Enhanced granulopoiesis in mice transplanted with colony-stimulating factor-producing BMA1 tumor

Inoculation of BMA1 cells into BALB/c nude mice formed tumors (BMA1 tumor) that were transplantable into ddY mice, and induced marked granulopoiesis in vivo. Histological study revealed that the tumor was a fibrosarcoma, some parts of which were calcified, and consisted of hemopoietic foci surrounded by adipose tissue. This tumor was regarded as producing CSF in vivo as well as in vitro, since CSF activity was detected in sera of the tumor-bearing mice and tumor extract. Granulopoiesis and splenomegaly developed, associated with an increase of stem cells in the spleen. The number of CFUc and CFUs in the spleen increased to about 91 times and 21 times those of control mice, respectively, whereas the number of stem cells in the tibia did not change significantly. The number of peripheral leukocytes increased to 15 times that of normal mice and amounted to 78% of matured granulocytes. After tumor resection these hematological changes were reversed. The findings suggest that the granulopoiesis in BMA1 tumor-bearing mice may be induced by CSF produced by BMA1 tumor and that the spleen may be a direct target organ of the excessive amount of CSF.

Properties and functions of a nucleolus-specific phosphoprotein of mouse ascites sarcoma cells

A 110K-dalton phosphoprotein previously was isolated from the nucleoli of mouse ascites sarcoma cells. The localization of this phosphoprotein in the nucleoli was confirmed by an indirect immunofluorescence assay with rabbit antisera to the phosphoprotein. This phosphoprotein formed a complex of 280K daltons with a nonphosphoprotein of 32K daltons in a molar ratio of 1 to 1. The protein complex dissociated in the presence of 6 M guanidine hydrochloride or 1% sodium dodecylsulphate. The nucleolus-specific phosphoprotein complex bound preferentially to nucleolar DNAs other than the ribosomal RNA gene in vitro and located in nucleosomes prepared from the nucleoli. The major phosphoamino acid in the phosphoprotein was phosphoserine, and slight though significant amounts of phosphotyrosine and phosphothreonine also were detected. These phosphorylated amino acids were concentrated in a specific polypeptide fragment of about 30K daltons obtained by partial digestion with V8 protease. The phosphoprotein was phosphorylated in vitro by the protein kinase activity presented in the complex itself.

[Fibronectin in cultured mouse sarcoma cells induced by foreign bodies]

Indirect fluorescence was used to study distribution of fibronectin in cultured cells of 5 mouse foreign body-induced sarcomas (PS-4, PS-84, PS-100, PS-103, PS-130) and cells of early (2-3 months postimplantation) capsules surrounding implanted plastic films. Accumulation of pericellular or matrix fibronectin in dense cultures compared to sparse ones was noted in all the lines except PS-84. In confluent cultures of these lines, a three-dimensional fibrillar network of fibronectin typical for fibroblast-like cells was observed. The pattern was very similar to that found in dense cultures of non-neoplastic early capsule cells. The data obtained show that loss of pericellular fibronectin would not serve as a marker of neoplastic transformation in this cellular system.

Structure and interactions of heparan sulfate proteoglycans from a mouse tumor basement membrane

Various forms of heparan sulfate proteoglycan were solubilized from the mouse Engelbreth-Holm-Swarm (EHS) sarcoma by extraction with 0.5 M NaCl, collagenase digestion and extraction with 4 M guanidine. They could be separated into high (greater than or equal to 1.65 g/ml) and low (1.38 g/ml) buoyant density variants. The high-density form from the NaCl extract and collagenase digest had Mr = 130000 and So20,W = 4.5 S and contained 4-10% protein, indicating Mr = 5 000-12 000 for the protein core. This proteoglycan exhibited polydispersity as shown by rotary shadowing electron microscopy and ultracentrifugation. An average molecule consisted of four heparan sulfate chains (Mr = 29 000) each with a length of 32 +/- 10 nm. The low-density form (Mr about 400 000) could not be completely purified and contained about 50% protein. As shown by radioimmunoassay, the various proteoglycans shared similar protein cores. Labeling of the tumor in vivo or in vitro demonstrated preferential incorporation of radioactive sulfate in the high-density form. The high-density proteoglycan interacted in affinity chromatography by virtue of its heparan sulfate chains with laminin, fibronectin, the globular domain NC1 and the triple helix of collagen IV. These interactions were abolished at moderate concentrations of NaCl (0.1-0.2 M) and in the presence of heparin, chondroitin sulfate or dextran sulfate. Interactions with the globule NC1 could also be demonstrated by velocity band centrifugation in sucrose gradients and a binding constant of about 10(6) M-1 was derived.

Localization of proteoheparan sulfate in rat aorta

This study describes the distribution of heparan sulfate proteoglycan ( HSPG ) within the rat aorta using immunocytochemical (biotin-avidin-peroxidase) and immuno-electron microscopy (125I-autoradiography). Heparan sulfate proteoglycan was isolated from a basement membrane producing mouse EHS sarcoma ( Hassell et al. 1980) and used to generate antisera in rabbits. Light microscopic observations revealed intense immunostaining of the intima and media of normal aorta, adventitial vasa vasorum, and aortic intimal fibromuscular thickenings induced by experimental injury (balloon de-endothelialization). Immunoelectron microscopy using 125I labeled antibodies to HSPG revealed that proteoheparan sulfate was localized to the amorphous layer of basement membrane below aortic and capillary endothelium. In addition, labeled anti- HSPG could be localized to the external lamina surrounding the smooth muscle cells in the hyperplastic intima. These studies reveal that antibodies prepared against a proteoheparan sulfate isolated from a basement membrane producing EHS sarcoma cross react with basement membrane structures within the aortic wall. Furthermore, these results demonstrate that the basement membranes beneath aortic and capillary endothelium and the external lamina surrounding aortic smooth muscle cells contain a heparan sulfate proteoglycan that is antigenically similar.

Glass-bead affinity chromatography of cell attachment and spreading-promoting factors of human serum

The glass-binding properties of a number of purified glycoproteins capable of promoting attachment and spreading of a variety of types of animal cells in culture have been examined. Two such factors in human serum, fibronectin and serum spreading factor, exhibited strong affinities for glass beads and could be eluted from glass-bead columns under similar conditions. A number of other glycoproteins of human serum that do not promote cell adhesion did not bind to glass beads under conditions that resulted in binding of serum spreading factor or fibronectin. At a sufficiently low ratio of serum volume to glass-bead volume, human serum could be simultaneously depleted of serum spreading factor, fibronectin, and cell spreading-promoting activity by glass-bead affinity chromatography. Laminin, another cell spreading-promoting glycoprotein, possessed glass-binding properties similar to those of serum spreading factor and fibronectin while chondronectin, a fourth cell spreading-promoting factor of more limited specificity of biological activity and distribution in vivo, did not exhibit a strong interaction with glass beads under the same conditions. These observations suggest that glass-bead column affinity chromatography may prove useful as a general method for isolation and study of glycoprotein factors promoting attachment and spreading of cells in culture.

Solubility of a bone-inducing substance from a murine osteosarcoma

A bone-inducing substance (osteogenic factor) from a murine osteosarcoma was found to be soluble in 1% sodium lauryl sulfate (SDS), 1% deoxycholate, 1% Triton X-100, and 1% Nonidet P-40. A precipitate formed on removal of the detergents by dialysis against phosphate buffer, and this precipitate induced ectopic bone formation when implanted into allogeneic mice. The insoluble residue left after extraction with SDS or deoxycholate did not evoke new bone formation, indicating that the substance was solubilized completely. The bone-inducing substance was also partially solubilized with weak acids (pH, 2.6-3.0) but not with acidic solutions of lower or higher pH. These findings indicate that the solubility of the substance depends on the hydrogen ion concentration of the solution. The substance was not solubilized with EDTA or 6 M urea.

Identification of a laminin-like substance on the surface of high-malignant murine fibrosarcoma cells

High- and low-malignant murine fibrosarcoma cells were stained with anti-laminin antibodies using immunoperoxidase techniques and examined by electron microscopy. With the high-malignant cells, specific staining was observed along the cell surface. Use of normal rabbit serum in place of the rabbit anti-laminin or pretreatment of the anti-laminin with soluble laminin completely eliminated this staining. No immunoperoxidase staining was observed with the low-malignant cells. In additional studies, membrane fractions were prepared from the high- and low-malignant cells and used to immunize rabbits. The animals immunized with the membrane fractions from the high-malignant cells produced antibodies that reacted by enzyme-linked immunosorbent assay (ELISA) with murine laminin obtained from the EHS sarcoma. The animals immunized with membrane fractions from the low-malignant cells did not. These studies provide strong evidence that the high-malignant cells (but not the low) express on their cell surface a substance that is immunologically cross-reactive with laminin. In addition, the high-malignant cells (but not the low) secreted a material into the cell culture fluid that could be specifically immunoprecipitated with antilaminin antibodies. The immunoprecipitated material co-migrated with purified laminin when examined by sodium dodecyl sulphate/polyacrylamide gel electrophoresis under reducing conditions. The existence of this substance associated with the surface of the high-malignant cells and its absence from that of the low-malignant cells may explain the previously noted difference between these cells in their ability to attach to type IV collagen. This difference may also contribute to the dissimilarity between these cells in their metastatic potential.

Nidogen: a new, self-aggregating basement membrane protein

Nidogen was purified from a mouse tumor basement membrane where it accounted for 2-3% of the total proteins. It was isolated as two forms (A and B) of a monomer (Mr = 80000) each consisting of a single polypeptide chain folded into a globular head connected to a small tail. The B form of the monomer was shown to be capable of aggregating into a nest-like structure (Mr greater than 250000). A smaller form (Mr = 45000) was observed in some of the extracts. The amino acid composition of nidogen was different to that of other basement membrane proteins. It contained about 10% carbohydrate, with N-linked and O-linked oligosaccharide chains in similar proportions. Isoelectrofocussing demonstrated a limited heterogeneity of nidogen with pI in the range 6.5 - 7. Monomeric nidogen failed to interact with other basement membrane components and heparin. Aggregation could be induced by limited proteolysis and was reversed by detergents or high salt concentrations. Together with the observation that most of the nidogen could be solubilized only after destroying the collagenous matrix, the data indicate that aggregation of nidogen reflects an activity involved in matrix assembly. Specific antibodies raised against nidogen did not distinguish between the monomeric and aggregated form of the protein but showed that the fragment was antigenically deficient. These antibodies did not cross-react with collagen type IV, laminin, entactin and heparansulfate proteoglycan. Immunofluorescence staining and absorption studies demonstrated that nidogen is a common component of authentic basement membranes. Larger forms of nidogen (Mr about 100000 and 150000) were found in organ cultures of Reichert's membrane suggesting that it is synthesized in precursor forms.

Incorporation of mannose 6-phosphate receptors into liposomes. Receptor topography and binding of alpha-mannosidase

A receptor that binds the lysosomal enzyme alpha-mannosidase via mannose 6-phosphate moieties (mannose 6-phosphate receptor) was purified from Swarm-rat chondrosarcoma and bovine liver microsomal membranes. Receptor-reconstituted liposomes were prepared by dialysis of taurodeoxycholate-dispersed lipids with purified mannose 6-phosphate receptor. Liposomes appeared by electron microscopy as 60-120 nm unilamellar vesicles. Receptor-reconstituted liposomes retained the ability to bind alpha-mannosidase specifically. Binding was saturable with an apparent Kd of 1 nM and was competitively inhibited by mannose 6-phosphate (Ki 2mM). Liposomes containing entrapped 125I-bovine serum albumin were used to demonstrate that treatment with 0.045% taurodeoxycholate rendered liposomes permeable to macromolecules without solubilizing the membrane. Receptor orientation in the liposome membrane was established by measuring binding of ligand to intact and detergent-treated liposomes. Unlike coated vesicles, which contain cryptic mannose 6-phosphate receptors [Campbell, Fine, Squicciarini & Rome (1983) J. Biol. Chem. 258, 2526-2533], treatment of liposomes with detergent revealed no additional cryptic binding sites. In addition, treatment of liposomes with 0.75% trypsin abolished total receptor binding activity. The results suggest that the receptor is inserted with its binding site facing the outside of the liposome.

Glycosaminoglycans of solid and ascites forms of the P1798 murine lymphosarcoma

Total glycosaminoglycan levels are similar from subcutaneous, ascites and mesenteric forms of the P1798 lymphosarcoma. However, P1798 cells implanted subcutaneously produce a solid tumor rich in hyaluronic acid with lesser amounts of chondroitin 4-/6-sulfates as well as an undersulfated species of chondroitin sulfate, while cells implanted intraperitoneally produce ascites tumors which generate hyaluronic acid, almost exclusively. Mice bearing advanced ascites tumors develop solid mesenteric tumors which exhibit chondroitin 4-/6-sulfates and under-sulfated chondroitin sulfate in addition to hyaluronic acid.

[Composition of gangliosides in experimental rat tumors]

Spectrum of gangliosides was studied in some tumors. It was the same in a hepatocellular carcinoma induced by N-nitrosomorpholine in Wistar rats as in control liver In addition, several tumors contained an unidentified fraction between GD1b and GT1b. There were total ganglioside differences both in tumours and controls. Lymphatic leukemia samples had lower contents of GD1a and higher contents of GM1 ganglioside. Spontaneous breast sarcoma of Lewis rats (SAM) failed to differ from a sarcoma of low grade malignancy induced by ferridextran (FL) with the exception of slight increase in GD1a and GD2. All the tumours contained higher gangliosides in concentration at least the same as controls.

Nuclear magnetic resonance imaging of a fibrosarcoma tumor implanted in the rat

Fibrosarcoma tumor cells were implanted in the hind legs of 25 rats and studied from the first to the sixth week postimplantation. Nuclear magnetic resonance imaging detected all tumors and did not yield any false-positives in five control rats. The T1 relaxation values of tumors overlapped those of muscle, and the T2 values overlapped those of fat, but the combination of the two values allowed discrimination of each of the three tissues with no overlap. The difference in relaxation time between tumor and muscle could be accounted for on the basis of water content, which was approximately 14% higher in the tumors. This study confirms data from previous studies suggesting that nuclear magnetic resonance imaging is a highly sensitive modality, but that T1 and T2 values are not specific for individual pathologic conditions.

Proteoglycans from the substratum adhesion sites of MSV-transformed BALB/c 3T3 cells

Kirsten murine sarcoma virus-transformed Balb/c 3T3 cells (KiMSV) are highly tumorigenic and metastatic in the appropriate murine host, are loosely adherent to the tissue culture substratum, and can be readily detached from the substratum by ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid treatment leaving their adhesion sites as substratum-attached material. Both long-term culture-generated adhesion sites (L-SAM) of KiMSV cells and newly formed adhesion sites of reattaching cells (R-SAM) contain high levels of hyaluronate (HA) and chondroitin sulfate (CS) whereas the R-SAM of parental Balb/c 3T3 cells is enriched in heparan sulfate (HS). A sizable fraction of KiMSV L-SAM proteoglycans (PG) and a smaller fraction of R-SAM PG's aggregate into two size classes of supramolecular complexes, after extraction off the substratum with 4 M guanidine hydrochloride, as determined by chromatography on columns of Sepharose CL2B in several buffer systems. Isopycnic density gradient analyses under associative conditions of KiMSV L-SAM generated three classes of material--high-density GA1 which contained some HA but principally CS and HS; intermediate-density GA2 which contained only HA; and low-density GA3 which contained some HA and principally glycoprotein. R-SAM gradients contained no GA2 but a sizable amount of "low-density" HA in GA3. When centrifuged under dissociative conditions, most of GA1 and all of GA2 from L-SAM shifted to the top of the gradient, whereas most of the HS-PG in R-SAM remained at the bottom of dissociative gradients. Comparison of these analyses with previous analyses of Balb/c 3T3 extracts demonstrates that (a) KiMSV cells generate adhesion sites with different PG contents than 3T3 sites; (b) the PG's of KiMSV sites have a reduced potential to aggregate into high-molecular-weight complexes but do form intermediate-size complexes not apparent in material from 3T3 sites; (c) these data support the hypothesis that HA is important in detachment of cells from extracellular matrices; and (d) HS-PG's in newly formed adhesion sites of KiMSV cells are considerably different from sites which have "matured," indicating that there is metabolic activity in these sites during prolonged adherence and movement of transformed cells.

Inhibition of glutathione synthesis augments lysis of murine tumor cells by sulfhydryl-reactive antineoplastics

GSH plays an important role in cellular defense against a wide variety of toxic electrophiles via the formation of thioether conjugates. We studied the role of GSH in murine tumor cell defense against a novel class of sulfhydryl-reactive antineoplastics, the sesquiterpene lactones (SL). Incubation of P815 mastocytoma cells with any of the four SL tested (vernolepin, helenalin, elephantopin, and eriofertopin) for 1 h resulted in 70-97% depletion of GSH. The importance of GSH resynthesis upon exposure of tumor cells to SL was evaluated with the use of buthionine sulfoximine (BSO), a selective, nontoxic inhibitor of gamma-glutamylcysteine synthetase. Inhibition of GSH synthesis with 0.2 mM BSO markedly enhanced SL-mediated cytolysis of four murine tumor cell lines. A 6- to 34-fold reduction in the amount of SL causing 50% lysis was obtained with BSO. Addition of BSO to P815cells either during or immediately after a 1-h pulse with 10 micrograms/ml of vernolepin increased cytolysis from less than 3% to 78-82%. However, a 1.5-h delay in the addition of BSO to such cells, which allowed for substantial resynthesis of GSH, reduced cytolysis to 30%. Recovery of GSH synthetic capacity after BSO treatment correlated with loss of the synergistic effect of BSO on lysis by vernolepin. BSO did not augment cytolysis by six other antineoplastics (doxorubicin, mitomycin C, vinblastine, cytosine arabinoside, maytansine, and 1,3-bis-[2-chloroethyl]-1-nitrosourea [BCNU]). Of these, only BCNU depleted cellular GSH. Lysis by jatrophone, another GSH-depleting antitumor agent, was increased 21-fold by BSO. Since prolonged incubation with BSO alone results in near-complete GSH depletion without loss of cell viability, SL-mediated cytolysis is probably not a result of GSH depletion. We have demonstrated, however, a critical role for GSH synthetic capacity as a determinant of tumor cell susceptibility to cytolysis by SL. GSH also plays an important role in cellular defense against oxidative injury. Vernolepin, acting as a GSH-depleting agent, markedly sensitized tumor cells to lysis by H2O2 (greater than 6.5-fold increase with 20 micrograms/ml of vernolepin). These findings suggest the possibility that the coordinated deployment of sulfhydryl-reactive antitumor agents, BSO, and oxidative injury might constitute an effective chemotherapeutic strategy.

Fibronectin in foreign body-induced sarcomas and preneoplastic cells

Foreign body (FB)-induced murine sarcoma cells and advanced preneoplastic cells as well as normal fibroblasts produce fibronectin (FN) in primary culture; cells at early preneoplasia do not. Hence, the neoplastic properties of FB-induced sarcomas do not depend on absence of FN. Temporary FN repression during early preneoplasia is associated with certain phenotypic cell characteristics.

Isolation and characterization of type IV procollagen, laminin, and heparan sulfate proteoglycan from the EHS sarcoma

We have studied the extractability of type IV collagen, laminin, and heparan sulfate proteoglycan from EHS tumor tissue growth in normal and lathyritic animals. Laminin and heparan sulfate proteoglycan were readily extracted with chaotropic solvents from both normal and lathyritic tissue. The collagenous component was only solubilized from lathyritic tissue in the presence of a reducing agent. These results indicate that lysine-derived cross-links and disulfide bonds stabilize the collagenous component in the matrix but not the laminin or the heparan sulfate proteoglycan. The majority of the collagen present in the extracts had a native triple helix based upon the pattern of peptides resistant to pepsin digestion and visualization in the electron microscope by the rotary shadow technique. This protein was composed of chains (Mr 185000 and 170000) identical in migration to the chains of newly synthesized type IV procollagen. This finding confirms earlier work that indicates that the biosynthetic form, type IV procollagen, is incorporated as such in the basement membrane matrix. Material with smaller chains (Mr 160000 and 140000) appeared on storage in acetic acid solutions. These results indicate that the lower molecular weight collagen in acid extracts of basement membrane arises artifactually due to an endogenous acid-active protease.

Structures of N-linked and O-linked oligosaccharides on proteoglycan monomer isolated from the Swarm rat chondrosarcoma

Monomer proteoglycans isolated from the Swarm rat chondrosarcoma contain O- and N-glycosidically linked oligosaccharides. The O-glycosidically linked ones were released from the protein core by alkaline borohydride treatment. After removal of sialic acid, the resulting oligosaccharide alditols were converted to N-trifluoroacetyl derivatives by trifluoroacetolysis. The N-trifluoroacetylated oligosaccharide alditols show shorter retention time on gas-liquid chromatography, as permethylated derivatives, than the corresponding N-acetyl derivatives. The mass spectra of these new derivatives also give more structural information and provide definitive structures. Alkaline borohydride treatment of the proteoglycans also released N-glycosidically linked oligosaccharide-peptides. These were purified and analyzed by Smith degradation, trifluoroacetolysis, and chromium trioxide oxidation. The results indicate that more than 70% of the N-glycosidically linked oligosaccharides have the following structure: (formula, see text) with the Fuc present on only about 60% of the oligosaccharides.

Cloned complementary deoxyribonucleic acid probes for untranslated messenger ribonucleic acid components of mouse sarcoma ascites cells

Mouse sarcoma ascites cells contain several abundant mRNA species that occur to a large extent in an untranslated state. RNA preparations enriched in these species were used as starting material to construct recombinant plasmids. Cloned plasmids bearing sequences homologous to four of the untranslated mRNA species were identified by translation of hybrid-selected material. These plasmids, as well as a recombinant plasmid derived from chick alpha-actin mRNA, were used as probes for the estimation of mRNA levels in polyribosomes and in small ribonucleoprotein (RNP) particles of the ascites cells. Considerable amounts of the mRNA molecules belonging to the untranslated species were present in polyribosomes as well as in mRNPs. The actin mRNA, on the other hand, was present almost exclusively in polyribosomes. The distributions obtained by the hybridization assay resembled those estimated by translation of the same RNA preparations in cell-free systems. This indicates that the mRNA molecules of a given species engaged in translation in the cells and those present as untranslated RNP particles are equally effective in cell-free translation systems.

[In vitro effect of culture fluids from neoplastic tissues on platelet aggregation. II. Experimental tumors]

We have investigated the effects on platelet function of culture media from 2 sublines of a benzopyrene-induced murine sarcoma (mFS6). Platelet aggregation was investigated according to Born's method. The cell line with greater "in vivo" invasiveness showed higher aggregating activity and higher increase on ADP-induced aggregation; these effects were inhibited by the preincubation of platelets with Aspirin (0,1 mM). These results suggest the role of platelets in metastasis formation; the possibility to inhibit pharmacologically the interactions between platelets and tumour cells could have important implications from both speculative and practical viewpoints.

Histological changes during regression induced by retinoic acid in a transplantable rat chondrosarcoma

Daily oral treatment with retinoic acid (100 mg/kg bodyweight) induced regression of a transplantable rat chondrosarcoma. In a previous biochemical investigation we have shown that the tissue breakdown is preceded by the loss of proteoglycan. The present study describes the histological changes induced by retinoic acid. A decrease in the intensity of metachromatic staining with toluidine blue was noted already after 1 day and the discoloration was almost complete after 4 days correlating with the loss of proteoglycan. Especially in the perichondrium there was a rapid proliferation of fibroblasts and monocytes. Osteoclast-like cells were missing, but tumor nodules were eroded and split up by penetrating perichondrium. After 4 days of treatment larger necrotic areas were found, initially in the center of tumor nodules only. In other areas the majority of tumorous chondroblasts survived. Tumor nodules appeared partly mesenchyma-like with some fibroblast-like cells suggesting a dedifferentiation of chondroblasts by retinoic acid. we believe that tumor regression induced by retinoic acid involved proteoglycan degradation by chondroblasts themselves and chondroclast-like activity of monocytes and fibroblasts.