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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The establishment of a new glioma cell line, DBTRG-05MG, in a modified RPMI 1640 medium is described. The cells were derived from an adult female with glioblastoma multiforme who had been treated with local brain irradiation and multidrug chemotherapy; the tumor showed substantial change in histologic appearance compared to the original biopsy 13 mo. previously. The line has been successfully cryopreserved and passaged up to 20 times. The karyotype of the cells demonstrated it as a hypotetraploid line; the DNA index of 1.9 confirmed the karyotype analyses. By immunocytochemical analysis, the cell line reacted with polyclonal antibodies to vimentin, S100, and neuron specific enolase, reflecting its primitive neuroectodermal character. Positive immunostaining for epidermal growth factor receptor correlated with the excess of chromosome 7 seen in the karyotype. The cell line reacted negatively to antibodies against platelet-derived growth factor and its receptor, neuronal cell adhesion molecule, and glial fibrillary acidic protein. By flow cytometry, the cells were major histocompatibility class I antigen positive and class I antigen negative. Growth kinetic studies demonstrated an approximate population doubling time of 34 to 41 h and a colony forming efficiency of 71.4%. Western blot analysis showed the presence of low levels of normal-sized retinoblastoma protein. When compared to the patient's lymphocyte DNA, no loss of heterozygosity of the p53 tumor suppressor gene was observed in the DBTRG-05MG cell line DNA.
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PMID:Characterization of a continuous human glioma cell line DBTRG-05MG: growth kinetics, karyotype, receptor expression, and tumor suppressor gene analyses. 133 Oct 21

Multi-autocrine loops of the epidermal growth factor (EGF), transforming growth factor alpha (TGF alpha), platelet-derived growth factor (PDGF) and TGF beta system are expressed in human gastrointestinal carcinomas. In esophageal and gastric carcinomas, they evidently play an important role in tumor progression. Gastrin, one of the major gut hormones, may also act as an autocrine growth factor for gastric and colonic carcinomas. The HST1 and INT-2 genes, belonging to the fibroblast growth factor gene family, are coamplified in approximately 50% of primary tumors and in all the metastatic tumors of esophageal carcinoma. TGF alpha and EGF are the ligands of the tumor cells that overexpress EGF receptor in esophageal carcinomas. The synchronous expression of EGF and its receptor, as well as TGF alpha and ras p21, is evidently correlated with the depth of tumor invasion, metastasis and prognosis of gastric carcinomas. Amplification of c-erbB-2 and EGF receptor genes has been observed in many metastatic sites of gastric carcinomas regardless of histological type. In addition to TGF alpha and EGF, TGF beta and PDGF A chain produced by tumor cells may stimulate collagen synthesis not only by fibroblasts but also by tumor cells themselves, resulting in extensive progression and diffuse fibrosis of scirrhous gastric carcinomas. Moreover, TGF alpha or EGF and estrogen may also play a cooperative role in the development of scirrhous gastric carcinoma. In colorectal carcinoma, it has been shown that the accumulation of several alterations in ras genes and p53 genes is most important for the conversion of adenoma to carcinoma. Critical genetic changes, including activation of oncogenes, mutation and deletion of tumor suppressor genes and disturbances in transcriptional regulatory sequences, may bring about aberrant expression of growth factors and their receptors in gastrointestinal carcinomas. The understanding of the significance of EGF-related growth factors in tumor progression provides a framework for a biological approach to the therapy of human gastrointestinal carcinomas. 8-Cl-cAMP, which inhibits expression of oncogenes and TGF alpha, may be useful not only for cancer therapy but also for the study of cell differentiation.
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PMID:Growth factors and oncogenes in human gastrointestinal carcinomas. 215 13

Contact-inhibited Kaposi's sarcoma-derived cells (KS cells) were transfected with Simian Virus 40 (SV40) DNA. Transformed cells (SV-KSC) were selected for their capacity to form foci on monolayers of the low-malignant KS cells. Isolated SV-KSC foci were found to contain integrated SV40 DNA sequences and to express SV40 large T-antigen. Several differentiation properties of KS cells are retained in the SV40 transformants, e.g., expression of vimentin and the endothelial cell marker BMA 120. In contrast to the maternal KS cells, SV-KSC are capable of growing in platelet-derived growth factor (PDGF)-depleted platelet-poor-plasma serum (PPPS) and in soft agar. However, they are not tumorigenic in nude mice. Expression of the oncogenes c-myc, c-N-ras, c-Ha-ras, and p53 is significantly elevated in SV-KSC, whereas c-fos and c-erb B expression is comparable to that of KS cells and fibroblasts. Conditioned medium from SV-KSC can substitute for PDGF when PDGF-dependent, nontransformed KS cells are grown in PPPS. Biochemical analysis of the SV-KSC supernatant and PDGF A and B mRNA expression analysis provide evidence that the mitogenic activity is not due to a PDGF-like growth factor. On the other hand, there is evidence to indicate that the SV-KSC mitogen is a member of the fibroblast growth factor family. SV-KSC represent an interesting model system for the study of different degrees of malignancy of cultured mesenchymal cells and especially provide an important source for the isolation of a potent growth factor for KS cells and other mesenchymal cells in vitro.
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PMID:Cytochemical and molecular properties of simian virus 40 transformed Kaposi's sarcoma-derived cells: evidence for the secretion of a member of the fibroblast growth factor family. 255 9

Cell lines have been permanently established from BALB/c3T3 cells that constitutively express either the murine p53, the human IGF-1 gene, or both (Gai et al., 1988). The derivative cell lines grow well in platelet-poor plasma or in serum-free medium supplemented with the appropriate growth factors, while BALB/c3T3 cells do not grow in platelet-poor plasma, nor do they grow in serum-free medium unless supplemented with both platelet-derived growth factor and insulin (or IGF-1). In BALB/c3T3 cells, steady-state levels of c-myc mRNA decrease promptly and sharply once the cells are transferred to platelet-poor plasma. In the derivative cell lines, constitutively expressing p53, IGF-1, or both, c-myc mRNA levels remain elevated and actually increase when the cells are transferred to platelet-poor plasma. In serum-free medium, the c-myc mRNA levels decreased in BALB/c3T3 cells, as well as in the derivative cell lines. However, in the latter cell lines, but not in BALB/c3T3, the addition of platelet-poor plasma or insulin again increased the expression of c-myc. The increase in c-myc mRNA levels could be partially explained by an increase in transcription. These results indicate that in certain cell lines the expression of c-myc mRNA can be induced by insulin or platelet-poor plasma.
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PMID:Regulation of c-myc mRNA levels by insulin or platelet-poor plasma. 269 56

Two constructs (co-transfected with selectable markers) were used to establish cell lines from BALB/c3T3 cells: a p53 mini-gene under the control of an LTR promoter and a synthetic IGF-1 coding sequence driven by the SV40 early promoter. BALB/c3T3 cells do not grow in plasma or in 1% serum or in soft agar and in defined media require both platelet-derived growth factor (PDGF) and insulin (or IGF-1). Cells carrying only the LTR/p53 mini-gene grew well in plasma (but not in 1% serum), in soft agar and in serum-free medium containing only insulin. Cells carrying only the SV40/IGF-1 gene grew (but not too vigorously) in soft agar and grew well in serum-free medium containing PDGF but no insulin. Cells carrying both constructs grew very well in plasma, in soft agar and in serum-free medium without PDGF nor insulin. The results indicate that the requirements for growth of BALB/c3T3 cells can be reduced to two genes: IGF-1 and a gene replacing PDGF (p53 in our case). An unexpected, but interesting observation was that cells carrying the LTR/p53 gene grew slower in 10% serum than in plasma.
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PMID:Abrogation of the requirements for added growth factors in 3T3 cells constitutively expressing the p53 and IGF-1 genes. 306 89

A number of genes and cDNA sequences (including at least four oncogenes) are known to be expressed in a cell cycle-dependent manner, i.e. the levels of specific mRNAs vary with the phases of the cell cycle. In order to explore the significance of some of these sequences in the mitogenic response, we have investigated the expression of 8 cell cycle-dependent sequences (plus two control sequences, not expressed in a cell cycle-dependent manner) under a variety of conditions. These conditions included cells of different types, from different species, stimulated to proliferate by different mitogens. The genes (or sequences) studied included five cDNA clones whose sequences are preferentially expressed in early G1, i.e. two cDNA clones inducible by platelet-derived growth factor (JE-3 and KC-1), and three cDNA clones inducible by serum (2A9, 2F1, 4F1); and three oncogenes (c-myc, c-rasHa and p53) whose expression is known to be cycle-dependent. All of the tested genes, except 2A9, c-rasHa and the control genes, are expressed in a cell cycle-dependent manner in human peripheral blood mononuclear cells stimulated by phytohemagglutinin and in serum-stimulated mouse and Syrian hamster fibroblasts. The inducibility of these genes by different mitogens in cells of different types and from different species strongly suggests that these genes play a role in cell cycle progression. This conclusion is further supported by the known structural and functional similarities between cell-cycle dependent genes, oncogenes and genes coding for cell-cycle related molecules.
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PMID:Cell cycle dependent genes inducible by different mitogens in cells from different species. 375 18

PDGF-B released from colon tumor cells regulated tumor growth in athymic mice in a paracrine manner by inducing blood vessel formation. A positive correlation was found between expression of PDGF B-chain in cells grown in vitro and the number of factor VIII-positive blood vessels in tumors induced by three classes of colon carcinoma cell lines. Elevated expression of PDGF-B was also correlated with tumor size. Each cell line had the same mutations in the colon cancer genes APC, DCC, and p53 and had wild type c-K-ras genes (Huang et al. [1994] Oncogene, 9:3701-3706.) eliminating the possibility that any differences in tumor blood vessel formation were due to mutations and/or deletions in these genes. Colon carcinoma cells released biologically active PDGF capable of stimulating the growth of NIH3T3 cells, which was inhibited by neutralizing antisera to PDGF-AB chains. An inverse correlation was found between induction of factor VIII-positive blood vessels and expression of vascular endothelial growth factor (VEGF), while no correlation was seen with expression of either TGF alpha or k-FGF. Basic fibroblast growth factor (FGF) expression was not detected in these tumor cells. TGF beta 1 was capable of inducing PDGF-B expression in the undifferentiated U9 colon carcinoma cell line, but this sensitivity was not seen in differentiated cells. In contrast, TGF beta 1 inhibited VEGF expression in both undifferentiated cells and differentiated colon cancer cells. Thus, TGF beta 1 has two roles in the growth of undifferentiated U9 colon carcinoma cells in vivo: direct stimulation of cell proliferation as we have showed in earlier studies, and an increase in angiogenesis by inducing PDGF-B.
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PMID:Platelet-derived growth factor-B increases colon cancer cell growth in vivo by a paracrine effect. 759 1

We have established and characterized a new glioblastoma cell line, termed GT9, from a biopsy sample of a female adult patient with glioblastoma multiforme. The line has now undergone over 60 passages and has been successfully cultured after cryopreservation. Immunofluorescence analyses with a panel of monoclonal antibodies were positive for glial fibrillary acidic protein and vimentin, and negative for neurofilament, galactocerebroside, and fibronectin, a pattern typical of glial cells. Based on a tetraploid, the composite karyotype of GT9 cells included the loss of chromosome 10, gain of chromosome 7, and the presence of double minute chromosomes, three of the most common karyotypic abnormalities in glioblastoma. Sequence analysis of p53 cDNA revealed a homozygous double mutation at codon 249 (commonly mutated in aflatoxin-associated hepatocellular carcinoma) and codon 250. Moreover, there was a complete absence of wild-type p53. However, unlike the majority of human glioblastomas previously described, the expression of platelet-derived growth factor-B (PDGF-B), a potent mitogenic autocrine factor, was low in GT9 cells. The expression and phosphorylation of c-Jun and Jun-B, downstream mediators of the PDGF pathway, were also low. Thus, deregulation of the PDGF pathway does not appear to be involved in the pathogenesis of the GT9 glioblastoma. Conversely, Jun-D, a negative regulator of cell growth, was also low. In addition, Phosphorylated Egr-1, a recently reported suppressor of PDGF-B/v-sis-transformed cells, was also low, suggesting that the lack of activation of the PDGF pathway was not due to these suppressive mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of a new human glioblastoma cell line that expresses mutant p53 and lacks activation of the PDGF pathway. 775 3

Breast carcinomas are known to express platelet-derived growth factor (PDGF), a known connective tissue mitogen. In order to further evaluate the potential role of PDGF in these epithelial tumors, expression of the PDGF B chain (PDGF-B) and the PDGF receptor beta subunit (PDGFR) was analyzed by immunocytochemistry and in situ hybridization in 49 benign and malignant breast tissues. PDGF-B expression was analyzed with respect to the expression of the proliferating cell nuclear antigen, as well as tumor grade, p53 overexpression, estrogen receptor, progesterone receptor, and c-erbB-2 expression. Expression of PDGF-B protein and mRNA was restricted to the breast epithelium and tumor cells except for scattered tissue macrophages. A strong correlation was found between increasing proliferating cell nuclear antigen indices and PDGF-B expression in both nonmalignant (P = 0.01) and malignant (P = 0.02) breast specimens. Decreased PDGF-B expression was found in postmenopausal atrophic breast tissue compared with normal breast tissue (P = 0.04). Within the subgroup of malignant tumors, no correlations were found between PDGF-B expression and tumor grade or p53 overexpression. In 16 of the malignant tumors evaluated for estrogen/progesterone receptor status and c-erbB-2 overexpression, no correlations with PDGF-B expression were found. Membranous PDGFR immunostaining was present within the fibroblastic cell population in all of the tissues examined but not in the nonmalignant breast epithelium. Six malignant specimens had detectable cytoplasmic expression of PDGFR. There was no correlation between this PDGFR expression and proliferating cell nuclear antigen indices, but a correlation was noted between increasing estrogen receptor expression and PDGFR cytoplasmic expression (P = 0.04). The results support a paracrine role for PDGF-B in malignant and benign breast epithelial cell proliferation.
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PMID:Expression of platelet-derived growth factor B-chain and the platelet-derived growth factor receptor beta subunit in human breast tissue and breast carcinoma. 778 Sep 88

We report expression of the wt1 (Wilms' tumor) gene by cultured human melanoma cells. Using RNA polymerase chain reaction analysis, wt1 transcripts were detected in 7 of 9 melanoma cell lines but not in 5 normal melanocyte strains. In Northern blot analysis, steady-state wt1 mRNA levels were found in 2 of 4 melanoma lines but not in normal melanocytes. Sequence analysis of the wt1 cDNA expressed by melanoma cell line WM 902-B revealed the presence of 4 previously published splice variants but no evidence for mutations in the coding region. Previous work has shown that WT1 modulates transcription after binding to the early growth response (EGR)-1 sites present in the platelet-derived growth factor (PDGF)-A chain promoter; the PDGF-A chain gene is known to be expressed by various melanoma cell lines. Based on these findings, we studied the relationship of wt1 and PDGF-A chain gene expression in melanoma cell lines. Co-expression of the wt1 and the PDGF-A chain genes was observed in 2 melanoma cell lines with mutated p53 but not in 2 melanoma cell lines with wild-type p53; this result is consistent with a previous report showing that, in the context of absent or mutated p53, WT1 acts as a transcriptional activator, whereas in the presence of wild-type p53 it acts as a repressor.
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PMID:Expression of the wt1 Wilms' tumor gene by normal and malignant human melanocytes. 792 8


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