SEARCH · Search PubMed

Results for “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.

SourceResearch connectionFrom yearThrough year

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

At least 37 records · Page 2Linked to original sources

PubMed1979

Increase in plasma membrane phosphodiesterase activity in contact-inhibited 3T3 cells and in phenotypically reverted SV-3T3 cells.

Contact-inhibited 3T3 mouse fibroblast cells, in contrast to logarithmically growing 3T3 cells and SV-3T3 transformed cells, have increased levels of plasma membrane-bound phosphodiesterase (oligonucleotidase, E.C.3.1.4.19; nucleotide pyrophosphatase, E.C. 3.6.1.9) activity. The increase in enzyme, recorded as increased specific activity, is reversible, as evidenced by the return to normal values following dilution of confluent 3T2 cells and re-initiation of growth. Increased enzyme activity is induced again when the cells regain the confluent state. Transformed SV-3T3 cells can be induced to mimic the contact inhibited state, including increased plasma membrane phosphodiesterase activity, by exposure to a combination of: (i) agents that are known to induce increased intracellular cAMP levels and (ii) additions of purified 3T3 or SV-3T3 plasma membranes. Additions of either alone fails to induce the increase in membrane phosphodiesterase activity, although each alone can significantly suppress cell growth, as measured by incorporation of 3H amino acids. We suggest that the elevation of plasma membrane phosphodiesterase activity may serve as a measure of conversion to the contact-inhibited state in both normal cells and phenotypically reverted transformed cells.

Animals↗

PubMed1977

The isolation of tubulin and actin from mouse 3T3 cells transformed by simian virus 40 (SV3T3 cells), an established cell line growing in culture.

Tubulin can be purified from mouse SV3T3 cells (3T3 cells transformed by SV40 virus) by several cycles of temperature-dependent polymerization and depolymerization. Electron microscopical analysis of the final product reveals morphologically normal microtubules. Homogeneous actin can be isolated as a byproduct of the purification procedure. Mouse SV3T3 actin and skeletal muscle actin were compared by fingerprint analysis of the tryptic peptides obtained from performic-acid-oxidized protein. The two actins show a high degree of homology although apparently five of the twenty-five spots visualized by fluorescamine show a difference in chromatographic mobility. The purification procedure described allows the rapid isolation of both actin and tubulin from tissue culture in sufficient amounts for comparative biochemicals studies.

Actins↗

PubMed1976

The decreased synthesis of chondroitin sulfate-containing extracellular proteoglycans by SV40 transformed Balb/c 3T3 cells.

Balb/c 3T3 cells synthesize 5--10 times more 35SO2/4- -labeled extracellular proteoglycan per cell than do Balb/c 3T3 cells transformed by SV40 (SV3T3). The extracellular 35SO2/4- -labeled proteoglycans of the Balb/c 3T3 and SV3T3 cells differ markedly in their acid mucopolysaccharide composition. Extracellular Balb/c 3T3 proteoglycans contain about 70--80% chondroitin sulfate, most of which is chondroitin 4-sulfate, and small amounts of heparan sulfate and/or heparin. On the other hand, extracellular SV3T3 proteoglycans contain 65-75% heparan sulfate and/or heparin and less than 15% chondroitin sulfate. Analysis of extracellular 35SO2/4- -labeled proteoglycan by sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals that Balb/c 3T3 alone synthesizes a class of proteoglycans capable of migrating in a 10% separating gel. This class of proteoglycans, designated as fraction C, accounts for up to 45% of the total extracellular Balb/c 3T3 35 SO2/4- -labeled proteoglycans and contains chondroitin sulfate extracellular SV3T3 proteoglycans. The absence of this and other classes of chondroitin sulfate-containing proteoglycans can account for the 5-10-fold decreased synthesis of 35SO2/4- -labeled proteoglycans by SV3T3 cells when compared to Balb/c 3T3 cells.

Cell Line↗

PubMed1978

Phagocytosis of latex particles in relation to the cell cycle in 3T3 cells.

Cultures of 3T3 cells, synchronised by serum deprivation, were shown to phagocytose latex beads of 0.81 micrometer diameter more avidly in the G1 phase of the cell cycle. The maximum rate of about 0.12 particles/cell/hour was recorded 12 h after stimulation with 10% fetal bovine serum. After 24 h, when mitosis was beginning, the uptake fell to just above the unstimulated level of 0.06 particles/cell/hour. Exocytosis was linear and only 7% of the total cell-associated latex was released in 30 h. Internalisation of latex beads was demonstrated by electron microscopy. No uptake was detected in experiments conducted at 4 degrees C.

Cell Cycle↗

PubMed1983

Microtubule-organizing centres during the cell cycle of 3T3 cells.

When Swiss 3T3 cells are treated with colcemid for 60 min (0.5-2 micrograms/ml), although the cytoplasmic network of microtubules is considerably reduced, a significant but variable number of microtubules remain. These residual microtubules appear to converge on a single, usually ciliated, organizing centre. In contrast, on removal of the colcemid, microtubule regrowth takes place from two organizing centres in approximately 50% of the cells. Surprisingly, whether a cell has one or two organizing centres during recovery does not depend on its position in the cell cycle, though recovery takes place earlier in serum-stimulated cells than in serum-starved quiescent ones. It seems likely that prior to colcemid treatment, cells contain two potential organizing centres only one of which is normally active, the inactive one becoming active after exposure to the drug.

Autoradiography↗

PubMed1993

Identification of AT2 angiotensin receptors on Swiss 3T3 cells.

Swiss 3T3 cells express high-affinity receptors for angiotensin II (KD = 0.8 nM, 110,000 receptors/cell). Binding of the peptide to these receptors did not activate phosphatidylinositol 4,5 bisphosphate hydrolysis, and did not increase intracellular [Ca2+] or activate protein kinase C. The relative binding affinities of highly-selective antagonists characterised these receptors as the AT2 subtype. However, in contrast to the signalling events reported in some other cells that express AT2 receptors, AII had no apparent effect on either cyclic GMP levels or phosphotyrosine phosphatase activity in Swiss 3T3 cells. Furthermore, angiotensin II (either alone or in combination with growth factors) was not mitogenic to Swiss 3T3 cells.

3T3 Cells↗

PubMedDate not supplied

Density-dependent growth adaptation kinetics in 3T3 cell populations following sudden [Ca2+] and temperature changes. A comparison with SV40-3T3 cells.

Lowered extracellular [Ca2+] cause low growth rates and low stationary cell densities in 3T3 cell cultures as compared to physiological [Ca2%]. Under otherwise constant conditions the extracellular [Ca2+] determines a stable stationary cell density, which can be reached by increase of net cell number or decrease of net cell number, depending on cell density at the time of [Ca2+] adjustment. SV40-3T3 cells do not show this [Ca2+] dependency. At 39 degrees C 3T3 and SV40-3T3 cell populations show an increased growth rate at low cell densities as compared to cell populations at 35 degrees C. Approaching the stationary density the growth rate of both cell sorts is reduced faster at 39 degrees C than at 35 degrees C, leading to lower stationary cell densities at 39 degrees C than at 35 degrees C. A temperature change from 39 degrees C to 35 degrees C or in the opposite direction can affect the stationary cell density of 3T3 cell populations only if applied before reduction of growth rate by density-dependent growth-inhibiting principles has taken place.

Animals↗

PubMed1986

Inhibition of Na+ flux in Chinese hamster ovary cells and Swiss 3T3 cells by a potent new derivative of amiloride, methylisopropyl-amiloride.

Amiloride inhibits the mitogen-stimulated Na+ influx of cultured fibroblasts with very low affinity. We have therefore analyzed eight new derivatives of amiloride for their efficacies of inhibiting the Na+ flux in Chinese hamster ovary cells (CHO-K1). Four of these analogs demonstrate markedly enhanced potencies relative to amiloride. One of the derivatives, methylisopropyl-amiloride (MIA), is approximately 900-fold more potent (ID50 = 42 nM) than amiloride in inhibiting Na+ uptake of these cells. Inasmuch as external Na+ ions antagonize amiloride inhibition of Na+ influx competitively, we investigated the ability of MIA to inhibit Na+ flux in the absence of external Na+ ions. The ID50 value determined for MIA inhibition of CHO-K1 cell Na+ efflux from Na+-loaded cells into Na+-free media is 15 nM. We also examined the efficacy of MIA for Na+ efflux inhibition in a nontransformed fibroblast cell line, Swiss 3T3. The ID50 value for inhibition of Na+ efflux from 3T3 cells is comparable to that for CHO-K1 cells. Thus, we have identified a highly potent derivative of amiloride, MIA, that inhibits Na+ flux at nanomolar concentrations in both a transformed and a nontransformed cell line. It is possible that MIA may serve as a useful tool for biochemical characterization of the mitogen-stimulated Na+ transporter and for assessment of the role of this transporter in mitogenesis.

Amiloride↗

PubMed1997

Interleukin-1beta-induced expression of protein kinase C (PKC)-delta and epsilon in NIH 3T3 cells.

NIH 3T3 cells express the alpha, delta, epsilon and zeta isoenzymes of protein kinase C(PKC). Following stimulation of cells (24 h) with the pro-inflammatory cytokine, interleukin 1beta (IL-1beta), we observed, by Western blotting, a dose-dependent effect on the levels of PKC-epsilon and delta, but not on alpha or zeta. Moreover, time course analysis revealed that the isoenzymes, PKC-delta and epsilon were induced by IL-1beta after 7 h. Again, no change in PKC-alpha or zeta levels after IL-1beta treatment were detected. Incubation with selective PKC inhibitor peptides blocked the PKC-alpha, delta, epsilon and zeta antibodies binding to their respective isoenzyme bands. We also observed that the addition of the tumour-promoting phorbol ester, Phorbol 12-myristate 13-acetate (PMA), downregulated PKC-alpha, delta and epsilon by 7 h in NIH 3T3 cells. PMA did not affect constitutively produced PKC-zeta protein levels even after 24-h treatment. In summary, these results demonstrate that IL-1beta induces protein synthesis of the Ca2+-independent PKC-delta and epsilon isoforms in NIH 3T3 cells. The differences observed here between PKC isoenzymes in response to IL-1beta suggest that each isoenzyme may have a unique role in the signal transduction pathways of IL-1beta and that such isoenzyme may have a unique role in the signal transduction pathways of IL-1beta and that such selective expression may influence the action of agents which require PKC for signal transduction acting in concert with IL-1.

3T3 Cells↗

PubMed1984

Inhibition of cell communication between Balb/c 3T3 cells by tumor promoters and protection by cAMP.

The effect of phorbol ester tumor promoters on the communication between individual cells in confluent culture was studied using a fluorescent dye transfer method. Cell-cell communication between mouse Balb/c 3T3 cells and between Chinese hamster V79 cells was inhibited almost completely by tumor-promoting phorbol esters, but not by nonpromoting derivatives; the effect was reversed upon removal of the promoter. Intercellular communication between Balb/c 3T3 cells, but not Chinese hamster V79 cells, was increased significantly in the presence of dbcAMP and caffeine, and these compounds counteracted the effects of tumor promoters. Inhibition of cell communication by phorbol esters appears to be receptor-mediated, since specific binding of 3H-phorbol-12,13-dibutyrate to Balb/c 3T3 cells was inhibited only by compounds that also inhibit intercellular dye transfer. A study with cycloheximide suggests that the reversible inhibition of intercellular communication by phorbol esters may not need de novo protein synthesis, while upregulation of communication by cAMP requires protein synthesis.

Animals↗

PubMed1989

Induction of blood coagulation factor VIII by sodium butyrate in Balb/c 3T3 cells.

Balb/c 3T3 cells have long been used in cell biological studies. When cells were treated with 2 mM sodium butyrate they became flattened and their nuclei became small relative to the cytoplasm. Electron micrographically, intracellular organellae developed significantly: the number of mitochondria increased and membranous structures, namely the rough-surfaced endoplasmic reticulum and Golgi apparatus, developed markedly. Blood coagulation factor VIII was induced in the presence of 2 mM sodium butyrate in a cell sonicate, but not in culture medium. The amount of this factor was almost 100-fold that in the nontreated cells 4 days after culture initiation, indicating that the cloned Balb/c 3T3 cells were of endothelial origin.

Animals↗

PubMed1990

Physiological induction and reversal of focus formation and tumorigenicity in NIH 3T3 cells.

NIH 3T3 cells undergo morphological transformation in response to conditions of constrained growth, such as occur in low serum concentrations or at confluence. Transformation is expressed in a small fraction of the cells by the appearance of discrete foci of multiplying cells on a confluent monolayer of quiescent cells. We isolated and expanded cell populations from three dense and three light foci. Cells from each of these populations efficiently reproduced foci of the same morphotype when grown on a background of nontransformed NIH 3T3 cells. Using cultures derived from one of the dense foci (subline D/2), we found that the number of focus-forming units was stable and the cells remained tumorigenic when they were subjected to repeated thrice-weekly passage in 2% calf serum. However, equivalent passage in 10% calf serum eventually rendered the cells incapable of both focus production and tumor formation. The results show that the capacity to produce tumors as well as morphological transformation are produced as a response to physiological constraints of growth and/or metabolism in the absence of carcinogens and that both properties can be reversed by lifting the constraints. This behavior is typical of an adaptational response and, taken together with other supporting evidence, shows that tumorigenesis does not require conventional genetic alteration.

Animals↗

PubMed1990

Enhanced expression of ganglioside GD3 in human and rat hepatocellular carcinoma cells and NIH 3T3 cells transfected with human tumor DNAs.

The gangliosides of human hepatoma biopsies, human hepatoma cell lines, and diethylnitrosamine-induced rat hepatomas were examined. These malignant tissues all expressed increased content of disialolactosylceramide (GD3) with respect to their normal counterparts. During the induction of rat hepatoma by diethylnitrosamine, an increase in GD3 levels appeared as early as 12 wk after initiation of diethylnitrosamine, concurrent with the appearance of precancerous hepatocytes. GD3 levels gradually increased to a peak of 4 times that of normal rat liver at 20 wk. CMP-NeuAc:GM3 sialyltransferase, the enzyme that synthesizes GD3 by transfer of sialic acid to GM3, also had tumor-associated elevation during the course of diethylnitrosamine-induction of rat hepatomas. To investigate the relationship of oncogene transformation and changes in ganglioside biosynthesis, NIH 3T3 cells transfected DNAs from human hepatoma or nasopharyngeal carcinoma were studied. The transfectants each expressed the same ganglioside composition, including a detectable level of GD3, as well as enhanced activity of CMP-NeuAc:GM3 sialyltransferase. A correlation between the tumor DNA transfection and the augmentation of GD3 in malignant cells is discussed. Because of the early appearance of GD3 in hepatoma and its possible relationship to oncogene activation, GD3 may be a potentially useful early tumor marker.

Animals↗

PubMed1989

Antisense RNA-induced reduction in murine TIMP levels confers oncogenicity on Swiss 3T3 cells.

Mouse 3T3 cell lines capable of constitutively synthesizing an RNA complementary to the messenger RNA encoding TIMP, tissue inhibitor of metalloproteinases, were constructed by transfection with appropriate plasmid constructs. Many of the lines were down-modulated for TIMP messenger RNA levels and secreted less TIMP into the culture medium. In comparison to noninvasive, nontumorigenic controls, these cells not only were invasive in a human amnion invasion assay, but also were tumorigenic and metastatic in athymic mice. These results indicate that TIMP suppresses oncogenicity, at least in immortal murine 3T3 cells.

Animals↗

PubMed1977

Surface exposure of glycosaminoglycans in resting, growing and virus transformed 3T3 cells.

Glycosaminoglycans (GAG's) were released by trypsin from the surface of cultured mouse cells (3T3) in two different growing states: during log-growth phase and during resting due to serum starvation. Doubly labelled molecules from resting cells were compared with those from growing as well as from trnsformed cells. Reproducible differences in the elution pattern during ion exchange chromatography and in susceptibility to specific hydrolytic enzymes have been demonstrated: the GAGs pattern of growing normal cells is similar to the pattern of the cells transformed by either Polyoma or SV-40 viruses and very different from the pattern of resting cells. Growing and transformed 3T3 show a relatively low amount of trypsin removable heparan sulphate (HS) and a relatively high amount of hyaluronic acid (HA) while resting cells exhibit an opposite ratio between the two GAG'S. The lowering of HS and the increase of HA in the cell coat is therefore suspected to be more dependent upon growth than upon transformation.

Animals↗

PubMed1990

Epidermal growth factor and bombesin differ strikingly in the induction of early responses in Swiss 3T3 cells.

Swiss 3T3 cells express receptors for both the polypeptide epidermal growth factor (EGF) and the tetradecapeptide bombesin and respond mitogenically to these substances. These cells thus provide a system to analyze potential signal transduction pathways involved in mitogenic stimulation. Here we have determined and compared the early ionic responses elicited by EGF and bombesin and their relation to diacylglycerol (DG) and inositolphosphate (InsPn) production. Whereas EGF fails to cause any significant change in intracellular Ca2+, bombesin effectively induces prompt and transient Ca2+ mobilization from intracellular stores. Further support of the idea that these receptors utilize distinct signalling pathways comes from the measurements of cytoplasmic pH (pHi). As in most target cells, EGF induces a delayed (1 min) but sustained intracellular alkalinization that reaches a new steady state after approximately 10 min. Bombesin, in contrast, elicits a biphasic response; within seconds, a rapid but transient rise in pHi is observed, followed by a further slower sustained alkalinization. Inhibition of the Na+/H+ exchanger prevents both EGF as well as bombesin-induced alkalinization. However, under these conditions, bombesin evokes a rapid and sustained acidification related to the Ca2+ response. Apparently, bombesin initiates a Ca2(+)-dependent acidifying process immediately after binding of the hormone to its receptor. Furthermore, we could demonstrate that the bombesin-induced alkalinization depends on protein kinase C activation whereas the EGF response does not. Determination of the total DG and InsPn accumulation revealed that EGF is ineffective in stimulating phospholipase C-mediated production of these second messengers. In contrast, bombesin causes a rapid DG and InsPn production coinciding with the Ca2+ response and the first phase of the rise in pHi followed by a slower DG accumulation coinciding with the second alkalinization phase. Our results show that in Swiss 3T3 cells the bombesin receptor activates the hydrolysis of inositol lipids as a mechanism of signal transduction, which consequently causes changes in Ca2+i and pHi. Clearly, the EGF receptor utilizes different pathways to evoke mitogenesis and stimulates Na+/H+ exchange independently of DG production and protein kinase C activation.

Animals↗

PubMed1990

Mitogen response and cell cycle kinetics of Swiss 3T3 cells in defined medium: differences from human fibroblasts and effects of cell density.

The mitogen requirement and proliferative response of Swiss 3T3 cells in serum-free, chemically defined culture medium were compared with those of early-passage human diploid fibroblasts. The effects of platelet-derived growth factor (PDGF), epidermal growth factor (EGF), insulin, transferrin, and dexamethasone on cell-cycle parameters were measured using 5'-bromo-deoxyuridine-Hoechst flow cytometry. Swiss 3T3 cells differ from human fibroblasts in several ways: (1) Swiss 3T3 cells showed a much higher dependence on PDGF than human fibroblasts; the growth of the latter, but not of the former, could be stimulated by the combination of EGF, insulin, and dexamethasone to the full extent of that when PDGF was present; (2) in the absence of PDGF, insulin was an absolute requirement for Swiss 3T3 cells to initiate DNA synthesis, while a substantial proportion of human fibroblasts could enter DNA synthesis without exogenous insulin or IGF-I; and (3) in the absence of PDGF, increasing insulin concentration increased the cycling fraction of Swiss 3T3 cells without an appreciable effect on the rate of cell exit from G0/G1, while under similar culture conditions, insulin showed its major effect on regulation of the G1 exit rate of human fibroblasts, without much effect on the cycling fraction. In addition, the proliferative response of high-density versus low-density, arrested Swiss 3T3 cells showed that the interaction of mitogens varied with cell density. At high cell density, the PDGF requirement was consistent with the "competence/progression" cell-cycle model. This growth response was not seen, however, when cells were plated at low density.

Animals↗

PubMed1989

Dual effect of activin A on cell growth in Balb/c 3T3 cells.

Effects of activin A on cell growth were studied in Balb/c 3T3 cells. When incubated with serum, activin A inhibited serum-induced increase in DNA synthesis in a concentration-dependent manner. Activin A also inhibited serum-induced increase in cell number. When added in quiescent cells, activin A did not affect competence-inducing activity of PDGF. Activin A by itself had a small competence-inducing activity. In contrast, when added in competent cells, activin A inhibited progression activity of platelet-poor plasma. These results indicate that activin A has dual action on cell proliferation in Balb/c 3T3 cells.

Activins↗