Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BALB 3T3 Cells”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1988

Transformation of Balb 3T3 cells by the BNLF-1 gene of Epstein-Barr virus.

The BNLF-1 protein is the only non-nuclear Epstein-Barr virus (EBV) encoded protein that has been detected in B-lymphocytes immortalized by EBV. We demonstrate that the BNLF-1 gene induces anchorage-independent growth and tumorigenic transformation of the murine cell-line, Balb/3T3. This demonstration extends the earlier observation that the BNLF-1 gene can transform Rat-1 cells. In addition we find that the BNLF-1 protein is located in the particulate fraction of cells, is phosphorylated, and is turned over with a half-life of 2.0 to 3.5 h in the BNLF-1 transformed Balb/3T3 cells, just as it is in EBV-genome-positive B-cell-lines.

Animals↗
PubMed1988

Generation of myc/fos transfectant Balb-3T3 cell lines.

Early and transient expression of proto-oncogenes c-fos and c-myc is involved in the mitogenic response to PDGF (platelet-derived growth factor). We used DNA-mediated transfection to approach the role played by these genes in cell growth control by PDGF and in growth deregulation (neoplasia). Cloned pFBJ-2 (v-fos) and glucocorticoid-inducible mouse c-myc were co-transfected with a neo genetic marker to allow a neutral selection on the basis of resistance to the neomycin derivative geneticin G418. pFBJ-2 transfection was found to interfere with the number of G418-resistant (G418r) colonies. By using a v-fos-deleted pFBJ-2 construct, the deleterious effect was attributed to v-fos coding sequences. Cellular fos gene disruption, by homologous recombination with exogenous v-fos, is proposed as the basis for the deleterious effect. Co-transfection with MMTV-H3-c-myc effectively counteracts the negative effects of v-fos. Different from the parental line or single myc or fos transfectants, double myc/fos transfectants are morphologically transformed. Double transfectants still retain the PDGF requirement for growth in monolayer cultures.

Animals↗
PubMed2003

Smad proteins regulate transcriptional induction of the SM22alpha gene by TGF-beta.

Smad proteins transduce signals from transforming growth factor-beta (TGF-beta) receptors and regulate transcription of target genes. TGF-beta is implicated in the regulation of the smooth muscle cell specific gene SM22alpha, but little is known about how Smads are involved in SM22alpha gene transcription. In this report, we demonstrate that TGF-beta activation of the SM22alpha promoter is Smad dependent in C3H10T1/2 cells, BALB 3T3 cells and neural crest Monc-1 cells. We find that the promoter region from -162 to +41 is sufficient to up-regulate the reporter gene upon TGF-beta induction. Smad3, Smad1 and Smad4 are found in TGF-beta inducible complexes that bind to a region containing a Smad binding site (SBS) and a medea box. Both the SBS and medea box are necessary for complex formation and are functionally important. Smad4 is limiting for TGF-beta induction, and Smad3, but not Smad1, significantly contributes to maximal activation. Time course luciferase assays and time course gel mobility shift assays reveal that the Smad3/4 complex is largely responsible for the immediate response of the SM22alpha promoter to TGF-beta induction, and also contributes to the maximal promoter activity. We further demonstrate that AP-1 elements contribute to induction of the SM22alpha promoter by TGF-beta.

3T3 Cells↗
PubMed2002

Glucocorticoids modulate transformation by v-Src in a cell-specific manner.

In Balb 3T3 murine fibroblasts infected with retroviruses carrying the v-src oncogene, treatment with the glucocorticoid hormone dexamethasone induces a 10-fold increase in the number of transformed foci and of anchorage-independent colonies. In contrast, in NIH-3T3-infected cells the number of foci and of colonies growing in soft agar is considerably reduced by the addition of the hormone. The effect of dexamethasone on both Balb 3T3 and NIH 3T3 cells is dose-dependent and mediated by specific receptors. The expression of glucocorticoid receptors as well as transactivation of a mouse mammary tumor virus promoter in the presence of dexamethasone is comparable in the two cell lines. Dexamethasone does not change the expression and kinase activity of v-Src proteins either in freshly infected Balb 3T3 and NIH 3T3 cells or in morphologically normal clones or in transformed foci derived from infected Balb 3T3 cells stably expressing v-Src. However, in cocultivation assays of phenotypically normal clones of v-Src expressing Balb 3T3 cells mixed with a large excess of parental Balb 3T3 cells, the hormone is able to rescue the ability to form transformed foci of these otherwise normal cells. The present data point out a new role of glucocorticoid hormones in controlling transformation in a cell-specific manner through epigenetic mechanisms.

3T3 Cells↗
PubMed1986

Visualisation, by immunocytochemistry, of p53 at the plasma membrane of both nontransformed and SV40-transformed cells.

The cellular protein p53 normally functions in the control of cell proliferation; but, when expressed abnormally p53 also contributes towards the process of cell transformation. The functioning of p53 is thought to involve interaction with specific cellular targets and, in SV40- and other transformed cells, p53 is located in the nucleus: thus p53 may function via interacting with specific nuclear components. In addition, there is indirect evidence that in SV40-transformed cells p53 is also associated with the plasma membrane; however, this is not evident in cells stained by immunofluorescence. We have sought to obtain direct evidence for p53 at the plasma membrane by staining with a very sensitive immunocytochemical procedure. We have compared SV40-transformed BALB 3T3 cells with BALB 3T3, NIH 3T3, and NIH 3T3 transfected with v-mos provirus. The last cell line is tumorogenic. We found direct evidence for p53 at the plasma membrane for each cell line. In nontransformed and SV40-transformed cells the association of p53 with the plasma membrane was restricted to the period of mitosis. These results indicate that association of p53 with the plasma membrane is a normal, rather than a transformation-related phenomenon, and is temporally linked to the period of mitosis.

Animals↗
PubMed1979

Binding, internalization, and degradation of epidermal growth factor by balb 3T3 and BP3T3 cells: relationship to cell density and the stimulation of cell proliferation.

Epidermal growth factor (EGF) stimulates the growth of both benzo[a]pyrene-transformed Balb 3T3 cells (BP3T3) and untransformed Balb 3T3 cells. We describe here the binding, internalization, and degradation of [125I]-EGF by BP3T3 cells and 3T3 cells. Binding of [125I]-EGF reaches a maximum after 45 to 90 minutes incubation at 37 degrees C. In both BP3T3 and 3T3 cells the extent of EGF binding required to stimulate DNA synthesis is density dependent; sparse cultures require a 15-30% occupancy to elicit a maximal response whereas dense cultures require a 70-85% occupancy. At physiological concentrations the total binding of [125I]-EGF to 3T3 cells is higher than to BP3T3 cells, and this difference increases at higher cell densities. The rate of degradation of [125I]-EGF is directly proportional to the total [125I]-EGF binding in each cell type. This supports the hypothesis that one cause of the diminished serum requirement of BP3T3 cells is a reduced rate of utilization of serum growth factors.

Animals↗
PubMed1996

Gastrin-releasing peptide receptor signaling resulting in growth inhibition.

We demonstrate that gastrin-releasing peptide (GRP) can inhibit the proliferation of human immortal nontumorigenic (184-B5) mammary epithelial cells ectopically expressing the human GRP receptor. Growth of Balb 3T3 cells ectopically expressing relatively high levels of the GRP receptor was also inhibited by GRP; however, growth of transfectants expressing lower levels of the receptor was not inhibited. Compared with Balb 3T3 cells, mammary epithelial cells could be rendered sensitive to growth inhibition by GRP by the expression of fewer GRP receptors. GRP also stimulated DNA synthesis in quiescent, serum-starved Balb 3T3 transfectants. In clones that were sensitive to growth inhibition by GRP by virtue of their expression of relatively high levels of the GRP receptor, the dose-response curve of GRP-stimulated DNA synthesis was bell shaped. This is consistent with our conclusion that the growth-inhibiting activity of GRP required the activation of a relatively large pool of receptors in Balb 3T3 cells. Significantly, prostaglandin H synthase inhibitors, which block the production of prostaglandins from arachidonic acid, reduced GRP-inhibitory effects on DNA synthesis. We also compared a number of GRP-stimulated signaling pathways in Balb 3T3 clones that were sensitive or insensitive to growth inhibition by GRP, including cAMP formation, phospholipase C activation, calcium mobilization, and arachidonic acid formation. Taken together, these results demonstrate a novel GRP receptor-coupled signal pathway promoting growth inhibition in which prostaglandin H synthase plays a significant role.

3T3 Cells↗
PubMed2003

The PLC-PKC cascade is required for IL-1beta-dependent Erk and Akt activation: their role in proliferation.

We investigated the signaling mechanisms that lead to IL-1beta-induced cell proliferation. Treatment of Balb 3T3 cells with IL-1beta activated two signaling pathways, Erk and Akt. IL-1beta also increased tyrosine phosphorylation of PLC-gamma in Src kinase-dependent manner. Pharmacological inhibition of the PLC-PKC cascade by using specific inhibitor for PLC-gamma (U73122) and PKC (GFX) strongly inhibited IL-1beta-induced Erk and Akt activation. Inhibition of MEK1 by its specific inhibitor, PD98059 substantially inhibited Erk activation. Similarly, inhibition of PI3K activation by its specific inhibitor LY294002 suppressed Akt phosphorylation. Moreover, IL-1beta-induced association of PLC-gamma with SHPS-1. SHPS-1 mutants lacking the tyrosine phosphorylation sites failed to associate with PLC-gamma. Finally, IL-1beta-induced proliferation of Balb 3T3 cells and inhibition of Erk and Akt signalings or their upstream signaling molecules, Src kinase and PKC by their inhibitors strongly inhibited IL-1beta-dependent cell proliferation. Taken together, our results suggest that a SHPS-1-PLC-gamma complex activate the PLC-PKC cascade, which is required for the activation of IL-1beta-dependent Erk and Akt signalings and cell proliferation.

Animals↗
PubMed1973

Contact-inhibited revertant cell lines isolated from SV 40-transformed cells. IV. Microfilament distribution and cell shape in untransformed, transformed, and revertant Balb-c 3T3 cells.

A COMPARISON IS MADE OF THE ULTRASTRUCTURE OF THE CELL PERIPHERY IN THREE CLONED CELL LINES: untransformed Balb/c 3T3 cells, SV40-transformed Balb/c 3T3 cells, and revertant cells obtained from the transformed cell line by a selection technique utilizing concanavalin A. Both thin-section and surface replication techniques are used for in situ examination of the cell lines. Microfilaments, 70 A in diameter (called alpha filaments), are abundant in untransformed and revertant cell lines, particularly in the anterior expansions of the cells, which tend to have many microvilli and small pseudopodia. Alpha filaments are diminished in the anterior expansions of transformed cells, which contain large blunt pseudopodia and relatively few microvilli. Surface replicas confirm the impression gained from thin sections that transformed cells have a greater proportion of their cell surface involved in bulging pseudopodia than either untransformed or revertant cells. Since alpha filaments are shown to bind heavy meromyosin and are similar to F-actin, these filaments are thought to be important in cell motility. These observations suggest that a close relationship exists between decreased alpha filaments, bulging pseudopodia, and loss of contact inhibition of movement in transformed cells.

Aneuploidy↗
PubMed1993

Paracrine induction of angiogenesis in vitro by Swiss 3T3 fibroblasts.

During angiogenesis, normally quiescent endothelial cells that line existing microvessels are induced to invade the surrounding extracellular matrix and to form capillary sprouts in response to paracrine factors released by neighboring cell types. In an attempt to mimic the physiological conditions under which angiogenesis is triggered in vivo, we have designed two co-culture systems that are suitable for the study of paracrine interactions between microvascular endothelial cells and cell types that might produce angiogenic factors. In the first model, cells to be co-cultured with endothelial cells were suspended within a collagen gel and overlaid with an additional collagen gel devoid of cells, onto which bovine microvascular endothelial cells were subsequently seeded and grown to confluence. In the second model, a small collagen gel disc containing a suspension of endothelial cells was embedded into a larger, cell-free collagen gel disc, which in turn was surrounded by an annular collagen gel containing other cell types. We show that Swiss 3T3 fibroblasts and their 3T3-L1 substrain induce the formation of capillary-like tubes by endothelial cells in these co-culture systems, whereas Balb 3T3 cells, as well as a number of other fibroblasts and epithelial cells, lack this ability. Thus, endothelial cells grown on a collagen gel containing Swiss 3T3 or 3T3-L1 cells invaded the underlying matrix to form a network of interconnecting tubules. In addition, Swiss 3T3 and 3T3-L1 cells stimulated extensive radial outgrowth of tubular sprouts from the periphery of endothelial-cell-containing collagen discs. Conditioned medium from Swiss 3T3 cells mimicked the effect of co-culture by inducing formation of capillary-like tubes, and also increased plasminogen activator activity in endothelial cells. Conditioned medium from Balb 3T3 cells, in contrast, lacked these activities. Preliminary evidence suggests that the factor(s) in Swiss 3T3 conditioned medium that induces tubule formation by endothelial cells may be different from a number of well-characterized angiogenic cytokines. The co-culture systems described here should prove to be useful for the identification of physiological regulators of angiogenesis produced by various cell types.

3T3 Cells↗
PubMed1984

The purification of an acid- and heat-labile transforming growth factor from an avian sarcoma virus-transformed rat cell line.

A new class of transforming growth factor (TGF), with chemical characteristics differing from previously reported TGFs, was isolated and purified from an avian sarcoma virus-transformed rat cell line, 77N1 . Purification steps were simple and consisted of ion-exchange chromatography on diethylaminoethyl (DEAE)-Sephacel, ammonium sulfate precipitation, Chromatofocusing, and DEAE-Sephadex A-25 chromatography. The purified TGF is a heat- and acid-labile protein with a molecular mass of 12,000 daltons and isoelectric point of 5.2-5.4. Because of the acid lability of this TGF, purification was carried out at neutral pH. The TGF induced DNA synthesis in growth-arrested BALB 3T3 cells and promoted anchorage-independent growth of nontransformed BALB 3T3 cells in soft agar; the latter activity is specific for the peptide growth factors, called TGFs, but it did not compete with epidermal growth factor (EGF) for binding to the EGF membrane receptors. The TGF activity was not potentiated by EGF. The purified preparation of the TGF stimulated BALB 3T3 cells to grow progressively in soft agar at a dose of 20 ng/ml.

Amino Acids↗
PubMed1993

Single channel study of a Ca(2+)-activated K+ current associated with ras-induced cell transformation.

1. Ras-transformed fibroblasts have a whole-cell Ca(2+)-activated K+ current which is either absent or unavailable for activation in their non-transformed counterparts. To better understand the physiological significance of this K+ current the single channel basis for the current was characterized in ras-transformed cells. 2. More than 90% of inside-out patches from ras-transformed balb 3T3 cells had a channel type which was Ca(2+)-activated (threshold < 0.2 microM internal Ca2+), K(+)-selective (permeability ratio PNa:PK < 0.02), and inwardly rectifying in symmetric 150 mM KCl solutions (conductances at -60 and 60 mV of 33 +/- 1 and 17 +/- 1 pS respectively). Channel opening probability increased 25-50% between -60 and 60 mV due to an increase in the frequency of opening. Single K+ channels in outside-out patches were blocked by externally applied 10 mM TEA or 100 nM charybdotoxin, as were whole-cell Ca(2+)-activated K+ currents. The properties of this class of K+ channel are sufficient to account for the whole-cell Ca(2+)-activated current in ras-transformed cells. 3. Inside-out patches from C3H10T1/2 and NIH 3T3 fibroblasts transformed by the H-ras oncogene had Ca(2+)-activated K+ channels identical to those observed in K-ras-transformed balb 3T3 cells. 4. As predicted from whole-cell experiments Ca(2+)-activated K+ channels were not observed in inside-out patches from non-transformed balb 3T3 cells. The purpose of the excised patch recordings was, instead, to rule out potential technical complications with the whole-cell experiments. For instance A23187, which evoked whole-cell K+ currents in transformed cells, may not have elevated Ca2+ sufficiently to allow K+ channel activation in non-transformed cells. Another possibility was that trypsin pretreatment used to round-up cells for whole-cell recording may have preferentially disabled channels in non-transformed cells. The first problem was addressed by exposing patches from non-transformed cells to 100-1000 microM Ca2+. Excised patches were also taken from non-transformed cells which had not been exposed to trypsin. K+ channel activity was not observed under either condition. 5. Patches from both ras-transformed and non-transformed cells had a type of non-specific cation channel which was activated at internal Ca2+ concentrations > or = 100 microM. This channel was sensitive to membrane voltage, mean open time increasing from 12 to 72 ms between -90 and 90 mV.

Animals↗
PubMed1985

Cyclic AMP-independent processes mediate Kirsten sarcoma virus-induced changes in collagen production and other properties of cultured cells.

Previous studies suggested that the decreased collagen production observed in Kirsten sarcoma virus (Ki-MSV)-transformed BALB 3T3 cells could be reversed by treating cells with Bt2cAMP. We examined the relationship between intracellular cAMP, collagen production, and other properties in NRK and BALB 3T3 cells transformed by Ki-MSV. Two 3T3 transformants (Ki-3T3-234 and Ki-3T3Cl1) had lower cAMP levels than nontransformed cells. The level in a temperature-sensitive transformant, tsKi-3T3-714, was similar to the level in its parent, 3T3-714, and when it was shifted to a temperature nonpermissive for transformation (40 degrees C), intracellular cAMP did not increase although the growth and morphological properties were normal. The relative rate of collagen production also increased to the normal level. These results indicate that transformation-induced changes were regulated independently of cAMP. Further observations supported this conclusion. Intracellular cAMP in a flat revertant of Ki-3T3Cl1 was lower, rather than higher, than in the transformant, although the relative rate of collagen production was higher. Treatment of Ki-3T3-234 and tsKi-3T3-714 with cholera toxin plus isobutylmethylxanthine increased intracellular cAMP concentrations to 2-20 times the level in untreated cells, levels much higher than in nontransformed 3T3. In spite of this, collagen production was not increased by these agents in tsKi-3T3-714 and it was only partially restored in Ki-3T3-234 relative to the level in the nontransformed cells. In contrast, these agents inhibited growth on a substratum or in soft agar and produced a flattened morphology in both lines. Similarly, collagen production in transformed NRK cells (K-NRK) was only 3% of normal but treatment with Bt2cAMP or cholera toxin plus isobutylmethylxanthine increased production to only one-third the normal level while increasing cAMP to four times the normal level. We conclude that in Ki-MSV-transformed BALB 3T3 cells, changes in cAMP may be secondary effects and not related to maintenance of the transformed phenotype. The high levels of cAMP induced by exogenous agents may act on similar targets as those affected by transformation, but reversal of the transformed phenotype by these agents probably occurs by a different mechanism than that originally used to impose the changes.

1-Methyl-3-isobutylxanthine↗
PubMed1979

Quantitative biochemical analysis of microtubule content in normal and transformed 3T3 cells.

Microtubules in normal and transformed BALB 3T3 cells were preserved in a stabilizing medium and measured by a [3H]colchicine-binding tubulin assay, and compared to total cellular tubulin measured under nonstabilizing conditions. Essentially no change in tubulin or microtubule content was seen with changes in cell density or with changes in cellular morphology at various stages of growth of normal or transformed cells or induced by dibutyryl cAMP treatment of transformed cells. Of five cell lines transformed by a variety of agents, four had a significantly higher total tubulin content than untransformed 3T3 cells and all of them had an increased microtubule content. None of the transformed lines had a lower fraction of tubulin recoverable as sedimentable microtubules compared to untransformed cells, and in three of them this fraction was significantly higher. These results establish that microtubules are present in transformed cells to at least the extent (if not greater) than in normal cells but that there are variations in the total amount of tubulin and microtubules as well as the fraction of the total tubulin present as microtubules which are not strictly correlated with transformation or cell morphology.

Animals↗
PubMed1976

Guanylate cyclase and cyclic guanosine 3':5'-monophosphate phosphodiesterase activities and cyclic guanosine 3':5'-monophosphate levels in normal and transformed fibroblasts in culture.

To investigate the role of guanosine 3':5'-monophosphate (cyclic GMP) in cultured cells we have measured guanylate cyclase and cyclic GMP phosphodiesterase activities and cyclic GMP levels in normal and transformed fibroblastic cells. Guanylate cyclase activity is found almost exclusively in the particulate fraction of normal rat kidney (NRK) and BALB 3T3 cells. Enzyme activity is stimulated 3- to 10-fold by treatment with the detergent Lubrol PX. However, enhancement of guanylate cyclase by fibroblast growth factor could not be demonstrated under a variety of assay conditions. In both NRK and BALB 3T3 cells guanylate cyclase activity is low during logarithmic growth and increases as the cells crowd together and growth slows. Guanylate cyclase activity is undetectable in homogenates of NRK cells transformed by the Kirsten sarcoma virus (KNRK cells) either in the presence or absence of Lubrol PX. Guanylate cyclase activity is also greatly decreased in NRK cells transformed by Moloney, Schmidt-Ruppin, or Harvey viruses. BALB 3T3 cells transformed by RNA viruses (Kirsten, Harvey, or Moloney), by a DNA virus (SV40), by methylcholanthrene, or spontaneously, all have diminished but readily detectable guanylate cyclase activity. Cyclic GMP phosphodiesterase activity is found predominately in the soluble fraction of NRK cells. This activity increases slightly as NRK cells enter the stationary growth phase. Cyclic GMP phosphodiesterase activity is undetectable in two clones of KNRK cells under a variety of assay conditions, and is decreased relative to the level present in NRK cells in a third KNRK clone. However, both Moloney- and Schmidt-Ruppin-transformed NRK cells have a phosphodiesterase activity similar to that found in NRK cells. Boiled supernatant from both NRK and KNRK cells is observed to appreciably enhance the activity of activator-deficient phosphodiesterase from bovine heart. This result indicates that the absence of cyclic GMP phosphodiesterase activity in KNRK cells is not due to a loss of the phosphodiesterase activator. The intracellular concentration of cyclic GMP is found to be very low in transformed NRK cells when compared to levels measured in confluent NRK cells. The low levels of cyclic GMP in transformed NRK cells reflect the greatly decreased guanylate cyclase activity observed in these cells. These results do not appear to support the suggestion that cyclic GMP promotes the growth of fibroblastic cells.

Cell Line↗
PubMed1998

Metabolism and metabolic actions of 6-methylpurine and 2-fluoroadenine in human cells.

Activation of purine nucleoside analogs by Escherichia coli purine nucleoside phosphorylase (PNP) is being evaluated as a suicide gene therapy strategy for the treatment of cancer. Because the mechanisms of action of two toxic purine bases, 6-methylpurine (MeP) and 2-fluoroadenine (F-Ade), that are generated by this approach are poorly understood, mechanistic studies were initiated to learn how these compounds differ from agents that are being used currently. The concentration of F-Ade, MeP, or 5-fluorouracil required to inhibit CEM cell growth by 50% after a 4-hr incubation was 0.15, 9, or 120 microM, respectively. F-Ade and MeP were also toxic to quiescent MRC-5, CEM, and Balb 3T3 cells. Treatment of CEM, MRC-5, or Balb 3T3 cells with either F-Ade or MeP resulted in the inhibition of protein, RNA, and DNA syntheses. CEM cells converted F-Ade and MeP to F-ATP and MeP-ribonucleoside triphosphate (MeP-R-TP), respectively. The half-life for disappearance of HeP-ribonucleoside triphosphate from CEM cells was approximately 48 hr, whereas the half-lives of F-ATP and ATP were approximately 5 hr. Both MeP and F-Ade were incorporated into the RNA and DNA of CEM cells. These studies indicated that the mechanisms of action of F-Ade and MeP were quite different from those of other anticancer agents, and suggested that the generation of these agents in tumor cells by E. coli PNP could result in significant advantages over those generated by either herpes simplex virus thymidine kinase or E. coli cytosine deaminase. These advantages include a novel mechanism of action resulting in toxicity to nonproliferating and proliferating tumor cells and the high potency of these agents during short-term treatment.

3T3 Cells↗