Increased type IV collagen-degrading activity in metastases originating from primary tumors of the human colon

The secretion of specific matrix metalloproteinases (MMPs) is considered a prerequisite step for tumor cell invasion and metastasis. In the present study we investigated the expression of type IV collagen-degrading activity in primary tumors of the human colon in correlation to tumor grade and in comparison to activity expressed in arising metastases. We observed that type IV collagen-degrading activity (MMP-2 and MMP-9), purified by ion exchange, gel filtration and affinity chromatography and characterized by gelatin zymography, correlates to tumor grade. Furthermore, in surgical specimens identified as metastases originating from primary tumors of the colon, we observed that enzyme activity was significantly enhanced, relatively to that identified in the primary tumor. This observation should be considered when targeting MMPs as a therapeutic intervention to prevent cancer progression.

A 340 kDa hyaluronic acid secreted by human vascular smooth muscle cells regulates their proliferation and migration

The formation of atherosclerotic lesions is characterized by invasion of vascular smooth muscle cells (VSMC) into the tunica intima of the arterial wall and subsequently by increased proliferation of VSMC, a process apparently restricted to the intimal layer of blood vessels. Both events are preceded by the pathological overexpression of several growth factors, such as platelet-derived growth factor (PDGF) which is a potent mitogen for VSMC and can induce their chemotaxis. PDGF is generally not expressed in the normal artery but it is upregulated in atherosclerotic lesions. We have previously shown that PDGF-BB specifically stimulates proliferating VSMC to secrete a 340 kDa hyaluronic acid (HA-340). Here, we present evidence regarding the biological functions of this glycan. We observed that HA-340 inhibited the PDGF-induced proliferation of human VSMC in a dose-dependent manner and enhanced the PDGF-dependent invasion of VSMC through a basement membrane barrier. These effects were abolished following treatment of HA-340 with hyaluronidase. The effect of HA-340 on the PDGF-dependent invasion of VSMC coincided with increased secretion of the 72-kDa type IV collagenase by VSMC and was completely blocked by GM6001, a hydroxamic acid inhibitor of matrix metalloproteinases. HA-340 did not exert any chemotactic potency, nor did it affect chemotaxis of VSMC along a PDGF gradient. In human atheromatic aortas, we found that HA-340 is expressed with a negative concentration gradient from the tunica media to the tunica intima and the atheromatic plaque. Our findings suggest that HA-340 may be linked to the pathogenesis of atherosclerosis, by modulating VSMC proliferation and invasion.

The differential distribution of hyaluronic acid in the layers of human atheromatic aortas is associated with vascular smooth muscle cell proliferation and migration

Vascular smooth muscle cells (VSMC), under conditions of induced proliferation, similar to those involved in atherosclerosis, secrete an acidic glycan, 82% of which exhibits structural homology with hyaluronic acid (HA), has a molecular mass of 340 kDa (HA-340) and inhibits VSMC proliferation in vitro. In this study, the expression of glycans was investigated in human atheromatic aortas and evidence is presented that a HA molecule, similar to HA-340, is distinctly expressed in all aortic layers. The isolation of the glycans from human aortas was performed after homogenization of the individual aortic layers (atheromatic plaque, tunica intima, tunica media and tunica adventitia), by lipid extraction and extensive digestion with pronase and DNase. The total glycans were purified from the digestion products by gel filtration on Sephadex G-25 and fractionated on a Superose 6 column. Enzymatic treatment of the ensuing glycan fractions with all known glycosaminoglycan-degrading enzymes, followed by electrophoresis on polyacrylamide gradient gels and cellulose acetate membranes, revealed that, in addition to HA, the tunica intima and the atheromatic plaque also contained dermatan sulfate, while the tunica media and the tunica adventitia also contained chondroitin sulfates and heparan sulfate. The highest concentration of the human aorta HA was found in the tunica media, exhibiting a negative concentration gradient from the tunica media to the atheromatic plaque. Investigation of the biological function of the human aorta HA revealed that this molecule acts as a negative regulator on the PDGF-induced VSMC proliferation and as a positive regulator on the PDGF-induced VSMC migration. The differential expression of HA within the aortic layers correlates with the biological function attributed to this acidic glycan and associates it with key events in the progression of atherogenesis.

Corticosteroids inhibit the expression of the vascular endothelial growth factor gene in human vascular smooth muscle cells

The vascular endothelial growth factor (VEGF) is a specific mitogen for vascular endothelial cells and enhances vascular permeability and edemagenesis. VEGF is also a major regulator of angiogenesis and may be a key target for inhibiting angiogenesis in angiogenesis-associated diseases. Among the extensively studied angiostatic compounds are several corticosteroids when used alone or in combination with heparin. In this study we present evidence for an additional mechanism of action of hydrocortisone, cortisone and dexamethasone in inhibiting edemagenesis or angiogenesis. In cultures of aortic human vascular smooth muscle cells these corticosteroids (1 x 10(-8) to 1 x 10(-12) M) abolished the platelet-derived growth factor-induced (PDGF) expression of the VEGF gene in a dose-dependent manner. In contrast, two precursors of corticosteroids, desoxycorticosterone or pregnenolone, did not affect PDGF-induced VEGF expression. Our findings indicate that the capacity of corticosteroids to reduce edema or to prevent new blood vessel formation may be attributed, at least in part to the ability of these agents to abolish the expression of VEGF.

Elevated serum prolactin concentrations in phenylketonuric patients on a 'loose diet'

OBJECTIVE

High levels of phenylalanine (Phe) have been shown to reduce dopamine (DA) and noradrenaline (NA) production. We have therefore evaluated whether increased serum Phe concentrations lead to increased prolactin (PRL) secretion in phenylketonuria.

PATIENTS

Forty-two patients with classical phenylketonuria were divided into two groups. Group A (n = 19) adhered very strictly to their special diet (Phe = 0.09 +/- 0.039 mmol/l) and Group B (n = 23) were on a 'loose diet' (Phe = 0.77 +/- 0.45 mmol/l). Thirty healthy children of comparable age served as controls.

MEASUREMENTS

PRL was measured by RIA, and Phe and tyrosine (Tyr) with an amino-acid autoanalyser. Adrenaline (A), noradrenaline (NA), and dopamine (DA) were measured by HPLC.

RESULTS

Serum PRL in group B patients (1595 +/- 57 mU/l) was significantly raised compared to Group A patients (243 +/- 57 mU/l) and controls (201 +/- 55 mU/l) (P < 0.001). Serum DA, A and NA in group B were lower than in group A patients and controls. Serum Phe in group B patients was significantly correlated to serum PRL (r = 0.59) and DA (r = -0.41). Irregular menses were observed in 1/10 women from group A but in 10/13 in group B.

CONCLUSION

High serum phenylalanine concentrations in phenylketonuric patients not strictly adhering to their diets are correlated with high serum PRL and low serum dopamine concentrations, and a high prevalence of menstrual irregularities.

Major histocompatibility complex (MHC)-I and MHC-II expression in Hodgkin's disease in relation to the presence of Epstein-Barr Virus (EBV)

We have investigated the immunohistochemical expression of beta2-microglobulin and HLA-DR proteins in Hodgkin's disease (HD) in relation to the expression of the EBV-encoded EBER1-2 mRNAs and the LMP-1 protein. beta2-microglobulin is expressed in association with MHC-I molecules on most nucleated cells and HLA-DR belongs to the MHC-II molecules which are expressed mostly on antigen-presenting cells. Formalin-fixed paraffin embedded tissue from 39 cases of lymphonodal HD were stained by immunohistochemistry for beta2-microglobulin, HLA-DR and LMP-1 proteins and by RNA in situ hybridization for EBER1-2 mRNAs. beta2-microglobulin positive staining was found in Reed-Sternberg and Hodgkin cells (HRS cells) in 18/39 cases of HD. HLA-DR positive staining was found in HRS cells in all cases of HD. EBER1-2 transcripts and LMP-1 protein were detected in HRS cells in 16/39 cases of HD. No correlation as found between the presence of EBER 1-2 transcripts or the LMP-1 protein and the detection of beta2-microglobulin and HLA-DR proteins in HD. Thus, EBV does not seem to use downregulation of MHC-I to avoid the T-cell cytotoxic immune response in HD. In addition, EBV does not seem to be the only factor responsible for the HLA-DR expression in HRS cells of HD, although it could participate in the induction of the expression of HLA-DR molecule in the EBV positive cases of HD.

Induction of interleukin 6 and interleukin 8 expression by Broncho-Vaxom (OM-85 BV) via C-Fos/serum responsive element

BACKGROUND

Broncho-Vaxom (OM-85 BV) increases the resistance of the respiratory tract to bacterial infections by modulating host immune responses. The compound increases serum IgG levels but decreases IgE levels in patients suffering from chronic bronchitis or chronic obstructive pulmonary disease. It increases concentrations of gamma-interferon (IFN-gamma), IgA, and interleukin (IL)-2 in bronchoalveolar lavage fluid of patients with bronchitis. Treatment with OM-85 BV increases the number of T helper and natural killer cells. In this study the effects of OM-85 BV on transcription of cytokines is investigated in human lung fibroblasts.

METHODS

Transcription and synthesis of IL-6 and IL-8 were assessed in cultured primary human lung fibroblasts using standard methods of Northern blot analysis for the level of mRNAs and enzyme linked immunosorbent assay for proteins.

RESULTS

Broncho-Vaxom (OM-85 BV) at different concentrations induced transcription of IL-6 and IL-8. The effect of the drug on transcription of IL-6 and IL-8 genes correlated with secretion of the proteins into cell supernatants. OM-85 BV-dependent expression of the interleukin genes involved C-Fos/serum responsive element (C-Fos/SRE).

CONCLUSIONS

The data suggest that the various immunopharmacological activities of OM-85 BV that have been described in clinical studies may be explained by its ability to induce expression of IL-6 and IL-8.

Platelet-derived growth factor stimulates the secretion of hyaluronic acid by proliferating human vascular smooth muscle cells

Total glycans from the cell layer and the culture medium of human vascular smooth muscle cells (VSMC) that had been cultivated in the presence of platelet-derived growth factor (PDGF) were isolated and purified by gel filtration after Pronase and DNase digestion and alkaliborohydride treatment. Measurements of the content of neutral hexoses and uronic acids revealed that PDGF stimulates total glycan synthesis by proliferating VSMC in a linear fashion from 24 h to 72 h of incubation. In contrast, total glycan synthesis by human fibroblasts, epithelial cells, or endothelial cells was not affected by PDGF, indicating cell-type specificity. Chemical, biochemical, and enzymological characterization of the total glycans synthesized by VSMC showed that PDGF stimulates the secretion of a 340-kDa glycan molecule in a time-dependent manner from 24 h to 72 h. This molecule is highly acidic, shares a common structure with hyaluronic acid, and exhibits a potent antiproliferative activity on VSMC. These results suggest that VSMC in response to PDGF are capable of controlling their own growth and migration by the synthesis of a specific form of hyaluronic acid with antiproliferative potency, which may be involved in the regulation of the local inflammatory responses associated with atherosclerosis.

A novel class of adhesion acidic glycans in sea urchin embryos. Isolation, characterization and immunological studies during early embryonal development

Total glycans were isolated and purified from Lytechinus pictus embryos at early developmental stages by gel-filtration chromatography after pronase and DNase digestion, and alkali-borohydride treatment. Fractionation by Superose 6 and HPLC gel-filtration chromatography revealed three major glycan fractions of 580, 150 and 2 kDa consistently throughout development up to the stage of end gastrula. The 580-kDa and the 150-kDa glycan fractions isolated from fertilized eggs up to the stage of end gastrula are highly acidic, whereas the 2-kDa glycan fractions have no detectable uronic acid residues and charged groups. Chemical analysis of the glycan fractions showed that their content of neutral hexoses, uronic acid, GlcNAc, GalNAc and sulphate changes during development. The resistance of the 580-kDa and the 150-kDa glycan fractions to glycosaminoglycan-degrading enzymes indicates a structure which is different from the glycosaminoglycans. The incorporation of [3H]glucosamine into the 580-kDa, the 150-kDa and the 2-kDa glycan fractions showed that glycan synthesis increases in a linear fashion from the stage of early blastulation to end of gastrulation. Maximal incorporation of the radioligand occurs in the 2-kDa glycan fractions, with the highest rate observed between the stages of mesenchyme blastula and early gastrulation. Immunological studies, using a monoclonal antibody which inhibits cell aggregation, showed that the total glycans isolated from morula, early blastulation, early gastrulation and the end of gastrulation carry cell-adhesion epitopes. The number of these epitopes, as indicated by the intensity of the immunostaining, increases from morula formation to end-gastrulation stages and correlates with the increased rate of morphogenetic movements. These results suggest that controlled expression of the cell-adhesion glycan epitopes play an important role in sea urchin gastrulation.

A granulocyte inhibitory protein overexpressed in chronic renal disease regulates expression of interleukin 6 and interleukin 8

Growing evidence suggests that cytokine expression is influenced by locally produced mediators, thus modifying the pluripotential effects of cytokines toward a tissue-specific inflammatory reaction. The granulocyte inhibitory protein (GIP), a 23-kDa protein found to be significantly overexpressed in patients with chronic renal failure, increases autocrine transcription and expression of interleukin (IL) 6 and IL-8 in human mesangial cells. Moreover, GIP alone induced the transcription of c-jun mRNA; however, in combination with IL-6, it stimulated de novo synthesis of DNA and the transcription of both c-jun and c-fos genes. The data suggest that the overall effect of GIP results in the modulation of the glomerular response to injury and contributes to the progression of glomerulosclerosis.

Isolation and characterization of a new class of acidic glycans implicated in sea urchin embryonal cell adhesion

Three major glycan fractions of 580 kDa (g580), 150 kDa (g150), and 2 kDa (g2) were isolated and purified from Lytechinus pictus sea urchin embryos at the mesenchyme blastula stage by gel filtration and high pressure liquid chromatography. Chemical analysis, by gas chromatography, revealed that g580 is highly sulfated and rich in N-acetylglucosamine, N-acetylgalactosamine, glucuronic acid, and fucose. The g150 fraction is less acidic than g580 and contains high amounts of amino sugars, xylose, and mannose. The g2 fraction is neutral, rich in N-acetylglucosamine, mannose, and galactose. The g580 and g150 fractions are resistant to glycosaminoglycan-degrading enzymes, indicating that they are distinct from the glycosaminoglycans. The g580 fraction resembles, with respect to chemical composition, a previously characterized 200 kDa sponge adhesion glycan (g200). The binding of the monoclonal antibody Block 2, which recognizes a repetitive epitope on g200, as well as of the anti-g580 polyclonal antibodies to both g580 and g200 indicated that these two glycans share similar antigenic determinants. The Fab fragments of the Block 2 antibody, which previously have been shown to inhibit cell adhesion in sponges, also blocked the reaggregation of dissociated sea urchin mesenchyme blastula cells. These results indicate that g580 carries a carbohydrate epitope, similar to the sponge adhesion epitope of g200, which is involved in sea urchin embryonal cell adhesion.

Expression of type IV collagen-degrading activity during early embryonal development in the sea urchin and the arresting effects of collagen synthesis inhibitors on embryogenesis

Type IV collagen-degrading activity was expressed in homogenates of Lytechinus pictus embryos during embryogenesis. Activity was concentrated 1,600-fold by ammonium sulfate fractionation, ion exchange, and gel chromatography and could not be activated further upon trypsin or organomercurial treatment. This enzyme activity could also degrade gelatin but had no affinity for type I, III, and V collagens. Activity was inhibited by addition of excess type IV collagen or gelatin, but was unaffected by addition of excess amounts of non-collagenous proteins of the extracellular matrix. Chelators such as 1,10-phenanthroline or Na2EDTA reduced activity to control levels. Inhibitors of plasmin and of serine and thiol proteases were without effect. Type IV collagen-degrading activity first became apparent at the stage of early mesenchyme blastula. It then increased by a small increment and remained stable up to the stage of late mesenchyme blastula, coinciding with first detection of collagen synthesis and the appearance of the archenteron. Thereafter, a sharp increase in activity was observed, concurrently with remodelling of the archenteron. Maximum activity was attained at prism stage and was retained throughout to pluteus-larva stage. The specific inhibitors of collagen biosynthesis 8,9-dihydroxy-7-methyl-benzo[b]quinolizinium bromide and tricyclodecane-9-yl xanthate arrested sea urchin embryo development at early blastula, prevented the invagination of the archenteron, and reverted the expression of type IV collagen-degrading activity to non-detectable levels. Removal of the inhibitors allowed embryos to gastrulate and express type IV collagen-degrading activity.