Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cholangiocarcinoma (CCC) is relatively hypovascular, in contrast to hepatocellular carcinoma (HCC), which is often highly vascular. We investigated if the diminished vascularity of CCC is related to altered expression of thrombospondin-1 (TSP-1), an antiangiogenic factor, and/or vascular endothelial growth factor (VEGF), a potent angiogenic factor, comparing the relationships with those of high- and low-vascular HCC. We also investigated the relationship between the mutation of the p53 gene and TSP-1 expression or VEGF expression. Northern blot analysis and immunohistochemical staining were performed on surgically resected human CCC and HCC. The ratios of TSP-1 mRNA level in cancer cells versus adjacent noncancerous cells (T/N ratios) were significantly higher in CCC (n = 11) than in HCC with high vascularity (n = 15). In contrast, T/N ratios of VEGF mRNA level in CCC (n = 11) were comparable with those in HCC with low vascularity (n = 5). In CCC, the cancer cells and fibroblasts were positively stained with anti-TSP-1 antibody. We observed that T/N ratios of VEGF mRNA level, but not those of the TSP-1 mRNA level, were significantly correlated with vascularity in HCC. The relative increase in TSP-1 and the relative decrease in VEGF in tumors compared with normal tissue may underlie the limited angiogenesis of CCC. The p53 gene did not affect the expression of TSP-1 in CCC or VEGF in HCC.
 ...
PMID:Enhanced expression of thrombospondin-1 and hypovascularity in human cholangiocarcinoma. 982 14

We previously developed a transgenic mouse model that expresses in the epidermis a murine p53172R-->H mutant (p53m) under the control of a human keratin-1-based vector (HK1.p53m). In contrast to mice with wild-type p53 and p53-knockout mice, HK1.p53m mice exhibit increased susceptibility to chemical carcinogenesis, with greatly accelerated benign papilloma formation, malignant conversion, and metastasis. In the study presented here, we examined the expression pattern of several differentiation markers and observed that p53m tumors exhibited a less differentiated phenotype than tumors elicited in non-transgenic mice. Metastasis in p53m tumors was also associated with a poorly differentiated phenotype. To determine whether genomic instability was associated with a putative gain-of-function role for this p53m, in situ examination of centrosomes was performed in HK1.p53m and equivalent p53-null papillomas. In contrast to HK1.p53m papillomas, which had centrosome abnormalities at high frequencies (75% of cells contained more than three centrosomes/cell), p53-null tumors exhibited few abnormal centrosomes (4% of cells contained more than three centrosomes/cell). To determine whether angiogenesis played a role in the rapid progression of p53m tumors, the expression of vascular endothelial growth factor, a promoter of angiogenesis, and thrombospondin-1, an inhibitor of angiogenesis, was examined in tumors derived from either p53m or p53-knockout mice. Regardless of their p53 status (wild type, p53m, p53-/-), all of the papillomas exhibited similar levels of vascular endothelial growth factor expression and decreased expression of thrombospondin-1 as did normal epidermis. In addition, tumors from different p53 genotypes showed a similar density of blood vessels. Because p53 status did not appear to play an overt role in angiogenesis, these data suggest that p53m accelerates tumorigenesis primarily by exerting a gain of function associated with genomic instability.
 ...
PMID:Analysis of centrosome abnormalities and angiogenesis in epidermal-targeted p53172H mutant and p53-knockout mice after chemical carcinogenesis: evidence for a gain of function. 983 79

The finding of frequent nitric oxide synthase expression in human cancers indicates that nitric oxide has a pathophysiological role in carcinogenesis. To determine the role of nitric oxide in tumor progression, we generated human carcinoma cell lines that produced nitric oxide constitutively. Cancer cells expressing inducible nitric oxide synthase that had wild-type p53 had reduced tumor growth in athymic nude mice, whereas those with mutated p53 had accelerated tumor growth associated with increased vascular endothelial growth factor expression and neovascularization. Our data indicate that tumor-associated nitric oxide production may promote cancer progression by providing a selective growth advantage to tumor cells with mutant p53, and that inhibitors of inducible nitric oxide synthase may have therapeutic activity in these tumors.
 ...
PMID:p53 and vascular endothelial growth factor regulate tumor growth of NOS2-expressing human carcinoma cells. 984 73

Cyclooxygenases (COXs) are key enzymes in the conversion of arachidonic acid to prostaglandins (PGs) and other eicosanoids. Nitric oxide synthase (NOS) is the enzyme that catalyzes the formation of nitric oxide (NO), a regulator of vascular permeability, from the guanidino nitrogen atom of L-arginine. Two isoforms of both enzymes occur: a constitutive one, Cox-1 and the inducible counterpart Cox-2; also NOS has a constitutive counterparts (cNOS) and an inducible form, called iNOS. The inducible isoforms of both enzymes are of maximum interest. It has been recently shown that cyclooxygenase-2 (Cox-2) is inducible by a variety of stimuli and that eicosanoids, mainly of the PGE2 species, are inducers of basic regulator of angiogenesis, including VEGF/VPF, bFGF, TGF-beta, PDGF, and endothelin-1. In addition, iNOS is inducible by Cox-2. p53 down-regulates the angiogenic process at various levels: it induces thrombospondin-1, a powerful antiangiogenic factor, down-regulates VEGF and NOS and, in addition, down-regulates hypoxia-induced angiogenesis, either inducing apoptosis or enhancing antiangiogenetic factors. It is noteworthy how important the p53 oncosuppressor is in the angiogenesis of solid tumor growth. Cox-2, iNOS and p53 are thus fundamental play-makers of the angiogenic process: they are discussed in detail and a tentative hierarchical cascade is proposed.
 ...
PMID:Cox-2, iNOS and p53 as play-makers of tumor angiogenesis (review). 985 Jul 41

Thrombospondin (TSP) is a Mr 450,000 multifunctional matrix glycoprotein that interferes with tumor growth, angiogenesis, and metastasis. It has recently been shown that TSP expression is enhanced by the product of the p53 gene and that a down-regulation of TSP may be observed when alterations of the p53 protein occur. Moreover, a number of studies have demonstrated a regulatory activity of p53 on human vascular endothelial growth factor (VEGF), although additional investigations will be necessary to understand their relationship. In non-small cell lung carcinoma (NSCLC), neoangiogenesis, p53 alterations, and VEGF expression seem to have meaningful implications in the development and progression of this type of cancer. The aim of this study is to identify and quantitate TSP I and TSP II mRNA in NSCLCs with respect to p53 alterations, angiogenic growth factor expression, and microvascular density. A series of 24 cases of NSCLC were analyzed. Eleven of 24 of the cases were positive for TSP II mRNA, whereas 8 of 24 showed TSP I mRNA expression. A significant inverse association was found between TSP I mRNA and fibroblast growth factor (FGF) protein expression (P = 0.00001). Tumors with low FGF protein expression (< or = 40% of positive cells) presented a number of TSP I cDNA molecules, significantly higher than tumors expressing high levels of FGF protein. No association was found between TSP mRNA expression and other angiogenic growth factors (i.e., VEGF) or tumoral neovascularization. On the contrary, tumors with high levels of FGF showed a higher number of microvessels (P = 0.05). By PCR-single-strand conformational polymorphism analysis, we observed aberrations of the p53 gene in 19 of the 24 tumor samples. No association was found between p53 alterations and TSP mRNA expression. Instead, an interestingly significant association was found between the presence of p53 mutations and high VEGF protein expression (P = 0.01) and neovascularization (P = 0.03). Highly vascularized tumors showed higher VEGF protein expression (r = 0.45; P = 0.02). These data support the concept that in NSCLC, p53 exerts an important role in the control of neoangiogenesis. This influence is probably mediated by VEGF. The inverse association we found between TSP I and basic FGF suggests a different role of TSP I and TSP II in the angiogenic "switch," supporting the hypothesis that especially TSP I may have a significant function in tumor angiogenesis.
 ...
PMID:Thrombospondins I and II messenger RNA expression in lung carcinoma: relationship with p53 alterations, angiogenic growth factors, and vascular density. 991 14

Angiogenesis is a prerequisite for solid tumor growth. Glioblastoma multiforme, the most common malignant brain tumor, is characterized by extensive vascular proliferation. We previously showed that transgenic mice expressing a GFAP-v-src fusion gene in astrocytes develop low-grade astrocytomas that progressively evolve into hypervascularized glioblastomas. Here, we examined whether tumor progression triggers angiogenetic signals. We found abundant transcription of vascular endothelial growth factor (VEGF) in neoplastic astrocytes at surprisingly early stages of tumorigenesis. VEGF and v-src expression patterns were not identical, suggesting that VEGF activation was not only dependent on v-src. Late-stage gliomas showed perinecrotic VEGF up-regulation similarly to human glioblastoma. Expression patterns of the endothelial angiogenic receptors flt-1, flk-1, tie-1, and tie-2 were similar to those described in human gliomas, but flt-1 was expressed also in neoplastic astrocytes, suggesting an autocrine role in tumor growth. In crossbreeding experiments, hemizygous ablation of the tumor suppressor genes Rb and p53 had no significant effect on the expression of VEGF, flt-1, flk-1, tie-1, and tie-2. Therefore, expression of angiogenic signals is an early event during progression of GFAP-v-src tumors and precedes hypervascularization. Given the close similarities in the progression pattern between GFAP-v-src and human gliomas, the present results suggest that these mice may provide a useful tool for antiangiogenic therapy research.
 ...
PMID:Early induction of angiogenetic signals in gliomas of GFAP-v-src transgenic mice. 1002 15

The early incidence of p53 mutation in astrocytomas suggests that it plays an important role in astrocyte transformation. Astrocytes isolated from homozygous p53 knockout mice grow rapidly, lack contact inhibition, and are immortal. Here we tested whether the loss of p53 is sufficient for progression to tumorigenicity of astrocytes. We grew primary astrocytes under three conditions for over 120 population doublings and assessed their antigenic phenotype, chromosome number, and expression of glioma-associated genes as well as their ability to form colonies in soft agarose and tumors s.c. and intracranially in nude mice. Under two conditions (10% FCS and 0.5% FCS plus 20 ng/ml EGF), cells acquired the ability to form colonies in soft agarose and tumors in nude mice, and this was accompanied by the expression of genes, including epidermal growth factor receptor, platelet-derived growth factor receptor alpha and beta, protein kinase Cdelta, and vascular endothelial growth factor, which are known to be aberrantly regulated in human astrocytomas. Under the third condition (0.5% FCS plus 10 ng/ml basic fibroblast growth factor), astrocytes gained the ability to form colonies in soft agarose and had abnormal chromosome numbers similar to cells in the first two conditions but did not form tumors in nude mice or overexpress glioma-associated genes. These data provide experimental evidence for the idea that the malignant progression initiated by the loss of p53 may be subject to modulation by extracellular environmental influences.
 ...
PMID:Malignant transformation of p53-deficient astrocytes is modulated by environmental cues in vitro. 1007 1

We examined the expression of vascular endothelial growth factor (VEGF) protein, p53 protein, and the MIB-1 index in 43 patients with malignant gliomas in relation to tumor vascularization by an immunohistochemical method. Factor VIII-related antibody was employed for the evaluation of the vascularity and endothelial proliferation. Of the 42 cases of malignant gliomas, 36 (86%) demonstrated immunoreactivity for VEGF in their tumor cells, whereas 22 (52%) had VEGF in their endothelial cells. There was a tendency for the vascularity to be correlated with the immunoreactivity for VEGF (coefficient, 0.340). In addition, a marked increase in endothelial proliferation was evident in cases showing moderate to strong positivity for VEGF as compared with the others. Immunoreactivity for VEGF was found mostly in the malignant gliomas without p53 overexpression and/or with p53 overexpression. However, statistical analysis revealed a correlation between the grade of p53 overexpression and the grade of VEGF expression (coefficient, 0.507), but not between the VEGF and MIB-1 index in our series. There was a tendency for the MIB-1 indices to increase in correlation with increasing vascularity.
 ...
PMID:Expression of vascular endothelial growth factor and p53 protein in association with neovascularization in human malignant gliomas. 1032 46

Angiogenesis is required for the growth and progression of malignancies. Recent studies have demonstrated that genetic alterations may accompany acquisition of the angiogenic phenotype. The tumor suppressor gene p53 is most frequently mutated in human cancers and is also known to be a transcriptional regulator of a variety of genes. Here, we investigated the antiangiogenic effect of the wild-type p53 (wt-p53) gene transfer on a human non-small cell lung cancer cell line. Mutant p53-expressing H226Br non-small cell lung cancer cells were transduced with the wt-p53 gene using a recombinant adenoviral vector (Ad5CMVp53) and applied to semiquantitative reverse transcription-PCRs for the detection of altered mRNA expression of angiogenic and/or antiangiogenic factors. In vivo neovascularization assay of Ad5CMVp53-infected cells was then performed using a membrane-diffusion chamber system s.c. transplanted in nu/nu mice. We also evaluated the effect of Ad5CMVp53-infected H226Br cells on nontransduced tumor cells in vivo by s.c. inoculating mixture of cells into nu/nu mice. Ad5CMVp53 infection markedly inhibited the expression of an angiogenic factor, vascular endothelial growth factor, and increased the expression of a novel antiangiogenic factor, brain-specific angiogenesis inhibitor 1, resulting in reduced neovascularization in vivo. Mixing experiments showed that tumor cells transduced with the wt-p53 gene inhibited the in vivo tumor growth of adjacent nontransduced cells. Our data suggest that a recombinant adenovirus expressing the wt-p53 gene is antiangiogenic, which may explain, in part, the mechanism of the bystander effect induced by the wt-p53 gene transfer on adjacent tumor cells.
 ...
PMID:Recombinant adenovirus expressing wild-type p53 is antiangiogenic: a proposed mechanism for bystander effect. 1035 34

Small cell carcinoma of the stomach has an aggressive feature, and the survival rate of the patients is poor. The purpose of this study was to determine the clinical course, and effects of histopathologic characteristics of specific tumors including DNA contents and immunohistochemical aspects in patients with small cell carcinoma of the stomach. Medical records of 8 patients who presented with small cell carcinoma of the stomach were retrospectively reviewed. Primary tumors were studied by flow cytometric analysis and immunohistochemical staining for the p53 protein, PCNA (proliferating cell nuclear antigen), factor VIII related antigen (specific for endothelial cells), VEGF (vascular endothelial growth factor) and PD-ECGF (platelet-derived endothelial cell growth factor). DNA aneuploid was observed in 4 cases. Staining for the p53 product was positive in 50% of all the cases. The average PCNA labeling rate (LR) was 71.3+/-9.9%. Positive VEGF expression was found in 7 tumors and positive PD-ECGF expression was found in all tumors. The estimated median survival was 252 days for all the patients. Liver metastases were observed in 4 of the 8 patients, however, surgery and chemotherapy have given us one long-term survivor (43 months). Higher PCNA LR of small cell carcinoma may be an unfavorable characteristic of biological behavior. Moreover, both VEGF and PD-ECGF positivity are well-characterized inducers of hepatic metastasis.
 ...
PMID:Highly aggressive behavior and poor prognosis of small cell carcinoma in the stomach: flow cytometric and immunohistochemical analysis. 1037 53


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>