Tumor promoters induce changes in the chick embryo fibroblast cytoskeleton

We have examined the effect of the tumor promoter, 12-0-tetradecanoyl phorbol-13-acetate (TPA), on the actin-containing elements of the cytoskeleton of chick embryo fibroblasts (CEF). TPA at concentrations as low as 7.3 times 10-10M indices a reversible change in the cytoskeleton as visualized by indirect immunofluorescence using anti-actin antibodies. Cells incubated with TPA lose the ordered actin-containing structures found in normal cells and resemble Rous sarcoma virus-transformed cells in that the immunofluorescent actin pattern is diffuse. The TPA effects are both dose-and time-dependent. Analogs of TPA which are inactive as tumor promoters do not induce cytoskeletal changes at the concentrations tested, while a second tumor promoter, PDD, is also able to cause alterations in actin-containing structures. The action of TPA requires de novo synthesis of both RNA and protein. The direct cytoskeletal changes are neither plasmin-dependent nor subject to inhibition by incubating the cells with high levels of protease inhibitors during the exposure to TPA. However, plasminogen does increase the sensitivity of cells to TPA.

Correlation of in vitro growth properties and tumorigenicity of Syrian hamster cell lines

Several in vitro phenotypic characteristics frequently associated with neoplastic cells were examined in a series of spontaneous and benzo(a)pyrene-induced Syrian hamster clonal cell lines which differed in their degree of tumorigenicity. Nonparametric statistical analysis demonstrated cloning efficiency in semisolid agar, enhanced fibrinolytic activity, decreased serum requirement for growth, decreased organization of intracellular actin, and increased cloning efficiency in liquid medium to be correlated with tumorigenicity. These correlations were not only qualitative but also quantitative. This suggests that the factors determining the degree of tumorigenicity of a cell can be cellular growth properties.

Tumorigenicity of revertant from an SV40-transformed line

A syndrome of in vitro properties correlates with the tumorigenicity of SV40-transformed rodent cells. These properties are: plasminogen activator production, loss of large actin cables, and anchorage-independent growth. An established rat fibroblast line, its SV40 transformant, several T-antigen negative revertants, and a spontaneous retransformant isolated from one of the revertants were analyzed in vivo for their tumorigenicity and in vitro for the syndrome. The two transformed lines were highly tumorigenic, and had clearly abnormal in vitro properties. The parental rat line was weakly tumorigenic in nude mice and demonstrated a slightly transformed response in the in vitro assays. The revertants were completely nontumorigenic. Expression of the in vitro syndrome was not uniform for all revertants; however, most cell lines maintained the correlation of the syndrome and tumorigenicity.

Rapid treatment of percodan addiction: a case report

This is a case study of narcotic addiction in which the patient was completely withdrawn from 12 to 20 Percodan tablets daily within 7 days. Signs and symptoms of the Abstinence Syndrome were minor and required minimal medication for their control. In addition, no electroshock treatment was necessary, nor were any other narcotic or other drug substituted for the Percodan.

2-amino-isobutyric acid and 3-O-methyl-D-glucose transport in 3T3, SV 40-transformed 3T3 and revertant cell lines

In order to further investigate the connection between transport and growth control, 3T3 cells, SV40 transformed 3T3 cells (SV101), and three revertant cell lines derived from SV101 which have regained certain manifestations of growth control were used. Transport rates of 2-amino-isobutyric acid and 3-O-methyl-D-glucose were measured in sparse, confluent, serum-starved, and serum-stimulated cultures. As shown before, cessation of 3T3 cell growth in G0 under conditions of confluence or serum deprivation was associated with reduced rates of transport for both compounds, whereas the density and serum dependence of growth and transport was largely eliminated in SV101. The density revertant F1SV101, which has regained density regulation of growth similar to 3T3 cells, has also regained density regulation of transport. Neither growth nor transport were serum dependent. The serum revertants AgammaSV7 and LsSV6 have regained both density and serum regulation of growth, but not according to the original mechanism of 3T3 cells of entry into a Go state. Transport was high under conditions of confluence or serum deprivation. Thus for these cells rates of transport were not reduced simply as a consequences of slower cell growth nor were low transport rates responsible for growth arrest. The data are consistent with the possibility that growth arrest specifically in the G0 state could shut off a number of cellular activities, including transport.

Isolation and characterization of T antigen-negative revertants from a line of transformed rat cells containing one copy of the SV40 genome

Negative selection with FUdR produced revertants from the transformed rat line 14B, which contains one insertion of the SV40 viral genome (Botchan, Topp and Sambrook, 1976). 14B contains nuclear T antigen, grows to a high density, grows in low serum and is anchorage-independent. The revertants fall into three classes with regard to viral DNA sequences: the SV40 DNA is retained; the SV40 DNA is retained but has undergone a deletion; and the SV40 DNA is lost, generating a cured cell. This heterogeneity is not a result of long-term passage. The revertants arise with a frequency of one in 8.4 X 10(5) cells after as few as 12 passages. All three classes of revertants are T antigen-negative, density-sensitive, more serum sensitive than 14B and anchorage-dependent. These data argue for a direct role of the functioning viral genome in the maintenance of the transformed state, and that with 14B, the phenotypes of transformation are not virus gene dosage-dependent.

The characterization of SV40-transformed cell lines derived from mouse teratocarcinoma: growth properties and differentiated characteristics

Mouse teratocarcinoma cells derived from embryoid bodies of 129SVsl mice were cultured in vitro to permit their differentiation. These cells were then infected with simiam virus 40 (SV40) and 31 cloned cell lines (SVTER) were derived from these cultures. All 31 SVTER cell lines contained the SV40 tumor (T) antigen and grew as permanent lines in culture. Mock-infected embryoid body cultures did not give rise to permanent cell lines. The morphology of each SVTER cell line was distinct and did not change during successive subclonings. The growth properties and tumorigenic potential of all 31 SVTER cell lines were investigated. None of these lines produced tumors in 129SVsl mice. Each cell line was tested for its ability to (1) grow in medium containing 1% serum, (2) plate on cell monolayer, and (3) form clones in methocel suspension. Only three of the SVTER cell lines were transformed with respect to all three of these criteria. Most of these cell lines were minimal transformants. The SVTER cell lines were tested for creatine phospholinase (CPK), an enzyme activity chracteristic of mouse brain and muscle tissue, and the protease, plasminogen activator (PA) which is found in embryoid bodies and several differentiated cell types. Some of the SVTER cell lines contained high levels of CPK, while others had high levels of PA and a third group of cells contained neither enzyme activity. No SVTER cell line was found with high levels of both these enzyme activities. This result suggests that mutually exclusive sets of genes are expressed in these cells as might be expected from the distinct tissue distribution of the two enzyme activities studied. These SVTER cell lines may be useful in reconstructing developmental pathways of differentiating teratomas in vitro.

Characterization of the myosin-phosphorylating system in normal murine astrocytes and derivative sv40 wild-type and A-mutant transformant

Myosin and myosin light-chain kinase have been isolated and characterized from small quantities of normal and SV40-transformed, murine astrocytic neuroglial cells in culture and from intact normal mouse brain. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of the astrocyte myosins revealed a heavy chain of 200,000 daltons and two light chains of 20,000 and 15,000 daltons. These myosins are similar to other cytyplasmic myosins. The astrocyte 20,000-dalton light chain can be phosphorylated by an endogenous myosin light-chain kinase which has properties similar to those of the myosin light-chain kinase found in human platelets. No differences were detected in either the astrocyte myosins or myosin light-chain kinases between (a) the normal and transformed cells, (b) the transformed cells grown at the permissive and nonpermissive temperatures, or (c) the SV40 wild-type and A-mutant transformants.

Defective organization of actin in cultured skin fibroblasts from patients with inherited adenocarcinoma

In the cytoplasm of well-spread cultured normal fibroblasts, actin is organized into a network of cables that run the length of the cell just inside the adherent cell membrane. A diffuse matrix replaces the cables in fibroblasts that have become tumorigenic as a result of oncogenic transformation. We have found a similar disruption in actin organization in cultured skin fibroblasts (passage 6-10) obtained by biopsy from patients with the inherited colonic cancer, adenomatosis of the colon and rectum (ACR). Because ACR is inherited as an autosomal dominant trait, about half the children of ACR patients will develop colon cancer, but they typically remain asymptomatic until at least the second decade of life. Actin distribution within cultured cells from children of ACR patients was identical either to that seen in cultured cells from normal persons or to that seen in cultured cells from ACR patients. The two different patterns were independent of age, sex, drug treatment, or infections of the donors. Apparently, this class of colonic carcinoma is accompanied by a systemic aberration in the organization of fibroblast cytoplasm, and this aberration can be detected by immunofluorescent localization of actin within cultured skin fibroblasts, prior to manifestation of any colonic symptoms.

Production of plasminogen activator by established cell lines of mouse origin

The correlation between malignant transformation and increased plasminogen activator synthesis has been studied in a variety of established cell lines. In contrast to the behavior of secondary mouse embryo cultures, which always show increased fibrinolytic activity when transformed, no such correlation was found within the BALB/c 3T3 line and its transformed derivatives. Cell lines were established from tumors initiated in BALB/c mice by several transformed cell lines. These lines were generally found to contain no more plasminogen activator than the cells used for inoculation. A correlation was found between transformation and plasminogen activator synthesis within Swiss 3T3 cell lines. However, the correlation was not maintained by serum revertants of transformed Swiss 3T3 cells.

In vitro differentiation of teratomas and the distribution of creatine phosphokinase and plasminogen activator in teratocarcinoma-derived cells

Mouse teratocarcinoma cells from embryoid bodies were cultured in vitro to permit their differentiation into a number of cell types. Two enzyme activities, creatine phosphokinase (CPK) and the protease plasminogen activator, were studied to follow the developmental sequence of events in these embryoid body-derived cell cultures. CPK activity increased with time in culture, indicating the appearance of new cell types with brain- or muscle-specific enzyme activities. Plasminogen activator was detectable in extracts of embryoid bodies. This protease activity first increased and then decreased to a low level as the embryoid bodies in culture developed into differentiated cell types. These cell cultures also showed a decreased potential for tumor formation in syngeneic mice as a function of time in culture. This decrease in tumorigenic potential was correlated with the appearance of differentiated cells in vitro. Simian virus 40 (SV40) was used to infect and transform cells derived from embryoid bodies in culture. This was done to permit the establishment of cloned teratocarcinoma-derived cell lines. Twenty-nine distinct cloned permanent cell lines (called SVTER) containing the SV40-specific tumor antigen were obtained. None of these cell lines was capable of producing tumors in syngeneic mice. An analysis of the levels of creatine phosphokinase and plasminogen activator in these SVTER cell lines indicated that : (a) some cell lines had high CPK activity and little or no plasminogen activator activity, (b) some cell lines contained high levels of plasminogen activator activity with little or no CPK activity, and (c) some cell lines contained neither of these enzyme activities. No example of a cell line with high levels of both enzyme activities was observed, indicating that these two enzymes may participate in mutually exclusive developmental pathways. The SVTER cell lines may therefore be useful in reconstructing these developmental pathways in vitro.

Tumorigenicity of virus-transformed cells in nude mice is correlated specifically with anchorage independent growth in vitro

Clonal isolates of mouse 3T3 cells and primary rat embryo cells, recovered nonselectively after infection by simian virus 40 (SV40), have been tested for tumorigenicity in the immune-deficient nude mice in order to determine the cellular growth properties in vitro specifically correlated with neoplastic growth in vivo. In addition, mouse 3T3 cells transformed by murine sarcoma virus (MuSV, Kirsten strain), and revertants isolated from cells fully transformed by either SV40 or MuSV were also studied. Results suggest that the single cellular property consistently associated with tumorigenicity in nude mice is the acquisition by virus-transformed cells of the ability to proliferate in vitro in the absence of anchorage. Other cellular parameters of virus-induced transformation, such as lack of sensitivity to high cell density and the capacity to grow in low serum concentration, are dissociable from cellular tumorigeneicity. This conclusion is supported further by the demonstration that specific selection in vivo for tumorigenic cells from anchorage-dependent cells results in the isolation of anchorage-independent cells. Conversely, a single-step selection in vitro for anchorage-independent cells from nontumorigenic cells results in a simultaneous selection of highly tumorigenic subclones.

Patterns of organization of actin and myosin in normal and transformed cultured cells

The patterns of distribution of intracellular actin and myosin were examined by specific immunofluorescence in a series of normal, simian-virus-40-transformed, and revertant cell lines of rat and mouse origin. A consistent correlation was found between sensitivity to anchorage-dependent growth control and the presence of large, thick sheaths of actin-containing material. The presence of these sheaths was temperature-dependent in a rat line transformed by a temperature-sensitive mutant in the complementation group A of the oncogenic virus simian virus 40.

Isolation and characterization of revertant cell lines. VII. DNA synthesis and mitotic rate of serum-sensitive revertants in non-permissive growth conditions

The ability to synthesize DNA and enter mitosis was studied in Balb/c and Swiss 3T3 cells, SV40 and MSV-transformed 3T3 cells and revertants of these transformed cells in cultures of different serum concentrations and cell densities. Three ways were found by which cells were able to maintain a constant cell number in non-permissive growth conditions: cessation of DNA synthesis, synthesis of DNA coupled with failure to enter mitosis, and the slow traverse of the cell cycle coupled with cell shedding. Growth control of the revertant of an MSV-transformed Balb/3T3 cell most closely resembled that of Balb or Swiss 3T3. This line did not grow in 1% serum and did not synthesize DNA in either non-permissive condition. Serum-sensitive revertants of SV40-transformed 3T3 cells are also unable to grow in 1% serum and also do not grow beyond confluence in 10% serum, but these cells differ from 3T3 in the manner in which this growth arrest is accomplished. In 1% serum, revertants synthesize DNA but do not enter mitosis. At confluence in 10% serum, they slowly traverse the cell cycle, with dividing cells replacing cells that are shed into the medium.

Antibody against tuberlin: the specific visualization of cytoplasmic microtubules in tissue culture cells

Cytoplasmic microtubules in tissue culture cells can be directly visualized by immunofluorescence microscopy. Antibody against tubulin from the outer doublets of sea urchin sperm flagella decorates a network of fine cytoplasmic fibers in a variety of cell lines of human, monkey, rat, mouse, and chicken origin. These fibers are separate and of uniform thickness and are seen throughout the cytoplasm. The fibers disappear either in a medium containing colchicine or after subjection of the cells to low temperature. The same treatments do not destroy the microfilamentous structures that are visualized by means of antibody against actin. When tryspin-treated enucleated cells are replated and then stained with antibody against tubulin, the fibers can be seen to traverse the entire enucleated cytoplasm.

Isolation and characterization of revertant cell lines. VI. Susceptibility of revertants to retransformation by simian virus 40 and murine sarcoma virus

The susceptibility of two classes of revertants of Simian virus 40 (SV40)-transformed 3T3 cells to retransformation by SV40 or murine sarcoma virus (MSV) was studied. Both serum-sensitive and density-sensitive revertants are not retransformable by SV40. MSV can transform both types of revertants. The MSV-transformed revertants grow to high cell densities and form colonies when suspended in semi-solid methylcellulose medium, but are unable to grow in 1% calf serum. The MSV-transformed revertants produce infectious MSV and murine leukemia virus and possess the same number of chromosomes as the untransformed revertants.

Plasminogen activator production accompanies loss of anchorage regulation in transformation of primary rat embryo cells by simian virus 40

We have isolated several lines of rat embryo cells transformed by simian virus 40. All these lines are fully transformed with regard to saturation density and serum sensitivity, but they differ greatly in their anchorage dependence, as assayed by efficiency of plating in methyl cellulose suspension. This set of lines reveals a consistent relation of plasminogen activator production to plating efficiency in methyl cellulose. T-antigen-positive transformed lines that synthesize activator grow in methyl cellulose suspension, while T-antigen-positive transformed lines that do not synthesize activator fail to form colonies in suspension. Normal rat embryo cells produce very little plasminogen activator and do not grow in methyl cellulose. Sera that permit high levels of plasmin formation and activity support growth in semi-solid medium better than sera whose plasminogen is activated poorly and/or sera that contain inhibitors to plasmin.