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PubMed1989

Enhancement of colony forming ability in the lung by transfer of the v-fos oncogene into a ras-transformed rat 3Y1 cell line.

Transfer of the v-fos oncogene into a rat 3Y1 cell line transformed by v-H-ras, which is tumorigenic but non-metastatic, enhanced lung metastasis, depending on the amount of fos-related transcripts. Enhancement of the metastatic potential was associated with increases in tumor growth rate i.m. of inoculated cells but not the rate of in vitro cell growth, irrespective of the addition of tissue (e.g. lung) extract to the regular medium. These results suggest that the v-fos oncogene increased the malignancy by altering biological factors of the recipient cells responsible for cell growth and/or survival rate in vivo.

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

Depression of catalase gene expression after immortalization and transformation of mouse liver cells.

To understand the molecular basis of the remarkable decrease of catalase activity after immortalization and malignant transformation of mouse liver cells, expression of the catalase gene was studied in in vivo mouse liver cells and nontransformed normal mouse liver cell line as well as liver cell lines transformed by N-methyl-N-nitro-N-nitrosoguanidine, SV40 virus or by conventional subcultivation. In vivo liver cells had much greater levels of catalase mRNA and immunoreactive protein than in vitro cell lines, which correlates with elevated enzyme activity. Among the cell lines, normal cells had in general higher mRNA levels and more catalase protein than that of the transformed cell lines, also correlating with enzyme activity. The down regulation of catalase gene expression seen in transformed lines may occur transcriptionally rather than posttranscriptionally as demonstrated by cycloheximide and/or actinomycin D treatment. The striking difference in catalase gene expression seen between liver tissue and liver cell lines was unlikely due to gross structural alterations in the catalase gene, but might be explained by a remarkable difference in methylation status of the catalase gene, as demonstrated by Southern blot analysis following HpaII digestion. Our results suggested that during cellular immortalization and malignant transformation, a change in the oxidant stress ultimately led to a cellular response that, in turn, led to down regulation of the catalase gene.

Animals↗
PubMed1991

The AIMS/GRXVIII cell line: 'spontaneous' transformation of hormonally induced primary cells derived from goat ovarian granulosa.

AIMS/GRXVIII is one of the cell lines developed in our laboratory from goat ovarian granulosa cells by luteinizing hormone (LH) stress. Unlike other cell lines in the AIMS/GR series which were contact-inhibited and non-tumorigenic, this one was 'spontaneously' transformed during passage 14 with a doubling time of 20 h. The morphology changed from a spindle shape to epithelial-like. Cultures lost contact inhibition and presented extensive mitotic and chromosomal abnormalities. The cultures secreted progesterone even without LH support after passage 8. The cells developed small tumours of luteal morphology in hamster cheek pouches, though they failed to form colonies in soft agar gel. This is a functional cell line and should be useful in understanding various processes in cell biology like function, signal transduction and mechanisms of cell transformation.

Animals↗
PubMed1988

E1A products of adenoviruses reduce the expression of cellular proliferation-associated genes.

Products of the adenovirus (Ad) E1A region are capable of modulating the expression of a variety of genes, both of viral and cellular origin. We have investigated the expression of two proliferation-associated genes, c-myc and JE, in various adenovirus-transformed cell lines. Rodent and human cell lines, transformed as primary cultures by the E1 region of Ad5 or of Ad12, exhibit a markedly reduced expression of both genes. Ad5 E1-transformed cells show a more pronounced reduction of c-myc RNA than Ad12 E1-transformed cells. Even the very low levels of E1A products in Ad5 E1A-immortalized cells are sufficient for this reduction. Analysis of c-myc and JE expression in cell lines, transformed by other viral or cellular oncogenes, indicated that this reduction is specific for adenoviruses. These observations show that E1A does not contribute to cellular transformation by activating the proliferation-associated genes c-myc and JE, but instead suggest an alternative mechanism of E1A-mediated transformation.

Adenovirus Early Proteins↗
PubMed1995

Cell cycle inhibition of HTLV-I transformed T cell lines by retinoic acid: the possible therapeutic use of thioredoxin reductase inhibitors.

Adult T cell leukemia derived factor (ADF), which was first reported as a cytokine-like factor produced by human T lymphotropic virus I (HTLV-I)-transformed T cells, is a human homologue of thioredoxin (TRX). ADF/TRX has multiple functions including growth promoting, antiapoptotic and radical scavenging activities, and is also involved in a wide variety of intracellular processes as a dithiol reducing agent in cooperation with the NADPH-TRX reductase system. In HTLV-1(+) T cell lines, HuT 102 and MT-2, which are ADF/TRX high producing cells, we found that the expression of ADF/TRX was dependent on the cell cycle and peaked at S phase. The reducing activity of ADF/TRX in these cells was also dependent on the cell cycle and elevated in S phase as determined by NADPH-dependent insulin degradation assay. Furthermore, inhibitors of TRX reductase, 13-cis-retinoic acid (13-cis-RA) and azelaic acid, inhibited the DNA synthesis of these cells. In contrast, the residual expression and reducing activity of ADF/TRX in HTLV-I(-) T cell lines did not show any significant correlation with the cell cycle. There was no distinct inhibitory effect of 13-cis-RA or azelaic acid on the growth of these ADF/TRX low producing cells. These results indicate that a high level of reducing activity of the ADF/TRX system may be required for the cell division of these virally transformed cells. This suggests that the TRX reductase inhibitors including retinoid derivatives have a potential therapeutic utility for treatment of HTLV-1(+) T cell leukemia without any effect on HTLV-I(-) cells.

Cell Cycle↗
PubMed1988

Colony stimulating factor-1 induced growth stimulation of v-fms transformed fibroblasts.

The v-fms oncogene, which is capable of transforming fibroblasts, was derived by recombination of a feline leukemia virus with a cellular gene (c-fms) that encodes the receptor for colony stimulating factor 1 (CSF-1). We examined the capacity of recombinant human CSF-1 (produced in a yeast expression system) to stimulate the growth of v-fms transformed rat fibroblasts. Recombinant human CSF-1 bound to v-fms transformed fibroblasts with high affinity (apparent Kd = 6.0 x 10(-10) M); only non-specific binding was observed on control cells. The number of colonies formed in soft agar by v-fms transformed cells was increased by CSF-1 treatment in a dose-dependent manner; a nine fold increase in the number of colonies was seen in the presence of 10(-8) M CSF-1. CSF-1 did not stimulate the growth of either non-transformed cell lines, a non-transformed cell line that expresses a mutated v-fms protein on the cell surface, or cells transformed by the v-fgr oncogene. The growth stimulating effect of CSF-1 on v-fms transformed cells was also seen in monolayer culture. The v-fms transformed cells treated with CSF-1 had a more refractile, rounded morphology than non-treated cells; no morphology change was observed in CSF-1 treated control cells. CSF-1 treatment also increased both the number and size of foci that arose from fibroblasts following transfection with the v-fms oncogene. These data show that the altered CSF-1 receptor encoded by the v-fms oncogene retains a capacity to bind, and be stimulated by, human CSF-1.

Animals↗
PubMed2003

Effect of the dithiocarbamate pesticide zineb and its commercial formulation, the azzurro. V. Abnormalities induced in the spindle apparatus of transformed and non-transformed mammalian cell lines.

Abnormalities induced in the mitotic spindle by zineb and azzurro (1.0-25.0 micro g/ml, 24h) were evaluated in Chinese hamster ovary (CHO) and HeLa cells, and in non-transformed human fibroblasts (NTHF). Spindles were stained with FITC-conjugated anti-beta tubulin. Treatment with 10.0 micro g/ml of zineb induced complete inhibition of cell viability in NTHF cells while 10.0 micro g/ml of azzurro decreased cell growth down to 62%. Higher doses of both compounds induced cell death. In HeLa and CHO cells, 15.0 micro g/ml of zineb and 10.0-15.0 micro g/ml of azzurro decreased viability, whereas 25.0 micro g/ml of both compounds was cytotoxic. A significantly decreased mitotic index (MI) was observed in NTHF treated with 5.0 micro g/ml zineb or azzurro, whereas 10.0 micro g/ml of both chemicals were necessary to induce the same phenomenon in HeLa and CHO cells. Treatment with 1.0-5.0 micro g/ml of zineb or azzurro induced a dose-dependent increase of degenerated spindles in NTHF and the number of degenerated or multipolar spindles in HeLa and CHO cells increased in a dose-dependent manner with 1.0-10.0 micro g/ml zineb and azzurro. Although zineb and azzurro were able to induce mitotic spindle abnormalities in all cell types, non-transformed cells were less resistant than immortalized cells.

Animals↗
PubMed2001

Carcinogenic potential and genomic instability of beryllium sulphate in BALB/c-3T3 cells.

Occupational exposure to beryllium (Be) and Be compounds occurs in a wide range of industrial processes. A large number of workers are potentially exposed to this metal during manufacturing and processing, so there is a concern regarding the potential carcinogenic hazard of Be. Studies were performed to determine the carcinogenic potential of beryllium sulfate (BeSO4) in cultured mammalian cells. BALB/c-3T3 cells were treated with varying concentrations of BeSO4 for 72 h and the transformation frequency was determined after 4 weeks of culturing. Concentrations from 50-200 microg BeSO4/ml, caused a concentration-dependent increase (9-41 fold) in transformation frequency. Non-transformed BALB/c-3T3 cells and cells from transformed foci induced by BeSO4 were injected into both axillary regions of nude mice. All ten Be-induced transformed cell lines injected into nude mice produced fibrosarcomas within 50 days after cell injection. No tumors were found in nude mice receiving non-transformed BALB/c-3T3 cells 90 days post-injection. Gene amplification was investigated in K-ras, c-myc, c-fos, c-jun, c-sis, erb-B2 and p53 using differential PCR while random amplified polymorphic DNA fingerprinting was employed to detect genomic instability. Gene amplification was found in K-ras and c-jun, however no change in gene expression or protein level was observed in any of the genes by Western blotting. Five of the 10 transformed cell lines showed genetic instability using different random primers. In conclusion, these results indicate that BeSO4 is capable of inducing morphological cell transformation in mammalian cells and that transformed cells induced by BeSO4 are potentially tumorigenic. Also, cell transformation induced by BeSO4 may be attributed, in part, to the gene amplification of K-ras and c-jun and some BeSO4-induced transformed cells possess neoplastic potential resulting from genomic instability.

3T3 Cells↗
PubMed1993

Monoclonal IgM, IgG, and IgA human rheumatoid factors produced by synovial tissue-derived, EBV-transformed B cell lines.

In an effort to study disease-related autoantibodies in rheumatoid arthritis (RA), rheumatoid factor (RF)-producing B cell lines were developed from the heterogeneous B cell populations infiltrating the synovial tissue of patients with arthritis. Over 125 EBV-transformed B cell cultures were derived from three patients: one with early pre-erosive RA, one with advanced RA, and one with osteoarthritis (OA). IgM, IgG, and IgA RF-producing B cell lines were found in all three series but with several significant differences. In each of the two RA patients, 22% of the Ig-producing cell lines secreted RF compared to 7% in the OA patient. The isotypes of these RF were mostly IgM in the early RA (62%) and the OA patient (60%) as contrasted to predominantly IgA (75%) and, to a lesser extent, IgG (12.5%) in the advanced RA patient. Analyses of the light (L) chain composition of these RF revealed that 82% of the IgM RF used kappa L chains whereas only 31% of the non-IgM RF used kappa chains. Antigen-binding analyses of these RF revealed that all the synovial tissue-derived RF from the advanced RA patient exhibited antigen binding specificities restricted to a narrow range of gamma globulins. In contrast, the synovial RF of the other two patients were either reactive with a broader spectrum of gamma globulins or reactive with a variety of unrelated antigens. In every instance, the gamma globulin-specific RF were of all three major isotypes whereas the polyreactive RF were restricted to the IgM isotype. These data demonstrate that synovial B cells from both RA and OA patients can produce RF and that significant differences can exist among patients in the percentage of RF generated and their H and L chain isotype distribution. The reversal of the kappa:lambda ratio among the IgG and IgA RF and the more restricted antigen-binding specificities of the IgG and IgA vs IgM RF suggest that a non-stochastic, possibly antigen-driven selection process was involved in their generation. The relevance of these differences in RF precursor frequency, H and L chain distribution, and antigen specificity to these two diseases warrants further investigation.

Aged↗
PubMed1999

Detection and characterization of HLA class I molecules in the supernatant of an hepatocarcinoma cell line and of EBV-transformed B cell lines.

Human leukocyte antigens (HLA) class I molecules can be detected in "soluble" form in the supernatant of cultured cell lines and in serum and plasma of humans. These "soluble" HLA class I molecules are assumed to play a role in liver transplantation. In order to define the nature and composition of HLA class I molecules found in solution, we studied the HLA class I production of an hepatoma carcinoma cell line (HepG2) and of EBV-transformed B-cell lines. Based on molecular weight (MW) analysis, it was demonstrated that different forms of HLA class I molecules were produced by HepG2 cells and EBV B-cells. Monoclonal antibodies (mAbs) specific for HLA class I alleles were able to recognize the mature 45 kDa form, but failed to interact with the 42 kDa and 39 kDa MW forms of HLA class I. Of these different MW forms of HLA class I molecules the mature 45 kDa product was found predominantly to be associated with subcellular vesicles whereas the alternative MW forms of 42 kDa and 39 kDa exist as truly free entities in supernatants.

Blotting, Western↗
PubMed1995

Transformed mouse cell lines that consist predominantly of cells maintaining bovine papilloma virus at high copy number.

Rare cells that contain large amounts of bovine papilloma virus (BPV) DNA have been observed in populations of BPV-transformed mouse ID13 cells. The viral DNA molecules in these "jackpot cells" have been thought to have switched from the controlled replication typical of latent BPV infection to the uncontrolled "runaway" prelytic replication characteristic of terminal stage infection of bovine epidermal cells. By sequential subcloning of high-BPV derivatives of ID13, we isolated stable cell lines enriched more than 1000-fold for cells showing large amounts of BPV by fluorescence in situ hybridization analysis. High-BPV subclones contained a variant plasmid as well as wild-type BPV DNA; analysis of the BPV variants in two independently isolated subclones that showed the high-BPV phenotype in 50 to 80% of cells in the population indicated that both variants had undergone tandem duplication of the BPV long control region, which contains the viral origin of replication and transcription enhancer sequences. Transfer of the high-copy-number phenotype by transfection of DNA from high-BPV cells was accompanied by transfer of the variant plasmid. Density gradient analysis of BPV plasmid replication in high-BPV subclones showed the random-choice mode of replication observed in the parental ID13 population, rather than the rapid BPV replication found in epidermal cells destined for lysis and death. Our results indicate that high-BPV cells in actively dividing ID13 populations are not produced by uncontrolled replication of viral DNA and suggest that they may result instead from abnormal plasmid partitioning.

Animals↗
PubMed1982

Differences in anchorage-dependent growth and tumorigenicities between transformed C3H/10T 1/2 cells with morphologies that are or are not reverted to a normal phenotype by ascorbic acid.

C3H/10T 1/2 mouse embryo cells were transformed with 3-methylcholanthrene. Several type III morphologically transformed cell lines were selected with morphologies that either could or could not be reverted back to normal at passage 1 by daily addition of ascorbic acid (1 or 5 microgram/ml). Those transformed cell lines with morphologies that could be caused to revert to normal did not produce colonies in agarose or tumors in nude mice at early passages. Such transformed cell lines at later passages all formed colonies in agarose, but only 2 of 8 lines produced tumors at any passage tested. Subsequently, clones of transformed cells from each cell line have been isolated which are tumorigenic. In contrast, the transformed cell lines which were unresponsive to ascorbic acid at passage 1 were able to form colonies and to produce tumors in early passages. The reversion of the transformed morphology by ascorbic acid is apparently not caused by cytotoxicity since no cell kill was observed following exposure to ascorbate in any newly transformed cell lines at the concentrations used. Thus, the use of ascorbic acid allowed morphologically transformed cell lines to be isolated which appeared to be at different stages in the progression of an initiated cell from a morphologically transformed cell to a highly tumorigenic one. These studies also suggest that low concentrations of ascorbic acid in C3H/10T 1/2/CL8 cells can be effective in suppressing oncogenic progression only prior to a stage where an initiated cell achieves the capacity to grow in semisolid medium and to produce tumors in immunosuppressed animals. The importance of these cell lines for elucidating key changes required for the promotion and/or progression of cells to a tumorigenic phenotype is also presented.

Animals↗
PubMed1980

Cyclic adenosine 3',5'-monophosphate-independent phosphorylation of externally oriented plasma membrane proteins in transformed and nontransformed mouse embryo cell lines.

Thirty transformed and nontransformed mouse embryo cell lines were analyzed to determine if increased plasma membrane phosphorylation is a characteristic of all transformed cell lines. Nontransformed, virally and chemically transformed, and smooth surface-transformed cell lines derived from Swiss, BALB/c, AKR, or C3H mice were studied. Cyclic AMP-independent phosphorylation of plasma membrane proteins was comparable in nontransformed and simian virus 40 (SV40)-transformed Balb/3T3 cells, in nontransformed and 3-methylcholanthrene (MCA)-transformed C3H/10T 1/2 cells, and in nontransformed and MCA-transformed AKR-2B cells. In contrast, increased plasma membrane phosphorylation was observed in MCA- and smoooth surface-transformed Balb/3T3 cells and in SV40-transformed Swiss 3T3 cells compared to the respective nontransformed parent cell lines. These observations suggest that increased cyclic AMP-independent phosphorylation of externally oriented plasma membrane proteins is not a universal marker for the transformed phenotype.

Animals↗
PubMed1996

Overexpression of MP41 gene in a transformed endothelial cell line correlates with the increased fibronectin expression and a decreased incidence of tumorigenicity.

mp41 gene, which was originally identified as a gene regulated by the circadian clock, showed some similarity with yeast cell cycle regulator, CDC25, and its mRNA expression is restricted mainly to non-dividing cell. To elucidate the growth regulatory of mp41, mp41 cDNA was transfected into a transformed human endothelial cell line. All stable mp41 transformants showed increased levels of fibronectin expression and reduced migratory activity in vitro. Although the in vitro growth rate of mp41 transformants and their ability to grow in soft agar were not significantly altered, their tumor formation was suppressed significantly in nude mice. The results imply that mp41 gene overexpression altered the tumorigenicity associated with fibronectin elevation in stable transformation of the transformed endothelial cell line.

Animals↗
PubMedDate not supplied

[Oncogene-directed mutagenesis in vivo. Polyalkylating derivatives of short single-stranded polynucleotides, complementary E1-adeno-oncogene, in the normalization of adenovirus-transformed rodent cell lines].

Polyalkylating derivatives of single-stranded polynucleotides (30-200-mers) complementary to the long E1 oncogene sequences of simian adenovirus SA7 cause inherited normalization of SH2 and G11 cells transformed with adenovirus SA7; certain deletions in the integrated proviral E1A oncogene were observed in several cases during this process. The transformed cells are indifferent to reagents noncomplementary to the E1 region. Thus polyalkylating derivatives of single-stranded 30-200-mers act as addressed mutagenes which react in a specific way with the integrated complementary DNA sequences of E1 oncogene in transformed rodent cells and realize oncogene-directed mutagenesis in vivo. During this treatment temporary normalized cells reverting to the initial transformed phenotype are also produced.

Adenoviruses, Simian↗
PubMed1996

Tumor-necrosis-factor-induced fibroblast growth factor-1 acts as a survival factor in a transformed endothelial cell line.

Endothelial cells undergo apoptosis after withdrawal of growth factors, alterations in the extracellular matrix, or exposure to cytokines. Here we report that tumor necrosis factor (TNF)-alpha induces apoptosis of human endothelial cells derived from the umbilical vein in a dose-dependent fashion. Apoptosis is triggered through a pathway that is independent from the levels of Bcl-2. On the contrary, TNF stimulates the growth of spontaneously transformed human umbilical vein endothelial cells. This proliferative effect is mediated through the up-regulation of fibroblast growth factor-1 by TNF. The addition of specific fibroblast growth factor-1 antisense oligonucleotides inhibits TNF-induced fibroblast growth factor-1 expression, thus inhibiting the growth and triggering apoptosis of spontaneously transformed human umbilical vein endothelial cells.

Apoptosis↗
PubMed1980

Specific glycolipid antigen(s) in SV40-transformed cell membranes.

A glycolipid extract was prepared from an SV40-transformed hamster cell line (EH-SV) according to the Folch partition procedure. The glycolipids from the aqueous layer were incorporated in liposomal membranes composed of lecithin/sphingomyelin/cholesterol (1:1:2 by weight). This liposomal preparation was inoculated in Syrian hamsters to raise immune sera. The sera were absorbed with trypsinized "normal" hamster cells (EH-N) and tested on various cell lines by the indirect immunofluorescence technique. When used for staining living cells, the immune serum produced a distinct cell-surface fluorescence with SV40-transformed cell lines regardless of the cell origin (e.g., rat or hamster). No reaction was observed with heterologous Py-transformed cell lines, spontaneously transformed cells, or sera from non-immunized hamsters. When used for staining acetone-fixed cells, the antiglycolipid serum reacted specifically with a thermostable antigen in the nuclear envelope and the cytoplasm of SV40-transformed cells. The sera lack interfering SV40 T reactivity. The results indicate the presence of related SV40-specific glycolipid antigen(s) in the plasma membrane, the nuclear membrane and probably other endomembranes of SV40-transformed cells.

Animals↗