bands at 482 bp, demonstrating positive CD44 expression. By contrast, the CD44v band (>600 bp) was observed in 132/153 total tumor samples (86.3%), including 114/128 gastric cancer samples (89.1%), 16/19 atypical hyperplasia samples (84.2%) and 2/6 intestinal metaplasia samples (33.3%). However, 18/153 non-cancerous tissues samples (11.8%) exhibited a CD44v band. Thus, CD44v expression was significantly higher in gastric cancer tissues and precancerous lesions compared with that of adjacent non-cancerous tissues (P<0.05). Furthermore, there was a significant difference in CD44v8-10 expression detected between gastric cancer and adjacent non-cancerous tissue samples (P<0.05). Among the 25 patients with precancerous lesions, 8/19 atypical hyperplasia cases and 1/6 intestinal metaplasia cases were positive for CD44v8-10 expression. The difference in the CD44v8-10 expression rate among the various pathological types of gastric cancer (n=128) cases was not significant (P>0.05). Additionally, immunohistochemical analysis identified CD44v positivity (++) in 59/76 (77.6%) cases of gastric cancer and 5/12 (41.1%) cases of atypical hyperplasia. The CD44v and CD44v8-10 PCR products were confirmed by sequencing analysis. The results of the present study indicated that nested RT-PCR technology may be exploited as a method for gastric carcinoma diagnosis.

CD44, Hyaluronan, the Hematopoietic Stem Cell, and Leukemia-Initiating Cells

CD44 is an adhesion molecule that varies in size due to glycosylation and insertion of so-called variant exon products. The CD44 standard isoform (CD44s) is highly expressed in many cells and most abundantly in cells of the hematopoietic system, whereas expression of CD44 variant isoforms (CD44v) is more restricted. CD44s and CD44v are known as stem cell markers, first described for hematopoietic stem cells and later on confirmed for cancer- and leukemia-initiating cells. Importantly, both abundantly expressed CD44s as well as CD44v actively contribute to the maintenance of stem cell features, like generating and embedding in a niche, homing into the niche, maintenance of quiescence, and relative apoptosis resistance. This is surprising, as CD44 is not a master stem cell gene. I here will discuss that the functional contribution of CD44 relies on its particular communication skills with neighboring molecules, adjacent cells and, last not least, the surrounding matrix. In fact, it is the interaction of the hyaluronan receptor CD44 with its prime ligand, which strongly assists stem cells to fulfill their special and demanding tasks. Recent fundamental progress in support of this “old” hypothesis, which may soon pave the way for most promising new therapeutics, is presented for both hematopoietic stem cell and leukemia-initiating cell. The contribution of CD44 to the generation of a stem cell niche, to homing of stem cells in their niche, to stem cell quiescence and apoptosis resistance will be in focus.

CD26-positive/CD326-negative circulating cancer cells as prognostic markers for colorectal cancer recurrence

The present study evaluated the presence and clinical relevance of a cluster of differentiation (CD)26⁺/CD326^- subset of circulating tumor cells (CTCs) in pre- and post-operative blood samples of colorectal cancer patients, who had undergone curative or palliative intervention, in order to find a novel prognostic factor for patient management and follow-up. In total, 80 colorectal cancer patients, along with 25 healthy volunteers were included. The easily transferable methodology of flow cytometry, along with multiparametric antibody staining were used to selectively evaluate CD26⁺/CD326^- CTCs in the peripheral blood samples of colorectal cancer patients. The multiparametric selection allowed any enrichment methods to be avoided thus rendering the whole procedure suitable for clinical routine. The presence of CD26⁺/CD326^- cells was higher in advanced Dukes' stages and was significantly associated with poor survival and high recurrence rates. Relapsing and non-surviving patients showed the highest number of CD26⁺/CD326^- CTCs. High pre-operative levels of CD26⁺/CD326^- CTCs correctly predicted tumor relapse in 44.4% of the cases, while 69% of post-operative CD26⁺/CD326^- CTC-positive patients experienced cancer recurrence, with a test accuracy of 88.8%. By contrast, post-operative CD26⁺/CD326^- CTC-negative patients showed an increase in the three-year progression-free survival rate of 86%, along with a reduced risk of tumor relapse of >90%. In conclusion, CD26⁺/CD326^- CTCs are an independent prognostic factor for tumor recurrence rate in multivariate analysis, suggesting that their evaluation could be an additional factor for colorectal cancer recurrence risk evaluation in patient management.

Alterations of high endothelial venules in primary and metastatic tumors are correlated with lymph node metastasis of oral and pharyngeal carcinoma

High endothelial venules (HEVs) are special blood vessels in the paracortical region of lymph nodes (LNs) and govern lymphocyte recruitment. LN metastasis has similarity to circulating lymphocytes homing to LNs, but the role of HEVs in the progression of oral and pharyngeal squamous cell carcinoma (OPSCC) is unclear. In this study, we found that HEVs experienced a series of morphological and functional changes during OPSCC progression and were correlated with LN metastasis. In 9 cases of 73 metastatic LNs, tumor emboli were located adjacent to HEVs or just out of the vessels but not lymphatic channels. Gap junctions of tumor cells close to HEVs decreased or disappeared, and gaps were left at contact points where tumor cells attached to the HEVs. Moreover, the proliferation rate of endothelial cells of HEVs was the highest in metastatic LNs. Finally, L-selectin was detected in both primary and metastatic tumors, and it facilitated tumor cells adhering to LNs. In conclusion, our findings suggest that remodeled HEVs are correlated with LN metastasis of OPSCC and play important role in this process by preparing premetastatic soil for cancer cell metastasis.

HSP72 and gp96 in gastroenterological cancers

Heat shock protein 72 (HSP72) and glycoprotein 96 (gp96) are highly expressed in cancer tissues. Recent studies indicate the possible roles of HSP72 and gp96 in the development and progression of gastrointestinal carcinomas but detailed mechanisms are still ambiguous. Human esophageal cancer, gastric cancer, colon cancer and liver cancer are common gastrointestinal malignant carcinomas in the world. The studies indicated that there existed a significant correlation between the expression of HSP72, gp96 and the development and progression of digestive carcinomas. HSP72 and gp96 expression were significantly associated with the presence of tumor infiltration, lymph node and remote metastasis. Interestingly, studies have found that HSP72 chaperoned alpha-fetoprotein (AFP), HBx in hepatocellular carcinoma, and CD44 in colonic carcinomas. The further researches demonstrated that HSP72-AFP or gp96-AFP recombined vaccine could elicit specific anti-tumor immunity. The high-level expression of HSP72 and gp96 may be not only used as diagnostic or prognostic markers for gastrointestinal carcinomas but also as better immunotherapeutic vaccines in the cancers.

Identification of specific chondroitin sulfate species in cutaneous autoimmune disease

Cutaneous lupus erythematosus and dermatomyositis (DM) are chronic inflammatory diseases of the skin with accumulated dermal mucin. Earlier work has shown chondroitin sulfate (CS) accumulation within the dermis of discoid lupus erythematosus (DLE), subacute cutaneous lupus erythematosus (SCLE), and DM lesions compared with control skin. Immunohistochemistry for C4S revealed a greater density in DLE and DM lesions, whereas SCLE lesions did not differ from controls. Scleredema and scleromyxedema are attributed to increased hyaluronic acid, and lesional samples from these diseases also demonstrated accumulated dermal C4S. Interferon-γ and interleukin-1α, but not interferon-α, treatment of cultured dermal fibroblasts induced mRNA expression of CHST-11, which attaches sulfates to the 4-position of unsulfated chondroitin. These studies on possible CS core proteins revealed that serglycin, known to have C6S side chains in endothelial cells, had greater density within DM dermal endothelia but not in DLE or SCLE, following the pattern of C6S overexpression reported previously. CD44 variants expand the CS binding repertoire of the glycoprotein; CD44v7 co-localized to the distribution of C4S in DLE lesions, a finding not observed in DM, SCLE lesions, or controls. Because C4S and C6S have immunologic effects, their dysregulation in cutaneous mucinoses may contribute to the pathogenesis of these disorders.

Clinical significance of pAKT and CD44v6 overexpression with breast cancer

PURPOSE

CD44v6 contributes to apoptosis resistance and metastasis via upregulated activity of the PI3K/AKT pathway. The purpose of this study was to investigate the expression patterns and predictive value of phosphorylated AKT (pAKT) and CD44v6 in breast cancer tissues.

METHODS

Expression of pAkt and CD44v6 protein was detected using immunohistochemistry in breast cancer tissues and lymph node tissues in 98 patients. The correlation between the expression of pAkt, CD44v6 and other disease-related characteristics was investigated. The prognostic value of pAKT and CD44v6 overexpression for overall survival (OS) and disease free survival (DFS) was determined.

RESULTS

37 cases (37.8%) were observed as positive for pAkt expression, and 38 cases (38.8%) for CD44V6 overexpression. Staining was positive for pAKT in 20 of 38 (52.6%) CD44v6(+) and 17 of 60 (28.3%) CD44v6(-) (P = 0.016). A progressively increased trend of CD44v6 overexpression was observed from node(-) primary breast cancer tissues to node(+) primary cancer tissues to node(+) lymph tissues (P = 0.000). In univariate analysis lymph node status, pAKT and CD44V6 were significantly associated with a decreased OS and DFS. Multivariate analysis revealed that CD44v6 status was associated with a reduced OS (P = 0.003), and pAKT and CD44v6 with a shorter DFS (P = 0.012 and 0.016, respectively).

CONCLUSIONS

Our data suggested that there had an intensive relationship between pAKT and CD44v6 expression in breast cancer tissues. The overexpression of CD44v6 was an independent prognostic marker for predicting OS and DFS of breast cancer patients.

Determination and validation of off-target activities of anti-CD44 variant 6 antibodies using protein biochips and tissue microarrays

We describe a novel procedure for determination and validation of off-target activities of anti-cluster designation antigen identity 44 (CD44) variant 6 recombinant antibodies by combining two complementary technology platforms; namely UNIchip AV-400, containing a printed serial dilution of CD44 variant 6 and approximately 400 different human proteins, and TISSOMICS, enabling human tissue microarray analysis in high-throughput mode. We have analyzed the performance of two human monoclonal recombinant antibodies directed against CD44 variant 6 protein, BMS 116 and BMS 125, in a blinded study. The antibodies exhibit a clear differentiation with regard to their binding profiles in the two systems. BMS 116 shows a low degree of specificity in the normal human Food and Drug Administration (FDA) tissue panel, which was confirmed by binding to more than 206 proteins on the protein biochip. In contrast, BMS 125 gives a highly selective membranous staining on selected human epithelial tissue components with no off-target activities observed on the protein biochip. Additionally, antibody BMS 125 shows a higher sensitivity to its antigen CD44 variant 6 than antibody BMS 116 as determined by the protein biochip.

Bladder cancer initiating cells (BCICs) are among EMA-CD44v6+ subset: novel methods for isolating undetermined cancer stem (initiating) cells

Bladder cancer stem (initiating) cell has not been isolated now, and no one verified its persistence experimentally. The aim of this study was to conclude the persistence of bladder cancer stem (initiating) cell in human primary bladder cancer and investigate the possibility of EMA(-) CD44v6(+) as markers of bladder cancer stem (initiating) cell. Genes differentially expressed between normal urothelium and low malignant bladder cancer were identified by DNA array assay. Overpressed stem cell related genes, Bmi-1 and EZH2, were verified by immunohistochemistry. Side population cells in bladder cancer were found under fluorescence microscope. The value of 28 potential surface markers of bladder cancer stem (initiating) cell for isolating them were judged by immunohistochemistry. Both EMA(-) and CD44v6(+) cells located in basal layer (potential location of stem cells). After gathering the CD44v6(+) cells and EMA(-) cells by magnetic cell sorting, their ability for colony-forming, self-renewal and extensive proliferation were assayed by cells culture. Both EMA(-) cells and CD44v6(+) cells posses the ability for colony-forming, self-renewal and proliferation. We conclude the persistence of bladder cancer stem (initiating) cell. Bladder cancer stem (initiating) cell might be among EMA(-) CD44v6(+) subset. Our strategies for isolating bladder cancer stem (initiating) cell might be useful for isolating other undetermined epithelial cancer stem cell, especially those in well-differentiated cancers.

Role of hyaluronan in glioma invasion

Gliomas are the most common primary intracranial tumors. Their distinct ability to infiltrate into the extracellular matrix (ECM) of the brain makes it impossible to treat these tumors using surgery and radiation therapy. A number of different studies have suggested that hyaluronan (HA), the principal glycosaminoglycan (GAG) in the ECM of the brain, is the critical factor for glioma invasion. HA-induced glioma invasion was driven by two important molecular events: matrix metalloproteinase (MMP) secretion and up-regulation of cell migration. MMP secretion was triggered by HA-induced focal adhesion kinase (FAK) activation, which transmits its signal through ERK activation and nuclear factor kappa B (NF-kappaB) translocation. Another important molecular event is osteopontin (OPN) expression. OPN expression by AKT activation triggers cell migration. These results suggest that HA-induced glioma invasion is tightly regulated by signaling mechanisms, and a detailed understanding of this molecular mechanism will provide important clues for glioma treatment.

Deletion of the WNT target and cancer stem cell marker CD44 in Apc(Min/+) mice attenuates intestinal tumorigenesis

Mutation of the genes encoding the WNT signaling components adenomatous polyposis coli or beta-catenin plays a critical role in the initiation of colorectal cancer. These mutations cause constitutively active beta-catenin/TCF-mediated transcription, driving the transformation of intestinal crypts to colorectal cancer precursor lesions, called dysplastic aberrant crypt foci. CD44 is a prominent WNT signaling target in the intestine and is selectively expressed on the renewing epithelial cells lining the crypts. The expression of CD44 is dramatically increased in aberrant crypt foci in both humans and tumor-susceptible Apc(Min/+) mice, suggesting a role for CD44 in intestinal tumorigenesis. To study this role, we crossed C57BL/6J-Cd44(-/-) mice with C57BL/6J-Apc(Min/+) mice. Compared with C57BL/6J-Cd44(+/+)/Apc(Min/+) mice, C57BL/6J-Cd44(-/-)/Apc(Min/+) mice showed an almost 50% reduction in the number of intestinal adenomas. This reduction was primarily caused by a decrease in the formation of aberrant crypts, implying the involvement of CD44 in tumor initiation. The absence of CD44 in the normal (nonneoplastic) crypts of Cd44(-/-)/Apc(Min/+) mice did not alter the proliferative capacity and size of the intestinal stem cell and transit-amplifying compartments. However, compared with Cd44(+/+)/Apc(Min/+) mice, Cd44(-/-)/Apc(Min/+) showed an increase in the number of apoptotic epithelial cells at the base of the crypt which correlated with an increased expression of the proapoptotic genes Bok and Dr6. Our results show an important role for CD44 in intestinal tumorigenesis and suggest that CD44 does not affect proliferation but is involved in the control of the balance between survival and apoptosis in the intestinal crypt.

Multisite and bidirectional exonic splicing enhancer in CD44 alternative exon v3

The human CD44 gene encodes multiple isoforms of a transmembrane protein that differ in their extracellular domains as a result of alternative splicing of its variable exons. Expression of CD44 is tightly regulated according to the type and physiological status of a cell, with expression of high molecular weight isoforms by inclusion of variable exons and low molecular weight isoforms containing few or no variable exons. Human CD44 variable exon 3 (v3) can follow a specific alternative splicing route different from that affecting other variable exons. Here we map and functionally describe the splicing enhancer element within CD44 exon v3 which regulates its inclusion in the final mRNA. The v3 splicing enhancer is a multisite bipartite element consisting of a tandem nonamer, the XX motif, and an heptamer, the Y motif, located centrally in the exon. Each of the three sites of this multisite enhancer partially retains its splicing enhancing capacity independently from each other in CD44 and shows full enhancing function in gene contexts different from CD44. We further demonstrate that these motifs act cooperatively as at least two motifs are needed to maintain exon inclusion. Their action is differential with respect to the splice-site target abutting v3. The first X motif acts on the 3' splice site, the second X motif acts on both splice sites (as a bidirectional exonic splicing enhancer), and the Y motif acts on the 5' splice site. We also show that the multisite v3 splicing enhancer is functional irrespective of flanking intron length and spatial organization within v3.

[Expression of adhesion molecule CD44 on subpopulations of lymphocytes in hypertrophied adenoids in children with otitis media with effusion]

INTRODUCTION

The CD44 on lymphocytes binding to its ligand hyaluronan can mediate primary adhesion (rolling interactions) of lymphocytes on high endothelial venules (HEV). This adhesion molecule plays an important role to maturation and proliferation of lymphocytes in the secondary lymphoid organs. CD44 has a crucial role in migrate of lymphocytes to inflammatory sites. The AIM of this study was evaluation of the percentage and MFI (mean fluorescence intensity) of lymphocytes CD4+, CD8+, CD19+ with expression of surface adhesive molecule CD44 in hypertrophied adenoids in children with otitis media with effusion.

MATERIAL AND METHODS

42 children with otitis media with effusion and 30 children with hypertrophied adenoids were tested. Children were also divided into two subgroups: young (below 5 years) and older children (above 5 years old). Expression of adhesion molecule CD28 on lymphocytes of adenoids tissue was estimated by flow cytometry method.

RESULTS

This study showed significantly higher percentage of lymphocytes CD19+CD44+ in children with otitis media with effusion (OME 87,83%) than in comparative group with hypertrophied adenoids (AH 85,61%). We did not find difference between OME and AH in mean fluorescence intensity of subpopulations lymphocytes T and B with expression CD44.

CONCLUSIONS

Adhesion molecule CD44 is important for developing of effectors lymphocytes in hypertrophy adenoid. Increase percentage of lymphocytes CD19 with expression CD28, especially in older children confirms their participation in developing and forming of immunological response in otitis media with effusion.

Inflammation, lymphatic function, and dendritic cell migration

The lymphatic system is not only essential for maintenance of normal fluid balance, but also for proper immunologic function by providing an extensive network of vessels, important for cell trafficking and antigen delivery, as well as an exclusive environment, the lymph node (LN), where antigen-presenting cells (APCs) and lymphocytes can encounter and interact. Among APCs, dendritic cells (DCs) have a remarkable capacity to traffic from peripheral tissues to the draining LN, which is critical for execution of their functions. To reach the LN, DCs must migrate towards and enter lymphatic vessels. Here, the authors review what is known about the factors that drive this process. They touch particularly on the topic of how DC migration is affected by inflammation and discuss this in the context of lymphatic function. Traditionally, inflammatory mediators are regarded to support DC migration to LNs because they induce molecules on DCs known to guide them to lymphatics. The authors recently showed that inflammatory signals present in a strong vaccine adjuvant induce swelling in LNs accompanied by lymphangiogenesis in the draining LN and radius of peripheral tissue. These increased lymphatics, at least for several days, lead to a more robust migration of DCs. However, the density of lymphatic vessels can become overly extended and/or their function impaired as observed during lymphedema and various chronic inflammatory reactions. Diseases characterized by chronic inflammation often present with impaired DC migration and adaptive immunity. Gaining a better understanding of how lymphatic vessel function may impact adaptive immunity by, for example, altering DC migration will benefit clinical research aiming to manipulate immune responses and manage chronic inflammatory diseases.

Osteopontin is an oncogenic Vav1- but not wild-type Vav1-responsive gene: implications for fibroblast transformation

Mammalian wild-type Vav1 (wtVav1) encodes a specific GDP/GTP nucleotide exchange factor that is exclusively expressed in the hematopoietic system. Despite numerous studies, the mechanism underlying transformation of fibroblasts by oncogenic Vav1 (oncVav1) is not well defined. We identified osteopontin, a marker for tumor aggressiveness, as an oncVav1-inducible gene. Osteopontin is highly expressed in oncVav1-transformed NIH3T3 cells (NIH/oncVav1) but is barely detected in NIH3T3 expressing wtVav1 (NIH/wtVav1) even following epidermal growth factor stimulation, which normally induces osteopontin. Depleting oncVav1 in NIH/oncVav1 using small interfering RNA led to a considerable decrease in osteopontin, whereas reducing osteopontin expression did not affect oncVav1 expression, suggesting that oncVav1 operates upstream of osteopontin. Vav1-depleted NIH/oncVav1 cells, but not osteopontin-depleted NIH/oncVav1 cells, exhibited impaired extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase phosphorylation. Inhibition of ERK phosphorylation in NIH/oncVav1 cells led to a decrease in osteopontin expression, implying that the elevated osteopontin expression in these cells is dependent on ERK phosphorylation. Vav1-depleted or osteopontin-depleted NIH/oncVav1 cells lost their tumorigenic properties as judged by the soft agar and invasion assays, although loss of osteopontin expression had a less dramatic effect. Suppression of Vav1 expression in NIH/oncVav1 cells led to reversion to "normal" morphology, whereas when only osteopontin expression was diminished cells retained their transformed morphology. This work strongly supports a role for oncVav1 as a master oncogene and provides clues to the molecular mechanism underlying oncVav1 transformation.

Identification and characterization of lin-28 homolog B (LIN28B) in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Several studies have identified signature gene sets that may be useful as potential diagnostic tools by global microarray analysis. Here we report the cloning and characterization of a novel gene, lin-28 homolog B (LIN28B), which is overexpressed in hepatocellular carcinoma. The heterochronic gene lin-28 is a key regulator of developmental timing in the nematode Caenorhabditis elegans. Similar with lin-28 proteins, LIN28B conserves a cold shock domain and a pair of CCHC zinc finger domains. Phylogenetic analysis suggests that they might arise as a result of duplication from an ancestral gene. Overexpression of LIN28B was noted in most HCC cell lines and clinical samples. By western blot analysis using a polyclonal antibody against LIN28B, a short LIN28B isoform was also identified in non-tumor liver tissue and fetal liver. Although predominantly localized in the cytoplasm, we found that LIN28B protein shows cell cycle-dependent nuclear translocation in Huh7 cells. Induced expression of exogenous LIN28B in a tet-off cell line promoted cancer cell proliferation. Interestingly, the segment of the unusually long 3'UTR of LIN28B contains complementary sites to let-7 microRNA of mammals. And our studies provided indirect evidence that LIN28B is a possibly natural target for let-7 mediated regulation. These findings strongly implicate a critical role of LIN28B during development and tumorigenesis and suggest a possible novel mechanism.

CD24 expression causes the acquisition of multiple cellular properties associated with tumor growth and metastasis

The glycosylphosphatidylinositol-anchored membrane protein CD24 functions as an adhesion molecule for P-selectin and L1 and plays a role in B-cell development and neurogenesis. Over the last few years, a large body of literature has also implicated CD24 expression in tumorigenesis and progression. Here, we show that ectopic CD24 expression can be sufficient to promote tumor metastasis in experimental animals. By developing a doxycycline-inducible system for the expression of CD24 in breast cancer cells, we have also analyzed the cellular properties that CD24 expression influences. We found that CD24 expression increased tumor cell proliferation. Furthermore, in addition to promoting binding to P-selectin, CD24 expression also indirectly stimulated cell adhesion to fibronectin, collagens I and IV, and laminin through the activation of alpha3beta1 and alpha4beta1 integrin activity. Moreover, CD24 expression supported rapid cell spreading and strongly induced cell motility and invasion. CD24-induced proliferation and motility were integrin independent. Together, these observations implicate CD24 in the regulation of multiple cell properties of direct relevance to tumor growth and metastasis.

Are serum levels of CD44 relevant in children with pediatric sarcomas?

BACKGROUND

Variation in serum levels of CD44, which acts as an adhesion receptor involved in lymphocyte migration and binding, have been reported in some malignancies. The aim of this study is to compare serum levels of CD44 in children with sarcomas with those in healthy children.

PROCEDURE

CD44 levels were measured by enzyme-linked immunosorbent assay (ELISA) in serum samples taken at diagnosis from 55 children with sarcomas and from 27 healthy children of similar age, sex, and socioeconomic status.

RESULTS

There was no statistically significant difference between CD44 serum levels of children with sarcomas and those of healthy children. No significant difference was observed between CD44 serum levels of each patient group and those of control group (P > 0.05). There was no significant difference among CD44 serum levels of patient groups according to stage or outcome.

CONCLUSIONS

In this study, serum CD44 levels were not found to be of value in the diagnosis or prognosis in children with sarcomas.

A five-amino-acid peptide blocks Met- and Ron-dependent cell migration

Various human cancers express elevated levels of the receptor tyrosine kinases Met or Ron and v6-containing isoforms of CD44. The activation of Met and Ron requires the presence of such CD44 v6-containing isoforms that act as coreceptors. Three amino acids within the v6 sequence were identified by mutational analysis to be essential for the coreceptor function: EWQ in the rat sequence and RWH in human. Peptides comprising these three amino acids (the smallest containing only five amino acids) efficiently act as competitors and block ligand-dependent activation of Met or Ron and subsequent cell migration.

Expression of N-acetylglucosamine 6-O-sulfotransferases (GlcNAc6STs)-1 and -4 in human monocytes: GlcNAc6ST-1 is implicated in the generation of the 6-sulfo N-acetyllactosamine/Lewis x epitope on CD44 and is induced by TNF-alpha

Sulfation at the 6-O position of N-acetylglucosamine (GlcNAc) in the context of sialyl 6-sulfo Lewis x occurs constitutively on specific glycoproteins present on high-walled endothelial venules (HEV) and is important for L-selectin dependent homing of lymphocytes. Here, the proinflammatory cytokine, TNF-alpha, induced the expression of 6-sulfo N-acetyllactosamine (LacNAc)/Lewis x on human peripheral blood monocytes (PBM). This epitope was detected by monoclonal antibody (mAb) AG107 after neuraminidase treatment suggesting a sialylated epitope, which was present on the cell adhesion molecule, CD44. Treatment of human PBM with TNF-alpha up-regulated the expression of N-acetylglucosamine 6-O-sulfotransferase-1 (GlcNAc6ST-1) and GlcNAc6ST-4, as determined by reverse transcriptase polymerase chain reaction (RT-PCR). However, only GlcNAc6ST-1 was induced by TNF-alpha in the human SR91 cell line, which also up-regulated the AG107 epitope. In ECV304 cells, the expression of GlcNAc6ST-4 alone was insufficient to generate the AG107 epitope. However, the transfection of GlcNAc6ST-1 resulted in significant sulfate incorporation into CD44 and generated the 6-sulfo LacNAc/Lewis x epitope on CD44, which was present largely on N-linked glycans. This demonstrates the induction of GlcNAc6STs in human monocytes in response to TNF-alpha and implicates GlcNAc6ST-1 in the generation of the 6-sulfo LacNAc/Lewis x epitope on CD44.

E-cadherin, CD44 and CD44v6 in squamous intraepithelial lesions and invasive carcinomas of the uterine cervix: an immunohistochemical study

OBJECTIVE

To evaluate the immunoexpression pattern of E-cadherin, CD44std and the variant isoform v6 in normal squamous epithelium, low and high squamous intraepithelial lesions (SILs) and invasive squamous cell carcinomas (ISCCs) of the uterine cervix. The purpose was to determine whether any distinctive change in antigenic expression could contribute to the recognition of the earliest commitment to neoplasia and/or the onset of the invasive phenotype.

METHODS

Immunohistochemistry using the avidin-biotin indirect immunoperoxidase method was used to study the protein expression of epithelial cadherin (E-cadherin), cluster differentiation 44 (CD44), and the isoform v6 (CD44v6) in 124 human cervical samples (5 normal, 39 low-grade, 54 high-grade and 26 ISCCS) in formalin-fixed, paraffin-embedded tissue blocks.

RESULTS

Membranous expression of E-cadherin, CD44 and CD44v6 was preserved in normal squamous epithelium and in low-grade squamous intraepithelial lesions. A significant association was observed with the histological grade of the SILs and the immunoreactivity (membranous versus cytoplasmic) pattern of E-cadherin (p < 0.001), CD44std (p = 0.027) and CD44v6 (p < 0.001). A loss of membranous staining and a progressive increase in cytoplasmic staining was observed from low to high grade SILs to ISCCs.

CONCLUSIONS

Our study demonstrates that during the development of cervical lesions substantial qualitative (subcellular localization-membrane to cytoplasmic) and quantitative alterations (changes in expression) occur in the protein expression of E-cadherin, CD44, and CD44v6 in cervical cancer. The most striking observation was the decrease in membranous immunoreactivity and the progressive increase in cytoplasmic staining of E-cadherin, CD44 and CD44v6, relating to loss of differentiation as a consequence of neoplastic transformation.

CD44 in cancer progression: adhesion, migration and growth regulation

It is well established that the large array of functions that a tumour cell has to fulfil to settle as a metastasis in a distant organ requires cooperative activities between the tumour and the surrounding tissue and that several classes of molecules are involved, such as cell-cell and cell-matrix adhesion molecules and matrix degrading enzymes, to name only a few. Furthermore, metastasis formation requires concerted activities between tumour cells and surrounding cells as well as matrix elements and possibly concerted activities between individual molecules of the tumour cell itself. Adhesion molecules have originally been thought to be essential for the formation of multicellular organisms and to tether cells to the extracellular matrix or to neighbouring cells. CD44 transmembrane glycoproteins belong to the families of adhesion molecules and have originally been described to mediate lymphocyte homing to peripheral lymphoid tissues. It was soon recognized that the molecules, under selective conditions, may suffice to initiate metastatic spread of tumour cells. The question remained as to how a single adhesion molecule can fulfil that task. This review outlines that adhesion is by no means a passive task. Rather, ligand binding, as exemplified for CD44 and other similar adhesion molecules, initiates a cascade of events that can be started by adherence to the extracellular matrix. This leads to activation of the molecule itself, binding to additional ligands, such as growth factors and matrix degrading enzymes, complex formation with additional transmembrane molecules and association with cytoskeletal elements and signal transducing molecules. Thus, through the interplay of CD44 with its ligands and associating molecules CD44 modulates adhesiveness, motility, matrix degradation, proliferation and cell survival, features that together may well allow a tumour cell to proceed through all steps of the metastatic cascade.

Expression of E-cadherin, and CD44s and CD44v6 and its association with prognosis in head and neck cancer

OBJECTIVES

In the current study, the expression of E-cadherin, CD44s, and CD44v6 has been noted as markers for tumor metastasis and prognosis in several tumors, so we examined whether or not E-cadherin, CD44s, and CD44v6 are useful markers for evaluating the prognosis of mesopharyngeal cancer patients.

METHODS

The expression of E-cadherin, CD44s, and CD44v6, was evaluated immunohistochemically using monoclonal antibodies against epitopes of standard and variant proteins, in paraffin-embedded mesopharyngeal cancer tissues from 57 patients who had received curative therapy.

RESULTS

Tumor tissues from 47 (82.5%) patients showed positive immunoreactivity with monoclonal antibody against E-cadherin, 43 (75.4%) patients showed positive expression with CD44, and 45 (78.9%) patients showed positive expression with CD44v6. The expression of CD44v6 was slightly correlated with tumor volume, and lymph node metastasis, and stage classification (P > 0.05). However, there was no significant correlation between the expression of E-cadherin, CD44s and CD44v6 and clinicopathological characteristics. Concerning the prognosis, the survival period of patients with CD44s positive tumors was shorter than that of patients with CD44s negative tumors (18.2% versus 52.1%, 5-year survival, P > 0.05). The survival period of patients with CD44v6 positive tumors was also shorter than that of patients with CD44v6 negative tumors (12.8% versus 55.6%, 5-year survival, P > 0.05).

CONCLUSION

These results suggest that CD44v6 may be related to tumor invasion and metastasis, and both CD44s and CD44v6 may be useful markers for poor prognosis in head and neck cancer.

Expression and clinical significance of CD44V5 and CD44V6 in resectable colorectal cancer

PURPOSE

This study was conducted to evaluate the prognostic significance of CD44v5 and CD44v6 in resectable colorectal cancer.

MATERIALS AND METHODS

Membranous CD44v5 and CD44v6 levels were measured by an immunoenzymatic assay in tumors and surrounding mucosal samples obtained from 105 patients with resectable colorectal carcinomas.

RESULTS

There were no significant differences of CD44v5 levels between tumors [median: 3.2 (range: 0.9-83.5) ng/mg protein) and surrounding mucosal samples (3 (3-146.2) ng/mg protein]. However, tumor samples showed significantly higher CD44v6 levels [19.5 (2.2-562.9) ng/mg protein] than mucosal samples [5 (5-230) ng/mg protein] (P=0.0001). Patients with higher CD44v5 or CD44v6 content in tumor samples had a considerably shorter relapse-free survival (P<0.05, for both). Patients with a higher CD44v6 content also had a shorter relapse-free and overall survival in the multivariate analysis (P<0.05).

CONCLUSION

The results of this study suggest a role of CD44v5 and CD44v6 in colorectal cancer progression. Membranous CD44v levels in primary tumors, measured by immunoenzymatic assay, may contribute to a more precise prognostic estimation in patients with resectable colorectal cancer.

A conserved signal-responsive sequence mediates activation-induced alternative splicing of CD45

Alternative splicing of nascent transcripts is a widespread mechanism for altering protein expression in response to extracellular stimuli. However, little is known about the sequences that mediate signal-induced alternative splicing, complicating efforts to identify genes whose splicing may be regulated in response to a particular stimuli. Here we define a sequence element that is both the primary determinant of CD45 variable exon exclusion following T cell stimulation by PMA and is sufficient to confer activation-induced skipping of a heterologous exon. Additionally, we show that this regulatory element has homology to sequences in other signal-regulated genes, suggesting that the alternative splicing of large families of genes may be regulated by common signaling pathways.

Role of VEGF and CD44v6 in differentiating benign from malignant ascites

AIM: To detect the vascular endothelial growth factor (VEGF) and soluble splice variant 6 of CD44 (sCD44v6) levels in ascites and to explore their role in differentiating benign from malignant ascites.

METHODS: Cirrhotic ascites (n = 36), tuberculosis ascites (n = 8) and malignant ascites (n = 23) were collected and studied. Concentrations of soluble VEGF and sCD44v6 in various kinds of ascites (n = 67) were measured using a sandwich enzyme-linked immunoadsorbent assay.

RESULTS: VEGF and sCD44v6 levels in malignant ascites were 640.74 ± 264.81 pg/mL and 89.22 ± 38.20 ng/mL, respectively, both of which were significantly higher than those in cirrhotic ascites and tuberculous ascites (q = 18.98, 11.89 and q = 8.92, 5.09; P < 0.01). However, the levels of VEGF and sCD44v6 in cirrhotic and tuberculous ascites had no significant difference (q = 0.48, 0.75; P > 0.05). Furthermore, VEGF levels in malignant ascites in patients with ovarian cancer were higher than those with gastric and colon cancer (q = 5.03, 6.79; P < 0.01, respectively). But differences of VEGF levels between gastric and colon cancer were not significant (q = 1.90, P > 0.05). Whereas, sCD44v6 levels in malignant ascites from patients with ovarian, gastric and colon cancer had no significant difference (q = 0.06, 0.91, 0.35; P > 0.05, respectirely). In comparison with cirrhotic and tuberculous ascites, when the upper limit of its VEGF mean levels 119.44 pg/mL (70.90 ± 48.54) and sCD44v6 mean levels 63.59 ng/mL (44.42 ± 19.17) was taken as the minimum cutoff limit, the sensitivity and specificity of VEGF and sCD44v6 of this assay to the diagnos is of malignant ascites were 91.3%, 90.9% and 73.9%, 88.7% respectively.

CONCLUSION: Elevated levels of VEGF and sCD44v6 may be useful in differential diagnosis of benign and malignant ascites.

Expression of CD44s in human colorectal cancer

CD44s is a cell adhesion molecule, which belongs to the family of hyaluronan binding proteins. Anti-body to CD44s is used to establish the association of its expression with the clinicopathological characteristics of colorectal cancer using immunohistochemical methods. The aim of this study is to investigate the expression of the standard form of CD44 (CD44s) in colorectal cancer tissues as compared to adjacent normal colonic tissues. Furthermore, the level of expression of CD44s in colorectal cancer tissues was correlated with the degree of histological differentiation, Duke s classification, sex, size and site of the tumor. Immunohistochemical analysis for CD44s was carried out in 49 paraffin-fixed sections of neoplastic colorectal tissues and non-neoplastic ones adjacent to the lesion, by the standard peroxidase-antiperoxidase method. Expression of these antigens were compared in normal and malignant epithelium and stromal cells. The results show that the level of CD44s in the epithelial and stromal cells was significantly higher in the colorectal cancer tissues than the normal ones. However, there was no association between the percentages of expressions of CD44s and the degree of histological differentiation, Duke s classification, sex or size of the tumor. There was however, a significantly higher expression of CD44s in the epithelium of rectal cancer than that of colonic cancer. This study indicates that the expression of CD44s is significantly higher in colorectal cancer tissues. However, further studies are required to understand its role in tumor progression and metastasis of this disease.

Dog leukocyte antigen-haploidentical stem cell allografts after anti-CD44 therapy and reduced-intensity conditioning in a preclinical canine model

OBJECTIVE

We previously described a nonmyeloablative hematopoietic stem cell transplantation regimen in dog leukocyte antigen (DLA)-identical littermate recipients consisting of low-dose total body irradiation (TBI) before and mycophenolate mofetil (MMF)/cyclosporine (CSP) given after transplant to control both graft-vs-host and residual host-vs-graft reactions. In this study, we sought to develop a reduced-intensity regimen to achieve engraftment across major histocompatibility complex barriers in DLA-haploidentical littermate recipients.

MATERIALS AND METHODS

We tested a regimen of 450-cGy TBI with or without postgrafting MMF/CSP for 28 and 35 days, respectively, and with the administration of monoclonal antibody (mAb) S5 (anti-CD44), at a dose of 0.2 mg/kg/day from days -7 through -2, prior to receiving TBI.

RESULTS

One of six dogs conditioned with 450-cGy TBI alone achieved engraftment of granulocyte colony-stimulating factor-mobilized peripheral blood stem cells. Three of six dogs achieved sustained donor cell engraftment using 450-cGy TBI and posttransplantation MMF/CSP. None of three dogs given mAb S5 followed by 450-cGy TBI showed signs of donor cell engraftment. However, when S5 mAb pretreatment was added to 450-cGy TBI and postgrafting MMF/CSP, 10 of 12 dogs achieved sustained engraftment (p = 0.008 or 0.007 vs 450-cGy alone or to S5 + 450-cGy TBI without MMF/CSP, respectively), with only three dogs developing severe graft-vs-host disease on this short regimen of immunosuppression.

CONCLUSION

These results show that engraftment across a DLA haplotype-mismatched barrier can be achieved after reduced-intensity conditioning when mAb S5 directed at CD44 is added to this regimen.

CD44 stimulation by fragmented hyaluronic acid induces upregulation of urokinase-type plasminogen activator and its receptor and subsequently facilitates invasion of human chondrosarcoma cells

It has been established that fragmented hyaluronic acid (HA), but not native high molecular weight HA, can induce angiogenesis, cell proliferation and migration. We have studied the outside-in signal transduction pathways responsible for fragmented HA-mediated cancer cell invasion. In our study, we have studied the effects of CD44 stimulation by ligation with HA upon the expression of matrix metalloproteinases (MMPs)-2 and -9 as well as urokinase-type plasminogen activator (uPA), its receptor (uPAR) and its inhibitor (PAI-1) and the subsequent induction of invasion of human chondrosarcoma cell line HCS-2/8. Our study indicates that (i) CD44 stimulation by fragmented HA upregulates expression of uPA and uPAR mRNA and protein but does not affect MMPs secretion or PAI-1 mRNA expression; (ii) the effects of HA fragments are critically HA size dependent: high molecular weight HA is inactive, but lower molecular weight fragmented HA (Mr 3.5 kDa) is active; (iii) cells can bind avidly Mr 3.5 kDa fragmented HA through a CD44 molecule, whereas cells do not effectively bind higher Mr HA; (iv) a fragmented HA induces phosphorylation of MAP kinase proteins (MEK1/2, ERK1/2 and c-Jun) within 30 min; (v) CD44 is critical for the response (activation of MAP kinase and upregulation of uPA and uPAR expression); and (vi) cell invasion induced by CD44 stimulation with a fragmented HA is inhibited by anti-CD44 mAb, MAP kinase inhibitors, neutralizing anti-uPAR pAb, anti-catalytic anti-uPA mAb or amiloride. Therefore, our study represents the first report that CD44 stimulation induced by a fragmented HA results in activation of MAP kinase and, subsequently, enhances uPA and uPAR expression and facilitates invasion of human chondrosarcoma cells.

Surface antigens of human mesangial cells: impact of growth surface or IL-1alpha

The interactions of mesangial cells (MC) with their environment are important events in glomerular physiology and pathology, yet a detailed characterization of the MC-surface antigens mediating these interactions is still lacking. In this study, a comparative phenotype analysis of primary human MC in culture using 191 monoclonal antibodies directed against 108 antigens was performed by flow-cytometry. The MC were grown on three different surfaces (human matrix, fibronectin, polystyrene) and cultured in the presence or absence of IL-1alpha. Seventy-one antibodies recognizing 35 different antigens (integrins: CD29, 49b, 49c, 49e, 51, 61; immunoglobulin gene family: CD54, 58, 90, 106, 146, 147, 166; growth factor receptors: CD105, 140b; apoptosis related: CD95; hemostatis related: CD141, 142; miscellaneous: CD44, 109, 138, 151, 157, 165, and 11 nonclustered antigens) reacted with mesangial cells. CD58, 109, 146, 147, 151, 157, 165, and 166 are reported for the first time to be present on human mesangial cells. In comparison to growth on polystyrene, CD44, 54, 95, 105, 109, 140b, 146, 147, 157, 165 and 166, were up-regulated on fibronectin, and CD44, 54, 90, 95, 105, 106, 109, 138, 140b, 141, 142, 146, 147, 151, 157, 165 and 166 were up-regulated on human matrix. The stimulation by IL-1alpha up-regulated CD44, 49e, 51, 54, 61, 106 on MC on polystyrene; CD49e, 51, 61, 106, 146, 165 on MC on fibronectin, and CD49e, 51, 54 on MC grown on human matrix. This analysis of surface antigen expression provides new information to enable a better understanding of the role of mesangial cells in glomerular pathophysiology.

Hyaluronic acid: its role in voice

The extracellular matrix (ECM), once regarded simply as a structural scaffold, is now recognized as an important modulator of cellular behavior and function. One component that plays a prominent role in this process is hyaluronic acid (HA)--a molecule found in many different tissues. Research into the roles of HA indicates that it plays a key role in tissue viscosity, shock absorption, and space filling. Specifically, research into the role of HA in laryngology indicates that it has profound effects on the structure and viscosity of vocal folds. This article provides an introduction to the structure and biological functions of HA and its importance in voice. In addition, an overview of the pharmaceutical applications of HA is discussed.

CD44 stimulation by fragmented hyaluronic acid induces upregulation and tyrosine phosphorylation of c-Met receptor protein in human chondrosarcoma cells

Hepatocyte growth factor/scatter factor (HGF/SF) can induce proliferation and motility and promote invasion of tumor cells. Since HGF/SF receptor, c-Met, is expressed by tumor cells, and since stimulation of CD44, a transmembrane glycoprotein known to bind hyaluronic acid (HA) in its extracellular domain, is involved in activation of c-Met, we have studied the effects of CD44 stimulation by ligation with HA upon the expression and tyrosine phosphorylation of c-Met on human chondrosarcoma cell line HCS-2/8. The current study indicates that (a) CD44 stimulation by fragmented HA upregulates expression of c-Met proteins; (b) fragmented HA also induces tyrosine phosphorylation of c-Met protein within 30 min, an early event in this pathway as shown by the early time course of stimulation; (c) the effects of HA fragments are critically HA size-dependent. High molecular weight HA is inactive, but lower molecular weight fragments (M(r) 3.5 kDa) are active with maximal effect in the microg/ml range; (d) the standard form of CD44 (CD44s) is critical for the response because the effect on c-Met, both in terms of upregulation and phosphorylation, is inhibited by preincubation with an anti-CD44 monoclonal antibody; and (e) phosphorylation of c-Met induced by CD44 stimulation is inhibited by protein tyrosine kinase inhibitor, tyrphostin. Therefore, our study represents the first report that CD44 stimulation induced by fragmented HA enhances c-Met expression and tyrosine phosphorylation in human chondrosarcoma cells. Taken together, these studies establish a signal transduction cascade or cross-talk emanating from CD44 to c-Met.

Cell adhesion molecules and oral cancer

Cell adhesion molecules (CAMs) are found on the surfaces of all cells, where they bind to extracellular matrix molecules or to receptors on other cells. As well as having a structural role, CAMs function as signaling receptors, transducing signals initiated by cellular interactions which regulate many diverse processes, including cell division, migration, and differentiation. Cell adhesion molecules are essential for maintaining stable tissue structure. However, cell adhesion must be dynamic to facilitate the mobility and turnover of cells. In dynamic situations, cells alter their cell-cell and cell-matrix interactions by virtue of altered expression and function of CAMs. The expression of CAMs is normally tightly regulated, thereby controlling cell proliferation, mobility, differentiation, and survival. Many of these processes are misregulated in malignant tumors, and it has been shown that many of the characteristics of tumor cells are attributable to the aberrant expression or function of CAMs. Integrins and E-cadherin are the most important CAMs expressed by stratified squamous epithelium. Altered expression of these molecules has been found in oral carcinoma, where loss of CAM expression is often seen in poorly differentiated lesions. However, up-regulation of certain integrins, such as alphavbeta6, has consistently been found in oral cancer, suggesting that it may play an active role in disease progression.

Expression of CD44 isoforms correlates with the metastatic potential of osteosarcoma

CD44 is a family of cell surface glycoproteins that not only function as receptors to hyaluronan and other extracellular matrix ligands but also is implicated in the invasiveness and metastasis of malignancies. The expression of CD44 and its variant isoforms was evaluated by immunohistochemistry in primary osteosarcoma, and the metastatic significance and prognostic relevance were assessed. Fifty formalin-fixed, paraffin-embedded conventional osteosarcoma samples were immunostained with monoclonal antibodies to CD44s, CD44v5, and CD44v6. When more than 50% of the tumor cells were stained, the result was regarded as ++ (overexpression). Staining patterns of CD44 mainly were membranous with a minor cytoplasmic pattern contribution. CD44s was overexpressed in 16% (eight of 50), CD44v6 in 20% (10 of 50), and CD44v5 in 46% (23 of 50) of the osteosarcomas. Of 26 patients with metastasis, CD44s was overexpressed in six (23%), CD44v6 in four (15%), and CD44v5 in 17 (65%). Overexpression of CD44v5 correlated significantly with metastasis. The survival rate of the patients in the CD44v5-positive (overexpressed) group was significantly lower than that of the patients in the CD44v5-negative group. Overexpression of CD44v5 may play a role in the metastatic behavior of osteosarcoma and may be a prognostic parameter of osteosarcoma.

The prognostic value of immunohistochemically detected CD44v3 and CD44v6 expression in patients with surgically staged vulvar carcinoma: a multicenter study

BACKGROUND

Isoforms of the adhesion molecule CD44 are involved in carcinogenesis and the metastatic cascade of tumor cells by increasing the affinity of malignant cells to their extracellular matrix. Preliminary data with respect to the prognostic value of the CD44 isoforms CD44v3 and CD44v6 in patients with vulvar carcinoma showed promising results. The current multicenter study aimed to determine the prognostic value of CD44v3 and CD44v6 in patients with surgically staged vulvar carcinoma.

METHODS

Expression of CD44v3 and CD44v6 in vulvar carcinoma tissue was assessed by immunohistochemistry. Immunohistochemical staining was performed according to established protocols. Results were correlated to clinical data.

RESULTS

A positive CD44v3 and CD44v6 staining was detected in 33.3% (33 out of 99) and 39.4% (39 out of 99) of the tumor samples, respectively. Overexpression of CD44v6 was associated with an impaired prognosis with respect to disease-free survival (P = 0.01) and overall survival (P = 0.04). Multivariate analysis showed that CD44v6 provided prognostic information with respect to disease-free survival (P = 0.001) and overall survival (P = 0.005) independently of the two established prognosticators, tumor stage and groin lymph node involvement. Overexpression of CD44v3 had no impact on patient survival.

CONCLUSIONS

The current multicenter study, involving a large series of patients with surgically staged vulvar carcinoma, allowed for multivariate survival analysis and showed that CD44v6 confers prognostic information in addition to that provided by the established clinicopathologic parameters of tumor stage and lymph node status.

CD44 variant exons in leukemia and lymphoma

CD44 is a cell surface glycoprotein expressed on different cell types that functions in lymphocyte activation and homing, extracellular matrix adhesion and cellular migration. CD44 is encoded by a single gene composed of at least 20 exons. The standard CD44 protein (CD44S or CD44H) is the hematopoietic form of CD44 in lymphoid cells. Variant isoforms (designated from v1 to v10) are formed by addition of new exons to the extracellular domain. High levels of CD44v6 expression has been observed in some tumors and are associated with metastatic spread. The aim of the present study was to investigate and evaluate expression of the CD44v6 and v6-containing variants as a possible marker in chronic myeloid leukemia and lymphoma by reverse transcription-polymerase chain reaction. CD44 exon v6 was detected in all patients and all individuals in the control group. CD44v6-v10 mRNA was observed in 25 patients but in none of the subjects in the control group. CD44v6/v9-10, CD44v6-v7, CD44v6/v10 transcripts were detected in 11, 6, and 2 patients, respectively. CD44v6-7/v9-10 transcripts were not observed in either the patients or the healthy individuals. We conclude that CD44v6-v10 expression may be associated with hematologic malignancies.

Altered CD44 variant 6 expression in FIGO stage IB cervical carcinoma

OBJECTIVE

CD44 is an adhesion molecule which plays an important role in metastatic cascade by mediating tumor cell interaction with the endothelium and the subendothelial matrix. In this study CD44v6 expression was immunohistochemically investigated on 88 uterine cervical cancers. Correlation between expression and prognostic variables and the survival was examined.

METHODS

Eighty-eight patients with stage IB disease, treated primarily with surgery, were examined histopathologically and immunohistochemically. CD44v6 expressions of tumoral tissue and the nonneoplastic tissue nearby were examined using antiCD44v6 monoclonal antibody. CD44v6 expression was compared to the known clinicopathologic prognostic variables and survival of patients.

RESULTS

Nonneoplastic epithelium of the sections showed CD44v6 expression predominantly in basal and parabasal layers at least in traces. CD44v6 overexpression in neoplastic islands was evaluated as "general," "basal" (only in the basal portion of neoplastic islands), and "nonbasal" (also in the central portion of the neoplastic islands) separately. When expression and prognostic variables were compared, CD44v6 non-basal expression was found to be significant in nonsquamous cancers, when the tumor diameter was greater than 3 cm and in the tumors that showed recurrences. Univariate survival analysis with the Kaplan-Meier method showed that only the age of the patient is significantly correlated with disease-free survival. Interestingly when the same analysis was done for 5-year overall survival, diameter of the primary tumor, depth of cervical stromal invasion, existence and number of lymph node involvement, positivity for general CD44v6 expression, and positivity for nonbasal expression were found to be statistically significant. Furthermore multivariate analysis with Cox regression showed that nonbasal CD44v6 expression and lymph node involvement are independent variables for 5-year overall survival.

CONCLUSION

These results indicate that CD44v6 expression is associated with some of the important clinicopathologic prognostic variables and appears to be a predictor of advanced pathological-surgical stage of early clinical stage cervical carcinoma. CD44v6 nonbasal expression is significantly correlated with overall survival.

Role of sulfation in CD44-mediated hyaluronan binding induced by inflammatory mediators in human CD14(+) peripheral blood monocytes

Activation of T cells by Ag or stimulation of monocytes with inflammatory cytokines induces CD44 to bind to hyaluronan (HA), an adhesion event implicated in leukocyte-leukocyte, leukocyte-endothelial cell, and leukocyte-stromal cell interactions. We have previously shown that TNF-alpha induces CD44 sulfation in a leukemic cell line, which correlated with the induction of HA binding and CD44-mediated adhesion. In this study, we establish that TNF-alpha and IFN-gamma induce HA binding and the sulfation of CD44 in CD14(+) PBMC, whereas no induced HA binding or CD44 sulfation was observed in CD14(-) PBMC stimulated with TNF-alpha. Treatment of cells with NaClO(3), an inhibitor of sulfation, prevented HA binding in a significant percentage of CD14(+) PBMC induced by TNF-alpha, LPS, IL-1beta, or IFN-gamma. Furthermore, stimulation with TNF-alpha or IFN-gamma in the presence of NaClO(3) reduced the ability of isolated CD44H to bind HA, demonstrating a direct effect of CD44H sulfation on HA binding. In contrast, the transient induction of HA binding in T cells by PHA was not affected by NaClO(3), suggesting that activated T cells do not use sulfation as a mechanism to regulate HA binding. Overall, these results demonstrate that inducible sulfation of CD44H is one mechanism used by CD14(+) peripheral blood monocytes to induce HA binding in response to inflammatory agents such as TNF-alpha and IFN-gamma.

In vitro selection of exonic splicing enhancer sequences: identification of novel CD44 enhancers

We have developed an in vitro selection procedure that allows the identification and isolation of functional splicing enhancer sequences from any cDNA. It is based on the enhancement of general splicing activity of a pre-mRNA reporter derived from the Drosophila dsx gene. Short DNase I fragments are cloned into a cassette in the second exon of the reporter construct, replacing the natural dsx enhancer. After splicing and reverse transcription-PCR, fragments are recovered from the mRNA product. Applying this selection to the CD44 gene, which undergoes extensive alternative splicing processes, we have identified several novel exonic enhancers. Two of them, which reside in CD44 variable exon 6, were further characterized by mutational analysis and confirmed to function within their natural CD44 context.

Antibody-induced shedding of CD44 from adherent cells is linked to the assembly of the cytoskeleton

CD44 is a widely expressed integral membrane glycoprotein that serves as a specific adhesion receptor for the extracellular matrix glycosaminoglycan hyaluronan. CD44 participates in a variety of physiological and pathological processes through its role in cell adhesion. Under appropriate conditions, the ectodomain of CD44 is proteolytically removed from the cell surface. In this study we show that excessive CD44 shedding can be induced in mouse fibroblasts and monocytes upon exposure of these cells to a CD44-specific Ab immobilized on plastic, whereas treatment with phorbol ester induces significantly enhanced CD44 release from the monocytes only. CD44 shedding proceeds normally in fibroblasts and monocytes deficient in TNF-alpha converting enzyme (TACE), a sheddase involved in the processing of several substrates. Conversely, activation of the CD44 protease has no effect on the release of TNF-alpha from TACE-expressing cells, although the same metalloprotease inhibitor effectively blocks both TACE and the CD44 sheddase. Concomitant with anti-CD44 Ab- or phorbol ester-induced CD44 shedding, dramatic changes are observed in cell morphology and the structure of the actin cytoskeleton. Disruption of actin assembly with cytochalasin reduces CD44 shedding, but not the release of TNF-alpha. Moreover, pharmacological activation of Rho family GTPases Rac1 and Cdc42, which regulate actin filament assembly into distinct cytoskeletal structures, has a profound effect on CD44 release. We conclude that the CD44 sheddase and TACE are distinct enzymes, and that Ab- and phorbol ester-enhanced cleavage of CD44 is controlled in a cell type-dependent fashion by Rho GTPases through the cytoskeleton.

Hyaluronidase activation of c-Jun N-terminal kinase is necessary for protection of L929 fibrosarcoma cells from staurosporine-mediated cell death

Hyaluronidase counteracts the growth inhibitory function of transforming growth factor beta (TGF-beta), whereas secretion of autocrine TGF-beta and hyaluronidase is necessary for progression and metastasis of various cancers. Whether hyaluronidase and TGF-beta1 induce resistance to staurosporine in L929 fibrosarcoma cells was investigated. When pretreated with TGF-beta1 for 1-2 h, L929 cells resisted staurosporine apoptosis. In contrast, without pretreatment, hyaluronidase protected L929 cells fromstaurosporine apoptosis. Hyaluronidase rapidly activated p42/44 MAPK (or ERK) in L929 cells and TGF-beta1 retarded the activation. Nonetheless, TGF-beta1 synergistically increased hyaluronidase-mediated inhibition of staurosporine apoptosis. Hyaluronidase rapidly activated c-Jun N-terminal kinase (JNK1 and JNK2) in L929 cells in 20 min. Dominant negative JNK1, JNK2, and JNK3 abolished the hyaluronidase inhibition of staurosporine apoptosis, but not the TGF-beta1 protective effect. Unlike the resistance to staurosporine, pretreatment of L929 cells with hyaluronidase is necessary to generate resistance to other anticancer drugs, including doxorubicin, daunorubicin, actinomycin D, and camptothecin, and the induced resistance was also blocked by dominant-negative JNKs. Together, hyaluronidase-mediated JNK activation is necessary to generate resistance to various anticancer drugs in L929 cells.

Differential expression of CD44 isoforms during liver regeneration in rats

BACKGROUND

CD44 is a transmembrane glycoprotein known to bind hyaluronic acid (HA). This molecule is a multifunctional cell surface glycoprotein involved in lymphocyte homing and activation, tumor growth and metastasis. We have investigated the qualitative modification of CD44 in the regenerating liver as a model for studying cellular proliferation in vivo. Molecules involved in cell adhesion and the extracellular matrix (ECM), which influence differentiation, growth, cell-cell interactions and cellular polarity, play an important role in the liver regeneration. We studied the modulation of CD44 gene expression and its post-transcriptional modifications, analyzing the expression of different isoforms containing exon v6 in the regenerating liver, in sham operated liver and in the hepatoma cells H-35.

METHODS

The expression of CD44 and CD44v6 were analyzed in RNA extracted from regenerating liver at different times after partial hepatectomy (PH), and H-35 hepatoma cells by Northern blot, RT-PCR and Southern blot, and in protein extracts from regenerating liver by Western blot. H-35 hepatoma cells were assayed with the antibody cross-linked technique with CD44 antibodies.

RESULTS

The standard CD44 form is expressed in regenerating liver and its levels were not modified following PH. However, our analysis revealed CD44 isoforms containing v6 in the first hours after PH as well as in the H-35 hepatoma cell line. H-35 cells treated with cross-linked anti-CD44 antibodies or HA show an increased rate of incorporation of [3H]thymidine (30 and 25%, respectively) with respect to the control.

CONCLUSION

These findings suggest that CD44 may play a role in the proliferation of residual hepatocytes following PH.