cytochalasin-b and Cell-Transformation--Neoplastic

Topics: Animals; Cell Adhesion; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Cytochalasin B; Fibroblasts; Mice; Microscopy, Electron, Scanning; Microvilli

Topics: Animals; Biological Transport; Calcium; Carrier Proteins; Cell Division; Cell Membrane; Cell Transformation, Neoplastic; Cell Transformation, Viral; Cytochalasin B; Glucose; Humans; Insulin; Kinetics; Magnesium; Membrane Fluidity; Membrane Proteins; Models, Biological; Monosaccharide Transport Proteins; Monosaccharides; Phloretin; Receptor, Insulin

LETS is a large surface glycoprotein that is found on normal fibroblasts, but is absent or exists in amounts on transformed cells. Immunofluorescent staining shows LETS protein fibrils arrayed around the cells, particularly concentrated beneath the cells and in the area between neighboring cells. LETS glycoprotein is disulfide-bonded at the cell surface into dimers and higher aggregates. Other surface proteins also appear to participate in disulfide bonding. Reduction of disulfide bonds leads to increased release of LETS protein from the cells, as does the addition of cytochalasin B. Purified LETS protein added to transformed cells binds to the cells in a fibrillar array similar to that seen on normal cells. Addition of LETS protein leads to increased attachment and spreading of cells and causes transformed cells to align like normal ones. It also causes the appearance of actin cables in transformed cells, which normally lack them. These effects are inhibited by specific antisera to LETS protein or by reduction of disulfide bonds in the protein and are blocked or reversed by proteolysis. The results suggest that LETS protein plays a role in adhesion of cells.

Topics: Actins; Cell Adhesion; Cell Count; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Cytochalasin B; Glycoproteins; Membrane Proteins; Protein Conformation

Topics: Cell Division; Cell Nucleus; Cell Transformation, Neoplastic; Cell Transformation, Viral; Chromosome Aberrations; Chromosome Disorders; Cytarabine; Cytochalasin B; DNA; DNA Replication

Topics: Agglutination Tests; Animals; Antigens; Avian Sarcoma Viruses; Cattle; Cell Count; Cell Line; Cell Transformation, Neoplastic; Chick Embryo; Colchicine; Cricetinae; Culture Media; Cyclic AMP; Cytochalasin B; Evaluation Studies as Topic; Methods; Mice; Mutation; Phenotype; Polyomavirus; RNA Viruses; Simian virus 40; Time Factors

Topics: Animals; Carcinoma, Hepatocellular; Cell Fractionation; Cell Fusion; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Cells; Cells, Cultured; Chickens; Cytochalasin B; Erythrocytes; Hybrid Cells; L Cells; Liver Neoplasms; Macrophages; Methods; Parainfluenza Virus 1, Human; RNA, Messenger; Ultracentrifugation; Virus Replication

Tumor necrosis factor-alpha (TNF-alpha) is an important inflammation cytokine without known direct effect on DNA. In this study, we found that TNF-alpha can cause DNA damages through reactive oxygen species. The mutagenic effect of TNF-alpha is comparable with that of ionizing radiation. TNF-alpha treatment in cultured cells resulted in increased gene mutations, gene amplification, micronuclei formation, and chromosomal instability. Antioxidants significantly reduced TNF-alpha-induced genetic damage. TNF-alpha also induced oxidative stress and nucleotide damages in mouse tissues in vivo. Moreover, TNF-alpha treatment alone led to increased malignant transformation of mouse embryo fibroblasts, which could be partially suppressed by antioxidants. As TNF-alpha is involved in chronic inflammatory diseases, such as chronic hepatitis, ulcerative colitis, and chronic skin ulcers, and these diseases predispose the patients to cancer development, our results suggest a novel pathway through which TNF-alpha promotes cancer development through induction of gene mutations, in addition to the previously reported mechanisms, in which nuclear factor-kappaB activation was implicated.

Topics: Animals; Cell Line, Tumor; Cell Transformation, Neoplastic; Colonic Neoplasms; Cytochalasin B; DNA Damage; Fluoresceins; Gene Amplification; Humans; Mice; Mutagens; Mutation; Oxidative Stress; Plasmids; Reactive Oxygen Species; Tumor Necrosis Factor-alpha

In the present study, using immunofluorescence microscopy, we have demonstrated that normal and Ha-ras-1 transformed Buffalo rat liver (BRL) cells which were exposed to cytoskeletal protein inhibitors, showed a differential resistance of their microfilament and microtubule networks. One hour exposure of normal BRL cells to 10(-5) M cytochalasin B provoked a clear and already total breakdown of actin filaments. However, at this concentration of cytochalasin B, the microfilaments of transformed BRLHO6T1-1 cells were not seriously affected; a higher cytochalasin B concentration (> or = 2 x 10(-5) M) was required to induce a significant breakdown of microfilaments in these transformed cells. The two cell lines also demonstrated differential microtubule stability when they were treated with either colchicine or triethyllead. Three hours exposure to 10(-6) M of either antimicrotubule agents was sufficient to disrupt the microtubules of normal BRL cells, without affecting their counterparts in the transformed BRLHO6T1-1 cells. A 10-fold higher drug concentration (10(-5) M) was required to induce microtubular breakdown in the transformed BRL cells. The differential stability of microfilaments and microtubules in normal and transformed BRL cells that was observed could not be attributed to a differential internalization of the agents, as shown by experiments on the uptake of [3H]-cytochalasin B and triethyllead. In addition, the transformed BRLHO6T1-1 cells did not express altered actin and tubulin isoforms, as demonstrated by isoelectric focusing followed by immunoblotting analysis. We conclude that the transformation of BRL cells with the Ha-ras-1 oncogene results in a greater stability of microfilaments and microtubules, leading to a structurally firmer cell shape.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Actin Cytoskeleton; Animals; Cell Line; Cell Line, Transformed; Cell Transformation, Neoplastic; Cytochalasin B; Cytoskeletal Proteins; Drug Resistance; Genes, ras; Liver; Microtubules; Rats

The effects of doxorubicin (adriamycin, ADR) and daunorubicin (daunomycin, DAU), two anthracyclinic antibiotics, on a human breast carcinoma cell line (CG5) were studied by cytochemical and morphological methods. Both ADR and DAU were capable of inducing the multinucleation and spreading phenomena, associated with a decrease of the cell growth rate. DAU appeared to be more effective than ADR at the tested concentrations (10(-5), 5 x 10(-5) mM), in affecting the cell growth as well as in inducing multinucleation. As revealed by scanning electron microscopy, spreading and multinucleation were accompanied by a remarkable redistribution of surface structures. Moreover, a dose- and time-dependent rearrangement of the underlying cytoskeletal components was clearly detected. In addition, both ADR and DAU at 5 x 10(-5) mM seemed to favor the rebuilding of microtubules after treatment with colcemid, while a higher dose (10(-4) mM) exerted the opposite effect. Furthermore, both anthracyclines prevented the action of the antimicrotubular agent. When recovered after treatment with cytochalasin B, in presence of ADR (or DAU) (5 x 10(-5), 10(-4) mM), cells showed a microfilament pattern rearranged differently as compared to that of cells recovered in anthracycline-free medium. The results reported here strongly suggest the involvement of actin and tubulin in CG5 cell response to ADR and DAU treatments. Thus, the cytoskeletal apparatus is confirmed as another target involved in the mechanism of action of anthracyclines.

Topics: Actins; Antibiotics, Antineoplastic; Breast Neoplasms; Cell Transformation, Neoplastic; Cytochalasin B; Cytoskeleton; Daunorubicin; Demecolcine; Doxorubicin; Humans; Microscopy, Electron; Microscopy, Electron, Scanning; Microscopy, Fluorescence; Tubulin; Tumor Cells, Cultured

Treatment of Friend erythroleukaemia cells with cytochalasin B (CB) resulted in multinucleation and loss of viability characteristic of a virus-transformed cell line. In an attempt to isolate pseudonormal revertants of this cell line mutagenized cultures were exposed to CB and surviving clones isolated. Many of these were found to be mutants resistant to the growth inhibitory effects of CB. The proportion of such mutants was reduced by simultaneous selection in CB and cytosine arabinoside. Of 699 clones examined none consistently exhibited reduced levels of multinucleation in the presence of CB. The inability of CB to select for revertants displaying a phenotype closer to normal cells is discussed.

Topics: Animals; Cell Line; Cell Separation; Cell Transformation, Neoplastic; Cell Transformation, Viral; Cytarabine; Cytochalasin B; Drug Resistance; Friend murine leukemia virus; Leukemia, Erythroblastic, Acute; Mice; Mutation; Tumor Cells, Cultured; Ultraviolet Rays

Uncontrolled nuclear division (UND), as indicated by progressive multinucleation when cell division is inhibited by cytochalasin B, is a very characteristic property of transformed cells growing in vitro. In an attempt to determine the genetic basis for this transformation phenotype we have produced a series of somatic cell hybrids between different transformed and normal cells. In all hybrids there was suppression of UND but in some this was only transient. In hybrids between transformed human cells and mouse 3T3 cells, UND was only re-expressed when the human parental cell line had been transformed by SV40 virus. The results lend tentative support to the suggestion that cellular mechanisms involved in the induction and suppression of UND may not be the same in all cell lines.

Topics: Animals; Antigens, Viral, Tumor; Cell Division; Cell Fusion; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Cell Transformation, Viral; Cytochalasin B; Humans; Hybrid Cells; Phenotype; Simian virus 40

In order to determine whether human breast epithelial cells undergo malignant transformation when treated with chemical carcinogens in vitro, and how host factors, such as degree of gland development, affect their response to that treatment, twenty-two reduction mammoplasty specimens from women ranging in age from 18 to 63 years and with different parity history were studied in their morphology and in their response to carcinogen treatment in vitro. Fixed tissues were processed for whole mount preparations; it was found that the lobules of the nonpregnant or resting breast tissue could be classified into three types based upon their size and number of alveolar buds composing each one of them, lobules type 1 being the least and lobules type 3 the most differentiated ones. Breast tissues were classified according to the relative proportion of lobules composing it and the reproductive and clinical history of the patient into groups A, B, or C. Fresh tissues from these three groups were digested for obtention of mammary epithelium organoids, which were plated in Dulbecco's minimal essential medium:Ham's F12 (1:1), with 5% horse serum to enhance attachment. When they reached confluence, the cells were replated in serum-free medium; 48 h postplating they were treated with 1.0 microgram/ml 7,12-dimethylbenz(a)anthracene for 24 h, or with 1.0 microgram/ml N-methyl-nitrosourea for 3 h. At every passage, the cells were monitored for colony formation efficiency, survival efficiency in agar-methocel, multinucleation assay, karyotyping, immunocytochemical detection of tumor associated antigens, lectin reactivity, and tumorigenic assay by injection into nude mice. By the fourth passage after treatment, both carcinogens induced increased survival, colony formation in agar-methocel, multinucleation, and increased reactivity with the tumor associated antigen B1:1, an epitope of carcinoembryonic antigen, and the lectins concanavalin A, Dolichos biflorus, and soybean agglutinin. This response was observed only in human breast epithelial cells obtained from less differentiated breasts (Groups A and B), whereas human breast epithelial cells from breasts exhibiting good lobular development (Group C) did not exhibit those changes. No karyotypic abnormalities were detected in treated cells, and they failed to induce tumors when injected into nude mice. It was concluded that mammary gland development is independent of age but is strongly influenced by both the reproductive and cl

Topics: 9,10-Dimethyl-1,2-benzanthracene; Adolescent; Adult; Animals; Antigens, Neoplasm; Breast; Cell Transformation, Neoplastic; Cells, Cultured; Cytochalasin B; Epithelium; Female; Humans; Karyotyping; Lectins; Male; Membrane Glycoproteins; Methylnitrosourea; Mice; Mice, Inbred BALB C; Mice, Nude; Middle Aged; Mucin-1; Oncogenes; Phenotype

Epithelial cell lines derived from rat tracheal implants 2 and 9 months after a 4-week exposure to 200 micrograms dimethylbenz(a)anthracene-beeswax pellets, and previously assayed for growth in soft agarose and tumorigenicity, were tested at the same time of subculture for cytochalasin B-induced multinucleation to determine the relationships between anchorage-independent growth, uncontrolled nuclear division, and tumorigenicity. The relationships among the three phenotypic markers could be separated into five distinct groups. Group I cell lines showed no growth in agarose, showed no cytochalasin-induced multinucleation, and formed no tumors in nude mice. Group II cell lines exhibited anchorage independence but were negative for the other markers. Group III cell lines were anchorage independent and exhibited a positive response to cytochalasin B (more than 10% of the cells had three or more nuclei), but were tumor negative. Group IV cell lines were positive for all three markers. Group V cell lines grew in soft agarose, were cytochalasin B negative, but formed tumors only 4 months after the cell inoculations. The 20 cell lines generated 2 months after carcinogen exposure distributed in the groups as follows: Group I, 20%; Group 2, 20%; Group III, 50%; Group IV, 15%; and Group 5, 10%. The 27 cell lines generated 9 months after carcinogen exposure distributed among the groups as: Group I, 4%; Group II, 18%; Group III, 26%; Group IV, 52% and Group V, 0%. The results indicate that: anchorage independence precedes the two other markers of growth autonomy; uncontrolled nuclear division appears as a separate property after anchorage independence and before tumorigenicity; tumorigenicity appears preferably in the cell populations that exhibit anchorage independence and uncontrolled nuclear division; and progression in growth autonomy occurs in the tracheal implants in vivo which can be detected in vitro as an increase in cell lines positive for the three phenotypic markers.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Cell Adhesion; Cell Division; Cell Nucleus; Cell Transformation, Neoplastic; Cytochalasin B; Epithelial Cells; Neoplasms, Experimental; Rats; Time Factors; Trachea

Motility of neuroblastoma cells in the culture of cell line C-1300, clone N-18-A was investigated microcinematographically. In the course of morphological differentiation of the cells, after cytochalasin B treatment (1.8 mkg/ml for 24 hours), in some differentiated cells a special type of movement of the cytoplasmic mass together with the nucleus along elongated pseudopodia was detected. Such a type of movement has never been described. Sometimes, a shift in the nucleus position resulted in the complete change or reversion of cell polarity. The phenomenon of cell nucleus displacement relative to the cell configuration or reversion of the cell polarity can possibly play an important functional role for neural cells.

Topics: Animals; Cell Line; Cell Movement; Cell Nucleus; Cell Transformation, Neoplastic; Cytochalasin B; Cytoplasm; Mice; Neuroblastoma; Pseudopodia; Tumor Cells, Cultured

A quantitative analysis based on centrifugal force requirements for enucleation was developed to examine the response of a number of untransformed and transformed cell lines to cytochalasin mediated enucleation. Examination of the extent of cell enucleation as a function of centrifugal force resulted in a series of response curves demonstrating that enucleation g force requirements varied between Balb/c 3T3, Swiss 3T3, and Kirsten sarcoma virus transformed Balb/c 3T3 (3T3-K). A four times greater centrifugal force was required to reach 50% enucleation for transformed Balb/c 3T3-K when compared to Swiss 3T3. A qualitative correlation could be observed between ease of enucleation and the existence of a well-formed stress fiber network. A comparison of cytochalasin B and D suggested that cytochalasin D was far more effective in the enucleation of transformed cells. Experiments with 2-deoxyglucose and monensin provided evidence that decreasing cellular ATP levels, either directly or potentially by uncoupling ion transport from ATP generation, can decrease the efficiency of enucleation. It is suggested that the organization of the cytoskeleton is affected by the altered cellular ATP levels which can affect the centrifugal requirements of enucleation.

Topics: Actins; Animals; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Centrifugation; Cytochalasin B; Cytochalasin D; Cytochalasins; Fibronectins; Fluorescent Antibody Technique; Mice; Monensin

Transformation of chicken embryo fibroblasts by infection with Rous sarcoma virus has been shown to cause disruption of actin filament organization as seen with fluorescence staining techniques. This study is an attempt to use quantitative biochemical techniques to compare actin-related parameters in normal and transformed cells. Normal cells and cells infected with a temperature-sensitive mutant virus (NY68) and grown at the restrictive temperature of 41.5 degrees C have normal bundles of actin filaments, or F-actin; these cells also have about the same number of high-affinity cytochalasin binding sites at the ends of F-actin (approximately 5 pmol of sites per mg of cellular protein; Kd, 20 nM). In contrast, infected cells grown at the permissive temperature of 37 degrees C have a more diffuse pattern of actin filaments, and the number of cytochalasin binding sites in these transformed cells was below the level of detection. DNase I inhibition assays showed that the percent of unpolymerized actin, or G-actin, in cell extracts was not significantly different between normal and transformed cells (approximately 50%). In assays of cell extracts for endogenous cytochalasin-like activity on actin filaments (i.e., retardation of filament assembly at the fast-growing end, inhibition of cytochalasin binding to actin "nuclei," and decrease of low-shear viscosity of solutions of actin filaments), infected cells at 37 degrees C showed a higher level of activity per mg of protein than did uninfected cells or infected cells at 41.5 degrees C. These results suggest that the increase in endogenous cytochalasin-like activity in transformed cells may relate to the decrease in measurable cytochalasin binding sites and the abnormal distribution of actin filaments previously seen by fluorescence staining techniques.

Topics: Actins; Animals; Avian Sarcoma Viruses; Cell Transformation, Neoplastic; Cell Transformation, Viral; Cells, Cultured; Chick Embryo; Cytochalasin B; Cytochalasins; Fibroblasts

Mouse bone marrow cells were irradiated in vitro with 300, 200 and 100 rad of 60Co gamma-ray. Morphological transformation ensued from day 42 after exposure, but only in cells receiving 300 rad. Malignant transformation appeared in the 2nd generation in the subcultures. Some biological characteristics of malignant transformation were observed as follows: The attaching rate was 40.0%. Malignant transformation rate was 0.10-0.45%; Some colonies and clusters were formed in the semi-solid agar medium; There was no cell proliferation or colony formation in anti-ouabain inhibition test which implies that no mutation took place in the malignant transformation cells; Cytochalasin B rendered the cells to form a large number of multinuclear cells; Obvious chromosome aberration in number and structure was observed; Subsequent induction of fibrosarcomas in sites of subcutaneous inoculation of the malignant transformed cells in immunosuppressed mice. The results show that mouse bone marrow mesenchymal cells can undergo malignant transformation by large dose of gamma-ray irradiation in vitro. Criteria of malignant transformation: some clusters of cells formed in the semi-solid agar medium, multinuclear cell formation by action of cytochalasin B, and tumor mass induced in the location of inoculation.

Topics: Animals; Bone Marrow; Bone Marrow Cells; Cell Transformation, Neoplastic; Chromosome Aberrations; Cobalt Radioisotopes; Cytochalasin B; Dose-Response Relationship, Radiation; Gamma Rays; Male; Mice; Mice, Inbred Strains; Mutation

Cytochalasin B (CB) prevents cytokinesis in animal cells. In normal cells nuclear division and DNA synthesis are also blocked and the cells, held in the G1 phase of the cell cycle, remain either mononucleate or binucleate. In transformed cell lines DNA synthesis and nuclear division continue and the cells become multinucleate. We have examined the response to CB in two sets of somatic cell hybrids made between cells that display multinucleation after CB treatment and cells that do not. In a cross between transformed mouse LMTK cells and normal rat embryo lung cells, very little multinucleation was observed after treatment with CB for 7 days. The ability of the LMTK cells to form clones in soft agar was also significantly reduced in these hybrids. Segregant sub-clones that re-expressed both of these transformation phenotypes were isolated. These had reduced chromosome numbers. A second cross was made between two variants of the BHK cell line, one of which displayed a high level of multinucleation in CB while the other did not. Again the hybrids showed a response similar to that of the non-multinucleating parent. From the results obtained with these two hybrids we conclude that the multinucleation induced in transformed cells by CB behaves as a recessive character in crosses with normal cells.

Topics: Animals; Cell Division; Cell Fusion; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Clone Cells; Cricetinae; Cytochalasin B; Hybrid Cells; Karyotyping; Lung; Mesocricetus; Mice; Rats

An early nuclear activation of transformed human amniotic epithelial (WISH) cells triggered by type IV collagen is visualized by a modification of the nuclear refringency obtained by mercury binding on condensed chromatin. This phenomenon is quantified by the nuclear refringency test. The nuclear activation of WISH cells by basement membrane collagen is also shown by the DNase I sensitivity of chromatin and by the measurement of mRNA synthesis. These nuclear phenomena are concomitant with WISH cell attachment and laminin synthesis. Reversible effects on nuclear refringency, cell attachment, and laminin synthesis are tested by the addition and removal of different metabolic inhibitors.

Topics: Amnion; Autoanalysis; Benzimidazoles; Birefringence; Cell Adhesion; Cell Line; Cell Nucleus; Cell Survival; Cell Transformation, Neoplastic; Cells, Cultured; Collagen; Cytochalasin B; Epithelium; Female; Humans; Kinetics; N-Acetylneuraminic Acid; Nocodazole; Poly A; Pregnancy; RNA; RNA, Messenger; Sialic Acids

Topics: Animals; Cell Adhesion; Cell Cycle; Cell Transformation, Neoplastic; Cell Transformation, Viral; Cytochalasin B; Demecolcine; DNA; DNA Replication; Mice; Peptide Hydrolases; Protein Biosynthesis; RNA; RNA, Heterogeneous Nuclear

We have studied the process of mammary cell transformation in vitro using a single cell clone (Clone 18) from a presumptive epithelial cell line, C57MG, derived from a normal mammary gland; a mouse mammary tumor virus (MMTV) host-range variant (RIII)vp4; and the potent initiating carcinogen 7,12-dimethylbenz(a)anthracene (DMBA). After several serial subcultures, cells treated with virus and then with carcinogen exhibited an altered (transformed) morphology, a dramatic increase in anchorage independence, an increase in multinucleation after exposure to cytochalasin B, an enhanced ability to proliferate in low Ca2+ (0.01 mM) medium, and tumorigenicity when inoculated subcutaneously into athymic (nude) mice. Although some of these phenotypic alterations were observed also in cultures treated singly with MMTV or DMBA and in cultures exposed to DMBA before infection with MMTV, enhanced cytochalasin B multinucleation and tumorigenicity were properties observed only in mass cultures of cloned cells first infected with MMTV and then exposed to DMBA. This demonstrates for the first time that exposure of presumptive mammary epithelial cells to MMTV followed by DMBA, but not to either agent alone or to DMBA followed by MMTV, results in malignant transformation of these cells.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Benz(a)Anthracenes; Calcium; Cell Division; Cell Transformation, Neoplastic; Cell Transformation, Viral; Clone Cells; Cytochalasin B; Epithelium; Mammary Glands, Animal; Mammary Neoplasms, Experimental; Mammary Tumor Virus, Mouse; Mice; Mice, Nude; Phenotype

Trypsinized chicken embryo dermal fibroblasts plated in the presence of cytochalasin B (CB) quickly attached to the substrate and within 24 h obtained an arborized morphology. This morphology is the result of the pushing out of pseudopodial processes along the substrate from the round central cell body. There were no microfilament bundles in the processes of these cells plated in the presence of CB; however, the processes were packed with highly oriented, parallel-aligned intermediate filaments. Only a few scattered microtubules were seen in these processes. These results demonstrated that in CB, cells are capable of a form of movement, i.e., the extension of pseudopodial processes, without the presence of the microfilament structures usually associated with extensions of the cytoplasm and pseudopodial movements. We also found that arborization did not depend on fibronectin since cells plated in CB did not have fibronectin fibers associated with the processes. Chicken fibroblasts transformed with tsLA24A, a Rous sarcoma virus which is temperature sensitive for pp60src, formed arborized cells with properties similar to those of uninfected fibroblasts when plated in the presence of CB at the nonpermissive temperature (41 degrees C). At the permissive temperature for transformation (36 degrees C), the cells attached to the substrate but remained round. These round cells were not only deficient in microfilament bundles but also lacked the highly organized intermediate filaments found in the processes of the arborized cells at 41 degrees C. Although both microfilament bundles and the fibronectin matrix were decreased after transformation with Rous sarcoma virus, neither was involved in the formation of processes in normal cells plated in CB. Therefore, the inability of the transformed cells to form or maintain processes in CB must be the result of another structural alteration in the transformed cells, such as that of the intermediate filaments.

Topics: Actins; Animals; Avian Sarcoma Viruses; Cell Adhesion; Cell Movement; Cell Transformation, Neoplastic; Cells, Cultured; Chick Embryo; Cytochalasin B; Cytoskeleton; Fibroblasts; Fibronectins; Intermediate Filament Proteins; Microscopy, Electron; Vimentin

It is widely accepted that the neoplastic B cells from patients with chronic lymphocytic leukemia (CLL) respond poorly to common mitogens. The fungal metabolite cytochalasin B (0.5 micrograms/ml) is a weak mitogen for normal lymphocytes. However, when peripheral blood lymphocytes from 19 patients with CLL of B cell origin (B-CLL) were cultured with 0.5 micrograms cytochalasin B/ml, significant new DNA synthesis ( [14C]thymidine incorporation) occurred in 18. Stimulation indices with cytochalasin B varied widely (range = 1.9-28.2, mean +/- SD = 10.6 +/- 7.5; delta cpm range = 1,157-153,818; n = 26) but in 11 cases exceeded those seen with concanavalin A (Con A), phytohemagglutinin, or pokeweed mitogen. In all 11, the mitogenic response to cytochalasin B exceeded that to pokeweed mitogen, which is believed to be a T cell-dependent B cell mitogen. In three cases, the responses to cytochalasin B were 8.6, 3.5, and 2.3 times greater than those to Con A. As with other mitogens, the DNA synthetic response to cytochalasin B was time and dose dependent. Peak thymidine incorporation occurred at 72-88 h and declined thereafter. Significant mitogenic effects were observed with 0.1-5 micrograms cytochalasin B/ml with a peak at 0.5-2 micrograms/ml. Stimulated DNA synthesis was abolished by 1 mM hydroxyurea. Cells from two patients with B-CLL were separated by rosetting with sheep erythrocytes (E). Depletion of E-rosette-positive cells from the CLL cell population abolished the response to Con A but did not affect the response to cytochalasin B. Cytochalasin B is a potent mitogen for B-CLL cells and may be useful in cytogenetic studies of this often indolent neoplasm.

Topics: Cell Transformation, Neoplastic; Cytochalasin B; Cytochalasins; Dimethyl Sulfoxide; DNA; Dose-Response Relationship, Immunologic; Female; Humans; Karyotyping; Kinetics; Leukemia, Lymphoid; Lymphocyte Activation; Male; Mitogens; Rosette Formation

Topics: Animals; Cell Line; Cell Transformation, Neoplastic; Cytochalasin B; Epithelium; Liver; Mice; Models, Biological; Neoplasm Proteins; Proteins

A number of virus and chemical carcinogen-transformed cell lines were generated in tissue culture and analyzed for growth control phenotypes prior to and following tumorigenesis in appropriate hosts. The cell lines include those of mouse, rat, human, and Syrian hamster, transformed by papovaviruses and adenoviruses (DNA) or murine (RNA) tumor viruses. Cell lines were assayed for: (a) multinucleation or uncontrolled nuclear division (UND+) and uncontrolled DNA synthesis in cytochalasin B (CB) medium; and (b) the continuation of DNA synthesis in media containing reduced (0.5%) amounts of serum. All or nearly all lines of DNA virus transformants exhibited UND+ and high frequencies of DNA-synthetic cells in CB medium. Two lines of SV40-transformed hamster cells also showed UND+ following tumorigenesis in weaning hamsters. In addition, DNA virus transformants showed the ability to continue DNA synthesis unabated in low-serum medium. In contrast, the mouse sarcoma virus (MSV)-transformed lines exhibited varying degrees of controlled nuclear division and reduced DNA synthesis in CB medium, both prior to and following tumorigenesis. However, the reduction in DNA-synthetic cells was often not as great as that found in untransformed cells. Results similar to the RNA virus transformants were observed with hamster cells transformed by chemical carcinogens. Nearly all of the MSV-transformed lines showed significantly reduced levels of DNA synthesis in low-serum medium as was found in untransformed cells. One cell line, KA31, was followed through three consecutive in vivo tumorigenic passages, but these cells did not acquire UND+ or the ability to continue DNA synthesis in low-serum medium. These results suggest that many MSV- and carcinogen-transformed rodent cells exhibit transformation phenotypes at levels barely above those of normal cells and markedly less than those of DNA virus transformants, and yet they are tumorigenic.

Topics: Animals; Carcinogens; Cell Line; Cell Transformation, Neoplastic; Cytochalasin B; DNA Replication; DNA Viruses; Humans; Mice; Mice, Inbred BALB C; Phenotype; Rats; RNA Viruses

Topics: Animals; Avian Sarcoma Viruses; Cell Differentiation; Cell Line; Cell Transformation, Neoplastic; Cytochalasin B; Mice; Muscles; Receptors, Cholinergic

Cytochalasin B (CB) treatment induces or accelerates the capping phenomenon in some cells. In Ehrlich ascites tumor cells (EATC) CB treatment apparently induced the capping of Con A binding sites as observed under a fluorescent microscope. However, electron microscopic examinations revealed that the CB treatment did not induce a rearrangement of Con A binding sites, but rather it only induced a change in cell shape. On the contrary, CB treatment inhibited the capping phenomenon induced by treatment with Con A. Electron microscopic observations may give exact information on the distribution of lectin binding sites.

Topics: Animals; Binding Sites; Carcinoma, Ehrlich Tumor; Cell Transformation, Neoplastic; Concanavalin A; Cytochalasin B; Immunologic Capping; Mice

Transformed mouse fibroblasts of L line and cells of their highly oncogenic TLSF subline are deficiently spread on the solid substratum, do not form focal contacts with it and do not contain microfilament bundles. Polykaryons were produced from these cells by polyethylene glycol-induced cell fusion or by cytochalasin B-induced block of cytokinesis. Multinuclear cells obtained by both methods were much better spread on the substrate than their mononuclear counterparts. Most of the polykaryons have numerous actin microfilament bundles and form focal contacts with substratum. Therefore, multinucleation of transformed results in their partial morphological normalization.

Topics: Animals; Cell Adhesion; Cell Fusion; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Cytochalasin B; Cytoskeleton; Mice; Polyethylene Glycols

In transformed mouse embryo cells, type II interferon had much less antiviral activity than type I interferon. In non-transformed cells, the two interferons had similar high activity, Reversal of the phenotype of Moloney sarcoma virus (MSV) transformed cells by sodium butyrate restored their sensitivity to the antiviral action of type II interferon. Additional evidence for a role of the cytoskeletal network in the action of type II interferon is that its antiviral effect is reduced by cytochalasin B, colchicine or vinblastine. MSV-transformed cells, selected for their resistance to the antiviral action of type I interferon, were sensitive to type II interferon. These differences in the effects of type I and II interferon on transformed cells are at present unexplained, but suggest that they have at least partially separate mechanisms of action.

Topics: Animals; Butyrates; Cell Line; Cell Transformation, Neoplastic; Cell Transformation, Viral; Colchicine; Cytochalasin B; Encephalomyocarditis virus; Fibroblasts; Interferons; Mice; Sarcoma Viruses, Murine; Vinblastine

The Chinese hamster ovary (CHO) cell, like other transformed cells, has lost the fibronectin deposit around its membrane. Treatment with cyclic AMP derivatives restores the typical fibroblastic deposit of fibronectin. Thus, the reverse transformation process induced by cyclic AMP (cAMP) in the CHO cell restores this important property as well as other morphological, biochemical, and growth behavioral characteristics of the normal fibroblastic state. The fibronectin deposit occurs significantly later in time than do other characteristics of the reverse transformation reaction and may therefore reflect a metabolic action that requires other cAMP effect to precede it. The restoration of fibronectin deposition in response to cAMP derivatives is also exhibited by vole cells transformed by avian sarcoma virus, but it is not by HeLa cell. Addition of Colcemid, which disrupts microtubules, to CHO cells containing a fibronectin deposit induced by cAMP derivatives causes little or no erosion of the deposit, but cytochalasin B, which disrupts 5-nm microfilaments, eliminates it completely. Thus, various features of the action of cAMP derivatives on CHO and related cells require integrity of the cellular microfibrils--in some cases microtubules only, in some cases 5-nm microfilaments only, and in some cases both classes of fibrils.

Topics: Animals; Bucladesine; Cell Line; Cell Transformation, Neoplastic; Cricetinae; Cyclic AMP; Cytochalasin B; Cytoskeleton; Demecolcine; Extracellular Space; Female; Fibronectins; Fluorescent Antibody Technique; Microtubules

Griseofulvin, 12-O-tetradecanoyl phorbol-13-acetate, melittin, epidermal growth factor, vinblastine, cytochalasin B, podophyllotoxin, colcemid, and colchicine were unable to transform cells but could increase from 8- to 40-fold the frequency of cell transformation by polyoma virus. The 3T3-like cells were resting at confluence and were exposed to the drug only during the 1st week after viral infection. Griseofulvin, a tumor promoter, reduced or increased the frequency of transformation depending on the dose with which the infected cells were treated. The antitumor activity of tumor promoters is discussed.

Topics: Cell Line; Cell Transformation, Neoplastic; Cell Transformation, Viral; Colchicine; Cytochalasin B; Epidermal Growth Factor; Griseofulvin; Melitten; Mutagens; Podophyllotoxin; Polyomavirus; Tetradecanoylphorbol Acetate; Vinblastine

RNA tumor virus-transformed cell cultures derived from rat, mouse, hamster, and mink were examined for their response to cytochalasin B (CB), and the expression of this marker was correlated with growth in soft agar and tumorigenicity in vivo. Continuous cell lines transformed and chronically infected with Moloney murine sarcoma-leukemia virus (M-MSV-MuLV) or Kirsten murine sarcoma-leukemia virus were extensively multinucleated when treated with CB. Similarly, nonproducer Moloney murine sarcoma virus- or Rous sarcoma virus-transformed cells multinucleated in response to CB treatment, whereas uninfected or murine leukemia virus-infected cells remained predominately binucleate under comparable conditions. Rat kidney or embryo cell cultures, one to two passages after infection with M-MSV-MuLV, were highly multinucleated following CB treatment and acquired the ability to grow in soft agar. Mouse 3T3 cell lines, newly infected with M-MSV-MuLV, exhibited a moderate degree of CB-induced multinucleation. CB-induced multinucleation was directly correlated with anchorage-independent growth for most of the cell lines tested. An exception was the Moloney murine sarcoma virus-transformed mink cells which multinucleated in response to CB treatment but were unable to proliferate in soft agar. CB-induced multinucleation was directly correlated with the tumorigenicity of M-MSV-MuLV-transformed rat cells in syngeneic animals. These results demonstrate that CB-induced multinucleation is a useful in vitro growth-related marker of cell transformation by RNA tumor viruses and, in addition, show that this parameter of cell transformation is closely correlated with anchorage-independent growth in vitro and tumorigenicity in vivo.

Topics: Animals; Cell Division; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Cell Transformation, Viral; Cricetinae; Cytochalasin B; Leukemia Virus, Murine; Mice; Neoplasms, Experimental; Rats; Sarcoma Viruses, Murine

Topics: Animals; Cell Division; Cell Line; Cell Transformation, Neoplastic; Chromosomes; Contact Inhibition; Cricetinae; Cytochalasin B; Humans; Hybrid Cells; Mice; Mitosis; Phenotype

Twelve human cell cultures derived from tumors, normal tissues, and derivative cultures transformed by either a RNA tumor virus or chemical carcinogen were examined for their response to cytochalasin B (CB) and the expression of this marker was correlated with growth in soft agar and saturation density in monolayer culture. Cell lines derived from carcinoma of the bladder (T24 and RT4), kidney (Caki-1), prostate (DU 145), and breast (MCF-7) multinucleated when growth in CB-supplemented medium, whereas cell cultures derived from benign bladder epithelium (HCV-29), and normal kidney (Flow 4000) and skin (GM10) remained binucleate under comparable conditions. Human osteosarcoma (HOS) cells transformed by murine sarcoma virus (MSV) or a chemical carcinogen extensively multinucleated in response to CB treatment, relative to a morphological revertant of MSV-transformed HOS and parental HOS cells. CB-induced multinucleation was consistently correlated with the ability of cells to form colonies in soft agar but inconsistently correlated with growth to high saturation densities. These results demonstrate a differential response to CB by normal and transformed human cells and that CB-induced multinucleation provides a convenient and useful in vitro marker for neoplastic transformation.

Topics: Cell Division; Cell Line; Cell Transformation, Neoplastic; Clone Cells; Contact Inhibition; Cytochalasin B; Humans; Mitosis; Neoplasms

Topics: Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Cytochalasin B; Humans; Neoplasms

Alloreactive cells generated by in vitro stimulation of C57BL/6 (H-2b) spleen lymphocytes with irradiated MOPC 315 or MOPC 104E(H-2d) cells were shown to lyse 51Cr-labeled myeloma targets at high effector:target ratios under conditions of inefficient cell contact, the alloreactive cells cause variable and frequently minimal lysis of myeloma targets but markedly suppress antibody secretion even by viable myeloma cells. The suppressor cells are radioresistant T cells lacking I-J subregion-encoded surface determinants; their precursors are insensitive to cyclophosphamide; suppression is H-2 specific and not mediated by secreted factors; and the suppression is blocked by Cytochalasin B, a known inhibitor of T cell-mediated cytolysis. These properties are typical of cytolytic T lymphocytes (CTL) and not of defined suppressor T cells, suggesting that inhibition of myeloma function probably represents a pre-lytic effect of the alloreactive CTL, although a CTL-like suppressor cell effect cannot be definitively excluded. These results are discussed with reference to the possible relationships between suppressor and cytolytic T lymphocytes.

Topics: Animals; Antibody Formation; Cell Communication; Cell Transformation, Neoplastic; Cytochalasin B; Cytotoxicity, Immunologic; Dose-Response Relationship, Immunologic; Egtazic Acid; Kinetics; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Plasmacytoma; T-Lymphocytes

Concanavalin A (Con A)-mediated red blood cell (RBC) adsorption with the RBC coating method (in which Con A-coated RBC's are adsorbed to fibroblasts) was greatly increased by glutaraldehyde fixation of RBCs before Con A-coating and decreased by the fixation of fibroblasts. On the other hand, RBC adsorption with the fibroblast coating method (in which RBCs are adsorbed to Con A-coated fibroblasts) was decreased by the fixation of RBCs and increased by the fixation of fibroblasts before Con A coating. The fixation of RBCs or fibroblasts after Con A coating did not have these effects. In addition, the fixation of both RBCs and fibroblasts nearly completely abolished RBC adsorption with either method. However, the amount of [3H] Con A binding was not affected by the fixation. RBC adsorption with the fibroblast coating method was also affected by cytochalasin B, colchicine, NaN3 and dibucane treatments of fibroblasts. These drug treatments of fibroblasts, however, did not affect RBC adsorption with the RBC coating method, except cytochalasin B. In addition, the effects of drug treatments of fibroblasts examined occurred nearly to the same extent for nonsenescent, senescent, and transformed cells. Our results suggest that secondary processes after Con A binding, receptor mobility and receptor association with cytoskeletals, play important roles in RBC adsorption, but that the roles do not change with aging or transformation.

Topics: Aldehydes; Azides; Calcimycin; Cell Survival; Cell Transformation, Neoplastic; Colchicine; Concanavalin A; Cytochalasin B; Dibucaine; Erythrocytes; Female; Fibroblasts; Fixatives; Glutaral; Hemadsorption; Humans

A noncloned subline of 3T3FL cells was developed that was resistant to the toxicity of the ansamycin alkaloid maytansine. Culture of 3T3FL cells with serially increasing concentrations of maytansine resulted in a cell line resistant to maytansine at concentrations 118-fold higher than concentrations cytotoxic for parental cells. Resistant cells (3T3r) exhibited cross-resistance to colchicine, vincristine, adriamycin, and, to a lesser extent, cytochalasin B. Studies of binding and uptake of tritiated colchicine suggested that drug resistance of 3T3r cells might reflect decreased uptake of drug without decreased binding to surface receptors. Murine sarcoma virus transformed 3T3r cells less efficiently than 3T3FL cells.

Topics: Animals; Cell Line; Cell Survival; Cell Transformation, Neoplastic; Colchicine; Cytochalasin B; Doxorubicin; Drug Resistance; Maytansine; Mice; Oxazines; Phenotype; Sarcoma Viruses, Murine; Vincristine

Seven different transformation stigmata of the transformed CHO cell line, including morphological characteristics, growth behavior, cell membrane biochemical properties, and failure of fibronectin deposition, are reversed by addition of cAMP derivatives to the medium. Simultaneously the microtubular pattern changes from a sparse, relatively random set to an orderly arrangement of tubules largely parallel to each other and to the long axis of the resulting fibroblastic cell. Agents like colcemid and cytochalasin B, respectively disorganizing microtubular and particular microfilamentous structures, prevent at least certain aspects of the reverse transformation reaction induced by cAMP in interphase cells. It is proposed that malignant transformation can be effected by damage to the microtubular and microfilamentous structures which changes cell constitution and behavior in two ways: (1) chromosomal instability is introduced which promotes continuous selection for variants better able to resist environmental signals to limit reproduction and (2) a variety of metabolic defects in biochemical processes such as specific membrane functions are introduced which may alter the growth responses of the cell. This picture offers a reasonable explanation for a number of aspects of normal and malignant cell behavior.

Topics: Animals; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Cricetinae; Cricetulus; Cyclic AMP; Cytochalasin B; Demecolcine; Female; Fibronectins; Microtubules; Ovary

Transformed cells often display knobs (or blebs) distributed over their surface throughout most of interphase. Scanning electron microscopy (SEM) and time-lapse cinematography on CHO-K1 cells reveal roughly spherical knobs of 0.5-4 micron in diameter distributed densely around the cell periphery but sparsely over the central, nuclear hillock and oscillating in and out of the membrane with a period of 15-60 sec. Cyclic AMP derivatives cause the phenomenon of reverse transformation, in which the cell is converted to a fibroblastic morphology with disappearance of the knobs. A model was proposed attributing knob formation to the disorganization of the jointly operating microtubular and microfilamentous structure of the normal fibroblast. Evidence for this model includes the following: 1) Either colcemid or cytochalasin B (CB) prevents the knob disappearance normally produced by cAMP, and can elicit similar knobs from smooth-surfaced cells; 2) knob removal by cAMP is specific, with little effect on microvilli and lamellipodia; 3) immunofluorescence with antiactin sera reveals condensed, amorphous masses directly beneath the membrane of CB-treated cells instead of smooth, parallel fibrous patterns of reverse-transformed cells or normal fibroblasts; 4) transmission electron microscopy (TEM) of sections show dense, elongated microfilament bundles and microtubules parallel to the long axis of the reverse-transformed CHO cell, but sparse, random microtubules throughout the transformed cell and an apparent disordered network of 6-nm microfilaments beneath the knobs; 5) cell membranes at the end of telophase, when the spindle disappears and cleavage is complete, display typical knob activity as expected by this picture.

Topics: Animals; Bucladesine; Cell Cycle; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Cricetinae; Cricetulus; Cytochalasin B; Cytoskeleton; Demecolcine; Female; Lung; Microscopy, Electron, Scanning; Microtubules; Ovary

We studied the translocation of dimeric IgA across epithelium, using neoplastic human colon cells in culture as a source of epithelial cells, and immunoelectronmicroscopy with peroxidase-labeled antigens and antibodies. The cells had some of the ultrastructural characteristics of normal, mature epithelial cells, i.e., polarity, desmosomal junctions, and secretory component on their basal and lateral plasma membranes. Horseradish peroxidase-labeled dimeric IgA, exposed to the cells at 0 degrees C, bound selectively to secretory component on the cell surfaces. At 37 degrees C, the bound dimeric IgA was taken into the cells by endocytosis and transported apically through the cytoplasm in vesicles. After 30 min, IgA was discharged across the apical surface. Neither colchicine (10(-4) M) nor cytochalasin B (10(-5) M) interfered with binding or endocytosis of dimeric IgA, but colchicine inhibited intracellular transport of the IgA-containing vesicles. These experiments demonstrated that dimeric IgA can be transported through living intestinal epithelial cells in vitro. The transport includes 1) specific binding of IgA dimers to secretory component on plasma membranes, 2) endocytosis of IgA in vesicles, 3) transcytoplasmic transport of the IgA-containing vesicles by a process involving microtubules, and 4) discharge of IgA at the apical surfaces.

Topics: Binding Sites, Antibody; Biological Transport; Cell Transformation, Neoplastic; Colchicine; Colonic Neoplasms; Cytochalasin B; Horseradish Peroxidase; Humans; Immunoglobulin A; Secretory Component; Trypsin

Liver tissue of a suckling rat was cultured. After 3 weeks of cultivation, the cultures consisting of epithelial cells were treated with 50 micrograms/ml or 100 micrograms/ml DEN for 7 days. 5 months after the treatment, the mode of chromosome number was found decreased from 42 to 40 in the 100 micrograms/ml DEN-treated group and shifted to triploid range after 21 months. The mode in the 50 micrograms/ml DEN-treated group maintained the diploid number until the 5th month but was found reduced to 40 in 21 months. On subcutaneous backtransplantation into young rats at the 22nd month, the treated cells produced tumors at the site inoculated in all the rats. Metastatic foci were also detected in lungs. These tumors were histologically diagnosed as hepatomas. Untreated control cells did not produce tumors. The differential effects of cytochalasine B on the cells with and without tumorigenicity were examined by the use of these cells and other cells, and it revealed that the capacity of multinucleated cell-formation by cytochalasin B fairly corresponds with the backtransplantability of the cells. Binucleated cell formation, not more than 2 nuclei, in the culture of normal cells was found by time-lapse cinemicrography to be not due to the non-capacity of multinucleation but to the destruction of multinucleated cells.

Topics: Animals; Animals, Suckling; Cell Nucleus; Cell Transformation, Neoplastic; Culture Techniques; Cytochalasin B; Diethylnitrosamine; Female; Liver; Liver Neoplasms, Experimental; Lung Neoplasms; Nitrosamines; Polyploidy; Rats

Topics: Actins; Bucladesine; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Cytochalasin B; Immunologic Capping

Cell-substrate adherence in cultures of chicken embryo fibroblasts was examined by determining the number of cells which could be detached from the culture dish by a stream of medium. Transformed cells were significantly less adherent than their normal counterparts. In cultures infected with a mutant of Rous sarcoma virus which is temperature-conditional for transformation, adherence changed promptly following a temperature shift. This change did not require progression through the cell cycle. The transformation-specific decrease in adherence required new protein synthesis, but the restoration of adherence which occurred following a shift to the restrictive temperature could occur in the absence of new protein synthesis. Inhibitor experiments suggested the importance of microfilaments and perhaps microtubules in the changes in detachability. In addition, there was a positive correlation between levels of surface LETS protein and cell substrate adherence following a temperature shift, although it seems probable that the bulk of the surface LETS is neither necessary nor sufficient for maintenance of normal cell substrate adherence.

Topics: Avian Sarcoma Viruses; Cell Adhesion; Cell Transformation, Neoplastic; Cells, Cultured; Colchicine; Cycloheximide; Cytarabine; Cytochalasin B; Dactinomycin; Membrane Proteins; Temperature

Athymic nude mice were inoculated with human embryo lung cells transformed in vitro by human cytomegalovirus (CMV). Of the inoculated animals, 62% developed tumors after an average latent period of 19 days. The tumors were composed of small, polygonal cells with large nulei and scanty cytoplasm embedded in an abundant collagenous matrix. The cells were poorly differentiated but may have been of epithelial origin. Adjacent structures were rarely invaded. CMV-related intracellular and membrane antigens were detected by indirect and anticomplement immunofluorescence techniques in cells cultured in vitro from the tumors.

Topics: Animals; Antigens, Neoplasm; Antigens, Viral; Cell Division; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Chromosome Aberrations; Contact Inhibition; Cytochalasin B; Cytomegalovirus; Humans; Mice; Mice, Nude; Neoplasm Transplantation; Neoplasms, Experimental; Transplantation, Heterologous

Chinese hamster primary fibroblasts derived from several embryos were treated with the carcinogens benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene or N-methyl-N'-nitro-N-nitrosoguanidine. Karyotype analysis, sister chromatid exchange frequency, evidence of transformation by growth in agar, cell morphology and reaction to cytocholasin B were tested at regular intervals over many culture passages. Carcinogen treatment was found to shorten the time period before onset of permanent karyotypically changed stem and side lines and in vitro transformation. Chromosomes X, 6 and 10 were more frequently involved in all cultures in these karyotype changes which were usually preceded by a period of chromosome variation. Spontaneous chromatid aberrations and aneuploidy increased in frequency with time in culture and generally appeared prior to the expression of transformation. No specific chromosomes were involved with the different carcinogens. There was no correlation between in vitro transformation and karyotype evolution and the criteria for transformation were present independently of one another. It is suggested that the lack of correlation between the parameters tested indicates that the expression of in vitro transformation is a result of selection for growth advantage from a cell population expressing an increasing degree of genetic instability and variation with time in culture.

Topics: Aneuploidy; Animals; Benz(a)Anthracenes; Benzopyrenes; Carcinogens; Cell Line; Cell Transformation, Neoplastic; Chromatids; Chromosome Aberrations; Chromosomes; Cricetinae; Cytochalasin B; Fibroblasts; Genetic Variation; Karyotyping; Nitrosoguanidines

Sodium butyrate produces reversible changes in morphology, growth rate, and enzyme activities of several mammalian cell types in culture. Some of these changes are similar to those produced by agents which increase the intracellular level of adenosine 3',5'-cyclic monophosphate (cAMP) or by analogs of cAMP. Sodium butyrate increases the intracellular level of cAMP by about two fold in neuroblastoma cells; therefore, some of the effects of sodium butyrate on these cells may in part be mediated by cAMP. Sodium butyrate appears to have properties of a good chemotherapeutic agent for neuroblastoma tumors because the treatment of neuroblastoma cells in culture causes cell death and "differentiation"; however, it is either innocuous or produces reversible morphological and biochemical alterations in other cell types.

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Acetylcholinesterase; Adenylate Kinase; Anti-Bacterial Agents; Bucladesine; Butyrates; Caproates; Cell Differentiation; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cells, Cultured; Cyclic AMP; Cytochalasin B; DNA; HeLa Cells; Humans; Neuroblastoma; Parabens; Propionates; Proteins; RNA; Transferases; Tyrosine 3-Monooxygenase; Vinblastine

The studies reviewed in this chapter provide further evidence that the secretion of lysosomal enzymes and other hydrolases is a constitutive function of certain cells whereas in other cells is an inducible process probably contributing to the pathology of a variety of diseases. Little is known of the mechanisms mediating the secretion of lysosomal enzymes. We have summarized evidence suggesting a role of microfilaments and microtubules in controlling enzyme release, but further studies of the biochemical mechanisms which control the activity of these subcellular structures are required. The fusion of lysosomes with the plasma membrane has been observed in several situations and the mechanisms underlying processes of this nature have been studied in lower organisms (Satir et al. 1973; Plattner 1974). Agents, such as concanavalin A, which interfere with the fusion of endosomes with lysosomes (Goldman 1974; Edelson and Cohn 1974a, b) should also be useful in determining the chemical nature of membrane components involved in the fusion process. New information on the fate of secreted acid hydrolases has been obtained from studies of the uptake of lysosomal enzymes by fibroblasts. Clearly, the mechanisms by which these cells endocytose secreted lysosomal enzymes will be a subject for detailed study in view of the important of directing enzymes and drugs into lysosomes (De Duve et al. 1974). The mechanisms by which extracellular inhibitors inactivate hydrolytic enzymes, particularly proteinases, is also being clarified (for review see Davies 1975) and this should aid in finding new ways for preventing tissue damage caused by the excessive secretion of these enzymes. Further investigation concerning the secretion of lysosomal enzymes should establish the essential physiological role which these enzymes play at both extracellular and intracellular sites. Also, a close examination of the interaction of both endogenous and exogenous stimuli of inflammation with cells resulting in the secretion of hydrolytic enzymes, will clarify the mechanisms underlying the initiation and progression of the inflammatory process in its diverse forms.

Topics: Animals; Anti-Inflammatory Agents; Antigen-Antibody Complex; Bone Resorption; Carrageenan; Cell Transformation, Neoplastic; Cell Wall; Complement System Proteins; Cytochalasin B; Dental Plaque; Glucuronidase; Humans; Hydrolases; Inflammation; Lysosomes; Macrophages; Microbial Collagenase; Muramidase; Neutrophils; Nucleotides, Cyclic; Plasminogen Activators; Pneumoconiosis; Streptococcus pyogenes

Native differences in cell shape and plasma membrane organization in contact-inhibited and transformed cells and the effects of cytochalasin B and colchicine on these cells have been examined by scanning electron microscopy and freeze fracture-electron microscopy. Confluent BALB/c 3T3 cells show a flat, polygonal shape with limited cell overlapping, some microvilli, and plasma membranes with an aggregated distribution of intramembranous particles. Simian virus 40-transformed BALB/c 3T3 cells, by contrast, have a pleomorphic, bipolar spindle shape, extensive cell overlapping, more numerous surface projections, and a random distribution of intramembranous particles. Treatment of 3T3 and SV3T3 cells with 10(-6) M colchicine produced changes in cell shape and induced intramembranous particle aggregation in SV3T3 cells but did not significantly affect the freeze fracture morphology of 3T3 plasma membranes. Treatment of 3T3 and SV3T3 cells with cytochalasin B (1 mug/ml) also produced marked changes in cell shape and induced intramembranous particle disaggregation in 3T3 cells, but it did not affect intramembranous particle distribution in SV3T3 cells. Lower doses of colchicine (10(-9) M) or cytochalasin B (1 to 50 ng) modulated intramembranous particle distribution in transformed and normal 3T3 cells, respectively, without seriously affecting cell shape. These results are interpreted to suggest that modulation of cell shape or cell surface topography and intramembranous particle distribution are separable phenomena.

Topics: Animals; Cell Membrane; Cell Transformation, Neoplastic; Cells; Cells, Cultured; Colchicine; Contact Inhibition; Cytochalasin B; Dose-Response Relationship, Drug; Freeze Fracturing; Mice; Mice, Inbred BALB C; Microscopy, Electron, Scanning; Simian virus 40

Cytochalasin B (CB) prevents cytoplasmic cleavage without directly affecting nuclear division. Secondary cultures of mouse embryo fibroblasts or 3T3 cells show controlled nuclear division when treated with CB: only binucleated cells are formed. Many CB-treated transformed cells show uncontrolled nuclear division and become highly multinucleated. When CB-treated normal cells are concurrently infected with high inputs of SV40, many of these cells become highly multinucleated. It is suggested that these highly multinucleated cells represent abortively transformed cells since the actual number of transforming units (focus-forming units) of simian virus 40 (SV40) is too low to account for the appearance of these cells. Also, if the CB treatment is begun 6 days after SV40 inoculation, the large increase in highly multinucleated cells is not observed. Most cells stably transformed by SV40 or adenovirus show uncontrolled nuclear division when treated with CB. However, 3T3 cells transformed by SV40 or adenovirus and analyzed shortly after transformation are an exception and show controlled nuclear division. This property of 3T3 cells is apparently overcome by high inputs of SV40 since abortively transformed cells become highly multinucleated.

Topics: Animals; Cell Division; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Cytochalasin B; Dimethyl Sulfoxide; DNA, Neoplasm; Mice; Simian virus 40

Steady-state kinetic tracer analysis and two-dimensional chromatography and autoradiography were used to examine the relation of glucose transport to its metabolism in cultured chick embryo fibroblasts. Cytochalasin B was added to Rous sarcoma virus-infected cells to bring the rate of glucose uptake to the level of uninfected cells. It is concluded for chick cells in culture that: (1) the transport of glucose, rather than its phosphorylation, is the rate limiting step and (2) the difference in aerobic glycolysis between normal and virus-transformed cells at physiological glucose concentration may be a consequence of the difference in the rates of glucose uptake.

Topics: Adenosine Triphosphate; Aerobiosis; Animals; Avian Sarcoma Viruses; Cell Transformation, Neoplastic; Cells, Cultured; Chick Embryo; Citric Acid Cycle; Cytochalasin B; Glucose; Glycogen; Glycolysis; Lactates; Pentosephosphates

To study the molecular basis of changes in sugar uptake rate in cultured mouse fibroblasts with different physiological states, we have measured the high affinity binding of [3H] cytochalsin B, a potent sugar transport inhibitor, to actively growing and contact inhibited Balb/3T3 cells as well as to 3T12 and SV3T3 cells. Binding was the same whether the cells were detached from dishes with EDTA or trypsin. The amount of drug bound to intact cells measured with a centrifugation assay was essentially the same as that bound to cell sonicates measured with equilibrium dialysis. Cytochalasin B binding to intact cells was extremely rapid and reversible over a wide range of drug concentrations, and was not affected by 0.1 M D--glucose in the assay medium. Actively growing and contact inhibited 3T3 cells had a similar number of high affinity cytochalasin B binding sites per cell, while 3T12 and SV3T3 cells had one third to one fourth the number of sites per cell. However, the number of sites per mug cellular protein appeared to be similar for cells in all of the physiological states examined.

Topics: Animals; Binding Sites; Cell Line; Cell Transformation, Neoplastic; Contact Inhibition; Cytochalasin B; Fibroblasts; Glucose; Mice; Mice, Inbred BALB C; Simian virus 40; Stereoisomerism

Multinucleation of simian virus 40-transformed mouse cells (mKS-A TU-7), which was induced by Cytochalasin-B, was depressed by the addition of crude interferon or by poly (riboinosinic)-poly(ribocytidylic) acid. In the absence of Cytochalasin-B, growth of the cells was not inhibited by interferon. Possible mechanism of this phenomenon is discussed.

Topics: Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Cytochalasin B; Interferons; Poly I-C; Simian virus 40

Cytochalasin B (CB) was applied to 13 kinds of non-tumorigenic or tumorigenic cells in vitro to investigate whether the drug would be applicable as an indicator to identify the transformation of cells. Normal cell strains suffered from more deteriorative changes in morphology than cell lines, showing arborization of their cytoplasm at 5 mug/ml. CB at 2.5 mug/ml consistently prevented cytoplasmic cleavage without interfering with nuclear division. Multinucleation of the cells exposed to CB was not related to their generation time. The correlation between multinucleation and tumorigenicity of the cells was found with some exceptions. It appears, however, that multinucleation induced by CB would not be a reliable parameter for identifying malignant transformation of cells in vitro.

Topics: Animals; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Cytochalasin B; Humans; Time Factors

The presence and localization of neoantigens induced in cultured cells, infected or transformed with avian tumor viruses (ATV), were studied ultrastructurally on carbon platinum replicas of cell surfaces. The use of antibody, labeled with hemocyanin molecules, provided sensitive detection and analysis of cell surface antigen distribution. The subgroup-specific antigens of the viral envelope were found in considerable amount in the plasma membranes of ATV-infected chick embryo fibroblasts. The distribution of these antigens over the cell surface, evaluated on cells which were prefixed with glutaraldehyde, was found to be diffuse with a greater density on the cell processes in some cells. Reaction of antibody to viral envelope antigens with living ATV-infected cells resulted in a number of patterns of redistribution of membrane antigen-antibody complexes (AAC). Redistribution occurred in symmetrical or asymmetrical modes. The former consisted of randomly oriented aggregates (patches) of AAC over the cell surface. The latter included: (a) linear accumulation of AAC at cell margins; and (b) condensation of compexes into one or more centers of coalescence. These observations could be made on chick embryo cells infected (but not transformed) by avian leukosis virus, or on cells oncogenically transformed by avian sarcoma virus. The regions of coalescence were suggestive of the "capping" phenomenon seen in other systems, and their formation was temporally correlated with endocytosis of labeled AAC and the gradual loss of AAC from the surface. The effects of several biologically perturbing substances on the processes of redistribution were investigated in ALV-infected fibroblasts. Sodium azide, puromycin, actinomycin D, and colchicine had no effect on either form of asymmetrical redistribution. Cytochalasin B (CB) and iodoacetic acid (IAA) appeared to have some effect on the marginal redistribution, and to completely prevent the condensation into foci of coalescence (FC). When treated with these compounds, reacted with antibody at low temperature, washed free of unbound antibody, and warmed at 37 degrees C, cells rapidly cleared their surfaces of AAC. This was not accompanied by formation of FC or endocytosis. In some of these cells, a distribution was observed which suggested a possible centrifugal flow of antigenic sites-perhaps an alternate route for disposal of AAC. None of the drugs tested affected symmetrical redistribution. Repeated attempts at detection a

Topics: Animals; Antigen-Antibody Complex; Antigens, Neoplasm; Antigens, Viral; Azides; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Chickens; Colchicine; Cytochalasin B; Dactinomycin; Iodoacetates; Puromycin; Rats

Recently we demonstrated that ethidium bromide altered the plasma and subcellular membrane glycoproteins in control and virus transformed cells. It is reported here that ethidium bromide also stimulated the membrane associated process of sugar transport. The KM of the virus transformed cells and the ethidium bromide treated cells is the same as that of the control cells while the maximum velocity as compared to the control cells is significantly increased. The transport of 2-deoxyl-D-glucose was inhibited by glucose, cytochalasin B and neuraminidase but was unaffected by variations in cell density or pH of the incubation medium.

Topics: Avian Sarcoma Viruses; Biological Transport, Active; Cell Count; Cell Line; Cell Transformation, Neoplastic; Cytochalasin B; Deoxy Sugars; Deoxyglucose; Ethidium; Glucose; Hydrogen-Ion Concentration; Kinetics; Neuraminidase; Stimulation, Chemical; Temperature

The chromosomes of an SV40-transformed mouse cell line, SVT2, were analyzed by the acetic-saline-Giemsa banding technique. By contrast to most established mouse lines, SVT2 cells possess a remarkably homogeneous chromosome complement and contain two copies of most chromosomes. However, trisomy for chromosome 3 is a distinct feature of this cell line. Chromosomes 1, 3, 14, and 19 have given rise to biarmed markers. Two Cytochalasin B-resistant sublines derived from SVT2 are also essentially diploid for all autosomes but contain only one chromosome X; they display an even greater homogeneity than does the SVT2 parental cell line. Each of the Cytochalasin B-resistant cell lines has lost one or several of the biarmed markers from SVT2 and new ones have appeared. Both cell lines have lost one copy of chromosome 3 and one chromosome X. The results presented illustrate the advantages of cells of defined chromosome constitution, like STV2 cells and derived sublines, to study specific interactions between transforming virus and host chromosomes. The possible role of SV40 in the maintenance of the pseudodiploid karyotype of SVT2 is also discussed.

Topics: Animals; Cell Line; Cell Transformation, Neoplastic; Chromosome Aberrations; Cytochalasin B; Drug Resistance; Karyotyping; Mice; Sex Chromosomes; Simian virus 40; Trisomy

Nutrient transport rates and cyclic AMP levels have been implicated in the regulation of cell proliferation. In the present study, however, changes in intracellular cyclic AMP level in several lines of cultured cells (normal 3T3 and SV40 and polyomavirus-transformed 3T3 cells; 3T6, C6 GLIOMA, MOUSE L, and Novikoff rat hepatoma cells) by treatment with papaverine, prostaglandine E1 or isoproterenol did not correlate with the inhibition of the uridine, hypoxanthine or deoxyglucose transport rates by these chemicals. Transport inhibitions by above chemicals or Persantin or Cytochalasin B occurred in most cell lines in the absence of any measurable change in intracellular cyclic AMP concentration. Furthermore, treatment of several cell lines with 1 mM dibutyryl cyclic AMP had no immediate effect on the transport of uridine, thymidine or deoxyglucose, although the transport capacity of the cells for uridine and thymidine, but not that for deoxyglucose, decreased progressively with time of treatment. We also observed that the uridine transport system of all cell lines derived from 3T3 cells and the hypoxanthine transport system of L cells exhibited high degrees of resistance to inhibition by the various chemicals. On the other hand, deoxyglucose transport was inhibited to about the same extent by these chemicals in all the cell lines investigated.

Topics: Animals; Biological Transport, Active; Bucladesine; Carcinoma, Hepatocellular; Cell Division; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Cyclic AMP; Cytochalasin B; Deoxy Sugars; Deoxyglucose; Depression, Chemical; Dipyridamole; Glioma; Hypoxanthines; Isoproterenol; L Cells; Liver Neoplasms; Mice; Papaverine; Prostaglandins; Rats; Thymidine; Uridine

Topics: Animals; Bromodeoxyuridine; Bucladesine; Cell Line; Cell Transformation, Neoplastic; Cells; Cells, Cultured; Cytochalasin B; Deoxyglucose; Dimethyl Sulfoxide; Dimethylformamide; Kidney Neoplasms; Male; Membranes; Mice; Mice, Inbred C3H; Neoplasms, Experimental; Theophylline

Untransformed, non-tumorigenic mouse cells respond to cytochalasin B (CB) with limited nuclear division. BALB/c mouse embryo fibroblasts (MEF) and both BALB/c 3T3 and Swiss 3T3 cells become binucleated in the presence of CB and cells with three or more nuclei are very rare or undetectable. MEF are diploid (40 chromosomes) and 3T3 cells are subtetraploid (74-76 chromosomes). Transformation of MEF by SV40 produces a dramatic change in response to CB. These cells, which contain SV40 T-antigen, become highly multinucleated in the presence of CB. More than 20% of the cells have at least seven nuclei. Also premature chromosome condensation (PCC), an abnormality rare in CB-treated normal cells but one which is common to highly multinucleated cells, is frequent and occurs in at least 10% of mitoses. SV40-transformed MEF have 40 or 80 chromosomes, e.g. are diploid or tetraploid. Transformation of 3T3 by SV40 or adenovirus type 12 does not result in a marked change in the response to CB. Although some trinucleate and tetranucleate cells are formed, cells with more nuclei are undetectable or rare. PCC is also rare. These cells show chromosome numbers somewhat lower than their untransformed parents and in one line the chromosome number appears to decrease with passage of the cells. This failure to undergo a marked change in responsiveness to CB following transformation is not a characteristic of all transformed 3T3 cells. SVT2, a line of 3T3 which was transformed by SV40 prior to its establishment as a continuous line, responds to CB with a high degree of multinucleation. These cells are diploid. These results suggests that 3T3 cells are constitutive for controlled nuclear division and that this feature may be related to chromosome constitution.

Topics: Adenoviridae; Animals; Antigens, Neoplasm; Cell Division; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Chromosomes; Clone Cells; Contact Inhibition; Cytochalasin B; Diploidy; Fibroblasts; Mice; Mitosis; Polyploidy; Simian virus 40; Time Factors

Treatment of untransformed mouse and hamster cells with the tertiary amine local anesthetics dibucaine, tetracaine and procaine increases their susceptibility to agglutination by low doses of the plant lectin concanavalin A. Agglutination of anesthetic-treated untransformed cells by low doses of concanavalin A is accompanied by redistribution of concanavalin A receptors on the cell surface to form patches, similar to that occurring in spontaneous agglutination of virus-transformed cells by concanavalin A. Immunofluorescence and freeze-fracture electronmicroscopic observations indicate that local anesthetics per se do not induce this redistribution of concanavalin A receptors but modify the plasma membrane so that receptor redistribution is facilitated on binding of concanavalin A to the cell surface. Fluorescence polarization measurements on the rotational freedom of the membrane-associated probe, diphenylhexatriene, indicate that local anesthetics produce a small increase in the fluidity of membrane lipids. Spontaneous agglutination of transformed cells by low doses of concanavalin A is inhibited by colchicine and vinblastine but these alkaloids have no effect on concanavalin A agglutination of anesthetic-treated cells. Evidence is presented which suggests that local anesthetics may impair membrane peripheral proteins sensitive to colchicine (microtubules) and cytochalasin-B (microfilaments). Combined treatment of untransformed 3T3 cells with colchicine and cytochalasin B mimics the effect of local anesthetics in enhancing susceptibility to agglutination by low doses of concanavalin A. A hypothesis is presented on the respective roles of colchicine-sensitive and cytochalasin B-sensitive peripheral membrane proteins in controlling the topographical distribution of lectin receptors on the cell surface.

Topics: Agglutination; Anesthetics, Local; Animals; Binding Sites, Antibody; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Colchicine; Concanavalin A; Cricetinae; Cytochalasin B; Dibucaine; Dose-Response Relationship, Drug; Freeze Fracturing; Lectins; Mice; Mice, Inbred BALB C; Polarography; Polyomavirus; Procaine; Proteins; Simian virus 40; Temperature; Tetracaine

Topics: Antigens, Viral; Cell Division; Cell Line; Cell Transformation, Neoplastic; Chromosome Mapping; Chromosomes; Contact Inhibition; Cytochalasin B; Defective Viruses; DNA; DNA, Viral; Drug Resistance; Karyotyping; Mitosis; Simian virus 40

Mouse, hamster, rat, human, and chick cells were transformed by RNA and DNA tumor viruses: simian virus 40, adenovirus type 7, Kirsten mouse sarcoma virus (Ki-MuSV), Moloney mouse sarcoma virus, and Rous sarcoma virus. All cultures of transformed cells grew to high concentration densities. Normal and transformed cells were treated with cytochalasin B (CB) at concentrations preventing cytoplasmic cleavage. Cells altered by DNA tumor viruses responded to CB with numerous nuclear divisions resulting in highly multinucleated cells. All but one line of cells transformed by RNA tumor viruses responded to CB with usually only one and occasionally two nuclear divisions. Only binucleated cells were formed. One clone of CB-treated BALB/c mouse embryo fibroblasts transformed by Ki-MuSV showed numerous cells with four and five nuclei. HOWEVER, IN CONTRASt to cells transformed by DNA viruses, few cells had seven or more nuclei. These results suggest that, in the presence of CB, cells transformed by DNA tumor viruses show uncontrolled nuclear division, whereas cells tranformed by RNA tumor viruses show controlled nuclear division.

Topics: Adenoviridae; Animals; Avian Sarcoma Viruses; Cell Division; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Cytochalasin B; DNA Viruses; Mice; Mice, Inbred BALB C; Moloney murine leukemia virus; RNA Viruses; Sarcoma Viruses, Murine; Simian virus 40

Multinucleation of SV40-transformed mouse cells was induced by Cytochalasin-B as a result of inhibition of cytokinesis. Multinucleated cells with nuclei, whose number is other than that that can be obtained by raising the power of 2, were frequently observed. By simultaneous addition of Cytochalasin-B and cylic dibutyryl-AMP to SV40-transformad mouse cellls, multinucleation was fairly inhibited and the predominance of the cells with 2 or 4 nuclei was characteristic. In case of normal mouse cells (BALB/3T3), addition of both Cytochalasin-B and cyclic dibutyryl-AMP lessened the number of nucleic in a cell compared with treatment of the cells with Cytochalasin-B alone. These results suggested that cyclic dibutyryl-AMP inhibited multinucleation of cells treated with Cytochalasin-B and that the chemical regulated the division of nuclei in a cell to divide simultaneously.

Topics: Animals; Bucladesine; Cell Division; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Cytochalasin B; Mice; Mitosis; Simian virus 40

Topics: Cell Line; Cell Transformation, Neoplastic; Cells, Cultured; Cyclic AMP; Cytochalasin B; Microscopy, Electron, Scanning; Microtubules; Neoplasms, Experimental; Oncogenic Viruses

Epithelioid cells from the livers of normal and genetically impaired (Gunn) rats were established in long-term cultures in vitro. These cells grew as flat, epithelioid cobble-stone-type monolayers and showed a diploid karyotype. They secreted rat serum albumin and proteins into their growth media and contained aryl hydrocarbon hydroxylase. Such cells were transformed by treatment with methylazoxymethanol acetate; they then exhibited an irregular, piling growth pattern, acquired the ability to grow in soft agar, and thereafter grew as tumors in hamsters given cortisone and in nude mice. These malignant spindle-cell tumors were reestablished in culture and still secreted serum albumin. The transformed cells became highly multinucleate when exposed to cytochalasin B and thus behaved like tumor cells. This behavior was not shown by the original cells. Cells transformed by benzo[a]pyrene failed to grow in soft agar culture or as tumor in animals. Cells were not affected by diethylnitrosamine.

Topics: Animals; Aryl Hydrocarbon Hydroxylases; Azo Compounds; Benzopyrenes; Blood Proteins; Cell Transformation, Neoplastic; Cells, Cultured; Cricetinae; Cytochalasin B; Diethylnitrosamine; Diploidy; Female; Immunosuppression Therapy; Liver; Male; Methylazoxymethanol Acetate; Mice; Mice, Nude; Neoplasms, Experimental; Nitrosamines; Rats; Serum Albumin

Topics: Biological Transport, Active; Cell Division; Cell Transformation, Neoplastic; Cells, Cultured; Cytochalasin B; Deoxy Sugars; Deoxyglucose; DNA Replication; Glucose; Kinetics; Mannitol

The distribution of surface-bound concanavalin A on the membranes of 3T3, and simian virus 40-transformed 3T3 cultured mouse fibroblasts was examined using a shadow-cast replica technique with a hemocyanin marker. When cells were prefixed in paraformaldehyde, the binding site distribution was always random on both cell types. On the other hand, labeling of transformed cells with concanavalin A (Con A) and hemocyanin at 37 degrees C resulted in the organization of Con A binding sites (CABS) into clusters (primary organization) which were not present on the pseudopodia and other peripheral areas of the membrane (secondary organization). Treatment of transformed cells with colchicine, cytochalasin B, or 2-deoxyglucose did not alter the inherent random distribution of binding sites as determined by fixation before labeling. However, these drugs produced marked changes in the secondary (but not the primary) organization of CABS on transformed cells labeled at 37 degrees C. Colchicine treatment resulted in the formation of a caplike aggregation of binding site clusters near the center of the cell, whereas cytochalasin B and 2-deoxyglucose led to the formation of patches of CABS over the entire membrane, eliminating the inward displacement of patches observed on untreated cells. The distribution of bound Con A on normal cells (3T3) at 37 degrees C was always random, in both control and drug-treated preparations. Pretreatment of cells with Con A enhanced the effect of colchicine on cell morphology, but inhibited the morphological effects of cytochalasin B. The mechanisms that determine receptor movement and disposition are discussed.

Topics: Agglutination; Animals; Binding Sites; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Colchicine; Concanavalin A; Cytochalasin B; Fibroblasts; Glucose; Hemocyanins; Iodine Radioisotopes; Mice; Mice, Inbred BALB C; Microscopy, Electron; Microscopy, Phase-Contrast; Pseudopodia; Simian virus 40; Staining and Labeling; Vinblastine

Topics: Animals; Antigens, Viral; Bromodeoxyuridine; Cell Transformation, Neoplastic; Cells, Cultured; Centrifugation, Density Gradient; Clone Cells; Complement Fixation Tests; Cytochalasin B; Enzyme Activation; Fibroblasts; Fluorouracil; Guinea Pigs; Hybrid Cells; Idoxuridine; Kidney; Mercaptopurine; Methylcholanthrene; Microscopy, Electron; Retroviridae; RNA-Directed DNA Polymerase; Spleen; Time Factors

Topics: Animals; Binding Sites; Blood Platelets; Borohydrides; Cattle; Cell Transformation, Neoplastic; Cells; Chromatography, Thin Layer; Cytochalasin B; Cytochalasins; Enterobacter; Erythrocytes; Fibroblasts; HeLa Cells; Isotope Labeling; Mitosporic Fungi; Myxomycetes; Oxidation-Reduction; Simian virus 40; Sodium; Spectrophotometry, Ultraviolet; Tritium

Topics: Animals; Antigens, Viral; Autoradiography; Cell Fusion; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Cricetinae; Cytochalasin B; Fluorescent Antibody Technique; Haplorhini; Kidney; Mice; Simian virus 40; Tritium; Viral Proteins; Virus Replication

Topics: Animals; Avian Sarcoma Viruses; Biological Transport, Active; Carbon Radioisotopes; Cell Transformation, Neoplastic; Cells, Cultured; Chick Embryo; Cycloheximide; Cytochalasin B; Dactinomycin; Deoxy Sugars; Diffusion; Fibroblasts; Glucose; Hexokinase; Kinetics; Methylglycosides; Mutation; Phosphates; Temperature; Time Factors

Topics: Animals; Cell Division; Cell Fractionation; Cell Movement; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Centrifugation, Density Gradient; Clone Cells; Contact Inhibition; Cytochalasin B; Mice; Microscopy, Electron, Scanning; Microscopy, Phase-Contrast; Polyomavirus

Topics: Animals; Cell Adhesion; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Chelating Agents; Colchicine; Cricetinae; Cyclic AMP; Cyclic GMP; Cytochalasin B; Dexamethasone; Ethylene Glycols; Kidney; Microscopy, Phase-Contrast; Microtubules; Polyomavirus; Theophylline

Topics: Animals; Cell Division; Cell Membrane; Cell Movement; Cell Transformation, Neoplastic; Cells, Cultured; Contact Inhibition; Cyclic AMP; Cytochalasin B; DNA; Fibroblasts; Freeze Etching; Mice; Microscopy, Electron; Mitosis; Proteins; Theophylline; Thymidine; Tritium

Topics: Adenoviridae; Animals; Cell Division; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Cells, Cultured; Cricetinae; Cytochalasin B; DNA; DNA Replication; Isotope Labeling; Kidney; Mice; Mice, Inbred Strains; Mitosis; Polyomavirus; Simian virus 40; Thymidine; Time Factors; Tritium

Topics: Animals; Avian Sarcoma Viruses; Binding Sites; Calorimetry; Carcinoma, Ehrlich Tumor; Cell Fractionation; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Colchicine; Cricetinae; Cyclohexanes; Cytochalasin B; Cytochalasins; Dactinomycin; Fibroblasts; Humans; Kidney; Lipid Metabolism; Liver; Lysine; Mice; Mice, Inbred BALB C; Ouabain; Polyomavirus; Proteins; Rats; Simian virus 40; Surface Properties; Tritium

Topics: Animals; Autoradiography; Avian Sarcoma Viruses; Cell Fusion; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Chick Embryo; China; Cricetinae; Culture Media; Cytochalasin B; Fibroblasts; Heterozygote; Parainfluenza Virus 1, Human; Species Specificity; Tritium; Virus Replication

Topics: Animals; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Colchicine; Cytochalasin B; Diffusion; Fibroblasts; Gold; Kinetics; Mice; Microscopy, Electron; Microtubules; Movement; Particle Size; Protein Binding; Proteins; Temperature; Tritium; Vinblastine; Viscosity

Topics: Agglutination; Animals; Binding Sites; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Concanavalin A; Cytochalasin B; Ferritins; Fibroblasts; Lectins; Ligands; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Microscopy, Electron; Staining and Labeling; Trypsin

Topics: Animals; Autoradiography; Cell Fusion; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Culture Media; Cytochalasin B; Cytoplasm; Haplorhini; Kidney; Leucine; Methods; Mice; Parainfluenza Virus 1, Human; Simian virus 40; Tritium; Virus Replication

Topics: Animals; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cytochalasin B; DNA; DNA, Neoplasm; Fibroblasts; Indoles; Mice; Mitosporic Fungi; Simian virus 40; Thymidine; Tritium

Topics: Animals; Biological Transport, Active; Cell Line; Cell Transformation, Neoplastic; Cells, Cultured; Chloromercuribenzoates; Chromatography, Paper; Cytochalasin B; Dipyridamole; Embryo, Mammalian; Fluorometry; Gammaretrovirus; Glucose; Leukemia Virus, Murine; Mice; Mice, Inbred BALB C; Time Factors; Tritium

Topics: Animals; Ascites; Calcium; Carbon Radioisotopes; Cell Fusion; Cell Transformation, Neoplastic; Choline; Cytochalasin B; Glucose; Kinetics; Mice; Parainfluenza Virus 1, Human; Permeability; Radiation Effects; Time Factors; Tritium; Ultraviolet Rays

Topics: Animals; Autoradiography; Carbon Radioisotopes; Cell Line; Cell Transformation, Neoplastic; Clone Cells; Cytochalasin B; Gammaretrovirus; Glucose; Mice; Mice, Inbred BALB C; Sarcoma, Experimental; Temperature; Time Factors