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

An epidermal cell model in which initiated, benign tumor-producing and carcinoma stages were derived from a cloned parental cell strain was used to examine p53 expression during multistage epithelial carcinogenesis. Increased steady-state levels of p53 RNA were detected in squamous cell carcinomas compared to papilloma and normal epidermal cells. Nontumorigenic initiated cell precursors of the carcinomas exhibited normal p53 expression, localizing altered p53 regulation to the malignant conversion stage. Immunoprecipitation and Western immunoblot analyses demonstrated elevated levels of p53 protein in the moderately differentiated carcinoma compared to normal cells, and negligible levels of p53 in the poorly differentiated carcinoma cells. Sequence analysis of p53 complementary DNA from normal and carcinoma cells revealed no mutations in the coding or 5'- and 3'-untranslated regions, suggesting a novel mechanism of p53 inactivation.
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PMID:Altered expression of wild-type p53 tumor suppressor gene during murine epithelial cell transformation. 137 Jun 52

Mutations in the TP53 tumor suppressor gene have been studied in different types of brain tumors. Little is known about this genetic event in human meningioma, a mostly benign tumor. To investigate the frequency of TP53 gene mutations in human tumors derived from meningeal tissues, paraffin-embedded tissues from 30 cases (including 2 malignant and 4 atypical meningiomas, as well as 2 hemangioblastomas and 3 hemangiopericytomas) were screened by immunohistochemistry. Polymerase chain reaction/single strand conformational polymorphism (PCR/SSCP) and direct DNA sequencing were thereafter performed in selected cases. Nuclear p53 staining was not seen in any of the 19 benign meningiomas tested, while atypical meningiomas, hemangioblastomas, and hemangiopericytomas displayed nuclear staining in a subpopulation of tumor cells in 4 out of 5, 2 out of 2, and 3 out of 3 cases, respectively. One malignant meningioma showed an intense nuclear staining and a band shift in SSCP. In this case, we identified a mutation in the TP53 gene at codon 161 changing GCC to ACC and resulting in an alteration of alanine to threonine in this position. Our results indicate that TP53 gene mutation may be considered as a marker for malignant transformation in meningioma. p53 immunoreactivity, even in the absence of detectable gene mutation, is also associated with atypia and does not appear in regular benign meningiomas.
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PMID:Detection of TP53 gene mutation in human meningiomas: a study using immunohistochemistry, polymerase chain reaction/single-strand conformation polymorphism and DNA sequencing techniques on paraffin-embedded samples. 765 83

Expression of transforming growth factor beta 1 (TGF beta 1) protein was examined in chemically induced benign skin tumors with genetically defined empirical risks for malignant conversion. Benign tumors induced in mice which have both alleles of the p53 gene deleted have a malignant conversion frequency of approximately 50%, whereas similar tumors induced in wildtype and heterozygous p53 mice have conversion probabilities of 3 and 8%, respectively (Kemp et al., Cell, 74: 813-822, 1993). The TGF beta 1 antibody, anti-CC (1-30-1), was shown to stain either the proliferative keratinocyte compartment of the tumor or the tumor stroma, whereas another TGF beta 1 antibody, anti-LC (1-30-1), stained highly differentiated granular cells of the tumors. A strong correlation was found between staining of the proliferative keratinocyte compartment of tumors with the anti-CC (1-30-1) antibody and tumor genotype. Only 18% (6 of 32) of homozygous p53 null tumors showed any basal keratinocyte staining with this antibody, whereas over 80% (32 of 38) of heterozygous and wild-type tumors showed positive staining. Additionally, in most tumors examined, the spatial distribution of staining for the proliferating cell nuclear antigen appeared to be mutually exclusive with that of TGF beta 1 on adjacent serial sections. This suggests that, in these cases, tumor keratinocytes are sensitive to negative growth regulation by TGF beta. TGF beta 1 protein staining in benign tumors is thus prognostic for a low probability of malignant conversion, and its expression may be mechanistically involved in limiting malignant conversion since, at the benign tumor stage examined, keratinocytes are still sensitive to growth inhibition by TGF beta 1.
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PMID:Lack of transforming growth factor-beta 1 expression in benign skin tumors of p53null mice is prognostic for a high risk of malignant conversion. 795 10

We quantitatively analyzed the c-myc and p53 products using flow cytometry in 28 cases of resected lung cancer and one case each of chorio-carcinoma, plasmacytoma, malignant mesothelioma and sclerosing hemangioma. In the lung cancer cases, c-myc and p53 products were detected in 10 cases (35%) and 7 cases (21%), respectively. These rates are higher than the DNA abnormal expression rates of the c-myc and p53 genes (15% and 12%, respectively) in our own data. In the adenocarcinoma of lung cancer cases, c-myc and p53 products were detected in 9 cases (53%) and 5 cases (29%), respectively. Among the squamous cell carcinoma cases, there were one case (11%) of c-myc expression and one case (11%) of p53 expression. DNA content analysis of the lung cancer patients revealed 7 cases of DNA diploidy and 21 cases of DNA aneuploidy. All 10 c-myc-positive cases showed DNA aneuploidy; thus the positive rate for c-myc products in the DNA aneuploidy cases was significantly different compared with the DNA diploidy cases (p < 0.05). In the sclerosing hemangioma case, we detected both c-myc and p53 products. Sclerosing hemangioma has been thought to be a benign tumor, but it may be a malignant tumor.
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PMID:[DNA content analysis and detection of c-myc and p53 products using flow cytometry in resected lung cancer cases]. 820 22

Pleomorphic adenoma (PA) is the most common benign tumor of salivary glands. Carcinomas in pleomorphic adenomas (CPAs) may arise by malignant transformation of the epithelial components of PAs. Occasionally, transitional zones containing cells with histological features intermediate between those of the benign PA and carcinomatous components of CPA are identified. After careful microdissection of archival microslides, the authors studied 12 cases of CPAs and their attendant adenomatous and transitional areas for mutations in the p53, RB, and K-ras genes, and at chromosomal loci 5q and 9p. The authors failed to find mutations in the K-ras gene or 9p locus. A relatively high rate of mutations (loss of heterozygosity [LOH] and microsatellite alterations) at the p53 gene were detected in CPAs (58%), and at somewhat lower frequencies at the RB gene (33%) and chromosomal location 5q (17%). Mutational frequency in the associated transitional and adenomatous areas were slightly lower than in the corresponding CPAs. No mutations were detected in adenomatous or transitional areas unless they also were present in the corresponding CPAs. Mutations of these three genes were absent in four cases of CPA, and in seven PAs without malignant change. These findings indicate that most CPAs arise from adenomas as the result of mutations in the three genes, especially p53. In addition, other, as yet unidentified genes may also be involved both in the development of PA and in its malignant progression to CPA. Mutational analysis of PAs may provide information of prognostic importance.
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PMID:Mutations associated with carcinomas arising from pleomorphic adenomas of the salivary glands. 876 10

Intact female Beagles from life-span studies in the Lovelace Respiratory Research Institute colony were examined for mammary tumor incidence. The breeding colony, founded in 1963, produced five generations from 28 founder females. After proportional hazards analysis, two maternal families were shown to have markedly different phenotypes, one susceptible and one resistant to mammary neoplasia, as compared with the entire colony. When tumors were subdivided into benign and malignant based on local invasiveness, familial differences in tumor incidence were preserved for each tumor type. Fifty-seven females in the susceptible family developed 149 benign and 39 malignant tumors, and 95 females in the resistant family developed 70 benign and 20 malignant tumors. The ratio of benign to malignant tumors of about 4:1 for both families was higher than expected. Using Kaplan-Meier and log-rank analyses, the susceptible family had a 50% malignant tumor incidence by age 13.6 years, whereas the resistant family did not have a 50% incidence until 17.0 years (P = 0.0065). Because of marked censoring, Kaplan-Meier analyses could not provide an estimate of the 50% benign tumor incidence; mean incidence age was calculated instead. These estimates for benign tumors for susceptible and resistant families were 10.8 and 13.8 years (P = 0.0001), respectively. Using chi(2) tests, families had no differences in the occurrence of the types of benign (P = 0.098) or malignant (P = 0.194) tumors or in the ratio of benign to malignant tumors (P = 0.778). Immunohistochemical analysis of malignant tumors from both families did not demonstrate differences in p53 mutation rate or p185erbB-2 expression. These results suggest that 1) genetic factors produce familial differences in the age of onset of both benign and malignant mammary tumors; histologic types do not segregate by family; 2) the ratio of benign to malignant tumors is greater than formerly reported; and 3) neither p53 nor p185erbB-2 alterations are the basis for the familial predisposition.
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PMID:A canine model of familial mammary gland neoplasia. 959 80

Oncoprotein E6 of the human papillomavirus (HPV) associated with cervical cancer (HPV-16 and -18) degrades tumor suppressor protein p53, but seems to have p53-independent transforming functions. We searched for other cellular targets for the N-terminal region of HPV-16 E6 using a yeast two-hybrid system. The E6 was found to bind to the C-terminal region of a human minichromosome maintenance 7 (hMCM7) protein, which is a component of replication licensing factors. The full-length hMCM7 translated in vitro was capable of binding to bacterially expressed E6. In yeast cells the E6s of the cancer-associated HPVs (HPV-16, -18, and -58) bound to hMCM7 more strongly than those of the HPVs associated with a benign tumor (HPV-6 and -11). Binding of E6 with hMCM7 may cause chromosomal abnormalities found in the human cells expressing E6s of oncogenic HPVs.
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PMID:Human papillomavirus oncoprotein E6 binds to the C-terminal region of human minichromosome maintenance 7 protein. 970 68

An in vitro carcinogenesis model of human skin keratinocytes has been developed based on the spontaneously immortalized keratinocyte cell line HaCaT. Immortalization, the initial stage in human carcinogenesis in vitro, was induced by ultraviolet-type mutations in the p53 gene followed by further genetic alterations leading to the loss of senescence genes, in particular on chromosome 3p. Despite multiple genetic changes, the HaCaT cell line sustained its genomic balance up to high passage levels and maintained a non-tumorigenic phenotype. Tumorigenic transformation was induced by ras oncogene transfection but also by culture stress and elevated temperature, resulting in benign and malignant tumorigenic clones. Malignant conversion was associated with the loss of a copy of chromosome 15, leading to a decrease in thrombospondin-1 (TSP-1) expression. Heat-induced malignant conversion was associated with a gain of material on chromosome 11, including the cyclin D1 gene. The microenvironment plays a major role in tumorigenic transformation and the control of malignant cells. Overexpression of platelet-derived growth factor in HaCaT cells caused mesenchyme activation and formation of benign tumors. Halting tumor angiogenesis completely prevented invasion of malignant cells and induced a benign tumor phenotype. Transfer of a normal chromosome 15 or TSP-1 transfection into a skin carcinoma line resulted in tumor suppression due to TSP-1-blocked tumor vascularization. Because of the reduced TSP-1 expression, blood vessels infiltrated the tumor, and it expanded. Progression to more aggressive tumor phenotypes required the in vivo environment and was caused by selection of a subpopulation and further genetic modifications. The improved autonomous growth of these cells was associated with new expression of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor, which acted in an autocrine manner to stimulate proliferation and migration. With this in vitro skin carcinogenesis model we were able to demonstrate multiple stages in the transformation process that were associated with different genetic and phenotypic characteristics. In addition, we documented that modulation of the tumor stroma plays an important and decisive role in tumor development and progression. From this we hypothesize that the growth restraints of the microenvironment are increasingly lost with advancing stages of carcinogenesis but can be restored by modulation of the tumor stroma.
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PMID:Multiple stages and genetic alterations in immortalization, malignant transformation, and tumor progression of human skin keratinocytes. 983 75

Fibroadenoma (FA) is the most common benign tumor of the breast in adult women. Some FA have a highly cellular stroma, making it difficult to differentiate from phyllodes tumors (PT). Forty-three FA were grouped into: (i) 27 conventional type (FACT) median stromal cellularity (SC) of highest cellular area (HCA), < or = 125 cells/1 high-power field (HPF); and (ii) 16 cellular variant (FACV) median SC of HCA, > 125 cells/1 HPF. These were studied for the proliferative activity of their stromal cells. Expression of c-fos, p53, basic fibroblast growth factor (bFGF), fibroblast growth factor receptor (FGFR), and vascular endothelial growth factor (VEGF) in the stromal cells were examined in the FA and 12 PT to determine whether it is possible to separate FACV from FACT. The proliferative activity of stromal cells was evaluated by the labeling index (LI) of proliferating cell nuclear antigen (PCNA). Conventional type fibroadenoma stromal cells had the lowest frequency of c-fos, p53, bFGF, FGFR and VEGF protein expression; PT stromal cells had the highest frequency of expression; and FACV stromal cells had an intermediate frequency of expression. Multivariate analysis demonstrated that bFGF and FGFR expression are significantly correlated with SC of FA. Separation of FACV from FACT by SC seems appropriate in revealing the phenotypic and biological differences of FA. The SC of FA seems to be regulated by bFGF and FGFR expression.
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PMID:Proliferative activity and tumor angiogenesis is closely correlated to stromal cellularity of fibroadenoma: proposal fibroadenoma, cellular variant. 1041 87

Intraductal papilloma is an extremely rare benign salivary gland tumor that occurs most commonly in the minor salivary glands. To our knowledge, a malignant counterpart of intraductal papilloma has not been described previously. We report one case each of benign and malignant intraductal papillary tumors. The benign tumor occurred in the sublingual gland and was a typical example of intraductal papilloma, with the exception that we found no previously published reports of this type of tumor in this location. The other patient had a left parotid gland tumor that was architecturally similar to the intraductal papilloma, with the addition of cytologic atypia, intraductal extension, microinvasion, and lymph node metastases. This tumor was diagnosed as intraductal papillary adenocarcinoma with an invasive component. Both patients were alive and well without evidence of recurrence 2 years and 6 months (case 1) and 6 years (case 2) after surgery. Immunohistochemical examination revealed that the tumor cells resembled duct luminal cells in both cases. The 2 tumors had different immunoreactivities for carcinoembryonic antigen, p53, and Ki-67. The malignant counterpart of intraductal papilloma should be considered in the differential diagnosis of salivary gland tumors with a predominantly papillary structure, even though this tumor is extremely rare.
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PMID:Intraductal papillary tumors of the major salivary glands: case reports of benign and malignant variants. 1065 42


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