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

It has been observed that the progressive ascitic growth of a transplantable T cell lymphoma of spontaneous origin, designated as Dalton's lymphoma (DL), induces inhibition of various immune responses and is associated with an involution of the thymus accompanied by a massive depletion of the cortical region and alteration in the distribution of thymocytes, with a decrease in CD4+CD8+, CD4+CD8- and CD4-CD8+ thymocytes. Morphological evaluation of thymocytes from DL-bearing mice revealed that with the progression of DL, a majority of thymocytes exhibited morphological features characteristic of apoptotic cell death, which included contracted cell bodies, condensed, uniformly circumscribed and densely stained chromatin, and membrane-bound apoptotic bodies containing one or more nuclear fragments. Quantitative and qualitative analysis of the DNA extracted from the thymocytes of DL-bearing mice revealed DNA fragmentation that increased concomitantly with the progression of DL and showed an oligonucleosomal DNA ladder pattern upon agarose gel electrophoresis, a hallmark of apoptotic cell death. Attempts to identify apoptotic factor(s) showed that the serum of DL-bearing mice contained certain soluble factor(s) that augmented the induction of apoptotis in thymocytes in a time- and dose-dependent manner. Although DL cells or their products, such as DL-cell-conditioned medium or DL-cell-free ascitic fluid, could also induce apoptosis of thymocytes in vitro, the magnitude of the same was consistently lower than that induced by the serum of DL-bearing mice. Further, elucidation of the mechanism of apoptosis induction in thymocytes with respect to the involvement of apoptosis-related genes revealed that the death pathway followed an interleukin-1 beta-converting-enzyme-dependent, Fas-mediated apoptotic cascade, with a concomitant increase in the protein products of the bax, bad, p53, fas and fasL genes and cleavage of the 23-kD N-terminal fragment of Bcl-2 that exhibited Bax-like death effector properties.
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PMID:Ascitic growth of a spontaneous transplantable T cell lymphoma induces thymic involution. 2. Induction of apoptosis in thymocytes. 1100 72

We investigated the functional impact of p53 on insulin-like growth factor I receptor (IGF-IR) expression in malignant cells. Using the BL-41tsp53-2 cell line, a transfectant carrying temperature-sensitive (ts) p53 and endogenous mutant p53 (codon 248), we demonstrated a drastic down-regulation of plasma membrane-bound IGF-IRs on induction of wild-type p53. However, a similar response was obtained by treatment of BL-41tsp53-2 cells expressing mutant ts p53 with a p53 antisense oligonucleotide. Thus, even if the negative effect of wild-type p53 predominates under a competitive condition, these data indicate that mutant p53 may be important for up-regulation of IGF-IR. To further elucidate this issue, three melanoma cell lines (BE, SK-MEL-5, and SK-MEL-28) that overexpressed p53 were investigated. The BE cell line has a "hot spot" mutation (codon 248) and expresses only codon 248-mutant p53. SK-MEL-28 has a point mutation at codon 145. SK-MEL-5 cells did not exhibit any p53 mutations, but the absence of p21Waf1 expression suggested functionally aberrant p53. Our data suggest that interaction with Mdm-2 may underlie p53 inactivation in these cells. Using p53 antisense oligonucleotides, we demonstrated a substantial down-regulation of cell surface expression of IGF-IR proteins in all melanoma cell lines after 24 h. This was paralleled by decreased tyrosine phosphorylation of IGF-IR and growth arrest, and, subsequently, massive cell death was observed (this was also seen in BL-41tsp53-2 cells with mutant conformation of ts p53). Taken together, our results suggest that up-regulation of IGF-IR as a result of expression of aberrant p53 may be important for the growth and survival of malignant cells.
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PMID:Increased expression of insulin-like growth factor I receptor in malignant cells expressing aberrant p53: functional impact. 1101 58

The concept of differential regulation of certain adhesion molecules on different cell subsets and their relevance to cell functions has emerged in recent years. The initial event in bone remodeling is an increase in osteoclastic bone resorption and cell adhesion between osteoclastic precursors and bone marrow stromal cells or osteoblasts is known to commit the osteoclast development. Here, we show that human osteoblasts can be divided into two subsets based on the expression of the intercellular adhesion molecule (ICAM)-1; ICAM-1+ osteoblasts highly adhered to monocytes, including osteoclast precursors, produced osteoclast differentiation factor (ODF), and induced multinuclear osteoclast-like cell formation. Anti-ODF monoclonal antibody (mAb) did not inhibit the adhesion of monocytes to osteoblastic cells, whereas anti-leukocyte function-associated antigen (LFA)-1, a receptor for ICAM-1, mAb blocked the adhesion. We thereby propose that the higher affinity adhesion via LFA-1/ICAM-1 is prerequisite for efficient function of membrane-bound ODF during osteoclast maturation. The functional characteristics of ICAM-1+ osteoblasts were emphasized further by cell cycle regulation, as manifested by (i) up-regulation of p53 and p21, (ii) reduction of activity of cyclin-dependent kinase (cdk) 6, (iii) underphosphorylation of retinoblastoma protein, (iv) increased Fas but reduced bcl-2 expression, and (v) majority of cells remained at G0/G1 phase. Furthermore, ICAM-1+ osteoblasts were induced by interleukin-1beta (IL-1beta). Taken together, we propose that the differentiation of osteoblasts to ICAM-1+ subpopulation by inflammatory cytokines plays an important role in osteoporosis, which is observed in patients with chronic inflammation, because ICAM-1+ osteoblasts can bias bone turnover to bone resorption, committing osteoclast maturation through cell adhesion with its precursor, and the majority of ICAM-1+ osteoblasts arrested at G0/G1 phase. Such regulation of cell cycle arrest also is an important determinant of the life span of cells in bone in which continuous bone remodeling maintains its homeostasis.
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PMID:Intercellular adhesion molecule 1 discriminates functionally different populations of human osteoblasts: characteristic involvement of cell cycle regulators. 1102 43

The authors report seven patients with carcinoid tumors of the extrahepatic bile ducts (EHBDs). All patients were women, with an average age at diagnosis of 49.8 years (range, 37-67 yrs). The most common presenting symptom was painless jaundice with or without pruritus. Although one patient had peptic ulcer disease before the onset of obstructive jaundice, none had systemic endocrine manifestations. These neoplasms were most often located in the common bile duct. Grossly, the carcinoid tumors were usually nodular and poorly demarcated, and ranged from 1.1 to 2.7 cm in size. Only one of the neoplasms was polypoid. Microscopically, the tumors had a trabecular or nesting pattern with occasional tubule formation, and were composed of relatively small cells with granular chromatin. All of the neoplasms expressed chromogranin and two expressed synaptophysin. Three expressed serotonin and two of the three were also immunoreactive for pancreatic polypeptide or somatostatin. Two tumors were focally positive for gastrin and one of these two tumors was also positive for serotonin and pancreatic polypeptide. All seven carcinoid tumors showed no immunoreactivity for p53, and assays for p53 loss of heterozygosity analysis were negative in two, suggesting that p53 mutations do not play a role in the pathogenesis of EHBD carcinoids. A mutation in codon 12 of K-ras was found in one carcinoid tumor whereas two of two showed immunoreactivity for Dpc4 protein. In view of the small number of carcinoids studied, the importance of these findings in the pathogenesis of these tumors is unclear. Ultrastructural examination of three of the tumors revealed numerous membrane-bound, round neurosecretory granules. Clinically, these lesions had an indolent course. Even in the presence of lymph node metastases (noted in two patients), all of the patients remained disease free 2 to 11 years (average follow up, 6.6 yrs) after segmental resection or pancreaticoduodenectomy (Whipple's procedure). Because carcinoid tumors of the EHBD are of low malignant potential, they should be separated from the more common adenocarcinomas in this location.
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PMID:Carcinoid tumors of the extrahepatic bile ducts: a study of seven cases. 1107 51

TNFalpha is a primary cytokine responsible for inflammatory and immunosuppressive responses in skin. After UV-B irradiation of cultured human keratinocytes, we found that TNFalpha was released into the media, as monitored by ELISA, and was bound to cells, as observed by immunofluorescence microscopy. The release of TNFalpha into cell culture supernatant during the 24 h after UV-B irradiation was augmented by the addition of IL-1alpha to the cells. Further, we found this secretion was unaffected by rapamycin, and therefore independent of FRAP DNA-protein kinase mediated signal transduction. However, UV-B also induced expression of membrane-bound TNFalpha, and this was dependent on FRAP signaling. In wild type mice, TNFalpha bound to skin increased immediately after irradiation, declined at 6 h, and then rose again at 12 h before falling by 24 h. This pattern of induction was confirmed by RT-PCR of TNFalpha mRNA message in cultured epidermal cells. Induction of membrane-bound TNFalpha was also found in c-fos gene knockout mice deficient in the AP-1 transcription factor, suggesting that, although AP-1 containing c-fos signaling is required for some UV responses, AP-1 containing c-fos is not required for this TNFalpha activation. However, in homozygous p53 knockout mice the basal level of TNFalpha bound to the epidermis was greatly elevated without UV irradiation. This level declined and remained constant following irradiation. This implies that p53 directly or indirectly represses TNFalpha gene expression and that modification of p53 mRNA stability or phosphorylation of p53 protein after UV may be responsible for TNFalpha induction in the membrane. Overexpression of the immunosuppressive cytokine TNFalpha in this locale may contribute to the carcinogen-susceptibility of p53 knockout mice.
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PMID:Regulation of TNFalpha production and release in human and mouse keratinocytes and mouse skin after UV-B irradiation. 1113 30

To elucidate the mechanisms underlying physiological development and neurodegenerative disorders of the human brain, information about molecular cell biology of human neurons is indispensable. Necdin, which is expressed in postmitotic neurons, binds to viral oncoproteins and the cell-cycle-related transcription factors E2F and p53. Ectopic expression of necdin in proliferative cells suppresses cell division. Necdin is expressed in neurons in phylogenetically old brain areas such as the brain stem and hypothalamus. The human necdin gene, which resides in the chromosome 15q11-q12 region, is not expressed in the Prader-Willi syndrome, suggesting that necdin is responsible for the pathogenesis of this genomic-imprinting-related neurobehavioral disorder. The Alzheimer amyloid precursor protein (APP) is a membrane-bound protein that is abundantly expressed in postmitotic neurons. The proteolytic processing of APP generates A beta, which is deposited in the brains of patients with Alzheimer's disease. APP is strongly expressed in neurons in phylogenetically new brain areas such as human association cortices. When APP is overexpressed in postomitotic neurons differentiated from human embryonal carcinoma by adenovirus-mediated gene transfer, it induces typical apoptosis through caspase-3 activation. Thus APP may be a proapoptotic molecule involved in neuronal death in Alzheimer's disease.
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PMID:[Molecular mechanisms of differentiation and death of human neurons: with special reference to necdin and APP]. 1121

A new cell line (SKS) established from ascites of a patient with neuroendocrine small cell carcinoma of the uterine cervix had a good tumorigenicity and caused marked peritoneal dissemination, and was also highly sensitive to gemcitabine in an in vitro chemosensitivity test. SKS cells were small round cells with a high nuclear/cytoplasmic (N/C) ratio and grew into colony-like aggregates, forming spherical aggregates of floating cells. The population doubling time was 44 h. The number of chromosomes ranged from 50 to 56. On examination of the ultrastructure, membrane-bound dense-core neurosecretory-type granules were observed in the cytoplasm. Neuron-specific enolase (NSE) was immunocytochemically positive in the cytoplasm, and 9.3 ng/ml of NSE was detected in the cell culture supernatant. Human papillomavirus was not detected. In the p53 gene, a 3-bp deletion, AAC (Asn), was detected at codon 131 in exon 5. SKS exhibited good tumorigenicity, and the tumor doubling time was 11 days. Intraperitoneal injection of the cells caused peritoneal dissemination, and marked ascites formation was observed. SKS was highly sensitive to gemcitabine, and the 50% growth inhibitory concentration was 30 nM. SKS cells are useful as a model of neuroendocrine small cell carcinoma of the cervix, and chemotherapy using gemcitabine may possibly be effective in this malignancy.
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PMID:Establishment and characterization of a new cell line (SKS) from neuroendocrine small cell carcinoma of the uterine cervix and its chemosensitivity. 1140 6

Recent evidence identified a genetic and functional link between Chk2 kinase and p53 as a candidate genome integrity checkpoint and a tumour suppressor pathway. Here we report that in human cells, Chk2 and p53 form protein-protein complexes whose abundance increased upon DNA damage, and whose formation was abrogated through cancer associated mutations in the FHA domain of Chk2, or mutations in the tetramerization domain of p53. Whereas among Li-Fraumeni syndrome families mutations of Chk2 or p53 occur in a mutually exclusive manner, we document that the colon cancer cell line HCT-15 concomitantly lacks functions of both Chk2 and p53, the latter demonstrated by a non-invasive reporter assay monitoring p53-dependent transactivation in live cells. Despite the preserved ability of common cancer-derived mutant p53 proteins to bind and potentially 'titrate' activated Chk2, the integrity of the S phase checkpoint response to ionizing radiation remained largely intact and dependent on Chk2 in cells with wild-type, mutant, or no p53. These results provide new mechanistic insights into the Chk2-p53 interplay, suggest how mutations in Chk2 may abrogate its tumour suppressor function, and indicate that compared with individual defects in either Chk2 or p53, concomitant mutations in both of these cell cycle checkpoint regulators may provide some additional selective advantage to tumour cells.
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PMID:Functional impact of concomitant versus alternative defects in the Chk2-p53 tumour suppressor pathway. 1157 48

Excess nitric oxide (NO) induces apoptosis in some cell types including macrophages; however, the cascade of NO-mediated apoptosis is not fully understood. We investigated the initial steps of NO-mediated apoptosis in mouse macrophage-like RAW 264.7 cells. When cells were treated with bacterial lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma), NO-mediated apoptosis occurred. Under these conditions, p53 accumulation was not observed, indicating that DNA damage is not the main trigger of NO-mediated apoptosis. On the other hand, mRNA and protein for CHOP, a transcription factor known to be induced by endoplasmic reticulum (ER) stress, were induced. The CHOP induction by LPS/IFN-gamma treatment preceded cytochrome c release from mitochondria. In addition, p90ATF6, an ER membrane-bound transcription factor involved in ER stress response, was cleaved to its active soluble form p50ATF6, which was transported to nucleus and bound to the ER stress response element of the CHOP gene. In the luciferase reporter assay, both the CHOP-binding element of the Rous sarcoma virus long terminal repeat and ER stress response element of the CHOP gene were activated by LPS/IFN-gamma treatment. When RAW 264.7 cells or COS-7 cells were transfected with expression plasmids for CHOP, p90ATF6, or p50ATF6, cell death was observed. In addition, apoptosis induced by p50ATF6 was prevented by a CHOP dominant negative form as well as by an ATF6 dominant negative form, and LPS/IFN-gamma-induced apoptosis was prevented by the CHOP dominant negative form. Peritoneal macrophages from CHOP knockout mice showed resistance to NO-induced apoptosis. These results indicate that the ER stress pathway involving ATF6 and CHOP plays a key role in NO-mediated apoptosis in macrophages.
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PMID:Nitric oxide-induced apoptosis in RAW 264.7 macrophages is mediated by endoplasmic reticulum stress pathway involving ATF6 and CHOP. 1180 88

Functional studies using freshly isolated tumor-infiltrating B lymphocytes(TIB) are difficult to perform and interpret. Here we document a novel function of TIB using fresh human lung cancer tissues engrafted in SCID mice; they are at activated state and produce tumor-specific antibodies in tumor microenvironment: (a) TIB engrafted in SCID mice produced human IgG; (b) IgG derived from TIB highly bound intracellular and membrane-bound antigens of autologous cancer cells; and (c) less recognition of autoantigens expressed on normal lymphocytes by IgG derived from TIB compared with IgG from the serum of the patient. On the basis of the novel findings presented in this study, we modified the original serological analysis of antigens by recombinant cDNA expression cloning design in a patient with lung cancer who expressed unusually favorable clinical evolution and analyzed humoral immunity against identified mutated p53 antigen. This study provides the first demonstration that antibodies derived from TIB recognize tumor antigens by serological analysis of antigens by recombinant cDNA expression cloning methodology and circulating anti-p53 antibodies in sera derived from TIB in tumor microenvironment. Our approach using TIB may allow the identification of key antigens in the humoral cancer-related immune system.
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PMID:Tumor-infiltrating B lymphocytes as a potential source of identifying tumor antigen in human lung cancer. 1191 50


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