[Show abstract][Hide abstract] ABSTRACT: Angiostatin, a proteolytic fragment of plasminogen consisting of the first 3 or 4 kringle domains, reduces tumor growth by specifically inhibiting tumor angiogenesis. Angiostatin is generated in vitro in a 2-step process. First, plasminogen is converted to plasmin by plasminogen activators. Next, plasmin excises the angiostatin fragment from plasminogen, a process requiring molecules that are able to donate a free sulfhydryl group. In this study, we investigated whether stimulation of in vivo angiostatin generation by administration of plasminogen activator and a free sulfhydryl group donor (FSD) has anti-tumor activity. First, we determined the optimal conditions for in vitro angiostatin generation by incubating murine plasma with different concentrations of plasminogen activator and/or the FSD captopril. Angiostatin generation was monitored by western blot analysis. Our results were extrapolated to the in vivo situation by administering the optimal dose of tissue-type plasminogen activator (tPA, i.v. injection 3 times/week) and captopril (in drinking water) to mice and analyzing the presence of angiostatin in the circulation. Angiostatin was readily detectable in mice receiving both tPA and captopril, but not in mice receiving either one of the agents. Finally, the anti-tumor activity of the tPA/captopril treatment was tested in a human melanoma xenograft model. Administration of tPA alone had only a marginal effect on tumor growth. Captopril alone reduced tumor growth by about 60%, whereas treatment with both captopril and tPA resulted in 83% inhibition of tumor growth.
Preview · Article · Nov 2004 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Multigenicity is one of the features of cancer/testis-associated genes. In the present study we analyzed the number and expression of genes of the SPANX(CTp11) family of cancer/testis-associated genes. Genomic database analysis, next to the four previously described SPANX genes, revealed the presence of a novel gene: SPANXE. Moreover, we detected an allelic variant of SPANXB resulting in one amino acid substitution in the encoded protein: SPANXB'. Most SPANX genes are present on contig NT_011574 located at Xq26.3-Xq27.1. Based on expressed sequence tag databases and RT-PCR analysis three additional novel SPANX sequences were identified, though not represented so far in the human genome sequence. Sequence alignments justify a subdivision of this gene family based on the absence (SPANXA-likes) or presence (SPANXB) of an 18 base pair sequence stretch in the open reading frame. The alignments also reveal an unusually high level (99%) of intron homology. Furthermore, the nucleotide variations in the open reading frame almost all lead to amino acid substitutions. Southern blot and database analyses indicate that SPANX sequences are exclusively present in primates. With RT-PCR analysis on human sperm cell precursors and tumor cell lines most family members could be detected. SPANXB was only found in sperm cell precursors and could not be detected in the tumor cell lines tested. Overall SPANXA was the most frequently expressed SPANX variant in melanoma and glioblastoma cell lines.
[Show abstract][Hide abstract] ABSTRACT: Cigarette smoking has been inconsistently associated with colon cancer risk. To evaluate the hypothesis that smoking is primarily linked to a specific colon tumor subgroup(s), we assessed associations between smoking and the occurrence of mutations in the APC, K-ras and p53 genes, p53 overexpression, and microsatellite instability (MSI) in a Dutch population-based case-control study on sporadic colon carcinomas. The study population consisted of 176 cases and 249 controls. Smoking status (never, ever), number of cigarettes smoked per day (never, <15, > or =15), total years of smoking (never, < or =30, >30), and years since first started smoking (never, < or =35, >35) were all evaluated. Cigarette smoking status was significantly differently related to p53 overexpression-positive (p53(pos)) tumors compared with p53 overexpression-negative (p53(neg)) tumors (p53(pos) versus p53(neg), OR 0.4, 95% CI 0.2-0.9), as well as to tumors with transversion mutations in APC, K-ras or p53 (transv(+)) compared with tumors without transversion mutations in one of these genes (transv(-)) (transv(+) versus transv(-), OR 2.5, 95% CI 1.0-5.9). Positive associations were observed with p53(neg) tumors and transv(+) tumors when compared with the population-based controls (ever versus transv(-), OR 1.5, 95% CI 0.9-2.8 and OR 2.2, 95% CI 0.9-5.6, respectively), inverse associations with p53(pos) tumors and transv(-) tumors (ever versus never, OR 0.5, 95% CI 0.3-1.0 and OR 0.8, 95% CI 0.5-1.3, respectively). Similar patterns of association were observed for the other smoking variables evaluated. In addition, although statistically non-significant, smoking was more notably positively associated with tumors that exhibit K-ras mutations, especially K-ras transversion mutations, than with tumors without K-ras mutations. An inverse relationship between smoking and the occurrence of APC mutations was suggested, whereas no clear associations were observed with MSI. Our data suggest that smoking-related colon cancers develop through a p53(neg) pathway and that smoking particularly results in colon carcinomas with transversion mutations.
[Show abstract][Hide abstract] ABSTRACT: The existence of XAGE genes was first reported after database homology searches for PAGE-like sequences identified 3 XAGE EST clusters. One of these clusters, XAGE-1, has in later studies been identified as a cancer/testis-associated gene. Here, we report the expression profiles of all 3 reported XAGE genes, as well as several splice variants of XAGE-1, in normal human tissues, Ewing's sarcoma and melanocytic tumors. We also provide the genetic structure of the corresponding genes. Moreover, by searching the databases for XAGE homologues, we identified 3 additional GAGE-like genes. RT-PCR studies showed frequent expression in melanoma metastases and Ewing's sarcoma for 2 XAGE-1-derived transcripts. XAGE-2 was expressed at lower frequency in these tissues, while XAGE-3 was seen only in normal placenta. Due to a frameshift, the largest XAGE-1 putative protein is far less homologous to GAGE-like proteins than the other XAGEs. Interestingly, all GAGE-like genes contain a large secondary open reading frame, coding for putative proteins homologues to the XAGE-1 primary protein. The XAGE family of cancer/testis-associated genes is located on chromosome Xp11.21-Xp11.22. The data outline a superfamily of GAGE-like cancer/testis antigens, consisting of at least 19 genes.
Preview · Article · May 2002 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Suppression subtractive hybridization, comparing mRNA expression profiles of common nevocellular nevi and melanoma metastases, was used to identify potential markers of melanoma progression. From the metastases we isolated XAGE-1b, a 470 bp transcript of the XAGE-1 gene. In general, expression of XAGE-1b was much more prominent than expression of the longer XAGE-1 transcript, isolated from Ewing's sarcoma. The XAGE-1b open-reading frame codes for a putative protein of 81 amino acids, harboring a functional bipartite nuclear localization signal and a C-terminal acidic transcription-activation-like domain. On the nucleotide level, XAGE-1b has a 50% homology with members of the GAGE family. However, homology between the corresponding proteins is weak. Expression of XAGE-1b in normal tissues was mainly restricted to testis, while placenta and brain were sporadically positive. In human tumor cell lines as well as in human tumor lesions, expression was most frequently found in melanocytic tumors and Ewing's sarcoma. In the different stages of melanocytic tumor progression, expression was exclusively seen in melanoma metastases (38%; n = 61), while all tested common and atypical nevi (n = 10) as well as primary melanomas (n = 8) were negative. Upregulation of expression after treatment with demethylating agent 5-aza-2'-deoxycytidine was detected in 1 of 4 human melanoma cell lines tested. The XAGE-1 gene consists of 4 exons and is located on chromosome Xp11.21-Xp11.22. After transfection into COS cells, the corresponding protein can direct the coupled fluorescent protein to the nucleus, showing a distinct speckled staining aspect. Our data imply the nuclear cancer/testis-associated XAGE-1b to be a marker for late melanocytic tumor progression.
Full-text · Article · Jan 2002 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Vaccination-based therapy of melanoma has so far mainly focused on monovalent approaches using either melanoma differentiation antigens or cancer/testis antigens. To study the complementarity of expression from these two families of antigens recognized by T-cells, we screened 47 metastatic lesions of cutaneous melanoma for the expression of three melanoma differentiation antigens and eight cancer/testis antigens using reverse transcription-polymerase chain reaction (RT-PCR). The melanoma differentiation antigens were expressed in a somewhat higher percentage of lesions (94% positive for at least one marker) than the cancer/testis antigens (91% positive for at least one marker). Nearly all the melanoma metastases (98%) expressed at least one of the markers tested. One melanoma metastasis was negative for all the markers. Two out of 47 lesions did not express any of the three differentiation markers but expressed one or more of the cancer/testis antigens, indicating some additional potential for these antigens compared with the melanoma differentiation antigens. Therefore, we conclude that polyvalent immunotherapy using multiple epitopes from both families of antigens might increase the eligibility of melanoma patients and the efficacy of the treatment.
No preview · Article · Nov 2001 · Melanoma Research
[Show abstract][Hide abstract] ABSTRACT: Activation of matrix metalloproteinase-2 (MMP-2) is mediated by binding to the complex of membrane-type matrix metalloproteinase-1 (MT1-MMP) with tissue inhibitor of MMP-2 (TIMP-2) on the cell surface. Binding of MMP-2 to integrin alpha(v)beta(3) has been implicated in presenting activated MMP-2 on the cell surface of invasive cells, but interactions with the MT1-MMP-TIMP-2 system have not been considered. Therefore, we studied the expression and interaction of MT1-MMP, MMP-2 and TIMP-2 in the alpha(v)beta(3)-negative melanoma cell line BLM and in its beta(3)-transfected, alpha(v)beta(3)-expressing counterpart BLM-beta(3), both on cell lines and in xenografts. Total expression levels of MMP-2, MT1-MMP and TIMP-2 did not differ markedly between the alpha(v)beta(3)-negative and alpha(v)beta(3)-positive cells. Remarkable differences, however, exist in the presence of active MMP-2 and MT1-MMP. Zymography on cell lysates revealed that active MMP-2 was restricted to alpha(v)beta(3)-positive cell line and clearly accumulated in xenografts derived from the BLM-beta(3) cells, confirming the relevance of this integrin for MMP-2 function. Western blotting of cell lysates showed that processing of proMT1-MMP to the activated form was enhanced in BLM-beta(3). The ratio of active and inactive MT1-MMP was 3-fold higher in the beta(3)-transfectants. Immunofluorescence double-labeling followed by confocal laser microscopy showed co-localization of MT1-MMP and alpha(v)beta(3) on BLM-beta(3) cells. In xenografts from BLM-beta(3) cells, active MT1-MMP was markedly increased. Our results demonstrate that expression of alpha(v)beta(3) in cell lines and xenografts was accompanied by an accumulation of active MT1-MMP and MMP-2. Furthermore, MT1-MMP and alpha(v)beta(3) are co-localized on the cell membrane of tumor cells. These findings suggest that activated MT1-MMP co-localized with alpha(v)beta(3) may be involved in activation of alpha(v)beta(3)-bound MMP-2.
No preview · Article · Aug 2000 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: K-ras gene mutations (codons 12 and 13) were determined by PCR-based mutant allele-specific amplification (MASA) in tumour tissue of 185 colon cancer patients: 36% harboured mutations, of which 82% were located in codon 12. High intakes of animal protein, calcium and poultry were differently associated with codon 12 and 13 mutations: odds ratios (OR) and 95% confidence intervals (95% CI) for codon 12 versus codon 13 were 9.0 (2.0-42), 4.1 (1.4-12) and 15 (1.4-160), respectively. In case-control comparisons, high intakes of animal protein and calcium were positively associated with colon tumours harbouring codon 12 mutations [for animal protein per 17 g, OR (95% CI) = 1.5 (1.0-2.1); for calcium per 459 mg, 1.2 (0.9-1.6)], while inverse associations were observed for tumours with K-ras mutations in codon 13 [for animal protein 0.4 (0.2-1.0); for calcium 0.6 (0. 3-1.2)]. Transition and transversion mutations were not differently associated with these dietary factors. These data suggest a different dietary aetiology of colon tumours harbouring K-ras codon 12 and 13 mutations.
[Show abstract][Hide abstract] ABSTRACT: Epidemiological studies have suggested that dietary factors may differently affect p53-dependent and p53-independent pathways to colon cancer. Results of such studies may depend on the method used to assess p53 status. This case-control study of 185 colon-cancer cases and 259 controls examines this relation, using both immunohistochemistry and SSCP(exons 5-8)/sequencing to detect p53 abnormalities. Of 185 carcinomas analyzed using immunohistochemistry, 81 (44%) were categorized as p53 over-expression. p53 mutations were detected in 59 tumors (32%). A slight increase in risk observed for intake of saturated fat was largely due to an increased risk in cases without p53 over-expression (OR per 16.1 g/day, 1.46; 95% CI, 1.08-1.97), and no association in cases with p53 over-expression (OR, 1.07, 95% CI, 0.78-1.47). However, findings were less pronounced when cases were classified by mutation analysis (wild-type OR, 1.33; 95% CI, 1.01-1.75; mutated OR, 1.16; 95% CI, 0.81-1.65). Similar results were observed for total fat intake. For other nutrients and for vegetable and meat food groups no differences in risk for either p53 pathway were observed, independent of the laboratory technique used. Interestingly, in cases with transversion mutations in the p53 gene, an increased risk was observed for saturated fat (OR, 2.00; 95% CI, 0.97-4.14), in contrast to those with mutations at CpG sites (OR, 0.93; 95% CI, 0.55-1.57). An increase in colon-cancer risk for the p53-independent pathway due to fat intake, is more pronounced when using immunohistochemistry. However, mutation analysis is needed to study the possible association with a small group of tumors with transversion mutations.
No preview · Article · Jun 1999 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Peptides containing the integrin recognition sequence, RGD, can inhibit experimental metastasis of mouse melanoma cells, but the integrin(s) affected in these experiments is unknown. Besides "classical" RGD-binding integrins such as alpha 5 beta 1 and alpha v beta 3, RGD has been reported to bind alpha 4 beta 1, and mAbs to alpha 4 beta 1 can inhibit melanoma metastasis. We investigated the mode of action of the disintegrin eristostatin, an RGD-containing peptide isolated from snake venom, in a human melanoma experimental metastasis model. Lung colonization following i.v. injection of MV3 cells in nude mice was strongly inhibited by eristostatin. MV3 cells bound FITC-eristostatin and adhered to eristostatin-coated wells. This adhesion was partially inhibited by a GRGDSP peptide and by alpha 4 mAb. Binding of FITC-eristostatin to Jurkat cells and adhesion of Jurkat (but not K562) cells to eristostatin-coated wells further suggested that eristostatin binds alpha 4 beta 1, even though, again, alpha 4 mAb only partially inhibited adhesion. Expression of alpha 4 beta 1 was enhanced in metastatic melanoma cells compared to normal melanocytes and nonmetastatic melanoma cells. Finally, eristostatin inhibited adhesion of both MV3 and CHO alpha 4 cells to the alpha 4 beta 1-ligand VCAM-1, while adhesion to other ligands via other integrins was not affected. These findings demonstrate that inhibition of melanoma cell metastasis by RGD-containing peptides such as eristostatin, may be due to interference with alpha 4 beta 1-VCAM binding, in addition to inhibition of the classical RGD-binding integrins.
No preview · Article · Feb 1998 · Experimental Cell Research
[Show abstract][Hide abstract] ABSTRACT: To investigate whether albuminuria in streptozotocin-induced diabetes mellitus in the rat is a symptom of a more generalized vessel wall permeability, and whether changes in vessel wall heparan sulfate (HS) are associated with alterations in vessel wall permeability.
The transcapillary escape rate of albumin (TERalb) was calculated from the disappearance rate from the circulation of i.v. injected radiolabeled albumin, together with the regional clearance of albumin (RCalb) in several tissues using a double isotope technique. These measurements were performed in seven rats one year after diabetes induction and in seven sex- and age-matched control rats. To evaluate the association between vessel wall HS and the transcapillary passage of albumin, we determined the content of basement membrane HS in tissue homogenates of heart, liver, kidneys, and lungs with a sensitive inhibition-ELISA using a monoclonal antibody (JM-403), which specifically recognizes basement membrane HS.
Diabetic rats developed albuminuria (31.7 +/- 10.8 mg/24 h) in contrast to control animals (2.2 +/- 1.5 mg/24 h; P = 0.0006). TERalb was increased from 13.3 +/- 1.7 in control rats to 15.6 +/- 2.6%/h in diabetic rats, P = 0.02. RCalb was significantly increased in heart, liver, skeletal muscle and aorta, unchanged in kidneys and skin, and significantly decreased in lung tissue. We found a decrease in HS content in heart tissue of diabetic rats, and a correlation between HS content and RCalb (r = -0.72, P = 0.004), in contrast with an increase in lung HS content that correlated with a decrease in RCalb (r = -0.64, P = 0.014). No changes in HS content were found in kidney and liver tissue.
These data indicate that in one-year diabetic rats albuminuria coincides with an increased TERalb and RCalb in most, but not all tissues, and that alterations in basement membrane HS content correlate with changes in the RCalb, which suggests a functional relationship.
No preview · Article · Feb 1997 · Nephrology Dialysis Transplantation
[Show abstract][Hide abstract] ABSTRACT: Even though integrin alpha v beta 3 is thought to play a role in invasive growth of melanomas, some metastatic melanoma cell lines lack alpha v beta 3, and downmodulation of alpha v beta 3, expression can enhance the invasive capacity of certain melanoma cells. To further investigate this apparent dualistic role of alpha v beta 3, we transfected beta 3 cDNA into the highly metastatic, beta 3-negative human melanoma cell line MV3. MV3 cells adhered to fibronectin but not to fibrinogen or a synthetic RGD peptide, while MV3-beta 3 adhered to all three RGD-containing adhesive ligands, and this adhesion was inhibited by LM609 alpha v beta 3 mAb. Expression of alpha v beta 3 did not affect MV3 in vitro proliferation or in vivo tumorigenicity upon subcutaneous inoculation into nude mice. In contrast, it strongly reduced invasion in matrigel and lung colonization in nude mice of MV3 cells. Thus, certain melanoma cell lines have adopted a metastatic strategy in the absence of alpha v beta 3, and in such cells expression of this integrin leads to a less aggressive phenotype.
Preview · Article · Oct 1996 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: Heparan sulphate-associated anionic sites in the glomerular basement membrane were studied in rats 8 months after induction of diabetes by streptozotocin and in age- adn sex-matched control rats, employing the cationic dye cuprolinic blue. Morphometric analysis at the ultrastructural level was performed using a computerized image processor. The heparan sulphate specificity of the cuprolinic blue staining was demonstrated by glycosaminoglycan-degrading enzymes, showing that pretreatment of the sections with heparitinase abolished all staining, whereas chondroitinase ABC had no effect. The majority of anionic sites (74% in diabetic and 81% in control rats) were found within the lamina rara externa of the glomerular basement membrane. A minority of anionic sites were scattered throughout the lamina densa and lamina rara interna, and were significantly smaller than those in the lamina rara externa of the glomerular basement membrane (p<0.001 and p<0.01 for diabetic and control rats, respectively). Diabetic rats progressively developed albuminuria reaching 40.3 (32.2-62.0) mg/24 h after 8 months in contrast to the control animals (0.8 (0.2-0.9) mg/24 h, p<0.002). At the same time, the number of heparan sulphate anionic sites and the total anionic site surface (number of anionic sites x mean anionic site surface) in the lamina rara externa of the glomerular basement membrane was reduced by 19% (p<0.021) and by 26% (p<0.02), respectively. Number and total anionic site surface in the remaining part of the glomerular basement membrane (lamina densa and lamina rara interna) were not significantly changed. We conclude that in streptozotocin-diabetic rats with an increased urinary albumin excretion, a reduced heparan sulphate charge barrier/density is found at the lamina rara externa of the glomerular basement membrane.
[Show abstract][Hide abstract] ABSTRACT: We investigated the influence of the activation state of integrin alpha 5 beta 1 on its dependence on the PHSRN synergy site for binding to RGD in fibronectin. K562 and MV3 cells lacked alpha v beta 3 expression and adhered to fibronectin through alpha 5 beta 1. Mel57 cells adhered through alpha v beta 3 and alpha 5 beta 1. A recombinant fibronectin polypeptide, containing five type III repeats from the central cell binding domain 3Fn6-10, and a mutated polypeptide lacking the synergy site were equally effective in promoting Mel57 adhesion. For K562 and MV3, the mutated polypeptide was not or poorly active compared to the control polypeptide. Expression of alpha v beta 3 in MV3 induced strong adhesion to the mutated polypeptide. TS2/16 stimulatory beta 1-integrin antibodies or Mn2+ induced alpha 5 beta 1-mediated adhesion of K562 and MV3 to GRGDSP. In the presence of TS2/16 or Mn2+, alpha 5 beta 1-mediated MV3 adhesion to the mutated polypeptide was equally strong as adhesion to the control polypeptide. Mn2+ or TS2/16 induced weak K562 binding to the mutated polypeptide, and in the presence of a combination of phorbol 12-myristate 13-acetate, Mn2+, and TS2/16, alpha 5 beta 1-mediated K562 adhesion to the mutated and control polypeptide was equally strong. Our findings demonstrate that requirement for the PHSRN synergy site for alpha 5 beta 1-mediated adhesion to RGD in fibronectin depends on the activation state of the integrin.
No preview · Article · Oct 1995 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: We investigated the influence of the activation state of integrin α5β1 on its dependence on the PHSRN synergy site for binding
to RGD in fibronectin. K562 and MV3 cells lacked αvβ3 expression and adhered to fibronectin through α5β1. Mel57 cells adhered
through αvβ3 and α5β1. A recombinant fibronectin polypeptide, containing five type III repeats from the central cell binding
domain 3Fn6-10, and a mutated polypeptide lacking the synergy site were equally effective in promoting Mel57 adhesion. For
K562 and MV3, the mutated polypeptide was not or poorly active compared to the control polypeptide. Expression of αvβ3 in
MV3 induced strong adhesion to the mutated polypeptide. TS2/16 stimulatory β1-integrin antibodies or Mn induced α5β1-mediated adhesion of K562 and MV3 to GRGDSP. In the presence of TS2/16 or Mn, α5β1-mediated MV3 adhesion to the mutated polypeptide was equally strong as adhesion to the control polypeptide. Mn or TS2/16 induced weak K562 binding to the mutated polypeptide, and in the presence of a combination of phorbol 12-myristate
13-acetate, Mn, and TS2/16, α5β1-mediated K562 adhesion to the mutated and control polypeptide was equally strong. Our findings demonstrate
that requirement for the PHSRN synergy site for α5β1-mediated adhesion to RGD in fibronectin depends on the activation state
of the integrin.
[Show abstract][Hide abstract] ABSTRACT: We investigated the expression of alpha v-integrins in different stages of human cutaneous melanocytic tumor progression. We observed that alpha v beta 5 was the alpha v-integrin expressed in all common nevocellular nevi, in 78% of dysplastic nevi, in 63% of early primary melanomas, in 43% of advanced primary melanomas, and in 33% of melanoma metastases. Hence, loss of alpha v beta 5 expression was related to melanocytic tumor progression. In line with earlier reports, alpha v beta 3 was exclusively detected in advanced primary melanomas and metastases (24% and 50% respectively). Staining with anti-alpha v monoclonal antibodies (MAbs) in lesions where both alpha v beta 3 and alpha v beta 5 were absent showed that alternative alpha v-integrins were expressed in advanced primary melanomas and metastases. By FACS analysis, we determined expression of alpha v beta 5 and alpha v beta 3 in 4 human melanoma cell lines with different metastatic capacities after s.c. inoculation into nude mice. One of the non-metastatic and both highly metastatic cell lines expressed alpha v beta 5 at their surface. Surprisingly, alpha v beta 3 was detected exclusively in the non-metastatic cell lines. Absence of alpha v beta 3 in the highly metastatic cell lines was confirmed by lack of immunoprecipitation from 35S-methionine-labeled cells and by absence of immunohistochemical staining on primary and metastatic xenograft lesions. Our findings indicate that alpha v beta 5 expression is often lost in advanced stages of melanocytic tumor progression in situ, while alpha v beta 3 is acquired, but that a decrease in alpha v beta 5 and an increase in alpha v beta 3 expression are not necessarily related to the metastatic behavior of human melanoma cells in nude mice.
No preview · Article · Jun 1995 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: In the present study we investigated whether glomerular hyperfiltration and albuminuria in streptozotocin-induced diabetic nephropathy in male Wistar-Münich rats are associated with changes in the heparan sulphate content of the glomerular basement membrane. Rats with a diabetes mellitus duration of 8 months, treated with low doses of insulin, showed a significant increase in glomerular filtration rate (p < 0.01) and effective renal plasma flow (p < 0.05), without alterations in filtration fraction or mean arterial blood pressure. Diabetic rats developed progressive albuminuria (at 7 months, diabetic rats (D): 42 +/- 13 vs control rats (C): 0.5 +/- 0.2 mg/24 h, p < 0.002) and a decrease of the selectivity index (clearance IgG/clearance albumin) of the proteinuria (at 7 months, D: 0.20 +/- 0.04 vs C: 0.39 +/- 0.17, p < 0.05), suggesting loss of glomerular basement membrane charge. Light- and electron microscopy demonstrated a moderate increase of mesangial matrix and thickening of the glomerular basement membrane in the diabetic rats. Immunohistochemically an increase of laminin, collagen III and IV staining was observed in the mesangium and in the glomerular basement membrane, without alterations in glomerular basement membrane staining of heparan sulphate proteoglycan core protein or heparan sulphate. Glomerular basement membrane heparan sulphate content, quantitated in individual glomerular extracts by a new inhibition ELISA using a specific anti-glomerular basement membrane heparan sulphate monoclonal antibody (JM403), was not altered (median (range) D: 314 (152-941) vs C: 262 (244-467) ng heparan sulphate/mg glomerulus). However, the amount of glomerular 4-hydroxyproline, as a measure for collagen content, was significantly increased (D: 1665 (712-2014) vs C: 672 (515-1208) ng/mg glomerulus, p < 0.01). Consequently, a significant decrease of the heparan sulphate/4-hydroxyproline ratio (D: 0.21 (0.14-1.16) vs C: 0.39 (0.30-0.47), p < 0.05) was found. In summary, we demonstrate that in streptozotocin-diabetic rats glomerular hyperfiltration and a progressive, selective proteinuria are associated with a relative decrease of glomerular basement membrane heparan sulphate. Functionally, a diminished heparan sulphate-associated charge density within the glomerular basement membrane might explain the selective proteinuria in the diabetic rats.