scholarly journals Loss of thrombospondin transcriptional activity in nickel-transformed cells.

1994 ◽  
Vol 14 (1) ◽  
pp. 851-858 ◽  
Author(s):  
K Salnikow ◽  
S Cosentino ◽  
C Klein ◽  
M Costa
Keyword(s):  
Chinese Hamster ◽  
Restriction Enzymes ◽  
Cell Types ◽  
Suppressor Gene ◽  
Transformed Cells ◽  
Normal Cells ◽  
Nickel Compounds ◽  
Embryo Cells ◽  
Rb Gene

mRNA from normal Chinese hamster embryo (CHE) cells was transcribed to cDNA and subtracted with an excess of mRNA from Chinese hamster embryo cells transformed by nickel compounds. Here we report the recovery of a sequence found to be highly homologous to the mouse thrombospondin 1 gene that was obtained by this subtraction procedure. Since thrombospondin is antiangiogenic, cancer cells expressing high levels of thrombospondin cannot grow in vivo because capillaries will not proliferate to cells secreting thrombospondin. To examine expression of thrombospondin, normal CHE cells were stained with monoclonal antibodies to human thrombospondin. The protein was present abundantly in the cytoplasm of normal cells but at greatly reduced levels in Ni-transformed cells. Analysis of mRNA by Northern (RNA) blot revealed transcripts in normal cells but little thrombospondin mRNA in Ni-transformed cells. Loss of thrombospondin mRNA expression was related to Ni treatment rather than transformation, since Ni-resistant cells also exhibited fewer thrombospondin transcripts than did wild-type cells. Digestion of genomic DNA with various combinations of restriction enzymes revealed thrombospondin gene patterns that were identical in both cell types, suggesting that there were no major deletions or rearrangements of the gene in the nickel-transformed cells. The inactivation of the thrombospondin gene was further investigated by analyzing the promoter activity of this gene linked to a chloramphenicol acetyltransferase (CAT) reporter plasmid that was transfected into normal and Ni-transformed cells. The CAT activity in normal cells was significantly higher than in Ni-transformed cells, suggesting that the promoter region of thrombospondin was less efficiently transcribed in Ni-transformed cells. We studied the consequences of enhanced expression of the retinoblastoma (Rb) gene, a known tumor suppressor gene, on CAT transcription driven by the human thrombospondin promoter. Cotransfection of an expression vector containing the mouse Rb gene greatly enhanced the transcription from the thrombospondin promoter such that the expression was higher in normal cells than in transformed cells.

Loss of thrombospondin transcriptional activity in nickel-transformed cells

1994 ◽  
Vol 14 (1) ◽  
pp. 851-858
Author(s):  
K Salnikow ◽  
S Cosentino ◽  
C Klein ◽  
M Costa
Keyword(s):  
Chinese Hamster ◽  
Restriction Enzymes ◽  
Cell Types ◽  
Suppressor Gene ◽  
Transformed Cells ◽  
Normal Cells ◽  
Nickel Compounds ◽  
Embryo Cells ◽  
Rb Gene

mRNA from normal Chinese hamster embryo (CHE) cells was transcribed to cDNA and subtracted with an excess of mRNA from Chinese hamster embryo cells transformed by nickel compounds. Here we report the recovery of a sequence found to be highly homologous to the mouse thrombospondin 1 gene that was obtained by this subtraction procedure. Since thrombospondin is antiangiogenic, cancer cells expressing high levels of thrombospondin cannot grow in vivo because capillaries will not proliferate to cells secreting thrombospondin. To examine expression of thrombospondin, normal CHE cells were stained with monoclonal antibodies to human thrombospondin. The protein was present abundantly in the cytoplasm of normal cells but at greatly reduced levels in Ni-transformed cells. Analysis of mRNA by Northern (RNA) blot revealed transcripts in normal cells but little thrombospondin mRNA in Ni-transformed cells. Loss of thrombospondin mRNA expression was related to Ni treatment rather than transformation, since Ni-resistant cells also exhibited fewer thrombospondin transcripts than did wild-type cells. Digestion of genomic DNA with various combinations of restriction enzymes revealed thrombospondin gene patterns that were identical in both cell types, suggesting that there were no major deletions or rearrangements of the gene in the nickel-transformed cells. The inactivation of the thrombospondin gene was further investigated by analyzing the promoter activity of this gene linked to a chloramphenicol acetyltransferase (CAT) reporter plasmid that was transfected into normal and Ni-transformed cells. The CAT activity in normal cells was significantly higher than in Ni-transformed cells, suggesting that the promoter region of thrombospondin was less efficiently transcribed in Ni-transformed cells. We studied the consequences of enhanced expression of the retinoblastoma (Rb) gene, a known tumor suppressor gene, on CAT transcription driven by the human thrombospondin promoter. Cotransfection of an expression vector containing the mouse Rb gene greatly enhanced the transcription from the thrombospondin promoter such that the expression was higher in normal cells than in transformed cells.

Methylation and expression of the Myo D1 determination gene

1990 ◽  
Vol 326 (1235) ◽  
pp. 277-284 ◽  
Keyword(s):  
De Novo ◽  
Cell Types ◽  
Model System ◽  
Parental Line ◽  
Molecular Control ◽  
Embryo Cells ◽  
End Stage ◽  
Derivatives Of

Mouse embryo cells induced to differentiate with the demethylating agent 5- azacytidine represent an excellent model system to investigate the molecular control of development. Clonal derivatives of 10T1/2 cells that have become determined to the myogenic or adipogenic lineages can be isolated from the multipotential parental line after drug treatment. These determined derivatives can be cultured indefinitely and will differentiate into end-stage phenotypes on appropriate stimulation. A gene called Myo D1, recently isolated from such a myoblast line, will confer myogenesis when expressed in 10T1/2 or other cell types (Davis et al. 1987). The cDNA for Myo D1 contains a large number of CpG sequences and the gene is relatively methylated in 10T1/2 cells and an adipocyte derivative, but is demethylated in myogenic derivatives. Myo D1 may therefore be subject to methylation control in vitro . On the other hand, preliminary observations suggest that Myo D1 is not methylated at CCGG sites in vivo so that a de novo methylation event may have occurred in vitro . These observations may have significance in the establishment of immortal cell lines and tumours.

Surface Modification and Electrophoresis of Normal and Transformed BHK21 Cells

1974 ◽  
Vol 14 (1) ◽  
pp. 203-214
Author(s):  
A. L. LATNER ◽  
G. A. TURNER
Keyword(s):  
Electrophoretic Mobility ◽  
Cell Types ◽  
Transformed Cells ◽  
Normal Cells ◽  
Neuraminidase Treatment ◽  
Total Histone ◽  
Electrophoretic Mobilities ◽  
Formaldehyde Treatment ◽  
The Mean ◽  
Number Of Cells

The mean electrophoretic mobilities at pH 7.5 of virus-transformed (Py6) and normal BHK21 cells were very similar, whether they were harvested mechanically or by the use of trypsin. After formaldehyde treatment, there was significantly increased mobility in both cell types; the transformed cells showed significantly the greater change. After neuraminidase treatment, the mean electrophoretic mobility was decreased to the same extent in both types of cell. Treatment with neuraminidase and formaldehyde had no effect on the mean electrophoretic mobility of the normal cells but slowed the transformed variety. The mobility in histone solution had no relationship to histone concentration but was statistically correlated with the amount of histone per cell, calculated from total histone present divided by the total number of cells; a linear relationship being obtained with the normal cells but an initial plateau was demonstrated with the transformed cells. The normal cell line showed a similar plateau after neuraminidase treatment. The possible significance of these results is discussed.

Tumorigenicity of cells transformed by Simian virus 40 and of hybrids between such cells and normal diploid cells

1979 ◽  
Vol 36 (1) ◽  
pp. 223-240
Author(s):  
C.J. Gee ◽  
H. Harris
Keyword(s):  
Mouse Embryo ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Transformed Cells ◽  
Sv40 T Antigen ◽  
Malignant Phenotype ◽  
Embryo Cells ◽  
Diploid Cells

A number of newly isolated clonal cell lines derived from diploid mouse embryo cells transformed by SV40 were examined in vitro and in vivo. Although these lines showed the properties that define transformation in vitro, they were not tumorigenic for many passages after their initial isolation. Cells from tumours eventually produced by the SV40-transformed cells were fused with diploid mouse embryo cells. The hybrids formed were initially non-tumorigenic. This indicates that a normal diploid cell can suppress the malignant phenotype of a tumorigenic SV40-transformed cell. The hybrid cells did, however, express the SV40 T antigen and they nad a clearly transformed phenotype in vitro. It thus appears that neither the transformed phenotype nor the expression of the SV40 T antigen are enough to endow a cell with the ability to grow progressively in vivo. The relationship between the transformed phenotype and tumorigenicity was further studied by fusing malignant mouse melanoma cells with non-tumorigenic SV40-transformed cells. The hybrids expressed the transformed phenotype in vitro but unable to form tumours in vivo. The changes that occur in cells after transformation by SV40 do not apparently affect the ability of these cells to suppress the malignant phenotype of tumour cells.

scholarly journals Characterization of phorbol ester-stimulated serine phosphorylation of the human insulin receptor

1994 ◽  
Vol 303 (1) ◽  
pp. 43-50 ◽  
Author(s):  
E P Feener ◽  
T Shiba ◽  
K Q Hu ◽  
P A Wilden ◽  
M F White ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Human Insulin ◽  
Rat Kidney ◽  
Phosphorylation Site ◽  
Chinese Hamster ◽  
Cell Types ◽  
Serine Phosphorylation ◽  
Human Insulin Receptor ◽  
Unstimulated Control

Phorbol 12-myristate 13-acetate (PMA)-stimulated phosphorylation of the human insulin receptor (IR) was characterized and compared in two cell types of different lineage: normal rat kidney epithelial (NRK) cells and Chinese hamster ovary (CHO) fibroblasts. PMA stimulation increased IR beta-subunit phosphorylation to 252 +/- 43 and 25- +/- 47% (+/- S.D.) of the unstimulated control in NRK and CHO cells respectively. Tryptic phosphopeptide analysis by Tricine/SDS/PAGE revealed significant differences in the PMA-stimulated phosphorylation of the IR in these two cell types. This phosphorylation of the IR was predominantly located in two tryptic phosphopeptides, and these phosphopeptides were absent in an IR mutant truncated by 43 C-terminal amino acids. The major PMA-stimulated tryptic phosphopeptide from in vivo-labelled CHO/IR was immunoprecipitated with an antibody against residues Ser1315 to Lys1329, and this precipitation was blocked with excess unlabelled peptide containing this sequence. Radiosequencing by manual Edman degradation revealed that this tryptic phosphopeptide was phosphorylated at Ser1315. This PMA-stimulated phosphorylation did not inhibit autophosphorylation of the IR in vivo. These results demonstrate that PMA-stimulated phosphorylation of the IR can exhibit significant differences when expressed in different cell types, and that Ser1315 is a major PMA-stimulated phosphorylation site on the human IR.

scholarly journals Transformation by Rous sarcoma virus induces clathrin heavy chain phosphorylation.

1989 ◽  
Vol 109 (2) ◽  
pp. 577-584 ◽  
Author(s):  
J Martin-Perez ◽  
D Bar-Zvi ◽  
D Branton ◽  
R L Erikson
Keyword(s):  
Heavy Chain ◽  
Rous Sarcoma Virus ◽  
Immunofluorescent Staining ◽  
Transformed Cells ◽  
Normal Cells ◽  
Clathrin Heavy Chain ◽  
Rous Sarcoma ◽  
Sarcoma Virus

We have shown that the heavy chain of clathrin is phosphorylated in chicken embryo fibroblast cells transformed by Rous sarcoma virus, but not in normal cells. Approximately 1 mol of phosphate is bound for every 5 mol of heavy chain in the maximally phosphorylated transformed cells. Two-thirds of the phosphate is on serine and one-third on tyrosine residues. Clathrin heavy chain is a substrate for pp60v-src in vitro. Cleveland analysis of the in vivo and in vitro clathrin heavy chain phosphopeptides, generated by protease V8 digestion, show labeled proteolytic fragments of similar molecular weight, suggesting that pp60v-src could be directly responsible for the in vivo phosphorylation of clathrin. Phosphate is equally incorporated into clathrin in both the unassembled and the assembled clathrin pools, whereas [35S]methionine is preferentially incorporated into the assembled pool. In normal cells, clathrin visualized by immunofluorescent staining appears in a punctate pattern along the membrane surface and concentrated around the nucleus; in transformed cells the perinuclear staining is completely absent. The phosphorylation of clathrin heavy chain in transformed cells may be linked to previously observed transformation-dependent alterations in receptor-mediated endocytosis of ligands such as EGF and thrombin.

Identification of toxic mineral dusts using mammalian cells

1980 ◽  
Vol 71 (3) ◽  
pp. 181-184 ◽  
Author(s):  
R. Davies ◽  
M. Chamberlain ◽  
R. C. Brown ◽  
D. M. Griffiths
Keyword(s):  
Cell Line ◽  
Mammalian Cells ◽  
Chinese Hamster ◽  
Cell Types ◽  
Peritoneal Macrophages ◽  
Alveolar Type ◽  
Mineral Dusts ◽  
Potential Pathogenicity

ABSTRACTCell culture systems have been developed to assess the potential pathogenicity of mineral dusts. The in vitro cytotoxicities of a variety of dusts towards mouse peritoneal macrophages, Chinese hamster lung cells (V79 cell line) and human alveolar type II cells (A549 cell line) were investigated.Non-pathogenic dusts were found to be inert in vitro. Fibrogenic non-fibrous dusts such as silica were only cytotoxic towards macrophages. Fibrous dusts which are both fibrogenic and carcinogenic in vivo are cytotoxic towards all three cell types, their cytotoxicity being dependent on fibre size. The size range important for the observed biological effect is longer than about 8 μm and thinner than about 1·5 μm.

scholarly journals Functional dissociation between PIKfyve-synthesized PtdIns5P and PtdIns(3,5)P2 by means of the PIKfyve inhibitor YM201636

2012 ◽  
Vol 303 (4) ◽  
pp. C436-C446 ◽  
Author(s):  
Diego Sbrissa ◽  
Ognian C. Ikonomov ◽  
Catherine Filios ◽  
Khortnal Delvecchio ◽  
Assia Shisheva
Keyword(s):  
T Cells ◽  
Chinese Hamster ◽  
Cell Types ◽  
Stress Fiber ◽  
Actin Stress Fiber ◽  
Low Doses ◽  
Lipid Kinase ◽  
Insulin Effect

PIKfyve is an essential mammalian lipid kinase with pleiotropic cellular functions whose genetic knockout in mice leads to preimplantation lethality. Despite several reports for PIKfyve-catalyzed synthesis of phosphatidylinositol 5-phosphate (PtdIns5P) along with phosphatidylinositol-3,5-biphosphate [PtdIns(3,5)P2] in vitro and in vivo, the role of the PIKfyve pathway in intracellular PtdIns5P production remains underappreciated and the function of the PIKfyve-synthesized PtdIns5P pool poorly characterized. Hence, the recently discovered potent PIKfyve-selective inhibitor, the YM201636 compound, has been solely tested for inhibiting PtdIns(3,5)P2 synthesis. Here, we have compared the in vitro and in vivo inhibitory potency of YM201636 toward PtdIns5P and PtdIns(3,5)P2. Unexpectedly, we observed that at low doses (10–25 nM), YM201636 inhibited preferentially PtdIns5P rather than PtdIns(3,5)P2 production in vitro, whereas at higher doses, the two products were similarly inhibited. In cellular contexts, YM201636 at 160 nM inhibited PtdIns5P synthesis twice more effectively compared with PtdIns(3,5)P2 synthesis. In 3T3L1 adipocytes, human embryonic kidney 293 and Chinese hamster ovary (CHO-T) cells, levels of PtdIns5P dropped by 62–71% of the corresponding untreated controls, whereas those of PtdIns(3,5)P2 fell by only 28–46%. The preferential inhibition of PtdIns5P versus PtdIns(3,5)P2 at low doses of YM201636 was explored to probe contributions of the PIKfyve-catalyzed PtdIns5P pool to insulin-induced actin stress fiber disassembly in CHO-T cells, GLUT4 translocation in 3T3L1 adipocytes, and induction of aberrant cellular vacuolation in these or other cell types. The results provide the first experimental evidence that the principal pathway for PtdIns5P intracellular production is through PIKfyve and that insulin effect on actin stress fiber disassembly is mediated entirely by the PIKfyve-produced PtdIns5P pool.

scholarly journals Concomitant loss of cell surface fibronectin and laminin from transformed rat kidney cells

1981 ◽  
Vol 88 (2) ◽  
pp. 352-357 ◽  
Author(s):  
EG Hayman ◽  
E Engvall ◽  
E Ruoslahti
Keyword(s):  
Molecular Weight ◽  
Cell Surface ◽  
Cell Attachment ◽  
Culture Media ◽  
Rat Kidney ◽  
Cell Types ◽  
Transformed Cells ◽  
Kidney Cells ◽  
Normal Cells ◽  
The Matrix

Both fibronectin and laminin were found by immunofluorescence as a matrix at the surface of normal rat kidney cells. These matrices were absent from the surface of virally transformed rat kidney cells. Soluble fibronectin and laminin were detected in the culture media of the transformed as well as the normal cells. Culture supernates of the transformed cells contained even more fibronectin than the supernates of the transformed cells contained even more fibronectin than the supernates of the normal cells while laminin was present in similar amounts in both culture media. This shows that the loss of fibronectin and laminin from the surface of the transformed cells is caused by failure of the cells to deposit these proteins into an insoluble matrix and not caused by inadequate production. Fibronectins isolated from culture media of the normal and transformed cells were similar in SDS polyacrylamide gel electrophresis. Laminin isolated from culture media by affinity chromatography on heparin-Sepharose followed by immunoprecipitation was composed of three main polypeptides, one with a molecular weight of 400,000 and two with a molecular weight close to 200,000 in both cell types. Fibronectins from both cell types were equally active in promoting cell attachment. Rat fibronectin from transformed cells, like normal cells, when applied to culture dishes coated with fibronectin, readily attached and spread on the substratum, requiring approximately the same amount of fibronectin as the normal cells. On the basis of these results it seem that the failure of the transformed cells to incorporate fibronectin into an insoluble cell surface matix is not a consequence of a demonstrable change in the functional characteristics of the fibronectin molecule or in the ability of the cells to interact with fibronectin. It may depend on as yet unidentified interactions of the cell surface. Similar interactions may be needed for the deposition of laminin into the matrix, because laminin was also absent from the surface of transformed cells, despite its being synthesized by these cells.

scholarly journals Cancer-specific overmethylation of histone H3 lysines is necessary for methionine addiction and malignancy

2020 ◽  
Author(s):  
Jun Yamamoto ◽  
Sachiko Inubushi ◽  
Qinghong Han ◽  
Yoshihiko Tashiro ◽  
Yu Sun ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Therapeutic Target ◽  
Methylation Status ◽  
Histone H3 ◽  
Cell Types ◽  
Lysine Methylation ◽  
Normal Cells ◽  
Molecular Changes

AbstractMethionine addiction is a fundamental and general hallmark of cancer. Methionine addiction results from the overuse of methionine by cancer cells for excess transmethylation reactions. In order to identify excess transmethylation reactions in cancer, we compared the histone H3 lysine methylation status between methionine-addicted cancer cells, normal cells and revertants of methionine-addicted cancer cells which regained methionine independence and lost malignancy. The levels of H3K4me3, H3K9me3 and pan-methyl lysine of histone H3 were elevated in methionine-addicted cancer cells in vitro compared to methionine-independent revertants isolated from the cancer cells and to normal cells. Tumorigenicity in nude mice was highly reduced in the methionine-independent revertants compared to the parental cells. The methionine-independent revertants no longer overmethylated pan-methyl lysine of H3, H3K4me3 and H3K9me3. Our previous studies showed that methionine restriction (MR) selectively arrests methionine-addicted cancer cells due to loss of histone H3 lysine methylation, which was stable in normal cells under MR. Our previous and present results suggest that overmethylation of histone H3 lysine is necessary for methionine addiction of cancer, required for the growth of cancer cells in vitro and in vivo, and necessary for malignancy. Methionine addiction has revealed fundamental molecular changes necessary for malignancy and presents great potential as a pan-cancer therapeutic target.Signiificance StatementAll cancer cell types are methionine-addicted. Methionine addiction is due to the overuse of methionine by cancer cells for excess transmethylation reactions. In the present study, we showed that the level of histone H3 lysine methylation was elevated in methionine-addicted cancer cells compared to normal fibroblasts and methionine-independent revertants with reduced malignancy that were derived from the methionine-addicted cancer cells. These results suggest that overmethylation of histone H3 lysine is necessary for methionine addiction of cancer and malignancy itself. Methionine addiction has revealed fundamental molecular changes necessary for malignancy and has been shown to be a universal therapeutic target in numerous pre-clinical studies of all major cancer types and has great clinical potential.

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