Syndecans and the lymphoid system

Aberrant Expression of Syndecan-1 in Cervical Cancers

Syndecan-1, is a transmembrane heparan/chondroitin sulfate proteoglycan necessary for cell-cell and cell-matrix interactions. Its decreased level on the cell surface correlates with poor prognosis in several tumor types. Aberrant stromal localization of syndecan-1 is also considered an unfavorable prognostic factor in various human malignancies. In the presented work the question was addressed if changes in syndecan-1 expression are related to the prognosis of cervical cancer. Immunohistochemistry for syndecan-1 extracellular domain was performed on surgical specimens of primary cervical cancer. To follow the communication between tumor cells and stromal fibroblasts, their mono-and co-cultures were studied, detecting the expression of syndecan-1, smooth muscle actin, vimentin, and desmin. Immunohistochemistry of tumorous specimens revealed that while cell surface syndecan-1 expression was reduced on cancer cells, it appeared on the surface of tumor-associated fibroblasts. Until year 7, the cohort with high cell surface syndecan-1 expression had significantly longer survival. No difference in the same time-period could be detected when stromal syndecan-1 expression was analyzed. In vitro analysis revealed, that tumor cells can induce syndecan-1 expression on fibroblast, and fibroblasts showed that fibroblast-like cells are built by two cell types: (a) syndecan-1 positive, cytokeratin negative real fibroblasts, and (b) syndecan-1 and cytokeratin positive epithelial-mesenchymal transformed tumor cells. Syndecan-1 on the surface of cancer cells appears to be a positive prognostic marker. Although syndecan-1 positive fibroblasts promote tumor cell proliferation in vitro, we failed to detect their cancer promoting effect in vivo.

Syndecan-1 (sCD138) levels in chronic lymphocytic leukemia: clinical and hematological correlations

BACKGROUND

Syndecan-1 (sCD138) has recently been suggested to predict the clinical course of early-stage chronic lymphocytic leukemia (CLL), but few studies have been reported. This study assessed the role of syndecan-1 in the prognosis of patients with CLL and its correlation with other prognostic markers.

METHODS

This prospective study was performed in the hematology department of an Indian tertiary care center, over nineteen months (Jun. 2009-Jan. 2011). Forty-nine new patients with CLL presented during this period and were included. Twenty age- and gender-matched healthy patients served as controls, and six patients with multiple myeloma were included as positive controls. Baseline serum syndecan-1 concentrations were measured for all patients at presentation using ELISA (Diaclone, Besancon, France). At baseline, patients were divided into low (N=10), intermediate (N=18) and high (N=21) risk cohorts. Serum syndecan-1 levels in these patient subgroups were compared with clinical and laboratory parameters.

RESULTS

The median syndecan-1 level in patients with CLL (73.32 ng/mL, range, 28.71-268.0 ng/mL) was marginally higher than that in healthy patients (63.10 ng/mL, range, 55.0-75.11 ng/mL). At presentation, syndecan-1 levels in patients with CLL correlated strongly with symptomatic disease (cytopenias, P=0.004) and higher clinical stage (Rai stage III and IV, P=0.001) markers and poorly with β2-microglobulin level (P=0.270), diffuse BM infiltration (P=0.882), and surrogate mutation status markers (CD 38, P=0.174 and ZAP-70, P=0.459). Syndecan-1 levels dichotomized by the median value were higher with progressive disease markers, e.g. shorter lymphocyte doubling time (LDT, P=0.015) and increased treatment (P=0.099).

CONCLUSION

In CLL, serum syndecan-1 (sCD138) levels at presentation correlate with disease burden, and higher baseline levels may predict early treatment.

Serum levels of syndecan-1 in B-cell chronic lymphocytic leukemia: Correlation with the extent of angiogenesis and disease-progression risk in early disease

Syndecan-1 is a transmembrane proteoglycan generally not expressed in mature B-cell neoplasias like chronic lymphocytic leukemia (CLL). Moreover, information dealing with the evaluation of soluble syndecan-1 in CLL are lacking. We measured syndecan-1 concentrations in serum drawn at the time of diagnosis from 67 B-cell CLL patients (Binet stage A, 46; stage B, 7; stage C, 14). For this purpose a syndecan-1 enzyme-linked immunosorbent assay (ELISA, Diaclone, Besancon, France) was used. Detectable levels of syndecan-1 were found in all patients, although serum concentrations were significantly lower in CLL patients in comparison to age- and sex-matched controls (P = 0.02; Mann-Whitney test). No correlation was found with Binet clinical stages (P = 0.796), beta2-microglobulin (P = 0.923), hemoglobin level (P = 0.605), platelet count (P = 0.992) and lymphocyte doubling time (P = 0.709). Only an association with absolute peripheral blood lymphocytosis (PBL) (P = 0.01) and LDH (P = 0.05) could be detected. Serum levels of syndecan-1 did not parallel those of several angiogenic cytokines such as vascular endothelial growth factor (VEGF) (P = 0.963), basic fibroblastic growth factor (FGF-2) (P = 0.216), angiogenin (P = 0.478), metalloproteinase-9 (MMP-9) (P = 0.125) as well as bone marrow (BM) microvessel density (P = 0.110). The same applied with adhesion molecules such as CD54 (P = 0.233), CD108 (P = 0.799), CD44 (P = 0.816) and CD31 (P = 0.508). Interestingly, the inverse correlation (r = -0.4967; P = 0.03) between serum concentrations of syndecan-1 and plasma levels of stromal derived growth factor-1 (SDF-1) is in keeping with the different function, respectively, pro- and anti-apoptotic, of these molecules. In 46 Binet stage A patients, serum levels of syndecan-1 were further evaluated as a dichotomous variable with respect to progression-free survival (PFS), an end-point surrogate for overall survival in early B-cell CLL. The best separation of curves was seen with a cut-off point at the median value of syndecan-1 (i.e. 36.5 pg/ml). Median PFS was not reached in the patient group with low syndecan-1, compared to a median of 34 months observed in the remaining patients (P = 0.018; HR = 0.208; 95% CI = 0.115 - 0.816). At the multivariate analysis performed including variables significant in the univariate analysis [i.e. PBL (P = 0.03) and syndecan-1 (P = 0.01)], only syndecan-1 retained a trend of significance (P = 0.08). Despite the pro-angiogenic activity of syndecan-1 which mediates FGF-2 binding and activity, no correlation with either angiogenic cytokines or the extent of BM angiogenesis was found in CLL. The inverse correlation with plasma levels of SDF-1 suggests an involvement in the processes leading to apoptosis. Finally, our results highlight the involvement of syndecan-1 in the mechanisms of disease-progression of early CLL.

Differential expression of syndecans and glypicans in chronically inflamed synovium

BACKGROUND

Membrane-bound heparan sulphate proteoglycans (HSPGs) act as co-receptors and presenters of cytokines and are involved in cell-matrix and cell-cell adhesion.

AIM

To investigate which HSPGs are expressed in knee joint synovia from patients with different forms of arthritis and normal individuals.

METHODS

Synovial samples were obtained from patients with early rheumatoid arthritis (n = 8), longstanding rheumatoid arthritis (n = 13), psoriatic arthritis (n = 7), osteoarthritis (n = 6) and normal joints (n = 12). Expression of syndecan-1, -2, -3 and -4 and glypican-1, -3 and -4 was analysed by immunohistochemistry and dual label immunofluorescence.

RESULTS

The expression of HSPGs in chronically inflamed synovium exhibited a differential distribution. Syndecan-1 was present in the mononuclear infiltrates of synovia from patients with rheumatoid and psoriatic arthritis where it was expressed by plasma cells. Syndecan-2 was present mainly in blood vessels where it occurred on endothelial cells, pericytes and smooth muscle cells. Syndecan-3 stained intensely in endothelial cells but also occurred in sublining macrophages and the lining layer. Glypican-4 occurred in the lining layer and blood vessels. Increased expression of these HSPGs was apparent in rheumatoid and psoriatic compared to osteoarthritic and normal synovia. Little or no staining for syndecan-4, glypican-1 and glypican-3 was seen in all samples.

DISCUSSION

Selected HSPGs, such as syndecan-1, -2 and -3 and glypican-4, could play a part in the pathophysiology of arthritis, such as the migration and retention of leukocytes and angiogenesis in the chronically inflamed synovium.

Stromal syndecan-1 expression is an adverse prognostic factor in oral carcinomas

Syndecan-1, a transmembrane proteoglycan, may exert anti-proliferative effects and promote cell growth by binding various growth factors. Malignant epithelial cells often down-regulate their own syndecan-1 production, and are capable of inducing an aberrant syndecan-1 expression in stromal fibroid cells. Decreased tumor cell syndecan-1 levels in human head and neck squamous cell carcinomas indicate poor prognosis, however, no correlation between stromal syndecan-1 expression and clinical parameters has previously been established. By means of immunohistochemistry, we observed a decrease in tumor cell syndecan-1 reactivity in 33/39 oral carcinoma cases, the degree of which, however, correlated only weakly with the clinical outcome (p = 0.097). Conversely, stromal syndecan-1 positivity proved to be a significant risk factor of recurrence (Cox analysis, p = 0.03) and tumor-specific death (p = 0.023) within a 24-month period after operation. Taken together, stromal expression of syndecan-1 is a reliable factor of adverse prognosis in oral carcinomas.

Requirement of 8-mercaptoguanosine as a costimulus for IL-4-dependent mu to gamma1 class switch recombination in CD38-activated B cells

Mature B-2 cells expressing surface IgM and IgD proliferate upon stimulation by CD38, CD40 or lipopolysaccharide (LPS) and differentiate into IgG1-producing plasma cells in the presence of cytokines. The process of class switch recombination (CSR) from IgM to other isotypes is highly regulated by cytokines and activation-induced cytidine deaminase (AID). Blimp-1 and XBP-1 play an essential role in the terminal differentiation of switched B-2 cells to Ig-producing plasma cells. IL-5 induces AID and Blimp-1 expression in CD38- and CD40-activated B-2 cells, leading to mu to gamma1 CSR at DNA level and IgG1 production. IL-4, a well-known IgG1-inducing factor, does not induce mu to gamma1 CSR in CD38-activated B-2 cells or Blimp-1, while IL-4 induces mu to gamma1 CSR, XBP-1 expression, and IgG1 production expression in CD40-activated B-2 cells. Interestingly, the addition of 8-mercaptoguanosine (8-SGuo) with IL-4 to the culture of CD38-activated B cells can induce mu to gamma1 CSR, Blimp-1 expression, and IgG1 production. Intriguingly, 8-SGuo by itself induces AID expression in CD38-activated B cells. However, it does not induce mu to gamma1 CSR. These results imply that the mode of B-cell activation for extracellular stimulation affects the outcome of cytokine stimulation with respect to the efficiency and direction of CSR, and the requirements of the transcriptional regulator and the generation of antibody-secreting cells. Furthermore, our data suggest the requirement of additional molecules in addition to AID for CSR.

Engagement of the B-cell antigen receptor (BCR) allows efficient transduction of ZAP-70-positive primary B-CLL cells by recombinant adeno-associated virus (rAAV) vectors

Engagement of the B-cell antigen receptor (BCR) by crosslinking of the surface immunoglobulin (sIg) homodimer was studied for recombinant adeno-associated virus (rAAV)-mediated gene transfer into B-cell chronic lymphocytic leukaemia (B-CLL) cells. Leukemic cells obtained from 20 patients were stimulated with anti-sIg-directed antibodies and transduced with rAAV vectors coding for enhanced green fluorescent protein (EGFP) (AAV/EGFP) or CD40L (AAV/CD40L). Transduction of B-CLL cells was enhanced after BCR engagement compared to unstimulated controls (P=0.0356). BCR crosslinking induced a significant, dose- and time-dependent upregulation of heparan sulfate proteoglycan (HSPG), the primary receptor for AAV, on B-CLL cells (mean: 38.2 versus 1.7%; P=0.0006). A correlation of HSPG expression after BCR crosslinking with transduction efficiency by AAV/EGFP (P=0.0153) and AAV/CD40L (P=0.0347) was observed. High expression of zeta-associated protein 70 (ZAP-70) in B-CLL cells correlated with a better transduction efficiency by AAV/EGFP (P<0.0001) and AAV/CD40L (P=0.002), respectively: 48 h after transduction of ZAP-70-positive samples, transgene expression was seen in a mean of 33.8% (s.e.m. 3.7%) and 28.9% (s.e.m. 6.7%) of cells, respectively, and could be specifically blocked by heparin, a soluble competitor of HSPG (P<0.0001). In summary, engagement of the BCR on ZAP-70 positive B-CLL cells allows efficient rAAV-mediated gene delivery.

Evidence from the generation of immunoglobulin G–secreting cells that stochastic mechanisms regulate lymphocyte differentiation

Naive B lymphocytes undergo isotype switching and develop into immunoglobulin-secreting cells to generate the appropriate class and amount of antibody necessary for effective immunity. Although this seems complex, we report here that the generation of immunoglobulin G-secreting cells from naive precursors is highly predictable. The probabilities of isotype switching and development into secreting cells change with successive cell divisions and interleave independently. Cytokines alter the probability of each differentiation event, while leaving intact their independent assortment. As a result, cellular heterogeneity arises automatically as the cells divide. Stochastic division-linked regulation of heterogeneity challenges the conventional paradigms linking distinct phenotypes to unique combinations of signals and has the potential to simplify our concept of immune complexity considerably.

Proteoglycans and tumor progression: Janus-faced molecules with contradictory functions in cancer

Understanding the details of the molecular mechanism of tumor dissemination revealed that several proteoglycan species are involved in the process but their role can be described as Janus-faced. One level of proteoglycan alterations is at the expression of their genes coding for the core protein. Characteristically, in progressing tumors two patterns emerged: loss or neoexpression of surface proteoglycans (PG) depending on the initial expression pattern of the cell type of origin. The situation is similarly complex concerning the changes of glycosaminoglycan (GAG) of the PG during tumor progression. This is due to the fact that the majority of PGs involved is hybrid molecule meaning that their core protein can be glycanated both with chondroitin and heparan sulfate. However, such an alteration in glycanation of PG may fundamentally change the function of the molecule, especially the one operating at the cell surface. Among the extracellular PGs, decorin emerged as inhibitor of progression while perlecan as a promoter of the process. Analysis of the available data indicate that during metastatization tumor cells must express at least one cell surface HSPG species from the syndecan-glypican-CD44v3 group. Furthermore, the HS-chain of these proteoglycan(s) carry important molecular signatures (suphution or epimerization patterns). Experimental data suggest that tumor cell surface heparan sulfate (PG) may provide a target for specific anti-metastatic interventions.

Effect of 5-azacytidine and galectin-1 on growth and differentiation of the human b lymphoma cell line bl36

BACKGROUND: 5-AzaCytidine (AzaC) is a DNA demethylating drugs that has been shown to inhibit cell growth and to induce apoptosis in certain cancer cells. Induced expression of the galectin1 (Gal1) protein, a galactoside-binding protein distributed widely in immune cells, has been described in cultured hepatoma-derived cells treated with AzaC and this event may have a role in the effect of the drug. According to this hypothesis, we investigated the effect of AzaC and Gal1 on human lymphoid B cells phenotype. METHODS: The effect of AzaC and Gal1 on cell growth and phenotype was determined on the Burkitt lymphoma cell line BL36. An immunocytochemical analysis for detection of Gal1 protein expression was performed in AzaC-treated cells. To investigate the direct effects of Gal1, recombinant Gal1 was added to cells. RESULTS: Treatment of lymphoid B cells with AzaC results in: i) a decrease in cell growth with an arrest of the cell cycle at G0/G1 phase, ii) phenotypic changes consistent with a differentiated phenotype, and iii) the expression of p16, a tumor-suppressor gene whose expression was dependent of its promoter demethylation, and of Gal1. A targeting of Gal 1 to the plasma membrane follows its cytosolic expression. To determine which of the effects of AzaC might be secondary to the induction of Gal1, recombinant Gal1 was added to BL36 cells. Treated cells displayed growth inhibition and phenotypic changes consistent with a commitment toward differentiation. CONCLUSIONS: Altered cell growth and expression of the cell surface plasma cell antigen, CD138 are detectable in BL36 cells treated by AzaC as well as by Gal1. It seems that AzaC-induced Gal1 expression and consequent binding of Gal1 on its cell membrane receptor may be, in part, involved in AzaC-induced plasmacytic differentiation.