methylcellulose and Cell-Transformation--Neoplastic

A rat carcinogenicity bioassay (CaBio) of quinacrine was reanalyzed to investigate its mode of tumor induction. Quinacrine's effects in the rat uterus when administered as a slurry in methylcellulose were contrasted with the human clinical experience which uses a solid form of the drug, to determine the relevance of the tumors produced in the rat to safe clinical use of quinacrine for permanent contraception (QS). A review was performed of the study report, dose feasibility studies, and clinical evaluations of women who had undergone the QS procedure. The top three doses of quinacrine in the CaBio exceeded the maximum tolerated dose, and produced chronic damage, including inflammation, resulting in reproductive tract tumors. Chronic inflammation was significantly correlated with the tumors; there was no evidence of treatment-related tumors in animals without chronic inflammation or other reproductive system toxicity. Because such permanent uterine damage and chronic toxicity have not been observed in humans under therapeutic conditions, we conclude that this mode of action for tumor production will not occur at clinically relevant doses in women who choose quinacrine for permanent contraception.

Topics: Animals; Cell Transformation, Neoplastic; Chemistry, Pharmaceutical; Chronic Disease; Contraceptive Agents, Female; Dose-Response Relationship, Drug; Drug Carriers; Endometriosis; Female; Humans; Male; Maximum Tolerated Dose; Methylcellulose; Mice; Quinacrine; Rats, Sprague-Dawley; Risk Assessment; Species Specificity; Uterine Neoplasms; Uterus

D-type cyclins (cyclins D1, D2, and D3) are regarded as essential links between cell environment and the core cell cycle machinery. We tested the requirement for D-cyclins in mouse development and in proliferation by generating mice lacking all D-cyclins. We found that these cyclin D1(-/-)D2(-/-)D3(-/-) mice develop until mid/late gestation and die due to heart abnormalities combined with a severe anemia. Our analyses revealed that the D-cyclins are critically required for the expansion of hematopoietic stem cells. In contrast, cyclin D-deficient fibroblasts proliferate nearly normally but show increased requirement for mitogenic stimulation in cell cycle re-entry. We found that the proliferation of cyclin D1(-/-)D2(-/-)D3(-/-) cells is resistant to the inhibition by p16(INK4a), but it critically depends on CDK2. Lastly, we found that cells lacking D-cyclins display reduced susceptibility to the oncogenic transformation. Our results reveal the presence of alternative mechanisms that allow cell cycle progression in a cyclin D-independent fashion.

Topics: Animals; Blotting, Northern; Blotting, Western; CDC2-CDC28 Kinases; Cell Cycle; Cell Division; Cell Transformation, Neoplastic; Cyclin A; Cyclin D1; Cyclin D2; Cyclin D3; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase Inhibitor p16; Cyclins; Embryo, Mammalian; Fibroblasts; Flow Cytometry; Gene Expression Regulation, Developmental; Hematopoietic Stem Cells; Methylcellulose; Mice; Mice, Transgenic; Models, Biological; Phenotype; Protein Binding; Stem Cells; Time Factors

The chimeric transcription factor E2a-Hlf is an oncoprotein associated with a subset of acute lymphoblastic leukemias of early B-lineage derivation. We employed a retroviral transduction-transplantation approach to evaluate the oncogenic effects of E2a-Hlf on murine B-cell progenitors harvested from adult bone marrow. Expression of E2a-Hlf induced short-lived clusters of primary hematopoietic cells but no long-term growth on preformed bone marrow stromal cell layers comprised of the AC6.21 cell line. Coexpression with Bcl-2, however, resulted in the sustained self-renewal of early preB-I cells that required stromal and interleukin-7 (IL-7) support for growth in vitro. Immortalized cells were unable to induce leukemias after transplantation into nonirradiated syngeneic hosts, unlike the leukemic properties and cytokine independence of preB-I cells transformed by p190(Bcr-Abl) under identical in vitro conditions. However, bone marrow cells expressing E2a-Hlf in combination with Bcl-2, but not E2a-Hlf alone, induced leukemias in irradiated recipients with long latencies, demonstrating both a requirement for suppression of apoptosis and the need for further secondary mutations in leukemia pathogenesis. Coexpression of IL-7 substituted for Bcl-2 to induce the in vitro growth of pre-B cells expressing E2a-Hlf, but leukemic conversion required additional abrogation of undefined stromal requirements and was associated with alterations in the Arf/Mdm2/p53 pathway. Thus, E2a-Hlf enhances the self-renewal of bone marrow B-cell progenitors without inciting a p53 tumor surveillance response or abrogating stromal and cytokine requirements for growth, which are nevertheless abrogated during progression to a leukemogenic phenotype.

Topics: Animals; B-Lymphocytes; Basic-Leucine Zipper Transcription Factors; Blotting, Southern; Blotting, Western; Bone Marrow Cells; Cell Division; Cell Separation; Cell Transformation, Neoplastic; Disease Progression; DNA; DNA-Binding Proteins; Flow Cytometry; Genotype; Interleukin-7; Leukemia; Methylcellulose; Mice; Mice, Inbred BALB C; Models, Genetic; Mutation; Oncogene Proteins, Fusion; Phenotype; Proto-Oncogene Proteins c-bcl-2; Retroviridae; Stem Cells; Time Factors; Transgenes; Tumor Suppressor Protein p53

Topics: 3T3 Cells; Agar; Animals; Antigens, Polyomavirus Transforming; Cell Adhesion; Cell Communication; Cell Count; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cell Transformation, Viral; Culture Media; Cytopathogenic Effect, Viral; Methylcellulose; Mice; Mice, Nude; Mutation; Neoplasm Transplantation; Polyhydroxyethyl Methacrylate; Rats; Simian virus 40; Virology

Cell hybrids (BIM) were produced between human neuroblastoma cells (IMR-32) and thymidine auxotrophs (B3T) of rat nerve-like cells (B103) in order to obtain cell lines undergoing stable neuronal differentiation. BIM cells exhibited the growth properties of partial transformation: 1) When the cell growth reached a plateau, BIM cells ceased to proliferate and expressed a differentiated phenotype. The shape of the cells changed from flat to round and they extended neurites. 2) When cultured in methylcellulose, BIM cells formed colonies, indicating that BIM cells have the ability of anchorage-independent growth. By Southern blot analysis, BIM cells had both human and rat types of N-myc genes. The human N-myc genes were amplified, but the extent of the amplification was lower in BIM cells than that in the parental cell line IMR-32. The rat N-myc gene was detected at a similar level in BIM, B3T, B103, and rat fibroblastic cells 3Y1. Therefore, the decrease in amplification of human N-myc genes may be involved in the properties of partial reverse-transformation in BIM cells. When treated with various drugs such as db-cAMP, forskolin, and cAMP with isobutyl-methylxanthine, BIM cells expressed a nerve-like phenotype. These findings indicate that cell hybridization yielded partial normalization of transformed nerve-like cells.

Topics: 1-Methyl-3-isobutylxanthine; Animals; Axons; Bucladesine; Calcimycin; Cell Cycle; Cell Transformation, Neoplastic; Colforsin; Cyclic AMP; Fibroblasts; Humans; Hybrid Cells; Methylcellulose; Neuroblastoma; Neurons; Phenotype; Rats; Thymidine; Tretinoin; Tumor Cells, Cultured

We have developed a hybrid methylcellulose/agar suspension culture system which permits long-term colony formation of transformed mesenchymal cells. In contrast to traditional agar suspensions, our system allows for recovery of cells and direct biochemical analysis of anchorage-independent growth. The ability to readily radiolabel cellular macromolecules in these preparative cultures permits a quantitative and objective analysis of colony formation by incorporation of [3H]thymidine into newly synthesized DNA.

Topics: Agar; Cell Count; Cell Division; Cell Transformation, Neoplastic; Cells, Cultured; Culture Media; DNA Replication; Gentian Violet; Methylcellulose; Phenotype; Suspensions; Thymidine; Tritium

Blast progenitors in acute myeloblastic leukemia (AML) grow in methylcellulose and suspension cultures. Blast colony formation in methylcellulose culture reflects the terminal divisions of blast progenitors, while secondary colony formation, by replating in methylcellulose and recovering clonogenic cells in suspension culture, reflects the self-renewal of blast progenitors. To analyze the regulatory mechanisms of the proliferation of leukemic blast progenitors, the effects of highly purified native granulocyte colony-stimulating factor (G-CSF) obtained from human squamous cell carcinoma line (CHU-2) on blast progenitors in AML patients were studied in methylcellulose and suspension cultures. Purified G-CSF stimulated the growth of blast progenitors in both culture systems, although sensitivity to G-CSF varied from patient to patient. No obvious maturation of leukemic blasts was noted in suspension culture in the presence of G-CSF. The data suggest that a normal hemopoietic regulator may play a role in the growth of blast progenitors in AML patients.

Topics: Adult; Aged; Cell Transformation, Neoplastic; Colony-Stimulating Factors; Culture Media; Female; Granulocytes; Humans; Leukemia, Myeloid, Acute; Male; Methylcellulose; Middle Aged; Neoplastic Stem Cells; Suspensions; Tumor Stem Cell Assay

Basophilia has been reported to indicate an accelerated phase of chronic myeloid leukemia (CML), heralding a poor prognosis. We have studied 47 patients with chronic-phase CML by basophil growth and differentiation assays in vitro, demonstrating an association between basophil growth index (BGI) and clinical time to blast crisis as well as overall survival. In addition to confirming an association between positive BGI and phase of CML in a larger group of patients, a positive BGI predicted death or blast crisis within 2 years' study of chronic phase CML (p less than 0.01), with a sensitivity of 78%, specificity, 81%; the positive predictive value of a positive test, 64%; and a negative predictive value of a negative test, 89%. The survival experience of the 22 evaluable patients with chronic-phase CML and a positive BGI was significantly worse than the survival of the 19 patients with a negative BGI (p less than 0.0001). At 1, 2, and 3 years the proportion of surviving patients with a positive BGI was 0.64, 0.32, and 0.23, respectively, compared with 1.00, 0.90, and 0.79 for those with a negative BGI. The median survival of chronic phase CML patients with a positive test at diagnosis (n = 14) was 27 months versus 54 months for those with a negative diagnosis (n = 14) (p less than 0.05). These findings emphasize the prognostic utility of basophil growth assays in CML and suggest a molecular relationship between leukemic transformation and basophil lineage expression.

Topics: Basophils; Cell Differentiation; Cell Division; Cell Transformation, Neoplastic; Colony-Forming Units Assay; Female; Hematopoietic Stem Cells; Histamine; Humans; Leukemia, Myeloid; Male; Methylcellulose; Prognosis

The present studies were undertaken to investigate the ability of Abelson murine leukemia virus (A-MuLV) to transform cells derived in vitro from pluripotent hemopoietic progenitor cells of high proliferative potential. We now report that continuously growing, autonomous cell lines could be obtained from a high proportion of individually infected multilineage colonies generated in assays of spleen cells from normal adult mice if the infected cells were cocultivated for the first two to three months with irradiated NIH-3T3 cells. No lines were obtained if the 3T3 cell feeders were not initially present. Similar results were obtained when the cells exposed to virus were from multilineage colonies originating from isolated single cells obtained by replating small blast colonies. Characterization of the transformants and a number of derivative cloned sublines revealed the consistent presence of a mast cell phenotype, with some suggestion of macrophage differentiation in a few cases. All cell lines tested produced virus, showed a variable pattern of A-MuLV integration, and gave rise directly to tumors when injected subcutaneously, as shown by both Southern analysis and cytogenetic studies. The early absolute but transient dependence of these A-MuLV mast cell transformants on a fibroblast feeder suggests a multistep process in their evolution, in which the acquisition of autonomy from factors of mesenchymal cell origin may play an important role.

Topics: Animals; Bone Marrow; Bone Marrow Cells; Cell Line; Cell Transformation, Neoplastic; Cell Transformation, Viral; Clone Cells; Culture Media; Mast Cells; Methylcellulose; Mice; Mice, Inbred BALB C; Phenotype; Retroviridae

The effect of tumour promoter, 12-0-tetradecanoylphorbol-13-acetate (TPA), on the cloning efficiency of different clones of mouse tumour cells was studied in semi-solid medium. The clones varied in their response to TPA. Inhibition and inherited stimulation of colony-formation efficiency in semi-solid medium was revealed. One clone did not respond to TPA. The influence of environmental factors on the clone structure and tumour progression is discussed.

Topics: Animals; Cell Transformation, Neoplastic; Clone Cells; Colchicine; Culture Media; Fibroblasts; Gene Amplification; Methylcellulose; Mice; Mice, Inbred AKR; Mice, Inbred CBA; Phorbols; Sarcoma, Experimental; Tetradecanoylphorbol Acetate

Poly I:C/poly-L-lysine (poly ICL) was effective in preventing or delaying the development of osteogenic sarcoma (OGS) in mice. C57BL/6J mice were inoculated subcutaneously with 5 X 10(4) OGS cells and treatment was evaluated by palpable tumor development and subsequent day of death. A significant antitumor effect resulted from injection of 150 microgram of poly ICL into the tumor site starting immediately after tumor implant and followed by four subsequent treatments. Seventy percent of treated animals remained tumor free at 50 days, a time at which 70% of placebo treated animals had died as a result of tumor development. A similar treatment regimen of mice inoculated with 2 X 10(5) OGS cells resulted in a significant delay of time to tumor and subsequent day of death. Treatments with poly ICL were ineffective if they were initiated after development of palpable tumor or if they were administered at a nontumorous site on the animal. These findings indicate that the optimal therapy resulted from repeated intratumor treatment prior to development of extensive tumor burden.

Topics: Animals; Antineoplastic Agents; Carboxymethylcellulose Sodium; Cell Transformation, Neoplastic; Interferon Inducers; Methylcellulose; Mice; Mice, Inbred C57BL; Osteosarcoma; Peptides; Poly I-C; Polylysine; Sarcoma, Experimental; Time Factors

The influence of ethyl methane sulfonate (methane sulfonic acid ethyl esther, EMS) on anchorage independence of tumor cells was studied. Mouse near-diploid spontaneously transformed clonal fibroblasts (CAK-25Agr were used. They were characterized by a stable low cloning efficiency in 1,2% methyl cellulose ((3-5) . 10(-5) per cell seeded into a semi-solid medium). EMS enhanced the quantity of CAK-25Agr colonies grown in methyl cellulose. However, this enhancement was only obtained when correction on the cloning efficiency of the cells in a liquid medium was introduced. Subclones of CAK-25Agr isolated from methyl cellulose were studied for their ability to form colonies in the semi-solid medium. The number of subclones with elevated anchorage independence in cultures treated by a mutagen and in untreated cultures did not differ.

Topics: Animals; Cell Line; Cell Transformation, Neoplastic; Cells, Cultured; Clone Cells; Culture Media; Ethyl Methanesulfonate; Fibroblasts; Gene Expression Regulation; Methylcellulose; Mice; Time Factors

We have developed simple methods for the rapid isolation and concentration of human leukemic colonies for cytologic evaluation. Colonies, grown in a medium containing methylcellulose, are gently washed from their culture dishes after reducing the viscosity of the colony layer. Colonies are washed and concentrated intact by mild centrifugation (10-20 g/5 min). Once isolated, colonies may enter any number of procedures for morphologic and cytokinetic analyses including exposure to radiolabeled compounds, cytocentrifugation, reaction with antibodies specific for certain cell surface markers, and fixation for routine light and electron microscopy. In addition, suspended or smeared colonies may be exposed to various substrates for the demonstration of endogenous enzymatic markers. Examples of possible preparations are presented.

Topics: Cell Separation; Cell Transformation, Neoplastic; Cells, Cultured; Clone Cells; Hematopoiesis; Humans; Interphase; Leukemia, Hairy Cell; Leukemia, Myeloid, Acute; Methylcellulose

The clone of near-diploid mouse transformed CAK-25AGr cells is characterized by the stable cloning efficiency in a semi-solid medium (about 10(-5) per cell plated in methylcellulose). It was shown that colonies in the semi-solid medium were formed by rare single cells and did not arise as a result of slow multiplication of all cells in the population. These cells are not genetical variants different from other cells in the culture. This is assumed on the basis of following data. First, the majority of the subclones arising in methylcellulose (9 of 12) retained parental cloning efficiency in the semi-solid medium. Second, all 6 subclones picked from the solid substratum had the ability to form colonies in methylcellulose with the frequency not lower than that of the parental clone. Apparently, the proliferation in methylcellulose of the transformed cells studied is a stochastic process. Each cell in the culture has the ability to initiate a colony in the semi-solid medium with the certain probability. This probability is a heritable characteristic of the cloned cell line. It is possible that this characteristic reflects the norm of reaction of the cells to some environmental factors.

Topics: Animals; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cells, Cultured; Clone Cells; Culture Media; Methylcellulose; Mice; Mice, Inbred AKR; Mice, Inbred C57BL; Time Factors

A patient with Ph1-positive chronic myelogenous leukemia (CML) who entered an erythroblastic transformation prior to the development of a typical myeloblastic crisis is described. In vitro methylcellulose cultures obtained at the time of erythroblastic transformation revealed that the erythroid progenitors were responsive to erythropoietin. Thus, similar to the findings in polycythemia vera, the erythroid progenitors in this case of erythroblastic transformation of CML retained responsiveness to erythropoietin in vitro.

Topics: Bone Marrow; Bone Marrow Cells; Cell Transformation, Neoplastic; Cells, Cultured; Culture Media; Erythroblasts; Erythrocytes; Erythropoietin; Female; Hematopoietic Stem Cells; Humans; Leukemia, Myeloid; Methylcellulose; Middle Aged

The chromosome constitution of CHEF/16 clones recovered from methylcellulose and of uncloned, tumor-derived CHEF/16 populations are compared. Nine of 11 clones recovered from methycellulose were initiated by diploid cells. Moreover, chromosomally diploid cells were still present in most CHEF/16 clones even after growth in anchorage-independent conditions. In contrast, none of the CHEF/16 cells recovered from tumors were diploid. Nonrandom chromosome changes were observed, but no specific chromosome alterations were consistently found in tumor-derived CHEF cells. Although CHEF/16 cells are uniformly tumorigenic in nude mice, each of 10 uncloned tumor-derived populations from inocula of 10(2), 10(4), and 10(6) CHEF/16 cells consisted of only 1-3 stemlines. Our results show that diploid CHEF/16 cells are premalignant and undergo karyotypic changes leading to successful and usually clonal establishment of tumors in nude mice.

Topics: Animals; Cell Transformation, Neoplastic; Chromosome Aberrations; Clone Cells; Cricetinae; Cricetulus; Culture Media; Embryo, Mammalian; Fibroblasts; Karyotyping; Methylcellulose; Mice; Mice, Nude; Neoplasm Transplantation; Neoplasms, Experimental

Three adenovirus-2-transformed rat embryo brain cell lines and their methylcellulose-selected sub-clones were examined for fibronectin expression, anchorage-independent growth, saturation density, T antigen expression and morphology. Tumorigenicity studies were carried out on newborn and ATS immunosuppressed syngeneic rats and congenitally athymic nude mice. With one exception the methylcellulose sub-clones contained significantly fewer fibronectin-positive cells than the parent lines; a number of sub-clones contained no fibronectin-positive cells. Methylcellulose selection did not always alter cell morphology, saturation density or anchorage-independent growth as compared with parent lines. However, the methylcellulose sub-clones were considerably more malignant than the parent cell lines as measured by invasion and metastasis in nude mice. No in vitro characteristic correlated with malignant behaviour.

Topics: Adenoviridae; Animals; Antigens, Viral; Antilymphocyte Serum; Brain; Cell Line; Cell Separation; Cell Transformation, Neoplastic; Cell Transformation, Viral; Clone Cells; Culture Media; Female; Fibronectins; Fluorescent Antibody Technique; Male; Methylcellulose; Mice; Mice, Nude; Neoplasm Transplantation; Neoplasms, Experimental; Rats; T-Lymphocytes; Transplantation, Isogeneic

By the calcium technique, intact DNA of bovine adenovirus type 3 (BAV3) was found to transform A31 cells, a clone of BALB/3T3. Transforming activity was resistant to RNase and Pronase but sensitive to DNase. The efficiency of transformation was approximately 5 to 10 foci per mug of DNA. Attempts were also made to test for transforming activity of BAV3 DNA fragments prepared with restriction endonucleases EcoRI and HindIII. The activity was found to associate exclusively with the EcoRI D fragment mapped in the region of 3.6 and 19.7 units (molecular weight, 3.9 x 10(6)). No transformation could be obtained with three HindIII fragments, J, E, and B, located at the left-hand end of the BAV3 genome. However, the enzymatic joining of J and E fragments (0 to 11.9 map units) with a ligase restored the transforming activity. These results suggest that all the genetic information of BAV3 required for transformation is located in the region between 3.6 and 11.9 units on the viral genome. Some properties of A31 cells transformed by BAV3 DNA EcoRI D fragment (TrD) and the ligated DNA of HindIII J and E fragments (TrJE), as well as those transformed by whole BAV3 DNA (Tr), were examined. As compared to untransformed A31 cells, all the transformed cell lines tested showed rapid growth, high saturation densities, and anchorage-independent growth. Moreover, they contained BAV3-specific T antigen and induced tumors in adult nude and BALB/c mice. These properties of Tr, TrD, and TrJE lines were similar to those of BAV3-transformed cells.

Topics: Adenoviridae; Animals; Cattle; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cell Transformation, Viral; Culture Media; DNA Restriction Enzymes; DNA, Viral; Methylcellulose; Mice; Neoplasm Transplantation

The net rate of spontaneous aggregation of cells suspended with EDTA was measured for various cell types including spontaneous transformants and cells transformed with DNA and RNA viruses. The anchorage dependence as determined by growth in methyl cellulose and the tumorigenicity in vivo were also determined. All cells that had lost their anchorage dependency and were tumorigenic showed a high net rate of spontaneous adhesion. A31 was the only nontransformed cell line to have a high net rate of adhesion. The net rate of spontaneous aggregation of cells is a quick and reliable index of tumorigenicity and offers a new approach to understanding the mechanisms of cell surface changes associated with transformation.

Topics: Cell Adhesion; Cell Aggregation; Cell Line; Cell Transformation, Neoplastic; Cells, Cultured; Concanavalin A; Edetic Acid; Methylcellulose; Neoplasms, Experimental; Polyomavirus; Sarcoma Viruses, Murine; Simian virus 40

The rate of hexose transport was compared in normal and virus-transformed cells on a monolayer and in suspension. It was shown that: 1) Both trypsin-removed cells and those suspended for an additional day in methyl cellulose had decreased rates of transport and lower available water space when compared with cells on a monolayer. Thus, cell shape affects the overall rate of hexose transport, especially at higher sugar concentrations. 2) Even in suspension, the initial transport rates remained higher in transformed cells with reference to normal cells. Scanning electron micrographs of normal and transformed chick cells revealed morphological differences only in the flat state. This indicates that the increased rate of hexose transport after transformation is not due to a difference in the shape of these cells on a monolayer.

Topics: Animals; Avian Sarcoma Viruses; Biological Transport; Cell Transformation, Neoplastic; Cells, Cultured; Chick Embryo; Deoxyglucose; Fibroblasts; Glucose; Methylcellulose; Methylglucosides; Microscopy, Electron, Scanning; Thymidine; Time Factors; Trypsin

Concentrations of 0.25 and 0.5 mug/ml calcium chromate (CaCrO4-2H2O)dissolved in Dulbecco's medium were found to alter the growth behavior of BHK21 cells in culture. Treated cells grew as shortened fibroblasts and in random orientation. The changes detected during the first two weeks of culture in the presence of the metal became more pronounced as the number of growth passages increased. In addition to the alterations noted above, chromate-treated cells grew into large clusters in Methocel (an alternative technique to the agar suspension system), while untreated cells underwent, at most, only one or two divisions in Methocel. These alterations in growth properties were irreversible and persisted after removal of the treated cells from chromate-containing medium, suggesting that a heritable change had occurred as opposed to a transient, chromate-dependent alteration of cell growth. This experimental observation suggests that chromate salts and perhaps salts of other metals can transform BHK21 cells in vitro or can select for spontaneously transformed cells.

Topics: Animals; Calcium; Carcinogens; Cell Division; Cell Line; Cell Transformation, Neoplastic; Chromates; Cricetinae; Culture Media; Kidney; Methylcellulose; Neoplasms, Experimental

3T3 cells do not grow in Methocel suspension culture, while other permanent cell lines do. The viability of 3T3 cells in suspension remains unchanged for at least three days with respect to plating efficiency, vital staining and resumption of normal growth when transferred into monolayer culture. When monolayer 3T3 cells in G1 phase are suspended they remain in G1 phase. Cells already in S phase which are suspended complete ongoing DNA synthesis and mitosis and then are arrested in the G1 phase. Progress through the cell cycle is reinitiated after suspended cells attach to a surface. When monolayer cells in late G1 phase (just before entering S phase) are put in suspension cultures they do not initiate DNA synthesis.

Topics: Cell Division; Cell Line; Cell Survival; Cell Transformation, Neoplastic; Cells, Cultured; Culture Media; DNA; Methylcellulose; Mitosis

Topics: Animals; Cell Line; Cell Transformation, Neoplastic; Cells, Cultured; Clone Cells; Contact Inhibition; Culture Media; Gammaretrovirus; Idoxuridine; Kidney; Male; Methods; Methylcellulose; Mice; Mice, Inbred BALB C; Neoplasms, Experimental; Rats

Topics: Animals; Antigens, Neoplasm; Antigens, Viral; Cell Line; Cell Transformation, Neoplastic; Clone Cells; Culture Media; Fibroblasts; Methylcellulose; Mice; Mice, Inbred Strains; Simian virus 40

Revertants of Kirsten sarcoma virus transformed nonproducer BALB/3T3 cells (KA31 cells) were isolated after exposing the transformed cells to 5-fluorodeoxyuridine at high cell density, or when suspended in methylcellulose. Revertants were also isolated by treating KA31 cells with the lectin, concanavalin A, which is manyfold more toxic to transformed cells than for normal cells. The revertants resemble BALB/3T3 cells in their morphology and growth characteristics in that they have a low saturation density, fail to grow in 1% calf serum or when suspended in methylcellulose, and cease to synthesize DNA after reaching their saturation density. Infection by murine leukemia virus rescues Kirsten sarcoma virus from only the concanavalin-A-selected variants, though all the revertants are susceptible to infection by leukemia virus. The concanavalin A revertants also become transformed after infection with murine leukemia virus. All the revertants can be transformed by Kirsten sarcoma virus but not by simian virus 40.

Topics: Animals; Autoradiography; Cell Transformation, Neoplastic; Cells, Cultured; Chromosomes; Concanavalin A; DNA; DNA, Neoplasm; Floxuridine; Gammaretrovirus; Helper Viruses; Leukemia Virus, Murine; Methylcellulose; Mice; Mice, Inbred BALB C; Simian virus 40; Thymidine; Tritium; Viral Plaque Assay; Virus Replication

Topics: Animals; Azaguanine; Cattle; Cell Adhesion; Cell Division; Cell Line; Cell Transformation, Neoplastic; Cricetinae; Culture Media; Diploidy; Drug Resistance; Glucosephosphate Dehydrogenase; Humans; Hypoxanthines; Immunosuppression Therapy; Isoenzymes; Karyotyping; L-Lactate Dehydrogenase; Methylcellulose; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Neoplasms, Experimental; Pentosyltransferases; Phenotype; Rabbits; Rats; Thioguanine; Thymus Gland

Topics: Benzopyrenes; Blood; Cell Transformation, Neoplastic; Concanavalin A; Culture Media; L Cells; Lectins; Methylcellulose

Topics: Animals; Cell Transformation, Neoplastic; Cellulose; Hydrogen-Ion Concentration; Methylcellulose; Neoplasms, Experimental; Rats

Topics: Animals; Carbon Isotopes; Cattle; Cell Line; Cell Transformation, Neoplastic; Chromatography; Cricetinae; Culture Media; DNA; Growth Substances; Horses; Kidney; Methylcellulose; Polyomavirus; RNA; Sheep; Swine; Thymidine; Tritium; Uridine

Topics: Agar; Animals; Bromodeoxyuridine; Cell Division; Cell Line; Cell Survival; Cell Transformation, Neoplastic; Clone Cells; Cricetinae; Culture Media; Culture Techniques; DNA; Kidney; Light; Methods; Methylcellulose; Polyomavirus; Trypsin

Topics: Agar; Animals; Antigens; Bromodeoxyuridine; Cell Division; Cell Line; Cell Nucleus; Cell Survival; Cell Transformation, Neoplastic; Chromosomes; Clone Cells; Complement Fixation Tests; Cricetinae; Culture Media; Culture Techniques; Genetic Variation; Kidney; Light; Methylcellulose; Mitosis; Oncogenic Viruses; Phenotype; Polyomavirus; Time Factors

Topics: Animals; Antibody Formation; Cell Count; Cell Transformation, Neoplastic; Drug Synergism; Female; Hemolysin Proteins; Methylcellulose; Methylcholanthrene; Mice; Neoplasms, Experimental; Organ Size; Papilloma; Skin Neoplasms; Spleen; Thalidomide