Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study evaluates the prognostic value of mutant p53 protein overexpression in 109 surgically treated cervical cancer stages IB to IIB. Squamous cell carcinoma stages IB, IIA, and IIB were present in 52, 13, and 44 cases, respectively. We performed immunohistochemistry using a monoclonal antibody against the p53 suppressor gene product (clone BP53-12). Data were analyzed for the end points of disease-free survival and overall survival. In 109 tissue specimens we detected 22 cases of p53 expression. Six of 22 patients with p53 expression and 21 of 87 patients without p53 expression showed tumor recurrences. p53 expression showed no significant correlation to age, tumor stage or lymph node involvement. In the univariate analysis p53 expression showed no prognostic value for disease-free (P = 0.5) and overall survival (P = 0.6). Multivariate analysis showed a significant prognostic value for established prognostic parameters while p53 expression had no prognostic value for recurrence-free (P = 0.6) and overall survival (P = 0.5). In contrast to other malignancies mutant p53 overexpression showed no relation to prognosis in surgically treated cervical cancer stage IB to IIB.
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PMID:Mutant p53 in patients with invasive cervical cancer stages IB to IIB. 772 36

The cytotoxicity of Doxorubicin and cis-dichloro-diammine-platinum (DDP) was evaluated in clones, obtained from a human ovarian cancer cell line transfected with a temperature-sensitive p53 mutant, which express mutant p53 at 37 degrees C and wild-type-like p53 at 32 degrees C. DDP was equally active in cells not expressing p53 (SKN) or cells expressing a mutated form of p53 (SK23a kept at 37 degrees C) or a wild-type-like form of p53 (SK23a cells kept at 32 degrees C). In contrast, Doxorubicin was less cytotoxic in cells expressing wild-type p53 than in cells expressing no p53 or mutated p53. This reduction was not due to a decreased intracellular accumulation or to a faster efflux of Doxorubicin. Topoisomerase II was found to be present in the same amount in all the systems utilized and to be functionally active, thus not accounting for the observed effect of Doxorubicin. A clear induction of WAF1/CIP1 and GADD45 genes in cells expressing wild-type p53 after Doxorubicin treatment was found. DDP, which was equally active in the cells utilized, caused an increase in the transcription only of GADD45 gene but not of WAF1/CIP1 gene. Doxorubicin was also able to induce the transcription of WAF1/CIP1 gene in SKN cells (not expressing p53) or in SK23a cells at 37 degrees C (expressing mutated p53), indicating that the expression of this gene also, in some tumor-cell lines, is not necessarily or uniquely induced by wild-type p53.
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PMID:Decreased cytotoxic effects of doxorubicin in a human ovarian cancer-cell line expressing wild-type p53 and WAF1/CIP1 genes. 772 53

Mutations in the p53 gene are implicated in the pathogenesis of half of all human tumors. We have developed a simple functional assay for p53 mutation in which human p53 expressed in Saccharomyces cerevisiae activates transcription of the ADE2 gene. Consequently, yeast colonies containing wild-type p53 are white and colonies containing mutant p53 are red. Since this assay tests the critical biological function of p53, it can distinguish inactivating mutations from functionally silent mutations. By combining this approach with gap repair techniques in which unpurified p53 reverse transcription-PCR products are cloned by homologous recombination in vivo it is possible to screen large numbers of samples and multiple clones per sample for biologically important mutations. This means that mutations can be detected in tumor specimens contaminated with large amounts of normal tissue. In addition, the assay detects temperature-sensitive mutants, which give pink colonies. We show here that this form of p53 functional assay can be used rapidly to detect germline mutations in blood samples, somatic mutations in tumors, and mutations in cell lines.
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PMID:A simple p53 functional assay for screening cell lines, blood, and tumors. 773 13

Wild-type p53 is a nuclear phosphoprotein that inhibits cell proliferation and represses transcriptionally most TATA box-containing promoters in transformed or tumor-derived cell lines. This study demonstrates that p53 alters transcription of the long control region (LCR) of human papillomavirus type 18 (HPV-18). Wild-type and mutant p53 143Val to Ala repressed the HPV-18 LCR promoter in normal human keratinocytes, the natural host cell for HPV infections. Repression by wild-type p53 was also observed in C-33A cells and in an HPV-16-immortalized cell line with an inducible wild-type p53. However, when C-33A cells were cotransfected with the HPV-18 LCR and mutant 143Val to Ala, repression did not occur. Mutant p53 135Cys to Ser did not induce repression in either normal human keratinocytes or in the C-33A line; although like 143Val to Ala, it is thought to affect the DNA binding activity of the wild-type protein. The ability of mutant p53 143Val to Ala to inactivate the HPV early promoter in normal cells (by approximately 60% reduction) suggests that this mutant may be able to associate with wild-type p53 and interact with TATA box-binding proteins. Therefore, these results demonstrate that the transcriptional activities of p53 mutants may be dependent upon the cell type assayed and the form of its endogenous p53. Furthermore, normal human keratinocytes represent an alternative model for determining the activities of p53 mutants.
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PMID:Transcriptional repression in normal human keratinocytes by wild-type and mutant p53. 775 99

Scientific research evaluates the prognostic importance of 53 expression and DNA flow cytometry controversially. To evaluate the prognostic relevance of mutant p53 protein overexpression and DNA flow cytometry in primary breast cancer we correlated these factors with the common prognostic parameters such as tumor size, lymph node status, grading, menopausal status and receptor status. Human breast cancer specimens from 180 previously untreated patients were collected and deep frozen. On each specimen DNA-analysis by Geohde's technique (Partec PAS II) and immunohistochemical evaluation of mutant p53 protein (PAb 1801 and 240, Novocastra Lab., Great Britain) were performed. Besides TNM- and histological classification, estrogen (ER)- and progesterone (PgR) receptor content was recorded. Overexpression of mutant p53 protein was found in 34 (19%) of all specimens. All these 34 tumors were aneuploid (p = 0.007), 86% of them were receptor negative (p 0.0001), 79% had a high tumor grade (p 0.0001), 73% a high S-phase-fraction (SPF) (p = 0.045) and 53% were premenopausal (p 0.0001). Tumor size and node status did not correlate significantly with p53 expression. 27 (15%) out of 180 carcinomas were diploid. There was a significant correlation between ploidy and the tumor grade (p = 0.003) and SPF (p 0.0001), but not correlation between ploidy and tumor size (p = 0.21), node status (p = 0.33) or receptor status (p = 0.18). A low SPF was predominantly found in tumors less than 2 cm in diameter (p 0.0001); no significant correlation was found between SPF, receptor status, tumor grade, node and menopausal status. Mutant p53 protein expression and DNA analysis in combination with common prognostic parameters might help to detect prognostically unfavourable subgroups of breast cancer patients.
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PMID:Mutant p53 expression and DNA analysis in human breast cancer comparison with conventional clinicopathological parameters. 776 41

The prognosis of gastric carcinoma remains unfavorable despite a greater understanding of its molecular pathology. This retrospective study of primary gastric carcinomas was collected from one of the highest risk regions of China and examined for the oncogenetic expression of p53, c-erbB-2, and PCNA using immunohistochemistry and DNA contents by flow cytometry and image analysis. These products are reported to influence the tumor behavior. The p53 nuclear and c-erbB-2 membrane-bound stainings were seen in 58% and 34% of cases, respectively. A high PCNA index was found in 90% of the tumors. The p53 expression did not correlate with the histological differentiation, gross morphology, and depth of tumor invasion. Additionally, p53 and c-erbB-2 reactivity did not correlate with the proliferative index (PI) or S-phase DNA content. However, the mutant p53 expression was detected in the dysplastic cells adjacent to the tumor, suggesting a possible role of the oncogene in tumor pathogenesis. Mutant p53 expression can also be helpful in early detection of cases with dysplasia in well-differentiated adenocarcinomas.
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PMID:Gastric carcinoma: recent issues in prognostic factors. 777 39

Hepatitis B virus (HBV) infection is closely associated with the development of hepatocellular carcinoma (HCC), but definite mechanisms by which it could play an etiologic role have not yet been identified. Modifications of the function of the RB tumor suppressor gene, which regulates the cell cycle, could provide such a mechanism. In the present study, the expression of the protein product of RB, pRB, was evaluated by immunohistochemical staining in HCC tissues from 25 patients from China and the United States, adjacent nontumorous liver from 19 of those patients, five human HCC cell lines, three human hepatoblastoma cell lines, and five specimens of normal human liver. Representative samples were also evaluated by western blot. Altered expression of RB was detected in eight HCC tissues (pRB undetectable in five HCCs and detected in < 1% of nuclei of HCC cells in three others); all eight had detectable hepatitis B surface or core antigen in the adjacent nontumorous liver, indicating active HBV infection. pRB was detected in 10-95% of nuclei (normal expression) in the remaining 17 HCCs, and in many nuclei in all 19 nontumorous livers, and in the 5 normal livers. No pRB staining was detected in the nuclei of three HCC cell lines, but pRB was detected in > 90% of nuclei of the other HCC and hepatoblastoma cell lines. The relationship of pRB expression to mutations of the p53 tumor suppressor gene was also examined. The absence of detectable nuclear pRB by immunohistochemical staining was associated with the presence of presumed mutant p53 detected by immunohistochemical staining in four out of five HCC cases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:RB tumor suppressor gene expression in hepatocellular carcinomas from patients infected with the hepatitis B virus. 779 88

Previously, we have shown that the chicken anemia virus-derived VP3 ("apoptin") protein induces apoptosis in chicken mononuclear cells. Here, we report that apoptin also induces apoptosis in human osteosarcoma cells, regardless of whether they expressed wild-type, mutant p53, or no p53 at all. Moreover, the nuclear location of apoptin appears to be important for its optimal induction of apoptosis. The fact that apoptin can induce p53-independent apoptosis in human tumor cells makes apoptin a potential candidate for treatment of frequently occurring types of cancer cells that do not contain functional p53.
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PMID:Apoptin, a protein derived from chicken anemia virus, induces p53-independent apoptosis in human osteosarcoma cells. 783 13

The bax gene promoter region contains four motifs with homology to consensus p53-binding sites. In cotransfection assays using p53-deficient tumor cell lines, wild-type but not mutant p53 expression plasmids transactivated a reporter gene plasmid that utilized the bax gene promoter to drive transcription of chloramphenicol acetyltransferase. In addition, wild-type p53 transactivated reporter gene constructs containing a heterologous minimal promoter and a 39-bp region from the bax gene promoter in which the p53-binding site consensus sequences reside. Introduction of mutations into the consensus p53-binding site sequences abolished p53 responsiveness of reporter gene plasmids. Wild-type but not mutant p53 protein bound to oligonucleotides corresponding to this region of the bax promoter, based on gel retardation assays. Taken together, the results suggest that bax is a p53 primary-response gene, presumably involved in a p53-regulated pathway for induction of apoptosis.
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PMID:Tumor suppressor p53 is a direct transcriptional activator of the human bax gene. 783 49

The oncoproteins from several DNA tumor viruses form a complex with p53 and inactivate its function. Wild-type p53 is a transcription factor and can regulate eukaryotic promoters both positively and negatively. To elucidate the basis of the opposing functions and to understand whether and how oncoprotein synthesis in papovaviruses is regulated by p53, we studied modulation of the early promoters of SV40, polyomavirus and BK virus in the absence of the interfering effect of viral large T antigens. We here show that murine p53 can regulate the viral promoters either positively or negatively depending on the cell type. A temperature-sensitive mutant p53, 135 Val, at 37 degrees C also showed a cell-specific effect. These results suggest that promoter activation by p53 is not solely determined by p53 binding site, but host factors modulate p53's transactivation function. A TATA-less polyomavirus late promoter was also repressed in HeLa cells and the level of repression was much less in the presence of active early promoter. As p53 and 135 Val were overexpressed to similar extent in different transfected cell lines, variation in transactivation function is not due to the difference in the level of expressed protein. Our observations thus suggest that p53 interactions with cellular factors in addition to the TATA binding protein (TBP) are important for activator and repressor functions of p53. Well-defined viral promoters could thus provide us with an important tool for the identification and characterization of cellular factors that modulate p53-binding dependent gene regulation in animal cells.
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PMID:Cell-specific modulation of the papovavirus promoters by tumor-suppressor protein p53 in the absence of large T-antigen. 784 69


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