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)

We examined the localization of DNA replicating cells and ras oncogene product p21 positive cells in proliferating skin diseases, such as psoriasis vulgaris, lichen planus, verruca vulgaris, verruca plana juvenilis and seborrheic keratosis. ras p21-positive cells were found rather in the differentiated layers than in the proliferating layers of the epidermis. We indicate that the expression of ras p21 can be associated with the differentiation of epidermal keratinocytes not only in tumor tissues but also in inflammatory skin disease.
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PMID:Association of ras p21 with differentiation of epidermal keratinocytes in proliferating skin diseases. 141 83

We review experimental models of carcinogenesis in which the role of ras activation has been most thoroughly studied: skin, thymus, mammary gland and liver. Qualitative changes (point mutations), as well as quantitative changes (over-expression, increased gene dosage) contribute to the transforming phenotype induced by ras genes. The activation of the three different ras family members is associated with particular tumor types, carcinogenic agents, and carcinogenic stages, suggesting the ras proteins may be involved in different biological functions. Depending on the system, ras activation has been shown to be an early and/or a late event in the multi-step process of carcinogenesis. These data underscore the possible relationship between ras activation and cell type specificity, proliferation, differentiation or cell-cell interaction.
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PMID:ras activation in experimental carcinogenesis. 142 Nov 67

In this study a ribozyme (catalytic RNA) was designed to site specifically cleave the mRNA of the activated H-ras gene expressed in human bladder carcinoma EJ cells. The optimal conditions for catalytic cleavage by the ribozyme were demonstrated in vitro. A synthetic DNA encoding the ribozyme was cloned into a mammalian expression vector (pH beta APr-1) and transfected into EJ cells. The expressed ribozyme significantly altered the morphology and suppressed the growth of EJ cells in vitro. These cell lines were examined for their malignant potential in athymic (nude) mice by an orthotopic (transurethral) implantation model, which recapitulates the invasive potential of various bladder carcinomas. EJ tumors expressing the H-ras ribozyme were characterized by a marked reduction in tumor take and invasion compared to those formed by control EJ cells. These differences resulted in almost a twofold increase in survival of mice implanted with ribozyme-containing EJ cells. These results further elucidate the role of ras genes in tumorigenicity and invasion, as well as introduce ribozymes as a new class of anticancer agents.
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PMID:Reversal of the malignant phenotype by an anti-ras ribozyme. 142 85

Odontogenic tumors that produce abnormal tooth-like structures are repeatedly observed in mandibles of mice that carry both albumin-myc and albumin-ras transgenes. The earliest lesions appear among the periodontal ligament mesenchymal cells, but later lesions include an epithelial component. Subsequent tumor development recapitulates the process of normal tooth formation, which requires multiple sequential cell signals, and results in cell differentiation, matrix secretion, and mineralization. Tumor cells with epithelial morphology produce ras oncoprotein, consistent with an epithelial origin of these tumors. As albumin regulatory sequences direct oncogene expression in these mice, our findings also suggest that some of the albumin present in normal teeth may be locally produced and have a role in tooth mineral formation. The reproducibility of this phenotype makes these mice an excellent model for studies of both normal and neoplastic odontogenesis.
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PMID:Odontogenic tumors in mice carrying albumin-myc and albumin-rats transgenes. 142 56

Five of six human squamous cell carcinoma (SCC) cell lines characterized as radiation sensitive (SQ-38, SCC-9, SQ-9G) or radiation resistant (SQ-20B, SCC-35, JSQ-3) exhibited alterations of the p53 gene. The point mutations and a deletion were detected by using single-stranded conformational polymorphism analysis and polymerase chain reaction-direct sequencing. Interestingly, three of three radiation-sensitive and two of three radiation-resistant cell lines revealed mutations in the p53 gene. Point mutations were located in exons 4, 6, and 8 (at codons 72 and 298 in JSQ-3; 273 in SCC-35; 196 in SQ-38), and deletions consisted of 32 base pairs between codons 274 and 285 in SCC-9 and 1 base pair at codon 271 in SQ-9G. Three mutations resulted in substitutions for an arginine residue. Immunocytochemical analysis confirmed p53 protein overexpression in SCC-35 cells which contained a missense mutation at codon 273. In contrast to previous studies which linked alterations in ras, myc, and raf expression with radiation resistance, this study indicates that mutations in the tumor suppressor gene, p53, do not directly correlate with such resistance.
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PMID:Mutations in the p53 gene in radiation-sensitive and -resistant human squamous carcinoma cells. 142 86

The Ha-ras oncogene has been shown to be point-mutated and overexpressed in papillomas induced by the two-stage skin tumorigenesis regimen of 7,12-dimethylbenz[a]anthracene (DMBA) and promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA). Glucocorticoids inhibit mouse skin tumorigenesis when applied with the initiation agent or with the promoting agent. We have extended these studies to evaluate whether dexamethasone (Dex) treatment could inhibit development of already established tumors. An additional objective of this study was to investigate whether glucocorticoids directly inhibit Ha-ras gene expression at the level of transcription during skin tumorigenesis. In this report we demonstrate that topical Dex treatments significantly suppressed the formation of additional tumors relative to the acetone control group. However, Northern blot analysis of total RNA isolated from representative tumors during a series of sequential weeks of promotion indicated that Dex did not have a direct effect on Ha-ras steady-state mRNA levels despite the decrease in additional tumor numbers in the Dex-treated groups. We also investigated short-term effects of Dex on endogenous Ha-ras expression in normal mouse epidermis. Topical Dex administration had no effect on endogenous Ha-ras steady-state mRNA levels in normal skin after 2 or 24 h. To ensure that endogenous corticosterone levels in the SENCAR mouse were not influencing our results, Ha-ras mRNA levels in epidermis from SENCAR mice adrenalectomized 48 h prior to being killed were compared to Ha-ras levels in normal epidermis by Northern blot analysis. The data from this analysis revealed that bilateral adrenalectomy had no effect on Ha-ras steady-state mRNA levels in epidermis compared to ras levels in normal mouse epidermis. In summary, our results demonstrate that although Dex can inhibit further tumor development in DMBA/TPA-treated mouse epidermis, it does not do so by directly effecting Ha-ras gene expression in mouse epidermis.
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PMID:Inhibition of mouse skin tumorigenesis by dexamethasone occurs through a Ha-ras-independent mechanism. 142 78

This report concerns the study of Ha-ras gene mutations and ras p21 expression in primary tumors of the urinary bladder. Polymerase chain reaction-based techniques and computerized image analysis were used. The data obtained were related to tumor grade, DNA ploidy, and tumor invasion. A point mutation (G-->T) at Ha-ras codon 12 was found in 30 of 67 tumors. The mutation frequency was greater in grade III (65%) than in grade II (44%) tumors; no mutations were observed in grade I tumors. The mutation was observed more often in aneuploid (58%) than in diploid (28%) tumors. No other substitution at codon 12 was seen and no codon 61 mutation was detected. The tumors were also tested for the A-->G mutation at position 2719 of Ha-ras intron D. Concurrent codon 12 and intron D mutations were identified in seven high-grade aneuploid tumors; six were invasive. The levels of the ras gene product p21 were approximately 10 times higher in tumors with intron D mutation than in those without. These findings confirm on human bladder tumors the observations of the effect of synchronous exon-intron mutations reported on the bladder cancer cell line T24. Our results are the first demonstration of Ha-ras intron D alterations in human tumor tissues and suggest that concurrent mutations at codon 12 and intron D of this gene within the same tumor may contribute to the aggressive behavior of human bladder carcinomas.
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PMID:Concurrent mutations of coding and regulatory sequences of the Ha-ras gene in urinary bladder carcinomas. 142 48

The overall coordination of cell structure and function that results in gene expression requires a spatial and temporal precision that would be unobtainable in the absence of structural order within the cell. Cells contain extensive and elaborate three-dimensional skeletal networks that form integral structural components of the plasma membrane, cytoplasm, and nucleus. These skeletal networks form a dynamic tissue matrix are composed of the nuclear matrix, cytoskeleton, and extracellular matrix. The tissue matrix is an interactive network which undergoes dynamic changes as cells move and change shape. Pathologists have long recognized cancer in pathologic specimens based on the altered morphology of tumor cells compared to their normal counterparts. The structural order of cells appears to be altered in transformed cells. This structural order is reflected in the altered morphology and motility observed in transformed cells compared to their normal counterparts, however, it is unclear whether the structural changes observed in cancer cells have any functional significance. We report here on the nature of the physical connections between the nucleus and cell periphery in nontransformed cells and demonstrate that the nucleus is dynamically coupled to the cell periphery via actin microfilaments. We also demonstrate that the dynamic coupling of the nucleus to the cell periphery via actin microfilaments is altered in Kirsten-ras transformed rat kidney epithelial cells. This loss of structure-function relationship may be an important factor in the process of cell transformation.
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PMID:Nuclear-cytoskeletal interactions: evidence for physical connections between the nucleus and cell periphery and their alteration by transformation. 142 64

All transformed foci of Balb/c 3T3 clone A31-1-1 cells induced by 7,12-dimethylbenz[a]anthracene (DMBA) (42 out of 42 examined) contained an A to T transversion at codon 61 (A182 to T) of the Ki-ras gene. The transformants induced by other carcinogens tested did not contain such a mutation, except one out of nine 12-O-tetradecanoyl phorbol 13-acetate (TPA)-induced transformed foci. Thus, we hypothesized that this mutation is a specific DMBA-induced initiating event in Balb/c 3T3 cell transformation and we have measured its frequency of induction before transformation occurs, employing our recently developed method. Such mutations can be detected in the cell population as early as 3 days after exposure to DMBA. The same mutation was also detected in the Ha-ras gene. No detectable level (< 10(-6) of these mutations was induced by other carcinogens tested. The mutation frequency of the Ha-ras gene reached a plateau after 1 week's exposure, but that of the Ki-ras gene continued to increase. These results suggest that the A182 to T mutation of the Ki-ras gene, but not that of the Ha-ras gene, contributes to morphological transformation of Balb/c 3T3 cells. We have demonstrated that the level of expression of ras genes determines the rate of recruitment of cells into transformation. Quantitative analysis of the frequencies of ras gene mutations (initiation) and of transformation suggests that about 25% of those cells with the Ki-ras mutation were recruited into the full transformation process and that, in the presence of the tumor promoter TPA, about 56% of them completed morphological cell transformation.
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PMID:Identification and quantification of a carcinogen-induced molecular initiation event in cell transformation. 143 51

Amplification of the c-myc oncogene has been detected by Southern blotting in the DNA of radiation-induced skin cancers in the rat. In the current work the localization of oncogene amplification within specific cells in the different cancers and in multiple biopsies of the same cancer was studied by in situ hybridization. The amount of amplification was measured by counting grains on tissue sections hybridized in situ to biotin-labeled human c-myc third exon, rat v-H-ras, and rat v-Ki-ras probes. The in situ estimates of c-myc amplification were generally correlated with previous findings using the Southern blot method, but within each cancer only a fraction of cells exhibited amplification. Multiple biopsies of a squamous carcinoma showed amplification of v-H-ras and c-myc but not v-Ki-ras during tumor growth, but none of these oncogenes were amplified during tumor regression. The c-myc-positive cells were distributed uniformly within the cancers and exhibited a more uniform nuclear structure in comparison to the more vacuolated c-myc-negative cells. A high [3H]thymidine labeling index was found in irradiated epidermal cells on Day 7 after exposure, and yet no evidence of c-myc oncogene amplification was found in situ. No c-myc amplification was found in unirradiated normal epidermis or in irradiated epidermal cells in the vicinity of radiation-induced cancers. The data indicate that c-myc amplification is cell-specific within radiation-induced carcinomas and does not occur in epidermal cells proliferating in response to radiation exposure.
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PMID:Oncogene amplification detected by in situ hybridization in radiation-induced skin cancers in rats. 143 1


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