Production of mucopolysaccharides by normal and transformed cells

Modulation of hyaluronan production by CD44 positive glioma cells

This study examines the functional relationship between glioma cell production of hyaluronan (HA), known to play a role in glioma invasion, expression of its CD44 receptor, and glioma cell viability. Production of HA by CD44 positive mouse G26 and human U373 glioma cell lines was evaluated and compared to that of a CD44 positive mouse fibroblast-like L929 cell line. We found that both G26 and U373 MG glioma cells, but not L929 fibroblast-like cells, synthesized HA. The synthesis of HA by glioma cells was found during the proliferative phase as well as post-confluency, as detected by fluorophore-assisted carbohydrate electrophoresis. Eighty to ninety percent of the HA synthesized was secreted into the medium and 10-20% remained associated with the cells. To examine a possible mechanistic link between the CD44-HA interaction and endogenous HA production, glioma cells were treated with either anti-CD44 antibodies (clones KM201 or IM7) or HA oligosaccharides (hexamer oligoHA-6 or decamer oligoHA-10). We found that oligoHA-10, which was previously shown to compete effectively with the CD44-HA interaction, enhanced glioma HA synthesis by approximately 1.5-fold, without affecting cell viability. IM7 treatment of human U373 glioma cells resulted in over 50% decrease of HA production, which was associated with changes in cell size and apoptosis. Taken together, these data show that CD44 specific ligands, such as the IM7 antibody or oligoHA-10 could down-regulate or up-regulate glioma HA production, respectively. Our results suggest that interference with CD44/HA may lead to the discovery and development of new treatment modalities for glioma.

Plasma hyaluronidase (Hyal-1) promotes tumor cell cycling

Paradoxically, both hyaluronan (HA) and hyaluronidase are involved in malignant transformation and cancer progression. Their mechanisms of action, given the apparent disparities, are not understood. In many malignancies, levels of HA correlate with metastatic behavior while hyaluronidases suppress malignant progression. Hyal-1, product of one of six paralogous hyaluronidase-like sequences, is the predominant circulating hyaluronidase. HYAL1, the gene that codes for Hyal-1, is located on chromosome 3p21.3, a region containing a tumor suppressor gene. Loss of HYAL1 often correlates with tumor progression, particularly in tobacco-related cancers. In other malignancies, however, hyaluronidase functions as a tumor promoter. Testicular hyaluronidase (PH-20), used as an adjuvant in chemotherapy, is assumed to enhance drug permeability. By an unknown mechanism, hyaluronidases recruit tumor cells back into the cycling pool, making these malignancies more sensitive to chemotherapeutic drugs. Such contradictory observations might be resolved by assuming that HA and hyaluronidase are required at different times in the multiple steps that lead to malignant transformation. We have undertaken a systematic investigation of their roles in cancer progression. Here, we investigate the effect of Hyal-1 expression on cell cycle kinetics. A tumor cell line was constructed with an ecdysone-inducible promoter located upstream from the cDNA of HYAL1. Fluorescent-activated cell sorting was used to monitor cell cycle kinetics following Hyal-1 induction. Enhanced cell cycling was observed, with a 13.6% increase in S phase and 9.6% decrease in G(1)/G(0) phase cells.

Infection of human cells by dengue virus is modulated by different cell types and viral strains

Although prior studies have investigated cellular infection by dengue virus (DV), many have used highly passaged strains. We have reassessed cellular infection by DV type 2 (DV2) using prototype and low-passage isolates representing genotypes from different geographic areas. We observed marked variation in the susceptibility to infection among cell types by different DV2 strains. HepG2 hepatoma cells were susceptible to infection by all DV2 strains assayed. Although the prototype strain generated higher titers of secreted virus than the low-passage isolates, this difference did not correspond to positive- or negative-strand viral RNA levels and thus may reflect variation in efficiency among DV2 isolates to translate viral proteins or package and/or secrete virus. In contrast, human foreskin fibroblasts were susceptible to the prototype and low-passage Thai isolates but not to five Nicaraguan strains tested, as reflected by the absence of accumulation of negative-strand viral RNA, viral antigen, and infectious virus. A similar pattern was observed with the antibody-dependent pathway of infection. U937 and THP-1 myeloid cells and peripheral blood monocytes were infected in the presence of enhancing antibodies by the prototype strain but not by low-passage Nicaraguan isolates. Again, the barrier appeared to be prior to negative-strand accumulation. Thus, depending on the cell type and viral isolate, blocks that limit the production of infectious virus in vitro may occur at distinct steps in the pathway of cellular infection.

Extracellular matrix components and proteolytic enzymes in uterine cervical carcinoma

The important components of mucopolysaccharides and collagen have been analyzed in tissues of control and carcinoma of uterine cervix. Among these components hyaluronic acid and chondroitin sulphate levels were found to be increased, whereas decreased level of collagen was observed in uterine cervical carcinoma. Serum cathepsin B, D and acid and alkaline phosphatases have also been analyzed in controls and carcinoma patients before and after treatments. The activities of these enzymes have been found to increase prominently in advanced stages. Among these enzymes cathepsin B and alkaline phosphatase have exhibited remarkable increase in activity in uterine cervical carcinoma. Different modes of treatment exerted reversion of the elevated activities of these enzymes. However, combined therapy type II (radiation combined with cisplatin and cyclophosphomide) seems to be more effective in reverting the activities of these enzymes to normal levels.

Regulation of collagen metabolism and cell growth by epidermal growth factor and ascorbate in cultured human skin fibroblasts

Epidermal growth factor (2-50 ng/ml), prepared from mouse submaxillary glands, stimulated growth and the synthesis of non-collagenous proteins and hyaluronic acid, but inhibited collagen synthesis in cultured human skin fibroblasts, both stimulation and inhibition being dose-dependent. All these effects may be intrinsic functions of the epidermal growth factor molecule, because these effects were cancelled by the co-presence of antiserum specific for epidermal growth factor and because they were also observed following the addition of human epidermal growth factor produced urogastrone cDNA. On the other hand, L-ascorbate (vitamin C) stimulated growth and collagen synthesis, as well as synthesis of non-collagenous proteins, with no significant effect on hyaluronic acid synthesis. Co-presence of epidermal growth factor and ascorbate gave additive effects on growth and protein synthesis of the cells. These results suggest that the two growth-promoting factors, epidermal growth factor and L-ascorbate, modulate metabolism of extracellular matrix components as well as cell growth in a quite different manner in human skin fibroblasts.

Ultrastructural features of the lymphocyte-stimulated halos produced by human glioma-derived cells in vitro

Many glioma-derived cell lines have the capability of escaping cell-mediated immune attack. One mechanism of escape is the secretion of a hyaluronidase-sensitive mucopolysaccharide coat by these cells. This coat prevents contact and tumor cell killing by specific cytolytic allogeneic lymphocytes. The production of the coat by the tumor cells is stimulated by a macromolecular factor released by peripheral blood mononuclear (PBMC) cells in culture. We have examined the morphologic and ultrastructural features of this extracellular matrix. Three coat-producing lines were studied. Under phase contrast light microscopy, the coat is a clear pericellular 'halo'. To stain this zone, ruthenium red and Alcian Blue 8 G stains, which bind to acid mucopolysaccharides (to a large extent, hyaluronic acid), were used. The two stains produced similar results. With light microscopy, a weblike pattern of stain was evident throughout the halo region. With transmission electron microscopy, staining was found along the plasma membrane of the glioma cells and their microvilli, stretching in long, branching filaments from these surfaces and, in some instances, from one microvillus to the next. Since mucopolysaccharide matrices have a large aqueous component, it was necessary to determine whether dehydration alters the stain pattern. Therefore, undehydrated ruthenium red stained specimens from each culture were embedded in Quetal 651 (Ted Pella, Inc., Tustin, CA), a water soluble plastic. No morphologic differences were noted between the hydrated and dehydrated specimens. This study indicates that numerous long microvilli and a secreted mucopolysaccharide matrix are important structural elements of the lymphocyte-stimulated tumor cell halo in vitro. The mechanism by which the PBMC factor stimulates coat formation and the importance of the coat in in vivo tumor defenses remain to be elucidated.

Stimulation of glycosaminoglycan production in murine tumors

Three types of murine tumors, B-16 melanoma, A-10 carcinoma, and S-180 sarcoma, were shown to contain elevated glycosaminoglycan (GAG) concentrations in vivo as compared to normal muscle or subcutaneous tissue. Hyaluronate was especially concentrated in the A-10 carcinoma, which contained approximately six times more hyaluronate than subcutaneous tissue and 18 times more than muscle. In all three tumors, chondroitin sulfates, especially chondroitin-4-sulfate, were present in higher concentrations than in the normal tissues. In culture, however, all three tumor cell lines produced less than 5% as much GAG as mouse fibroblasts, when measured by incorporation of [3H] acetate or by chemical analysis. Varying the culture passage number or the medium composition, ie, glucose, serum, and insulin concentrations, had little effect on GAG synthesis by the tumor cells. The low GAG levels in the tumor cell cultures were not due to hyaluronidase activity in their media. In an attempt to mimic possible host-tumor cell interactions that could account for the elevated GAG levels in vivo, tumor cells were cocultured with fibroblasts, but no stimulation above the amount made by the tumor cells alone plus that by the fibroblasts alone was observed. Conditioned media from the tumor cells, either dialyzed or not against fresh complete medium, had no effect on fibroblast GAG synthesis. Tumor extracts, however, were found to stimulate synthesis of hyaluronate by fibroblasts. Stimulation by extracts of A-10 carcinoma was greater than and additive to that of serum. The above results strongly suggest that GAG production in these tumors is in part regulated by host-tumor interactions.

Dimethyl sulfoxide affects colony morphology on agar and alters distribution of glycosaminoglycans and fibronectin

We have found striking changes in the morphology of colonies of Chinese hamster ovary cells grown on agar containing low doses of dimethyl sulfoxide. Effects on morphology of cells grown on plastic at the same dimethyl sulfoxide concentrations were not as pronounced. Computer-assisted analysis of darkfield photographs of growing colonies proved very useful in measuring the magnitude of morphological changes at various doses. A large decrease in total cell-bound and released glycosaminoglycans (GAGs) was observed in the presence of dimethyl sulfoxide by measuring incorporation of radiolabeled precursors into cetylpyridinium chloride-precipitable GAGs in Chinese hamster ovary cells. By contrast, dimethyl sulfoxide was found to cause an increase in the network of fibronectin (the large external transformation-sensitive protein) at the cell surface. These observations demonstrate the association of GAGs and fibronectin in processes affecting the three-dimensional growth patterns of aggregates of mammalian cells and also demonstrate the sensitivity of agargrown colonies as model systems for quantitatively measuring the morphological changes induced by exogenous agents such as drugs, hormones, growth factors, mutagens, and carcinogens. These findings might be relevant to the study and treatment of the important class of genetic diseases called mucopolysaccharidoses which result in mental, skeletal, and ocular defects as a consequence of GAG accumulation.

Fibronectin--mediator between cells and connective tissue

Fibronectin, previously also termed LETS-protein, is a high-molecular-weight protein (mol. w. ca. 450,000) present in the form of thin fibrils in the pericellular space of fibroblasts and other adherent cells, as well as in distinct areas of the connective tissue. A soluble form, immunologically identical and chemically at least very similar to the cell-attached protein, is found in plasma in a concentration of about 300 micrograms/ml. It is also denominated cold-insoluble globulin. The protein has affinity both to cell surfaces and to various matrix substances such as fibrin and collagen and, therefore, is capable of mediating cell attachment to these substrates. In addition, it serves as an opsonin for the phagocytosis of gelatin-containing compounds and probably is essential for the removal of soluble fibrin from the circulating blood by the reticulo-endothelial system. Bacterial cell walls are also recognized by fibronectin. A conversion of soluble fibronectin to fibrils is achieved by heparin which also enhances the binding of soluble fibronectin to cells. Heparin or, as suggested, the related heparan sulfate present on the surface of various cells, appears to function as a cofactor in the formation of pericellular fibrils. The fibronectin fibrils precipitated with heparin, compared to soluble fibronectin, show a considerably improved affinity to native collagen, especially to type III. Hyaluronic acid has an antagonistic function which, at higher concentrations, prevents the fibronectin fibrils from interacting with collagen and cell surfaces. Masking of fibronectin fibrils was also achieved by sulfated proteoglycans of cartilage. Virus-transformed fibroblasts produce less fibronectin and are less capable of maintaining surface pericellular fibrils. A reasonable explanation is that they have an elevated secretion of hyaluronic acid. The transformed cells attach only weakly to a surface and exhibit a rounded shape in contrast to healthy ones. This phenotype can be corrected to a great extent with fibronectin. It is suggested that fibronectin also influences the formation of connective tissue by accumulating collagen precursors on the surface of fibroblasts and facilitating fibrillogenesis.

Detection of transformed cells using a fluorescent probe: the molecular basis for the differential reaction of fluorescamine with normal and transformed cells

Normal and transformed fibroblasts can be discriminated by a flow cytometry assay on the basis of their differential reaction with fluorescamine. The cause of altered reactivity of transformed cells with this fluorescent probe has been investigated by a detailed analysis of its reaction with chicken embryo fibroblasts transformed by a temperature sensitive mutant of Rous sarcoma virus. The subcellular distribution of fluorescent adducts characterized by cell fractionation and gel electrophoresis procedures supports the hypothesis that transformed cells possess a surface barrier which decreases the accessibility of fluorescamine to reactive macromolecules. The barrier has been identified as being composed at least partly of hyaluronic acid, because of the ability of purified and specific hyaluronidase (from Streptomyces hyalurolyticus) to modulate the response of transformed cells to fluorescamine. Enzyme treatment of transformed cells prior to reaction with fluorescamine causes them to resemble nontransformed cells both in the nature of components labeled and in their fluorescence intensity. It is suggested that fluorescamine monitors an altered surface hyaluronic acid composition which occurs upon transformation. Its significance is discussed in terms of the known physical properties of the molecule and the finding that it is an early event in the process of transformation.

Codistribution of heparan sulfate proteoglycan, laminin, and fibronectin in the extracellular matrix of normal rat kidney cells and their coordinate absence in transformed cells

We used antibodies raised against both a heparan sulfate proteoglycan purified from a mouse sarcoma and a chondroitin sulfate proteoglycan purified from a rat yolk sac carcinoma to study the appearance and distribution of proteoglycans in cultured cells. Normal rat kidney cells displayed a fibrillar network of immunoreactive material at the cell surface when stained with antibodies to heparan sulfate proteoglycan, while virally transformed rat kidney cells lacked such a surface network. Antibodies to chondroitin sulfate proteoglycan revealed a punctate pattern on the surface of both cell types. The distribution of these two proteoglycans was compared to that of fibronectin by double-labeling immunofluorescent staining. The heparan sulfate proteoglycan was found to codistribute with fibronectin, and fibronectin and laminin gave coincidental stainings. The distribution of chondroitin sulfate proteoglycan was not coincidental with that of fibronectin. Distinct fibers containing fibronectin but lacking chondroitin sulfate proteoglycan were observed. When the transformed cells were cultured in the presence of sodium butyrate, their morphology changed, and fibronectin, laminin, and heparan sulfate proteoglycan appeared at the cell surface in a pattern resembling that of normal cells. These results suggest that fibronectin, laminin, and heparan sulfate proteoglycan may be complexed at the cell surface. The proteoglycan may play a central role in assembly of such complexes since heparan sulfate has been shown to interact with both fibronectin and laminin.

Transformation-dependent loss of the hyaluronate-containing coats of cultured cells

The sizes of hyaluronate-containing coats on the surfaces of parent and virus-transformed cell lines (3T3 vs. SV-3T3; BHK vs. PY-BHK) were compared according to the method of Clarris and Fraser (1968, Exp. Cell Res., 49: 181-193) in which fixed red blood cells were allowed to settle slowly on the surface of culture dishes containing the cells. The coats were seen as areas devoid of red blood cells surrounding each of the cultured cells and could be destroyed by the addition of small amounts of streptomyces hyaluronidase, an enzyme specific for hyaluronate. In the case of the parent cell lines (3T3 and BHK), the coats were clearly visible, whereas for their virus-transformed counterparts (SV-3T3 and PY-BHK), the coats were either greatly reduced or absent. To confirm these observations, the amount of hyaluronate associated with each of the cell lines was measured using a direct chemical assay and shown to be significantly greater for the parent cell lines than for their virus-transformed counterparts. In addition, the parent cell lines secreted greater amounts of hyaluronate into the medium and retained a larger fraction of the total amount of hyaluronate at the cell surface than the virus-transformed cells. Thus the larger amount of hyaluronate on the surfaces of the parent cell types may be the result of both a faster rate of production and a decreased rate of release.

Glycosaminoglycans in human lung cancer

The quantitative changes of glycosaminoglycans in tumor tissue of human lung cancers (2 squamous cell carcinomas, 4 adenocarcinomas and 5 small cell carcinomas) were studied. The total amount of glycosaminoglycans in human lung cancer tissues increased 1.4 to 4 times in comparison with that in normal lung tissues. The increase in tissue content of glycosaminoglycans was accompanied by an increase in the chondroitin sulfate level in every histologic type of lung cancer, as well as by a marked increase in hyaluronic acid level in squamous cell carcinomas, and a moderate increase in its level in small cell carcinomas. The concentrations of dermatan sulfate and heparan sulfate in lung cancer tissues did not show any significant changes compared with those in normal lung tissues. The increase in total amount and changes in the composition of glycosaminoglycans in human lung cancer tissue were closely related to the histologic type of the tumor.

Concomitant loss of cell surface fibronectin and laminin from transformed rat kidney cells

Both fibronectin and laminin were found by immunofluorescence as a matrix at the surface of normal rat kidney cells. These matrices were absent from the surface of virally transformed rat kidney cells. Soluble fibronectin and laminin were detected in the culture media of the transformed as well as the normal cells. Culture supernates of the transformed cells contained even more fibronectin than the supernates of the transformed cells contained even more fibronectin than the supernates of the normal cells while laminin was present in similar amounts in both culture media. This shows that the loss of fibronectin and laminin from the surface of the transformed cells is caused by failure of the cells to deposit these proteins into an insoluble matrix and not caused by inadequate production. Fibronectins isolated from culture media of the normal and transformed cells were similar in SDS polyacrylamide gel electrophresis. Laminin isolated from culture media by affinity chromatography on heparin-Sepharose followed by immunoprecipitation was composed of three main polypeptides, one with a molecular weight of 400,000 and two with a molecular weight close to 200,000 in both cell types. Fibronectins from both cell types were equally active in promoting cell attachment. Rat fibronectin from transformed cells, like normal cells, when applied to culture dishes coated with fibronectin, readily attached and spread on the substratum, requiring approximately the same amount of fibronectin as the normal cells. On the basis of these results it seem that the failure of the transformed cells to incorporate fibronectin into an insoluble cell surface matix is not a consequence of a demonstrable change in the functional characteristics of the fibronectin molecule or in the ability of the cells to interact with fibronectin. It may depend on as yet unidentified interactions of the cell surface. Similar interactions may be needed for the deposition of laminin into the matrix, because laminin was also absent from the surface of transformed cells, despite its being synthesized by these cells.

Glycosaminoglycan content and synthesis in gastric carcinoma

The glycosaminoglycan (GAG) content of stomach carcinoma tissue was compared with that of non-neoplastic mucosa. GAG synthesis was also studied, by an analysis of 35S-labelled material after incubation of tissue segments in medium containing 35SO4. No significant difference was found between the amount of GAG and its components in the medullary carcinoma tissue and in non-neoplastic mucosa, but GAG synthesis of the carcinoma tissue was at a much higher rate than that of the non-neoplastic mucosa. In the autoradiograph, high 35S uptake in the carcinoma cells was observed. The GAG content of the scirrhous-carcinoma tissue was about twice that of medullary carcinoma.

A human liposarcoma cell line producing hyaluronic acid

A human liposarcoma cell line COLO 222, derived from a primary tumor in a 62-year-old male, elaborates hyaluronic acid. COLO 222 is characterized on the basis of histochemical, ultramorphological, and cytogenetic properties, along with isozyme phenotype and cell products. A chromosome mode of 53 predominates and unique Giemsa-banded marker chromosomes are identified. An autochthonous lymphoid cell line, COLO 143v, was established after the addition of exogenous Epstein-Barr virus. Cytogenetic analysis of Colo 143v is consistent with a normal male karyotype. COLO 143v possesses B-cell characteristics. This autochthonous system had been used for immunological studies and cytotoxicity assays.

Hyaluronate and invasiveness of the rabbit V2 carcinoma

We propose that hyaluronate, a major component of extracellular matrices through which cells migrate during embryonic tissue development and in regenerative processes, is also concentrated in the environment through which neoplastic cells invade local host tissues and may facilitate this process. The hyaluronate content of invasive V2 carcinoma grown in rabbit was found to be 3-4 times greater than that of the same tumor grown in the nude mouse, in which it is noninvasive. Moreover, hyaluronate concentrations were most elevated in the connective tissue interface between the tumor mass and the neighboring host tissue in the invasive rabbit tumors. The particular site of tumor implantation in the rabbit or nude mouse did not affect the concentrations of hyaluronate in either the parenchyma or the surrounding connective tissue. Similar values were obtained for neoplasms grown in muscle, which normally contains little hyaluronate, and in subcutaneous tissue, which is relatively rich in this glycosaminoglycan.

Atheroarteriosclerosis induced by infection with a herpesvirus

Atheroarteriosclerosis closely resembling that in humans was induced in normocholesterolemic and hypercholesterolemic chickens by infection with Marek's disease herpesvirus (MDV). Four comparably sized groups of chickens were used. Each group was initially fed a diet relatively poor in cholesterol. Group I and II were inoculated intratracheally at 2 days of age with MDV. At 15 weeks, one group of virus-infected chickens (Group II) and one group of uninfected controls (Group IV) were fed a 2% cholesterol supplement for an additional 15 weeks. Group I, infected, and III, uninfected, were continued on a cholesterol-poor diet. All groups were killed at 30 weeks. Striking grossly visible atherosclerotic lesions were seen in large coronary arteries, aortas, and major aortic branches of both Groups I and II but not in those of Groups III and IV. Microscopically, arterial changes in infected animals were characterized by occlusive fibromuscular intimal thickening, which formed fibrous caps overlying areas of atheromatous change. This change closely resembled chronic atherosclerosis in humans. These results may be important to our understanding of human arteriosclerosis, since there is widespread and persistent infection of human populations with as many as five herpesviruses.

A comparative study of glycosaminoglycans in cultures of human, normal and malignant glial cells

The glycosaminoglycans (GAG) of human cultured normal glial and malignant glioma cell lines were studied using 35S-sulphate or 3H-glucosamine as markers. 35S-labelled GAG were assayed by precipitation with cetylpyridinium chloride; 3H-labelled sulphated GAG and 3H-labelled hyaluronic acid were quantitated after separation on a DEAE-cellulos column. The net production of GAG and the distribution, composition and turnover of GAG were similar in all of the normal cell lines tested, but showed a great variability in the malignant cell lines. Most of the glioma cell lines produced more hyaluronic acid and less sulphated GAG than the normal cell lines, but exceptions were noted. The GAG of the trypsin susceptible (pericellular pool of normal glial cells consisted mainly of heparan sulphate with only minor amounts of other GAG. The analogous material of most glioma cells showed hyaluronic acid as the major GAG. Material liberated by trypsin from EDTA-detached cells (membrane fraction) was enriched in heparan sulphate as compared to the entire pericellular pool. Substrate attached material (SAM) left with the plastic dish after EDTA treatment of normal cultures was rich in heparan sulphate, whereas SAM of glioma cells lacked heparan sulphate or showed greatly reduced amounts of this component. Release of newly synthesized GAG to the extracellular medium was a rapid process in the normal cells but was more or less delayed in the glioma cells. The extracellular medium of the malignant glioma cultures was consistently poor in dermatan sulphate, as compared to that of normal cultures.

Composition and distribution of glycosaminoglycans in cultures of human normal and malignant glial cells

The glycosaminoglycans of human cultured normal glial and malignant glioma cells were studied. [35S]Sulphate or [3H]glucosamine added to the culture medium was incorporated into glycosaminoglycans; labelled glycosaminoglycans were isolated by DEAE-cellulose chromatography or gel chromatography. A simple procedure was developed for measurement of individual sulphated glycosaminoglycans in cell-culture fluids. In normal cultures the glycosaminoglycans of the pericellular pool (trypsin-susceptible material), the membrane fraction (trypsin-susceptible material of EDTA-detached cells) and the substrate-attached material consisted mainly of heparan sulphate. The intra- and extra-cellular pools showed a predominance of dermatan sulphate. The net production of hyaluronic acid was low. The accumulation of 35S-labelled glycosaminoglycans in the extracellular pool was essentially linear with time up to 72h. The malignant glioma cells differed in most aspects tested. The total production of glycosaminoglycans was much greater owing to a high production of hyaluronic acid and hyaluronic acid was the major cell-surface-associated glycosaminoglycan in these cultures. Among the sulphated glycosaminoglycans chondroitin sulphate, rather than heparan sulphate, was the predominant species of the pericellular pool. This was also true for the membrane fraction and substrate-attached material. Furthermore, the accumulation of extracellular 35S-labelled glycosaminoglycans was initially delayed for several hours and did not become linear with time until after 24 h of incubation. The glioma cells produced little dermatan sulphate and the dermatan sulphate chains differed from those of normal cultures with respect to the distribution of iduronic acid residues. The observed differences between normal glial and malignant glioma cells were not dependent on cell density; rather they were due to the malignant transformation itself.

Sulphated acid mucopolysaccharides in SV40-transformed human cells from normal and mucopolysaccharidosis patients

Lines of fibroblasts have been established from normal individuals and from patients diagnosed as suffering from one of the mucopolysaccharidoses or mucopolysaccharide-storage diseases. Transformation of these lines with SV40 virus has been found to reduce their capacity to secrete sulphated mucopolysaccharides into the growth medium. No differences were detected between the individual cell types in their secretory capacity, either before or after viral transformation. A direct relationship was found to exist between the rate of acid mucopolysaccharide production and cell-doubling time. The level of sulphated mucopolysaccharide detected within the cell was also reduced for all cell types after transformation by SV40. Transformed fibroblasts from mucopolysaccharidosis patients, however, showed a relatively greater reduction in storage capacity than those derived from normal individuals.

Distribution of glycoconjugates in mouse fibroblasts with varying degrees of tumorigenicity

Analysis of glucosamine labeled glycoconjugates in cultured cells has been made comparing 2 clones and the parent embryonic mouse cell line. Hyaluronic acid, heparan sulphate, and chondrotin sulphate as well as a complex mixture of glycopeptides were found in the medium, the trypsinate, and the trypsinized cells, although the distribution was not uniform. The 3 cell lines had very similar in vitro growth properties, including their plating efficiency in viscous medium. However, the tumorigenicity of the cells, determined syngeneic mice, was found to differ. All 3 cell lines were found to have similar glycoconjugate distributions, although a slight relative increase in labeled hyaluronic acid was found in the more tumorigenic mass cell line than either of the clones. The possible significance of this increase is discussed.

Enhanced synthesis and extracellular accumulation of hyaluronic acid during stimulation of quiescent human fibroblasts by mouse epidermal growth factor

The effect of mouse epidermal growth factor (mEGF) on the synthesis of glycosaminoglycans and glycoproteins by human fibroblasts has been studied. The addition of physiological concentrations (10(-9)M) of mEGF to quiescent cultures preincubated in the absence of serum was found to elicit an increased incorporation of 3H-glucosamine into the glycosaminoglycans and glycoproteins of both the cellular and extracellular fractions. Although the growth response to the factor, as measured by DNA replication, was minimal under these conditions as compared with the effect of serum, the mEGF-induced incorporation of glucosamine into these cellular constituents and into the extracellular glycoproteins was comparable to that elicited by serum shift-up. Serum, however, caused a significantly larger incorporation of glucoasimine into extracellular, acid-soluble glycosaminoglycans, which were shown to contain hyaluronic acid as the major component. As previously demonstrated, the growth response to mEGF can be enhanced several fold by an mEGF-binding arginine esterase, which is normally associated with the factor in vivo, and by ascorbate. The esterase was found to increase markedly the mEGF-induced incorporation of glucosamine into extracellular hyaluronic acid, while the addition of ascorbic acid did not significantly alter glucosamine incorporation.

Relationship of transformation, cell density, and growth control to the cellular distribution of newly synthesized glycosaminoglycan

Mouse 3T3 cells and their Simian Virus 40-transformed derivatives (3T3SV) were used to assess the relationship of transfromation, cell density, and growth control to the cellular distribution of newly synthesized glycosaminoglycan (GAG). Glucosamine- and galactosamine-containing GAG were labeled equivalently by [3H=A1-glucose regardless of culture type, allowing incorporation into the various GAG to be compared under all conditions studied. Three components of each culture type were examined: the cells, which contain the bulk of newly synthesized GAG and are enriched in chondroitin sulfate and heparan sulfate; cell surface materials released by trypsin, which contain predominantly hyaluronic acid; and the media , which contain predominantly hyaluronic acid and undersulfated chondroitin sulfate. Increased cell density and viral transformation reduce incorporation into GAG relative to the incorporation into other polysaccharides. Transformation, however, does not substantially alter the type or distribution of newly synthesized GAG; the relative amounts and cellular distributions were very similar in 3T3 and 3T3SV cultures growing at similar rates at low densities. On the other hand, increased cell density as well as density-dependent growth inhibition modified the type and distribution of newly synthesized GAG. At high cell densities both cell types showed reduced incorporation into hyaluronate and an increase in cellular GAG due to enhanced labeling of chondroitin sulfate and heparan sulfate. These changes were more marked in confluent 3T3 cultures which also differed in showing substantially more GAG label in the medium and in chondroitin-6-sulfate and heparan sulfate at the cell surface. Since cell density and possibly density-dependent inhibition of growth but not viral transformation are major factors controlling the cellular distribution and type of newly synthesized GAG, differences due to GAG's in the culture behavior of normal and transformed cells may occur only at high cell density. The density-induced GAG alterations most likely involved are increased condroitin-6-sulfate and heparan sulfate and decreased hyaluronic acid at the cell surface.

Mucopolysaccharides associated with nuclei of cultured mammalian cells

Mucopolysaccharides have been isolated, fractionated, and characterized from the nuclei of cultured B16 mouse melanoma cells grown in the presence of (3-H)-glucosamine and (35-S)sulfate. Digestion of the nuclei with DNase followed by Pronase gave a mixture of complex carbohydrates from which the mucopolysaccharides were isolated by precipitation with cetylpyridinium chloride. After fractionation by differential salt extraction and chromatography on controlled pore glass bead columns, the components were identified by chemical and enzymatic methods. The major polysaccharide components were a family of high-molecular-weight chondroitin sulfates with different degrees of sulfation; a minor component has been characterized as heparan sulfate.

Heparan sulfate of skin fibroblasts grown in culture

Primary cultures of normal human skin fibroblasts were examined for glycosaminoglycan content. Heparan sulfate was found in the growth medium of these cells, in fractions obtained by sequential collagenase and trypsin treatments, and in the remaining intact cells. Heparan sulfate was found to be the major sulfated glycosaminoglycan of the trypsin fraction but appeared as a smaller proportion of the collagenase fraction. The heparan sulfate of the growth medium, the collagenase fraction, and the trypsin fraction appeared to be proteoglycan while intracellular material appeared to be mainly free polysaccharide. The collagenase fraction is thought to be representative of "matrix" material produced by the cells, while the trypsin fraction may represent external cell surface material. The trypsin fraction heparan sulfate polysaccharide was relatively homogeneous in size with an average molecular weight of approximately 40,000 relative to a chondroitin sulfate standard. It was also relatively homogeneous in sulfate content, containing an average of 0.8 sulfate groups per disaccharide repeating unit. Approximately 50% of this was N-sulfate.

Dynamics of metabolism of normal and virus-transformed chick cells in culture

Application of steady-state tracer technique to normal and transformed cells in tissue culture allows quantitation of intracellular pool sizes of many metabolites and determination of rate of carbon flow along diverse paths. Using a unique apparatus to control the environmental conditions, we show that the glucose carbon flow into tricarboxylic acid cycle intermediates and amino acids is unchanged upon transformation. The increased glycogen formation and glycolysis varies with the glucose concentration in the medium, correlates with the faster glucose transport of transformed cells, and cannot be explained by a difference in growth rate alone.