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At high in vitro passage levels HSV-2-transformed hamster and rat cell lines were oncogenic for the homologous animals, inducing fusocellular or round-cell sarcomas. The cell lines obtained by in vitro cultivation of the tumors were free of infectious virus.
Human peripheral blood monocytes and mature macrophages were found to produce significant procoagulant activity (PCA), identified as tissue factor, on exposure to a variety of human (K562, HL60, Raji) and murine (TU5, NS-1) transformed cell lines. The monocyte procoagulant response was vigorous, generating PCA to a level nearly comparable to the response to endotoxin, a known stimulant for monocyte PCA. The response was rapid and could be fully elicited, in a dose-dependent fashion, within 4 hr with HL60 and Raji cell lines and within 14 hr with K562, TU5, and NS-1 cells. The monocyte PCA-inducing activity was found to reside in the membrane fraction of transformed cells. Other transformed human (Laz 509, Laz 221, Laz 156, U937, CEM) and murine (L1210, P815, TLX9, WEHI 164) cell lines had little, if any, activity. The induction of monocyte PCA by transformed cells most probably was not due to an allogeneic signal, as 1) the K562 and HL60 cell lines were potent PCA inducers despite the lack of class II histocompatibility antigen expression, whereas Laz 156, which did express HLA antigens, was ineffective; 2) mouse peritoneal macrophages responded with the production of strong PCA to the syngeneic transformed cell lines TU5 and NS-1. The monocyte-macrophage procoagulant response to transformed cell lines appeared to be independent of T lymphocytes. Indeed, monocytes purified on the basis of reactivity with monoclonal antibody Mo2 and sorting or depleted of contaminating T cells by anti-T3 antibody and complement responded similarly to conventional monocyte preparations. The production of tissue factor by monocyte-macrophages in response to exposure to some tumor cells may represent a mechanism whereby blood coagulation is activated in malignancy.
Visna-maedi of sheep and arthritis encephalitis of goats are slowly progressive diseases caused by serologically related lentiviruses. Lesions are inflammatory and can occur at one or many sites including the central nervous system, lungs, joints, and mammary glands. The viruses replicate in macrophages, and in the animal large numbers of infected macrophages can be obtained from inflamed tissues. To study virus-macrophage interactions we transformed sheep alveolar macrophages, which are natural virus target cells, with simian virus 40 and produced a macrophage cell line. The transformed cells grew into density-dependent monolayers and were subcultured after trypsin dissociation. They maintained histochemical and physiologic properties of macrophages as well as the ability to support replication of the lentiviruses. Rabbit antisera to these cells reacted with blood monocytes and only selected populations of tissue macrophages, including those in lung, synovium, mammary gland, and spleen. Microglia, Kupffer cells, and connective tissue histiocytes were not recognized by the sera. Since the tissues in which virus localizes in infected animals are the same as those recognized by the sera, the antimacrophage serum may provide an immunologic marker for virus-susceptible macrophages in the animal.
Fibroblasts transformed by v-sis have elevated levels of c-fos relative to non-transformed controls. Transfection and integration of plasmids directing the synthesis of antisense RNA to the c-fos gene leads to restoration of density-dependent growth arrest in monolayer culture, but does not inhibit colony formation in soft agar.
Serum factors activating the alternative pathway of the complement (APC) were detected in 5 of 14 patients with systemic lupus erythematosus (SLE). Epstein-Barr virus (EBV)-transformed B cell lines were subsequently established from these patients and 6 of these produced factors capable of activating the APC. Using a limiting dilution technique, we obtained a clone which was producing a factor activating the APC (AF); by affinity column fractionation and polyacrylamide gel electrophoresis, the AF was found to have heavy and light chains comparable to those of normal human IgG. Normal human serum exhibited C3 split products (demonstrated by immunoelectrophoresis) in the presence of AF and under conditions permitting activation of the APC. Sera devoid of factor B, but not of C2 and C4, failed to catabolize C3 in the presence of AF. The AF failed to stabilize erythrocyte-bound C3bBb or C4b2a convertases, indicating that it was not a nephritic-factor-like molecule. We conclude that IgG molecules present in the sera and produced by EBV-transformed B cell lines from patients with SLE are apparently responsible, at least partially, for complement consumption in these patients.
The effect of malignant transformation of cells on phosphatidylinositol metabolism was investigated using C3H10T1/2 cells and its chemically transformed cell line, MCA CL-16 cells. We found that incorporation of [32P]Pi into polyphosphoinositide was greatly increased in the transformed cells. A similar tendency was observed when myo-[2-3H]inositol was used as a labelling reagent. It is also observed that influx of labelled inorganic phosphate is enhanced 2-fold by the cell transformation. Therefore, promotion of polyphosphoinositide labelling in the transformed cell might be caused not only by the enhanced metabolism of phosphatidylinositol but also by the increased membrane permeability for radioactive labelling reagents.
The present study describes the establishment of both B- and T-cell lines from the peripheral blood cells of two Bloom's syndrome (BS) patients and one healthy female by using Epstein-Barr (EBV) and adult T-cell leukemia viruses (ATLV). The cell lines from normal and BS subjects exhibited cell surface markers compatible with B- and T-cell origin; in addition, the BS B- and T-cell lines retained the original cytogenetic characteristics of the syndrome. Even though phytohemagglutinin-stimulated BS lymphocytes from the two BS patients studied all showed high levels of sister chromatid exchange (SCE), the established BS B-lines with EBV yielded two separate lines each, i.e., one with increased SCE and another with normal levels of SCE; also, one of the BS T-lines retained high SCE levels in 100% of the cells, whereas the other BS T-line contained two populations, one with high SCE (70%) and the other with normal SCE levels (30%), at a relatively constant frequency over a period of 6 months. Neither EBV nor ATLV caused a significant increase in chromosome instability in the established lines compared to fresh lymphocytes. Reinfection of the BS B- and T-cell lines with EBV or ATLV did not alter the SCE or karyotypes. These results strongly suggest that BS patients have two populations in vivo, one with high and another with normal levels of SCE, at least in the lymphoid cell system.
Fibroblasts transformed by Abelson murine leukemia virus differ from normal fibroblasts in that they contain several cellular proteins, including one of 29 and one of 36 kilodaltons, which are phosphorylated at tyrosine residues. Since it has been shown before that these proteins also become phosphorylated at tyrosine after transformation of fibroblasts by a number of other retroviruses, their phosphorylation may play an important role in the transformation of these cells. In contrast, the 36-kilodalton phosphoprotein was not detectable in three of the four lines of Abelson virus-transformed B lymphoma cell lines studied here. These three cell lines, RAW307.1.1, 18-48, and 18-81, and a B lymphoma induced by mineral oil, WEHI 279, were all found to lack both the phosphorylated and unphosphorylated forms of the 36-kilodalton protein. It thus appears that expression of this major cell protein is not essential for the survival of B lymphoma cells in culture and that the phosphorylation of the 36-kilodalton protein at tyrosine is not essential for transformation of pre-B lymphocytes by Abelson virus.
Glycosphingolipids are assumed to play a crucial role in cell-cell and cell-substrate interactions, including cell adhesion, proliferation, differentiation and apoptosis. Furthermore, cell surface glycolipid profile changes in the so called "social disorders", such as malignant transformation. To better investigate these modifications, the ganglioside composition in different solid tumours and in two transformed cell lines was analyzed. In some of these models we also tried to correlate the pattern of gangliosides to the key enzymes involved in their metabolism. The results we obtained can be summarized as follows:(1), meningiomas with or without chromosome 22 deletion: predominance of ganglioside GD3 in the former and of ganglioside GM3 in the latter. Correlation between GM3/GD3 ratio and SAT-2 activity; (2), mammary carcinomas developed in MMTV/c-neu transgenic mice: accumulation of GM3-derived species. The different ganglioside distribution seems to correlate with the tumour size; (3), Sarcoma Galliera-strain cells SGS/3A and normal syngenic murine fibroblasts FG: transformed cells exhibit a lower activity of sialyltransferases (SAT-1, SAT-2, SAT-4) compared to normal fibroblasts, suggesting a possible correlation with the ganglioside pattern. The neuraminidase activity seems to correlate to the glycoprotein sialic acid content; (4), 3T3 normal murine fibroblasts and SVT2 transformed cells: GM3 is absent in 3T3, while it accounts for the main ganglioside species in SVT2. On the contrary, GM2 present in a large amount in normal fibroblasts, is practically absent in transformed cells. No correlation has been observed between ganglioside profile and glycosyltransferase activities so far examined.
The objective of this study was to determine whether N6, O2-dibutyryl 3',5'-adenosine monophosphate (db-cAMP)-induced reverse transformation in a chemically transformed mouse cell line, AKR-MCA, would restore normal cell cycle regulation, particularly with regard to their growth arrest in the early G1 period. The AKR-MCA cells were grown to confluency in the presence or absence of db-cAMP (0.5 mM) plus theophylline (1 mM). The confluent cultures were trypsinized and a portion of the cells were fused with mitotic HeLa cells to induce premature chromosome condensation, while the remaining cells were used to study the kinetics of initiation of DNA synthesis. The prematurely condensed chromosomes (PCC) of the control and the treated cultures were classified into G1, S, or G2 types on the basis of their morphology. The G1 PCC were further subclassified into six groups (+1 - +6); +1 being the most condensed and +6 the most decondensed. The cyclic AMP (cAMP)-treated cells exhibited better attachment to the culture dish, were blocked in early G1 period at confluency, and entered S phase about 4 h later than the control following subculturing. In contrast, a majority of cells in the control cultures were arrested in S phase at confluency. These data indicate that the db-cAMP-induced reverse transformation in AKR-MCA cells at least partially restores normal cell cycle regulation in these chemically transformed cells.
Spontaneously transformed hamster cells were examined for the presence of TSTA by employing the tumor rejection test. It was demonstrated that each of the spontaneously transformed cell lines as well as cells derived from tumors induced by these cells possess an individual distinct antigen, capable of evoking a significant anti-tumor immunity. The immunizing potential of these antigens and their specificity were not affected by either in vivo or in vitro environment. The results suggest that the spontaneously transformed hamster cells undergo antigenic modification, which resembles the TSTA of chemical-carcinogen induced tumors.
'High-risk' human papilloma viruses (HPVs) cause cervical tumours. In order to treat these tumours therapeutic approaches must be developed that efficiently target the tumour cells. Using phage display, we selected tumour-targeting peptides from a library of constrained nonamer peptides presented multivalently on pVIII of M13. Three different consensus peptide sequences were isolated by biopanning on HPV16-transformed SiHa cells. The corresponding phage-peptides targeted and were internalized in HPV16 transformed SiHa and CaSki cells as well as in HPV18-transformed HeLa cells, but failed to bind a panel of normal or transformed cell lines. Two of the three selected peptides targeted cells only when presented on phage particles in a constrained conformation. However, all three peptides retained their targeting capacity when presented on the reporter protein enhanced green fluorescent protein (EGFP) in a monovalent form. These peptides may be useful for the design of drug or gene delivery vectors for the treatment of cervical cancer.
A human T-lymphoblastoid cell line, TCL-Fuj, constitutively produced a large amount of human gamma interferon (IFN) in culture fluids and has sustained stable IFN production for more than two years. When cells were incubated in RPMI-1640 medium with 10% fetal calf serum for three days, IFN activity was detectable at a cell density of 6 X 10(4) cells/ml, whereas 2,000-16,000 units of IFN per ml were produced at 5-10 X 10(5) cells/ml. IFN production was also detected even in serumfree medium and as early as 2 hr after cultivation in fresh medium. IFN was inhibited by treatment of cells with either actinomycin D or cycloheximide, indicating the requirement of IFN-mRNA and protein for de novo synthesis. The molecular weight of the IFN was 45,000-60,000 as determined by Sephacryl S200 gel filtration. Two activity peaks corresponding to molecular weights of 22,000 and 39,000 were obtained by SDS-polyacrylamide gel electrophoresis. Analysis by isoelectric focusing revealed charge heterogeneity with four species at pIs of 6.0, 7.1, 8.6, and 9.3. Conventional IFN-gamma inducers, concanavalin A and 12-O-tetradecanoyl-phorbol-13-acetate, further enhanced the production of IFN in this cell line.
cAMP production and the activity of cAMP dependent protein kinase (Kinase-A) were examined in a mutant clone of a NIH/3T3 cell line transformed by a human activated H-ras-1 oncogene (EJ-NIH/3T3). The mutant (R1) shows the characteristics of a flat revertant. The amount of cAMP increases more significantly in R1 than that in EJ-NIH/3T3 in the presence of PGE1. Enhanced activity of Kinase-A was also noted in R1 when compared to that in EJ-NIH/3T3. Further, EJ-NIH/3T3 treated with agents which increase intracellular cAMP content partially lost some characteristics of malignantly transformed phenotypes in vitro. These data suggest that Kinase-A might be involved in the reversion of EJ-NIH/3T3. In addition, reduced cytosolic free Ca2+ concentration measured with Ca2+ indicator in R1 cells was noted. This might also be associated with the reversion of the malignantly transformed cell line.
Seven cell lines transformed by adenovirus type 5 and its DNA were obtained. It was shown that different cell lines contain the fragments of viral DNA which differ in length and number of copies per DNA of diploid cells. They contain from the left end 6% of the viral DNA to complete or almost complete viral genome. All studied cell lines were sensitive to reinfection with adenovirus type 5. They produced no virus being cocultivated with cell sensitive to the virus. No cell line was able to induce tumors even in immunosuppressed newborn rats. All cell lines formed colonies in soft agar. The level of virus-specific antigens was higher in cells that contained a large part of the viral genome. The methods used did not allow to correlate the biological properties of the transformed cells with the length and the number of copies of the integrated part of the viral genome.
We have examined the effects of different inhibitors of glycosylation processing on the proliferation of a spontaneously transformed murine cell line (3T6) in vitro. It was found that whereas two compounds that specifically inhibit distal steps in the glycosylation chain (swainsonine and castanospermine) only exerted marginal inhibitory effects on cell multiplication, a proximal inhibitor (tunicamycin) efficiently decreased the rate of DNA synthesis in a dose-dependent fashion. This tunicamycin-induced inhibitory effect on cell proliferation was cell cycle-specific, in the sense that cells in G1 only were blocked in their cell cycle progression. Like others (Volpe & Goldberg, 1983), we found that tunicamycin inhibited the activity of 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMG-CoA), which constitutes the ratelimiting step in the biosynthesis of cholesterol and isoprenoid derivatives, by catalysing the reduction of HMG-CoA to mevalonate, and it has been suggested that it plays a role in the control of cell proliferation and in tumour transformation. This raises the question as to whether tunicamycin exerts its inhibitory effects on cell proliferation via the isprene-synthetic pathway in addition to its effects on aspargine-linked glycosylation. By adding exogenous mevalonate, the rate-limiting step at which HMG-CoA reductase converts HMG-CoA to mevalonate can be bypassed. We found that addition of mevalonate partially reverses the effects of tunicamycin on cell proliferation. This suggests that tunicamycin exerts different effects, which taken together lead to a cessation of cell proliferation. One of these effects is likely to be mediated via the mevalonate-synthetic pathway.
A revertant cell line, KSR-4111, cloned from a sarcoma virus transformed non-virus producing murine 3T3 cell line, K-BALB-23, was found to inhibit in vivo growth in newborn syngeneic mice of the transformed cells when grafted to the same locus, but not when grafted separately from the grafted tumor cells. No inhibition of outgrowth of the transformed K-BALB-23 cells was obtained with another revertant, KSR-12121, also cloned from the transformed K-BALB-23 cell, nor with the normal 3T3 cell. Furthermore, grafting of two syngeneic mammary tumors was unaffected by the presence of the protective revertant cells. The protective revertant KSR-4111 was furthermore characterized by inducing cytoxic non-theta-antigen-bearing spleen lymphocytes in grafted syngeneic recipients.
The localization of the Epstein-Barr virus (EBV) genome in chromosomes of human B-lymphoblastoid cell lines (LCLs) transformed with EBV, and the effect of EBV DNA on the level of sister chromatid exchange (SCE) in Bloom's syndrome (BS) B-LCLs, were examined with chromosomal in situ hybridization techniques using a 3H-EBV DNA probe. EBV DNA was detected in chromosomes 1-5 and 13-15 at specific G band regions in BS as well as in normal B-LCLs, regardless of SCE. Several chromosomal sites (1p31, 1q31, 4q22-24, 5q21, 13q21, 14q21) carrying EBV DNA seemed to be very characteristic in normal as well as in BS B-LCLs. There was no statistically significant difference in silver grain counts due to EBV DNA and their distribution in different chromosomes or groups among normal and BS B-LCLs with normal and high SCE. These findings strongly indicate that EBV infection did not introduce a correcting factor for BS SCE.