Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0178874 (tumor progression)
 40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Overexpression and amplification of the neu (c-erbB2, ERBB2) protooncogene have been implicated in the development of aggressive human breast cancer. To directly assess the effect of mammary gland-specific expression of the neu protooncogene, transgenic mice carrying unactivated neu under the transcriptional control of the mouse mammary tumor virus promoter/enhancer were established. By contrast to the rapid tumor progression observed in several transgenic strains carrying the activated neu transgene, expression of unactivated neu in the mammary epithelium resulted in the development of focal mammary tumors after long latency. The majority of the mammary tumors analyzed expressed elevated levels of neu-encoded mRNA and protein. Overexpression of neu in the mammary tumors was also associated with elevated neu intrinsic tyrosine kinase activity and the de novo tyrosine phosphorylation of several cellular proteins. Interestingly, many of the tumor-bearing transgenic mice developed secondary metastatic tumors in the lung. These observations suggest that overexpression of the unactivated neu protein can induce metastatic disease after long latency.
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PMID:Expression of the neu protooncogene in the mammary epithelium of transgenic mice induces metastatic disease. 135 41

The accumulation of genetic damage in the forms of activated proto-oncogenes and inactivated tumor-suppressor genes is the driving force in the evolution of a normal cell to a malignant cell. For example, both the activation of ras oncogenes and the inactivation of several suppressor genes, including p53, have been observed in the development of human colon and lung tumors. Point mutations in key codons can activate ras proto-oncogenes and inactivate the p53 suppressor gene. Thus, several critical genes for tumorigenesis are potential targets for carcinogens and radiation that can induce point mutations at low doses. The ras proto-oncogenes are targets for many genotoxic carcinogens. Activation of the ras gene is an early event--probably the "initiating" step--in the development of many chemical-induced rodent tumors. ras Oncogenes are observed in more human tumors and at a higher frequency than any other oncogene, and activation of the proto-oncogene may occur at various stages of the carcinogenic process. Numerous proto-oncogenes other than the ras genes have been shown to be activated in human tumors and to a lesser extent in rodent tumors. Mechanisms that induce aberrant expression of proto-oncogenes are gene amplification and chromosomal translocation or gene rearrangement. Amplification of proto-oncogenes and possibly gene overexpression during the absence of gene amplification occur in the development of many human tumors. For a specific tumor type, amplification of any one proto-oncogene may occur at a low frequency, but the frequency of tumors in which at least one proto-oncogene is amplified can be much higher. Proto-oncogene amplification is usually associated with late stages of tumor progression; however, amplified HER2/neu has been observed in early clinical stages of mammary neoplasia. Activation of proto-oncogenes by chromosomal translocation has been detected at a high frequency in several hematopoietic tumors. Non-ras genes have been detected by DNA transfection assays in both human and rodent tumors. For example, ret and trk genes were found to be activated by gene rearrangements in human papillary thyroid carcinomas. Several potentially new types of oncogenes have also been detected by DNA transfection assays. The etiology of the genetic alterations observed in most human tumors is unclear at present. Examples of ras gene activation and those documented for mutations in the p53 gene demonstrate that exogenous conditions can induce oncogenic mutants of normal genes. The genetic alterations observed in most human tumors are probably generated by both spontaneous events and exogenous conditions.
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PMID:Role of proto-oncogene activation in carcinogenesis. 148 40

Amplification and rearrangement of cellular proto-oncogenes are two of the several possible genetic alterations implicated in carcinogenesis and tumor progression. Although morphologically similar tumors may be heterogeneous at the level of the genome, some tumor types have shown relatively frequent and consistent abnormalities of specific oncogenes. In order to determine the frequency of oncogene amplification and rearrangement in several types of human sarcomas and to determine if histologically similar tumors have common genetic alterations, we analyzed 26 primary sarcomas by Southern hybridization. The oncogene probes utilized were N- and H-ras, sis, EGF-R (erb-B-1), neu (erb-B-2), fos, N- and c-myc, mos, and yes. The tumors studied included: five rhabdomyosarcomas (one alveolar, four embryonal), six malignant fibrous histiocytomas, six leiomyosarcomas, four liposarcomas, two Ewing's sarcomas, one osteosarcoma, and two fibrosarcomas. Oncogene abnormalities were identified in three tumors. One rhabdomyosarcoma showed 12-fold amplification and concurrent rearrangement of sis. This particular tumor also revealed rearrangement of H-ras and 15-fold amplification of c-myc. A second rhabdomyosarcoma revealed rearrangement of neu. A liposarcoma had a sis rearrangement. These findings suggest that many sarcomas show no common structural oncogene abnormalities. The presence of differing oncogene alterations within the rhabdomyosarcoma group indicates genetic heterogeneity among histologically similar sarcomas. The finding of a sis rearrangement in both a liposarcoma and a rhabdomyosarcoma, however, may suggest common oncogenesis among different tumor types.
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PMID:Genomic alterations in sarcomas: a histologic correlative study with use of oncogene panels. 149 46

Tumor specimens from 116 untreated patients with primary breast carcinoma at different clinical stages were analyzed for the structure and/or the expression of c-myc and c-erbB-2/neu proto-oncogenes. An amplification of the c-myc proto-oncogene (3 to greater than 50 fold) was detected only in 6% of carcinomas, with no evidence of locus rearrangement. High c-myc RNA levels detected in 45% of tumors were found significantly (p less than 0.01) correlated with lymph node involvement. Amplification (3 to greater than 30 fold) of the c-erbB-2/neu gene was observed in 20% of cancers. A 5 kb c-erbB-2/neu gene transcript was detected in the 103 cancer specimens analyzed. High levels of transcripts were observed in 36% of tumors. Overexpression did not depend only on amplification since found in 14 tumor samples with a single gene copy. The gene amplification and overexpression were found significantly associated with cancers of poor prognosis. Moreover our data show that both proto-oncogenes are overexpressed only in 12.5% of tumor samples and suggest that each gene might play a different role in tumor progression.
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PMID:Overexpression of either c-myc or c-erbB-2/neu proto-oncogenes in human breast carcinomas: correlation with poor prognosis. 290 33

Steady-state levels of myc, fos, p53, sis, and neu mRNAs were measured in eight variants derived from the Dunning R3327 rat prostate adenocarcinoma and compared to levels in normal dorsal prostate. Expression of the myb and erbB oncogenes in the Dunning tumors was below the limits of detection. Myc, p53, and sis mRNA levels in all tumors were at or above control levels. Fos mRNA levels were below control levels in four of five anaplastic tumors and were above control levels in the remaining tumors. A comparison of mRNA levels along the two Dunning lineages revealed that increased expression of these oncogenes did not correlate with tumor progression.
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PMID:Oncogene expression in prostate cancer: Dunning R3327 rat dorsal prostatic adenocarcinoma system. 321 75

Oncogene amplification has been observed in various primary tumors and tumor-derived cell lines. In several types of cancer, amplification of specific oncogenes is correlated with the stage of tumor progression. To estimate the frequency of gene amplification in other tumor types and to determine whether the ability to grow in vivo is associated with gene amplification in tumor cell lines, we have developed a modified version of the in-gel renaturation assay that detects human DNA sequences of unknown nature amplified as little as 7- to 8-fold. This assay was used to screen 16 cell lines derived from various solid tumors and leukemias. Amplified DNA sequences were detected in only one cell line, Calu-3 lung adenocarcinoma. This cell line was found to contain coamplified NGL (formerly termed neu) and ERBA1 oncogenes. However, when one of the amplification-negative cell lines, PC-3 prostatic carcinoma, was selected for in vivo growth in nude mice, amplified DNA sequences became detectable in these cells. The amplified sequences included the MYC oncogene, which showed no amplification in the parental cell line but was amplified 10- to 12-fold in the in vivo-selected cells. MYC amplification may, therefore, provide tumor cells with a selective advantage specific for in vivo growth.
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PMID:Analysis of gene amplification in human tumor cell lines. 341 26

Inappropriate expression of Her-2/neu (ERBB2) gene has been associated with impaired breast cancer prognosis, suggesting a functional role in tumor progression. Herein we describe a quantitative method for analysis of Her-2/neu gene messenger RNA (mRNA), which employs reverse transcriptase polymerase chain reaction (RT-PCR) on a 10-microns cryostat section. The technique combines modified RNA extraction with complementary DNA (cDNA) synthesis to achieve a high level of sensitivity. Utilizing this PCR-based gene expression assay, we were able to quantitate variable amounts of Her-2/neu mRNA in cell lines with established levels of gene expression and in clinical human breast cancer specimens. In clinical samples, mRNA levels correlated with intensity of immunoperoxidase staining for corresponding oncoprotein. We conclude that PCR-based mRNA quantitation can be applied to quantitative analysis of Her-2/neu gene expression, and potentially many other genes, in samples of limited size.
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PMID:Quantitative analysis of Her-2/neu (ERBB2) gene expression using reverse transcriptase polymerase chain reaction. 750 83

The HER2/neu (c-erbB2) protooncogene, which encodes a transmembrane receptor (p185neu), contributes to tumor cell invasion/metastasis through mechanism(s) which are, at present, poorly defined. Since basement membrane degradation is a prerequisite for tumor progression, we undertook a study to determine if the expression of urokinase, a key protease implicated in extracellular matrix proteolysis, was regulated by this oncogene. Stable overexpression of a cDNA encoding HER2/neu in H460 lung cancer cells led to elevated secretion of urokinase which was a consequence of a higher level of protease mRNA. Transfection of the HER2/neu-overexpressing B 104-1 cells with a CAT reporter construct driven by the urokinase promoter, gave rise to increased CAT activity when compared with parental NIH3T3 cells, which have low levels of HER2/neu, suggesting that the protooncogene can enhance urokinase promoter activity. Since the enhanced expression of HER2/neu results in increased tumor invasion/metastasis (1), these data suggest that, at least in vitro, HER2/neu-induced expression of urokinase may contribute to tumor progression in p185neu-positive cancers.
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PMID:Up-regulation of urokinase-type plasminogen activator expression by the HER2/neu proto-oncogene. 765 95

Transgenic mice bearing the rat neu proto-oncogene under the transcriptional control of the mouse mammary tumor virus (MMTV) promoter develop focal mammary adenocarcinomas after long latency that are metastatic to the lung in a high percentage of the tumor-bearing animals. Because expression of the neu gene in the mammary epithelium precedes the occurrence of tumors, it appears that another genetic event in addition to neu transgene expression is required for tumorigenesis. We have investigated the expression of PEA3, a new member of the ets oncogene family of transcriptional regulatory factors, in neu-induced mammary tumors to learn whether PEA3 plays a role in tumor progression in this organ. We observed high levels of PEA3 RNA in neu-induced tumors, but little, if any, PEA3 RNA in the surrounding mammary epithelium. Moreover, mammary tumors that had metastasized to the lung also overexpressed the PEA3 gene, whereas normal lung tissue did not. Similar results were obtained after analyses of other transgenic mouse lines bearing metastatic mammary tumors induced by polyomavirus middle T antigen. These findings suggest that enhanced expression of PEA3 may be required to facilitate mammary tumor progression and metastasis.
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PMID:PEA3 is overexpressed in mouse metastatic mammary adenocarcinomas. 769 72

Neuregulin, the putative ligand of the c-neu receptor tyrosine kinase, can induce differentiation or growth of epithelia and other cells. To gain insight into the biological role of this factor, we have analyzed the expression of neuregulin during mouse embryogenesis and in the perinatal animal by a combination of in situ hybridization and RNase protection experiments. We identify sites of expression that correspond to mesenchymal cells of various parenchymal organs. Our finding implies a function of neuregulin as a mesenchymal factor that acts on epithelia. The mesenchymal expression of neuregulin could thus provide a molecular basis for the biological phenomenon of mesenchymal-epithelial interactions. It also has implications on the molecular mechanism by which amplification of c-neu can affect tumor progression of carcinomas. In addition, neuregulin expression is found in neuronal cells during development. We show by RNase protection experiments that distinct isoforms of neuregulin are expressed in the brain. Therefore, our data indicate in vivo a dual role for neuregulin as mesenchymal and neuronal factor.
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PMID:Distinct isoforms of neuregulin are expressed in mesenchymal and neuronal cells during mouse development. 830 32


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