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

Cytogeneticists first proposed that the karyotypic abnormalities identified on chromosomes 1, 3, 6, 11, 13, 16, 17, and 18 supported a genetic basis for breast cancer. Such abnormal banding patterns, however, may represent either loss-of-function or gain-of-function molecular events. RFLP analyses have since confirmed that 20-60% of primary and spontaneous human breast tumors exhibit allelic losses on these same chromosomes, although the exact genes involved at these chromosomal sites remain largely unknown. Knowledge gained about the Rb-1 and p53 tumor suppressor genes at 13q14 and 17p13 in breast and other human tumors supports the paradigm that for any chromosomal locus, allelic loss associated with a mutation in the remaining tumor allele signifies an involved tumor suppressor gene. Given this paradigm, there are nearly a dozen putative breast tumor suppressor genes under active investigation, with most investigators now focusing on various chromosome 17 loci. Among the known proto-oncogenes found activated in breast cancer, amplification of c-erbB-2 at 17q21 is the most widely studied and clinically significant gain-of-function event uncovered to date, occurring in about 20% of all primary breast tumors. The involvement of this overexpressed membrane receptor has engendered interest in related tyrosine kinase receptors, such as EGFR, IR, and IGF-I-R, as well as their respective ligands, which may be overexpressed in a greater fraction of tumors, contributing to the autocrine and paracrine regulation of breast cancer growth and metastasis. New attention is being given to the potentially oncogenic function of structurally altered nuclear transactivating steroid hormone receptors, such as ER, whose overexpression has long been used to determine endocrine therapy and prognosis for individual breast cancer patients. While c-myc was one of the first known proto-oncogenes to be found amplified and overexpressed in human breast cancers, the actual incidence and clinical significance of its activation remain disputed and in need of further study. Lastly, we can expect greater clarification about the importance of various 11q13 genes found coamplified in nearly 20% of primary breast cancers, and pursuit into the intriguing possibility that a cyclin-encoding gene represents the overexpressed locus of real interest in this amplicon. Virtually all of these important genetic abnormalities identified thus far are associated with but not restricted to human breast cancers. The absence of identifiable molecular defects relating to the tissue specificity of this malignancy must be considered a substantial gap in our basic understanding of breast carcinogenesis.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Activated oncogenes and putative tumor suppressor genes involved in human breast cancers. 136 56

Three hundred and one primary breast cancers from patients with tumor infiltrated lymph nodes were analyzed for the presence of HER-2/neu oncoprotein by two procedures: Western blot (WB) and immunohistochemistry (IHC). Overexpression of this protein was found by WB in 16.6% of the tumors, and by IHC in 16.3%. Concordance between the two methods was found in 95% of tumors (286/301). In 7 cases we found HER-2/neu by IHC but not by WB, while the opposite was found in the remaining 8 patients. This discrepancy was found mainly in samples with HER-2/neu values just above the cut points and were therefore close to the sensitivity limits of the procedures used here. This study helps to define the parameters that should be considered to evaluate the immunostaining for HER-2/neu as positive (i.e., membrane staining, IHC score of 2 or more). The results obtained by both techniques were correlated with several currently used prognostic factors. Higher HER-2/neu protein expression was found in tumors lacking estrogen or progesterone receptors, in tumors with high S-phase fraction and in patients with more than 3 positive lymph nodes. In contrast, no relationship was found between overexpression of this protein and tumor size, ploidy, or age of the patient. Patients with elevated HER-2/neu expression showed a significantly worse overall survival by both methods, IHC (p = 0.05) and WB (p = 0.001). In conclusion, there is very high agreement between IHC and WB when measuring expression of HER-2/neu and both techniques showed prognostic significance.
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PMID:Expression of HER-2/neu oncoprotein in human breast cancer: a comparison of immunohistochemical and western blot techniques. 136 11

The goal of this study was to evaluate the extracellular matrix (ECM) as a model for growing human lung cancers and to study the feasibility of its application for cellular and molecular studies of tumor biology. Bovine corneal endothelial cell ECM coated dishes were evaluated as a growth substrate for tumor cultures. Growth success, morphology and oncoprotein/growth factor expression for 74 different lung cancers (adenocarcinoma, epidermoid carcinoma and small cell carcinoma) were compared after seeding fresh surgical explants onto bovine corneal endothelial cell ECM and plastic culture substrate. Nineteen out of 74 tumors (26%) plated on ECM demonstrated measurable growth. Growth on ECM was superior to growth on plastic for the lung tumors. All 19 tumor cultures showed malignant morphology and functions. They were examined under the light microscope, and in all cases pre- and post-cytology confirmed malignancy. Tumor cells seeded on ECM retained their malignant phenotype in comparison to tumors grown on plastic. Several oncoproteins (c-myc, c-Ha-ras, c-erbB-2) and growth factors/receptors (EGF, EGF-R, TGF alpha) were immunostained. These analyses were performed immediately after disaggregation of tumor cells obtained surgically and after seeding on ECM or plastic. Strong expression of oncoproteins/growth factors was detected in tumor cells immediately after surgery or when the cells were plated on ECM. On the other hand, moderate or no expression was observed in the same type of cells on plastic.
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PMID:Human lung cancers growing on extracellular matrix: expression of oncogenes and growth factors. 136 16

The c-erbB-2 oncoprotein is a transmembrane protein the presence of which has been associated with poor prognosis in several human neoplasms. However, there has been no comprehensive assessment of its value as a potential prognostic marker in head and neck squamous cell carcinoma. Archival specimens from 93 patients, treated surgically for squamous cell carcinoma of the head and neck between 1981 and 1989, were analyzed by immunohistochemistry using an anti-c-erbB-2 monoclonal antibody; of these, 43 (46%) were positive for c-erbB-2 staining. The majority of stained specimens (41%) displayed staining predominantly at the cell surface, while mixed membrane and cytoplasmic staining was less common (9%). Only 4% shared exclusively cytoplasmic staining. Since the specimens were archival, the cytoplasmic staining is probably a consequence of variable handling and/or fixation at the time of tissue removal. Therefore, only cases exhibiting distinct cell surface membrane staining in more than 10% of tumor cells were regarded as positive. There is a definite association between immunohistochemical detection of c-erbB-2 and head and neck squamous cell carcinoma, since almost half of the tumor specimens manifested detectable c-erbB-2 protein. However, this association could not be extended to a predicted disease progression or outcome, since there was no significant correlation between c-erbB-2 staining and tumor size, stage of disease, histologic differentiation, lymph node status or patient survival.
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PMID:Expression of c-erbB-2 gene in human head and neck carcinoma. 136 18

Monoclonal antibodies to the extracellular domain of the c-erbB-2 oncoprotein (p185) react with routinely processed, paraffin-embedded human tissues, and positive staining with these reagents has been shown to correlate with gene overexpression. To determine whether such antibodies would add prognostic data to the analysis of a pre-defined subset of transitional cell carcinoma (TCC) of the bladder, we studied 20 high-grade (Grade 3) TCCs from patients known to have limited disease (Jewett-Strong stages B1, B2, and C) and for whom at least 3-yr clinical follow-up was available. Data procured from this immunohistochemical analysis were compared with tumoral DNA content (determined by flow cytometry) and conventional clinicopathologic features. Overall, 13 of 20 TCC (65%) were reactive for p185-erbB-2. However, there was no apparent relationship between p185-reactivity and either DNA content, tumor stage or clinical outcome. These results suggest that c-erbB-2 expression may be augmented in localized high-grade TCC but that there is no evidence for the contention that this phenomenon has any effect on the biologic behavior of these neoplasms. The only factor that predicted a more favorable outcome was a relatively low stage at the time of diagnosis.
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PMID:c-erbB-2 (HER-2/neu) oncopeptide immunoreactivity in localized, high-grade transitional cell carcinoma of the bladder. 136 64

We have constructed genes expressing single-chain antigen binding proteins (scFv) which recognize the human erbB-2 receptor. These genes encode the heavy and light chain variable domains of an erbB-2 receptor specific monoclonal antibody, MAb FRP5, connected by a peptide linker. In order to express a bifunctional molecule, a bacterial alkaline phosphatase gene was fused 3' to the scFv gene. The scFv(FRP5) and scFv(FRP5)-alkaline phosphatase fusion protein (scFv(FRP5)-PhoA) expressed in E. coli specifically recognize the human erbB-2 protein and compete with MAb FRP5 for binding to the receptor. The bound scFv(FRP5)-PhoA protein can be detected directly on tumor cells using a substrate for alkaline phosphatase, showing that the chimeric protein retains both binding and enzymatic activity.
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PMID:Construction, bacterial expression and characterization of a bifunctional single-chain antibody-phosphatase fusion protein targeted to the human erbB-2 receptor. 136 87

The HER-2/neu protooncogene (also called erbB-2) encodes a tyrosine kinase receptor for a polypeptide growth-regulatory molecule. Amplification and overexpression of the gene have been frequently observed in human adenocarcinomas and correlated with poor prognosis. To explore the potential of antibody therapy directed at the HER-2/Neu receptor, we have raised a panel of murine monoclonal antibodies to the human protein, and tested their effect on the tumorigenic growth of HER-2/neu-transfected fibroblasts in athymic mice. We previously reported that the i.p. injected antibodies either inhibited or accelerated the tumorigenic growth of HER-2/neu transfectants in athymic mice. Here we report that these opposing effects were induced also by i.v. injected antibodies, they lasted over 7 weeks, and were probably mediated by distinct epitopes on the receptor molecule. To understand the cellular mechanisms underlying antibody-induced tumor inhibition, we tested the effect of the monoclonal antibodies on various cultured human breast cancer cells. Our analysis revealed that the tumor-inhibitory antibodies specifically induced phenotypic cellular differentiation that included growth arrest at late S or early G2 phase of the cell cycle, markedly altered cytoplasm and nuclear morphology, synthesis and secretion of milk components (casein and lipids), and translocation of the HER-2/Neu protein to cytoplasmic and perinuclear sites. The extent of cellular differentiation by various antibodies could be correlated with their tumor-inhibitory potential, whereas a tumor-stimulatory monoclonal antibody or control immunoglobulin were completely inactive with respect to cellular differentiation. Taken together, our in vivo and in vitro studies correlate the tumor inhibitory potential of monoclonal antibodies to HER-2/Neu with their capacity to induce cellular differentiation in vitro. This observation may hold promise for immunotherapy of cancers that express the HER-2/neu oncogene.
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PMID:Tumor-inhibitory monoclonal antibodies to the HER-2/Neu receptor induce differentiation of human breast cancer cells. 137 72

The immunohistochemical detection of the c-erbB-2 oncopeptide (p185erbB2) has been shown to be a valid marker for over-expression of this oncogene. To evaluate the possible relevance of gene expression to the proliferation of hepatocytes and bile ducts in human disease, the authors applied a monoclonal anti-p185 antibody to formalin-fixed, paraffin-embedded tissues from 67 examples of benign proliferative and neoplastic hepatic lesions and fetal liver. Focal membrane-based reactivity for the oncopeptide was detected on tumor cells in two of eight hepatocellular carcinomas and on tumor cells and adjacent bile ducts and hepatocytes in four of six cholangiocarcinomas. Each of the latter four lesions were in patients with primary sclerosing cholangitis. No reactivity was obtained in examples of hepatoblastoma, mixed cholangiocarcinoma-hepatocellular carcinoma, bile duct adenoma, or hepatocellular adenoma. Weak staining for p185erbB2 also was seen in two of seven cases of (sub)massive hepatic necrosis and two examples of postnecrotic cirrhosis, all of which were secondary to either hepatitis B or C virus infection. No other benign proliferative lesions were labeled by the anti-p185 antibody, including cases of chronic allograft rejection, necrosis secondary to hepatic artery thrombosis, metabolic-associated and nonmetabolic-associated cirrhosis, focal nodular hyperplasia, and nodular regenerative hyperplasia. The authors' results indicate that c-erbB-2 may be amplified in specific neoplastic and hepatitis B virus and hepatitis C virus infectious lesions of liver. The authors postulate that: (1) c-erbB-2 immunoreactivity may be a marker for malignant transformation in primary sclerosing cholangitis; and 2) overproduction of p185erbB2 may be an epiphenomenon of hepatitis B virus or hepatitis C virus infection.
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PMID:Immunoreactivity for c-erbB-2 oncopeptide in benign and malignant diseases of the liver. 137 19

Previous studies of tumor necrosis factor (TNF) action on tumor cells revealed a possible role for tyrosine phosphorylation of epidermal growth factor (EGF) receptor in the growth-regulatory activities of this cytokine (N. J. Donato, G. E. Gallick, P. A. Steck, and M. G. Rosenblum, J. Biol. Chem., 264: 20474-20481, 1989). EGF receptor immunoprecipitated from [32P] phosphate-equilibrated A431 cells demonstrated that TNF treatment resulted in both a time- and concentration-dependent stimulation of EGF receptor phosphorylation, which was maximal (approximately 3-fold) after 10-20 min of TNF exposure (10 nM). Incubation of A431 cells with an equivalent concentration of EGF resulted in similar stimulation of EGF receptor phosphorylation, albeit at different phosphotyrosine levels. Antiphosphotyrosine immunoblot analysis confirmed these results but suggested that the extent and kinetics of TNF-induced tyrosine phosphorylation were distinct from those obtained in EGF-treated cells. Resolution of tryptic phosphopeptides from EGF receptor demonstrated that TNF-induced phosphorylation of EGF receptor was similar, but not identical, to profiles obtained from EGF-treated cells and distinct when compared to the actions of phorbol ester. Unlike EGF, TNF was unable to directly stimulate EGF receptor tyrosine kinase activity in membranes prepared from A431 cells. In addition, TNF treatment had no significant effect on either the high- or low-affinity ligand-binding sites on EGF receptor and did not alter the kinetics or extent of ligand-induced internalization of EGF receptors. However, EGF receptor biosynthesis was consistently increased upon prolonged treatment with TNF (4-12 h). Our results suggest that TNF regulates both phosphorylation and biosynthesis of EGF receptor in a manner distinct from that of both EGF and phorbol ester, and studies of the differential phosphorylation of EGF receptor may aid in understanding the molecular mode of TNF action.
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PMID:Tumor necrosis factor regulates tyrosine phosphorylation on epidermal growth factor receptors in A431 carcinoma cells: evidence for a distinct mechanism. 137 52

We are evaluating strategies for the inhibition of growth or the selective killing of tumor cells. Cell surface antigens which are exclusively expressed or which are enhanced in their expression in tumor cells might provide the means to target cytotoxic or cytostatic agents to these cells. Few tumor specific cell surface antigens have been found, but the enhanced expression of growth factor receptors has been described for several types of tumors. A prominent example is the overexpression of the c-erbB-2 receptor in a high percentage of primary breast and ovarian carcinomas. We have derived monoclonal antibodies against the extracellular domain of the c-erbB-2 receptor. The antibody molecules were genetically engineered to minimize their size and to allow for their functional modification. For this purpose the cDNA sequences corresponding to the variable domains of one monoclonal antibody (FRP5) were molecularly cloned and joined by a short linker. The resulting single chain antibody molecule (scFv) was expressed in bacteria and purified. We show in an immunoprecipitation experiment that this molecule retains its ability to recognize the c-erbB-2 extracellular domain. This molecule could become a valuable vehicle to specifically transport anti-tumor agents to breast cancer cells.
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PMID:Diminution of antibodies directed against tumor cell surface epitopes: a single chain Fv fusion molecule specifically recognizes the extracellular domain of the c-erbB-2 receptor. 138 44


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