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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The neu receptor oncoprotein tyrosine kinase, capable of transforming cultured fibroblasts and causing mammary carcinomas in transgenic mice, carries a point mutation in its transmembrane domain and shows a constitutive tyrosine kinase activity. We analyzed the neu tyrosine kinase and its substrates in transfected NIH 3T3 fibroblasts by phosphotyrosine immunoblotting. Tyrosine phosphorylated proteins were similar but not identical in epidermal growth factor (EGF)-stimulated cells expressing the human EGF receptor (EGFR) or a chimeric EGFR/neu receptor but differed from phosphotyrosyl proteins constitutively expressed in neu oncogene-transformed cells. The neu oncoprotein in the latter cells was phosphorylated in tyrosine in a ligand-independent manner and had a shortened half-life in comparison with the normal neu protein. Tumor promoter pretreatment inhibited ligand-induced receptor tyrosine phosphorylation and decreased tyrosine phosphorylated neu oncoprotein. Prolonged pretreatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) also prevented the induction of immediate early growth factor-regulated genes in response to neu activation. Expression of the neu oncogene but not the protooncogene in NIH 3T3 cells was associated with enhanced levels of the jun and fos oncoproteins and loss of serum growth factor induction of immediate early mRNA responses. The constitutively activated neu oncoprotein tyrosine kinase thus deregulates cellular genomic responses to growth factors.
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PMID:Constitutively activated neu oncoprotein tyrosine kinase interferes with growth factor-induced signals for gene activation. 170 46

The major objectives of this study were twofold: to determine 1) if growth factors or growth factor receptors were expressed similarly or differently in a clinically well-characterized group of breast cancer patients and 2) if these phenotypic characteristics were associated with any of the commonly used prognostic parameters. Formalin-fixed paraffin-embedded tumor tissue from 51 node-positive breast cancer patients were analyzed for the expression of neu, epidermal growth factor-receptor (EGF-R), and transforming growth factor alpha (TGF alpha) using immunoperoxidase staining. Positive membranous staining for neu was observed in 15 (29%) tumors. Over-expression of neu was observed in high-grade, estrogen-receptor-negative tumors (P less than 0.05). Epidermal growth factor receptor was expressed in 22 (43%) of the tumors analyzed and found to a greater degree in estrogen-receptor-negative and high-grade tumors (P less than 0.025). A significant correlation between neu and EGF-R expression was also noted. Tumors expressing membranous staining of neu had a greater than 70% chance of expressing EGF-R (P less than 0.01). Expression of TGF alpha was found in 68% of tumors and TGF alpha was detected in grade 1 and 2 tumor to a greater degree than EGF-R. The authors conclude that assaying tumors for these antigens may give additional phenotypic characteristics that can give further insight into the biology of breast cancer.
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PMID:Expression of neu protein, epidermal growth factor receptor, and transforming growth factor alpha in breast cancer. Correlation with clinicopathologic parameters. 171 Dec 94

The ERBB2 (also called HER2, neu, and c-erbB-2) gene product, which encodes a growth factor receptor, was implicated in the malignancy of human adenocarcinomas. An antibody directed to the rat oncogenic receptor has been previously shown to have an antitumor effect in model systems. In an attempt to extend this observation to the protooncogenic human receptor and also to understand the underlying mechanism, we generated a panel of monoclonal antibodies specific to the extracellular portion of the ERBB2 protein. The effects of the antibodies on tumor growth were compared with their cellular and biochemical actions in vitro. Surprisingly, opposing in vivo effects were observed: although some antibodies almost completely inhibited the growth in athymic mice of transfected murine fibroblasts that overexpress Erbb-2, other antibodies either accelerated tumor growth or resulted in intermediate responses. When tested on cultured human breast carcinoma cells or ERBB2 transfectants, the tumor-stimulatory antibody was found to induce significant elevation of tyrosine phosphorylation of the ERBB2 protein. In contrast, only partial correlation was observed between the capacity to restrict tumor growth and the effects of the antibodies on receptor degradation and cellular proliferation in vitro. This suggests that the antitumor antibodies affect both receptor function and host-tumor interactions. Our results may help establish experimental criteria for the selection of specific antibodies for use either alone or in conjunction with other molecules as pharmacological antitumor agents.
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PMID:Mechanistic aspects of the opposing effects of monoclonal antibodies to the ERBB2 receptor on tumor growth. 171 84

We assayed rat colon tumors induced by N-methyl-N-nitrosourea (MNU) for transforming oncogenes by the NIH 3T3 transfection and nude mouse tumorigenicity assays. Transfection of DNA from 3 of 3 adenomas and 3 of 5 carcinomas induced transformed foci on NIH 3T3 cells. DNA from 2 of 3 primary foci also possessed focus-forming activity, and rat-specific sequences were observed in secondary focus DNAs. Furthermore, NIH 3T3 cells transfected with DNA from a carcinoma and from a primary focus derived from it, both positive in the focus-forming assay, induced tumors in nude mice. We found no evidence for rat H-ras, K-ras, or N-ras sequences in the DNA of any of 16 primary foci derived from 6 rat tumors; thus, in contrast to other animal tumor models induced by MNU, activation of the ras genes does not appear to predominantly occur in MNU-induced rat colon tumors. We also did not observe, in any of these foci, sequences corresponding to the rat neu, raf, fms, met, or hst genes, thus indicating that none of these is the transforming oncogene in our model. These results suggest that an as yet unidentified transforming oncogene may be activated in rat colon tumors induced by MNU.
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PMID:Detection of transforming oncogenes in rat colon tumors induced by direct perfusion with N-methyl-N-nitrosourea. 173 Jan 34

Amplification of the c-myc and HER2/neu genes was found in 20 and 23%, respectively, of primary breast cancer tissues derived from 282 patients (median follow-up, 74 months). c-myc amplification was observed more frequently in larger tumors (P = 0.01) and in lymph node-positive patients (P = 0.01) but was not associated with age, menopausal status, or with differentiation grade or steroid receptor status. c-myc amplification was strongly negatively correlated with HER2/neu amplification (P less than 0.001). In univariate analysis, amplification of c-myc proved to be a significant predictor of reduced relapse-free and overall survival (for both, P less than 0.001). In multivariate analysis for relapse-free survival, c-myc amplification significantly (P = 0.001) added to the prognostic power of tumor size (P less than 0.001), lymph node status (P less than 0.001), and estrogen receptor status (P = 0.003), with the highest relative failure rate (1.8) after lymph node status (2.2). In this pilot study, c-myc amplification was predictive for outcome, especially among patients with node-negative disease or steroid receptor-positive tumors; 51 and 46% differences in actuarial 5-year recurrence rates when compared to patients with tumors with normal c-myc gene copy numbers, respectively. HER2/neu amplification was not associated with relapse-free survival but weakly with shorter overall survival in univariate analysis (P = 0.035). Only in the relatively small subgroup of steroid receptor-negative tumors, HER2/neu amplification may identify those patients with an increased risk of death. In conclusion, amplification of c-myc is an independent powerful prognosticator, particularly in node-negative and steroid receptor-positive breast cancer, whereas HER2/neu amplification may be of limited prognostic value, only in steroid receptor-negative disease.
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PMID:c-myc amplification is a better prognostic factor than HER2/neu amplification in primary breast cancer. 173 70

We performed immunohistochemical analyses of 568 breast/cancer specimens using Ki-67, a monoclonal antibody specific for a nuclear antigen present in proliferating cells. The specimens were divided into three groups (I-III) according to the proportion of Ki-positive cells detected. These findings were compared with features of tumor extension as well as with certain prognostic variables. There was no detectable correlation between Ki-67 reactivity and either tumor size or node involvement. In contrast, a statistically significant correlation was found between Ki-67 reactivity and tumor grading, in that G-I tumors had small growth fractions, while a high proportion of G-III tumors exhibited strong (group III) Ki-67 positivity. When growth fractions were compared with biochemical receptor status, a significant difference was detected between tumors with negative and positive findings for receptors. The same co-variation was observed with respect to the overexpression of neu-protein P185, with most neu-positive carcinomas being strongly positive for Ki-67 (group III). In the relapse cases examined, there was a close correspondence between Ki-67 reactivity and the duration of the disease-free period. Long-term observation of patients with primary breast carcinoma revealed that, with regard to overall survival, the less reactive groups I and II differed significantly from group III. With respect to disease-free survival, no difference was detectable between Ki-groups II and III, but when these two groups together were compared with group I, a significant trend emerged. Similar results for both overall and disease-free survival were obtained for subgroups of pT2 and G-II carcinomas as well as for receptor expression.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Immunohistochemical evaluation of growth fractions in human breast cancers using monoclonal antibody Ki-67. 175 57

The present study was undertaken to elucidate the ultrastructural differences between tumor cell clones with high growth or highly metastatic potential and those with low growth or weakly metastatic potential. Transmission, scanning and immuno-electron microscopy revealed a remarkable variance of surface microvilli between these two types of tumor cell clones. Greater numbers of microvilli appeared on the tumor cells which possess high growth or highly metastatic potential than on those of tumor cells with low growth or weakly metastatic potential. In contrast, gap junctions and desmosomes were more occasionally seen on the weakly metastatic tumor cells than the highly metastatic tumor cells. Immuno-electron microscopy revealed that epidermal growth factor (EGF) receptor and c-neu oncogene product, which is closely related to the EGF-receptor, were positively stained on the microvilli of tumor cells with high growth potential, whereas the tumor cells with low growth potential showed almost no staining. Western blot analysis also revealed that in the tumor cells with high growth potential, positive expression of c-neu at 185 kDa was stronger than in the tumor cells with low growth potential. The findings suggest that increased numbers of microvilli are closely related to the growth and metastatic potential of tumor cells.
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PMID:Relationship between development of microvilli on tumor cells and growth or metastatic potential of tumor cells. 182 34

The effects of three hormonal agents with a different mechanism of action (tamoxifen [TAM], medroxyprogesterone acetate [MPA] and estradiol [E2]) on tumor growth, differentiation and oncogene expression were evaluated using the estrogen-receptor positive human breast carcinoma cell line MCF-7 transplanted into nude mice. In MCF-7 tumors treated with E2, tumor incidence, mean weight of tumors, 3H-thymidine labelling index, differentiation antigen HMFGM (human milk-fat globule membrane) and ras p21, c-myc, neu oncogene products, the level was significantly increased. On the other hand MPA suppressed all of them. TAM increased the level of c-myc expression and HMFGM antigen, but suppressed the others. This evidence indicates that E2 induces both proliferation and differentiation of MCF-7 tumor cells. MPA suppresses both proliferation and differentiation, and TAM induces differentiation and suppresses proliferation.
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PMID:Effects of tamoxifen, medroxyprogesterone acetate and estradiol on tumor growth and oncogene expression in MCF-7 breast cancer cell line transplanted into nude mice. 183 73

The distribution of various oncogenes in the tumor tissues of 8 cases of malignant mesothelioma related to asbestos exposure was evaluated by monoclonal antibodies against oncogenes. There was no staining for K-ras, H-ras and erb-B in all cases and C-abl slightly stained in only one case of a biphasic type of tumor. On the other hand, C-myc positively stained in epithelioid type and the epitheloidal portion of the biphasic type of tumors. C-neu, C-fos and N-myc positively stained in almost all cases. Of these 9 oncogenes, C-neu was most frequently stained in all cases. These results suggest that C-myc, N-myc, C-neu and C-fos oncogenes may have some role in the appearance of malignant mesothelioma related to asbestos exposure.
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PMID:[The distribution of various type of oncogenes products in the tumor tissue of malignant mesothelioma]. 183 8

Six families of activated protooncogenes, ras, raf, fur, neu, jun and myc have so far been associated with human lung cancer. Human bronchial epithelial cells in vitro are being used to investigate the functional role of these specific oncogenes and growth regulatory genes in carcinogenesis and tumour progression. When transferred into normal human bronchial epithelial cells by the highly efficient protoplast fusion method, the v-Ha-ras oncogene initiates a cascade of events leading to decreased responsiveness of these cells to inducers of squamous differentiation, aneuploidy and, less frequently, 'immortality' and tumorigenicity with metastasis in athymic nude mice. Transfection of the SV40 T antigen gene results in nontumorigenic cell lines that have a nearly normal pathway of terminal squamous differentiation and can be transformed into malignant cells by transfected Ha-ras, N-ras or Ki-ras. The combination of transfected c-myc and c-raf-1 also transforms human bronchial epithelial cells into neoplastic cells that exhibit some phenotypic traits found in small-cell carcinomas. These and other results indicate that proto-oncogenes dysregulate the pathways of growth and differentiation of human bronchial epithelial cells and play an important role in human carcinogenesis. Analyses of allelic deletion and somatic cell hybrids are being used to identify the chromosomal localization of tumour suppressor genes. We have examined 54 non-small-cell bronchogenic carcinomas with 13 polymorphic markers. Loss of heterozygosity was more frequent than among 23 squamous-cell carcinomas than among 23 adenocarcinomas or eight large-cell carcinomas. Loss of heterozygosity for chromosome 17p was found in 89% of cases of squamous-cell carcinoma and 18% of adenocarcinomas. Analysis of chromosome 11 for allelic deletions revealed two commonly deleted regions (11p13 and 11p15.5). Somatic cell hybrids between normal human bronchial epithelial cells and Hut292DM, a lung carcinoma cell line, had a finite lifespan in vitro and were nontumorigenic in athymic nude mice. Tumour suppressive effects of individual or combinations of specific human chromosomes on Hut292DM are being examined by formation of microcell-cell hybrids. Chromosome 11 has tumour suppressor activity in these hybrids. Both of these studies suggest that tumour suppressor genes play a dominant role in lung carcinogenesis and provide in-vitro model systems for isolating these genes by subtraction library and insertional mutagenesis techniques.
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PMID:Role of oncogenes and tumour suppressor genes in human lung carcinogenesis. 185 68


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