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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cancer has been defined as a fundamental disorder of cellular growth control. Which arises in some cells through changes in genes (DNA-level: geneamplification, mutation and rearrangement) or their expression (RNA- and protein-level), and gives these cells a growth advantage in comparison to the surrounding cells. Since the last decade we know the identity of these genes and the nature of the changes they underwent in the cancer cell. Only a few of the known oncogenes play a role in head and neck cancer. These are the EGFR (epidermal growth factor receptor), c-myc, the ras gene family, int-2, hst- 1 and bcl- 1. In some clinical disorders, like childhood neuroblastoma and breast cancer, oncogenes play already an important role in tumor staging as well as a prognostic parameter. The aim for the future is the therapeutic application of oncogenes better known as gene therapy.
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PMID:Oncogenes related to head and neck cancer. 813 94

Breast cancer is a complex but increasingly well-understood disease. Clearly, multiple alterations from normal mammary cells are required to achieve a transformed phenotype. Furthermore, there may be several possible alterations within broad categories that will produce the transformations leading to the malignant state. The specific set of alterations within a given cancer may thus provide necessary information about how it is unique and how it may best be treated. Several of the newer biologic markers of breast cancer may provide very specific treatment information. erbB-2 may predict for improved response to doxorubicin, rather than CMF. hsp 27 may predict for failure of doxorubicin. pS2 or EGFR may provide supplemental information predicting response to hormonal therapy. Each of these variables has strong evidence to support its use in this manner, but that evidence has been obtained on limited numbers of patients treated in a limited number of ways. The most established markers, with multiple studies indicating their prognostic benefit, are erbB-2, cathepsin D, and proliferation markers. Of the several proliferation markers there may be no one choice that is best. However, very clearly, any marker must be carefully assessed for appropriate cut-off values, and cut-off values established by one cohort of patients should be verified against another cohort of patients. The oncoproteins associated with cell cycle regulation (cyclin D, p53, Rb, and c-myc) have shown strong promise of providing important prognostic information. The limited studies to date indicate that these markers are independent of one another. Cell cycle regulation may be an area in which any defect may serve to deregulate the cell, and therefore several defects in one cell would be unlikely. The specific nature of the defect in a given cancer may be very important. With the advent of immunohistochemical methods to measure most of the markers, more information may become available. Finally, the burgeoning area of tumor-stromal interactions is replete with potentially important markers of cancer prognosis. The growth factors, which are marginally a part of this area owing to the probable importance of paracrine effects on cancer cell growth, have progressively developed a body of literature supporting their prognostic potential. However, they have rarely been studied in conjunction with the other aspects of tumor-stromal cooperation. The markers of metastatic potential, nm23 and angiogenesis, have been shown in small cohorts to have considerable prognostic import.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Overview of the biologic markers of breast cancer. 815 Jul 84

mRNA expression of stromelysin-3 (ST3) and 72K type IV collagenase (cIVase) in 4 human breast cancer cell lines and 55 resected breast tumors were examined using Northern blot analysis. In 4 cell lines ST3 was not expressed at all, while cIVase gene expression was detected in 3 of them. The ST3 expression was found more specifically in malignant tumors (39/40, 97.5%) than in benign ones (4/15, 26.7%), although cIVase was expressed in all tumor specimens. The quantitative analysis showed that ST3 expression in malignancies was significantly greater than that in benign tumors (P = 0.0007), while cIVase expression was not (P = 0.1381). ST3 gene expression was also closely related to the presence of lymph node metastasis (P = 0.047), while cIVase was not (P = 0.1091). These results suggest, therefore, that ST3 is expressed more specifically by stromal cells surrounding cancer cells than cIVase. Since ST3 mRNA expression was independent of the EGFR, ER and erbB2 protein expression, ST3 may be a new potent prognostic guide for breast carcinomas, which can detect highly malignant subpopulations.
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PMID:Stromelysin-3 mRNA expression and malignancy: comparison with clinicopathological features and type IV collagenase mRNA expression in breast tumors. 829 52

Immunocytochemical assays for EGFR were performed on frozen sections from breast carcinomas (n = 209). Results were evaluated by computer assisted image analysis to accurately define the percentage of immunostained surface and the mean optical densities. Thirty seven percent (n = 77/209) of the tumors were EGFR positive, but about one third of them were faintly reactive (35%). No significant relationship was observed between EGFR tumor content and patient age, tumor size, histological type, histoprognostic grade, or axillary lymph node status. A negative correlation was observed with the results of estrogen receptor immunocytochemical assays and a positive correlation with immunodetectable cathepsin D and Ki 67 antigen evaluated according the same method. No correlation was found with HER-2/neu protein, aneuploidy, nucleolar organizor region distribution, and nuclear morphometry, also assessed by image analysis. These results suggest that immunocytochemical assays assessed on frozen sections and evaluated by image analysis are suitable for current and standardized evaluation of EGFR which has been previously documented as a prognostic indicator in breast carcinomas.
Breast Cancer Res Treat 1993
PMID:Epidermal growth factor receptor in breast cancer: correlation of quantitative immunocytochemical assays to prognostic factors. 836 21

We have previously demonstrated that O-phospho-L-tyrosine (P-Tyr), a substrate for a wide range of PTPases, inhibits the growth of human renal cell carcinoma and human breast cancer cell lines and suppresses EGF-mediated EGFR tyrosine phosphorylation. We now show that P-Tyr inhibited the growth of the human hepatoma cell line HEPG2, and src transformed NIH3T3 cells, but did not inhibit the growth of human ovarian carcinoma SKOV-3 cells. Addition of exogenous P-Tyr inhibited the insulin triggered insulin receptor (IR) tyrosine phosphorylation in the HEPG2 cell line and the tyrosine phosphorylation of a variety of cellular proteins in src-transformed NIH3T3 cells. P-Tyr did not inhibit the tyrosine phosphorylation of gp185 erbB-2 in P-Tyr resistant SKOV-3 cells. Thus, inhibition of cell growth by P-tyr was associated with decreased tyrosine phosphorylation of cellular proteins.
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PMID:Association of inhibition of cell growth by O-phospho-L-tyrosine with decreased tyrosine phosphorylation. 860 80

It is a truism that a better understanding of the biology of breast cancer should lead to improvements in diagnosis and therapy. Despite this, our significantly improved grasp of breast cancer biology has had little direct therapeutic impact to date. The technologies used to treat breast cancer (surgery, radiation therapy, chemotherapy, and hormonal therapy) were in general developed decades ago. With the exception of the prognostic factor area, advances in biological knowledge have not translated into either new therapies or altered outcomes. Fortunately, this now appears to be changing. This paper will focus on three emerging areas in which the new biology is most likely to have a therapeutic impact. The first area involves growth factors and their receptors. It is now clear that the growth of breast cancer is regulated by growth factor receptors (eg, EGFR and Her-2/neu), and that their upregulation is associated with impaired prognosis. Growth factors and their receptors represent a promising therapeutic target, both alone and in combination with other standard agents. Recent evidence suggests that growth factors and their receptors may be important for regulating programmed cell death (apoptosis) in breast cancer. A second emerging area involves matrix metalloproteinases. Breast cancer invasion and metastasis involves and requires activation of enzymes capable of dissolving natural barriers to spread. The most heavily studied of these are the matrix metalloproteinases, for which considerable in vitro and in vivo evidence suggests an important role in breast cancer. The recent advent of compounds with matrix metalloproteinase inhibitory activity makes a therapeutic intervention against matrix metalloproteinases appear reasonable. In vivo laboratory evidence suggests that their use may occur in the very near future. A third emerging area revolves around the question of neoangiogenesis (new blood vessel formation) in breast cancer. Breast cancers (indeed, all solid tumors) are incapable of growth beyond a certain critical diameter without new blood vessel formation. Recent work has demonstrated that breast cancers produce angiogenic factors stimulating this new growth. Therapies aimed at blocking this stimulation, and preventing neovascularization represent a promising therapeutic target. Numerous agents capable of preventing new blood vessel formation have been discovered in the laboratory and are poised to enter clinical trials.
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PMID:Implications of the new biology for therapy in breast cancer. 861 50

Mammalian pancreatic ribonuclease (RNase) was conjugated chemically via a disulfide bond to human or murine epidermal growth factor (EGF). The conjugation between EGF and RNase was ascertained by SDS-PAGE using reduced and nonreduced conjugates. The EGF-RNase conjugate retained potent RNase activity and competed with 125I-EGF for binding to EGFR to the same extent as unconjugated EGF. Both the human and murine EGF-RNase conjugates showed dose-dependent cytotoxicity against EGFR-overexpressing A431 human squamous carcinoma cells with IC50 values of 3 x 10(-7) M and 6 x 10(-7) M, respectively, whereas free RNase had an IC50 of 10(-4) M. Against the EGFR-deficient small-cell lung cancer cell line H69, the EGF-RNase conjugate had no cytotoxic effect. The Human EGF-RNase conjugate showed dose-dependent cytotoxicity against other squamous carcinoma cell lines (TE-5, TE-1) and breast cancer cell lines (BT-20, SK-BR-3, MCF-7) and the cytotoxicity of the conjugate correlated positively with the level of expression of EGFR by each cell line. An unconjugated mixture of EGF and RNase had no greater effect than RNase alone on any cell line. Excess free EGF blocked EGF-RNase conjugate cytotoxicity against A431 cells. These results suggest that the EGF-RNase conjugate may be a more effective anticancer agent with less immunogenicity than coventional chimeric toxins.
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PMID:Epidermal growth factor receptor-dependent cytotoxic effect by an EGF-ribonuclease conjugate on human cancer cell lines--a trial for less immunogenic chimeric toxin. 867 51

Epidermal Growth Factor (EGF) is a mitogenic peptide that binds to surface membrane receptors (EGFR) of breast cancer cells. After binding, secondary transmitter molecules are activated by tyrosine phosphorylation of the intracellular receptor domaine. The activity of the EGF/EGFR system can be modulated by a variety of chemically unrelated compounds including cytostatic agents. The purpose of our present study was to determine the effects of vinorelbine, a novel semisynthetic vinca alkaloid on EGF receptor binding on human breast cancer cells. We have found that MDA-231 and MDA-468 cells bind substantially more [125I]-EGF after preincubation with vinorelbine. This effect was concentration- and time-dependent reaching a maximum at 100 ng/ml and 24 h incubation. Subsequent experiments showed an increase in the rate of EGF binding as well as maximal binding capacity. Scatchard analysis of binding experiments under equilibrium conditions indicated that this was mainly due to an increase in the number of apparent EGF binding sites. Modulation of EGF receptor binding by vinorelbine was not detectable when isolated membranes were used indicating that intact cytoplasmatic mechanisms are required for the upregulation of EGF receptors.
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PMID:Effects of vinorelbine on epidermal growth factor-receptor binding of human breast cancer cell lines in vitro. 872 45

Human breast cancer is often characterized by a progression to an ER (estrogen receptor)-negative, estrogen-independent, antiestrogen-resistant, EGFR (epidermal growth factor receptor)-positive, and highly metastatic phenotype. The molecular and biochemical mechanisms behind this progression are not well defined. Most studies of breast cancer have focused on one or another aspect or this progression but have not found a common pathway. By constructing stable and complete human-human somatic cell fusions between a highly metastatic, undifferentiated, ER-negative line of melanoma lineage and the estrogen-dependent, ER-positive MCF-7 line, this study produced hybrids that were ER negative, highly expressive of EGFR, estrogen independent, estrogen unresponsive, fully tumorigenic, and highly metastatic. ER negativity was on the basis of complete suppression of ER transcription as evidenced by Northern blot analysis and nuclear run-on assay, not on the basis of gene rearrangement. EGFR positivity was not due to gene amplification or rearrangement but rather to increased EGFR transcription. Mechanisms, including ras activation, fibroblast growth factor 4 expression, and human DNA methyltransferase activation causing ER promoter methylation, which are respectively known to induce estrogen-independent growth, induce spontaneous metastasis, and decrease ER levels in breast carcinoma experimentally, were not mechanisms operating in the hybrids. This model demonstrates that many of the common denominators of human breast carcinoma progression can be regulated by dominant trans-acting factors.
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PMID:Human breast cancer progression can be regulated by dominant trans-acting factors in somatic cell hybridization studies. 875 27

In breast cancer, epidermal growth factor (EGF) receptor (EGFR) expression is inversely correlated with expression of estrogen receptor (ER) and predicts the prognosis and failure of endocrine therapy. We report here, for the first time, that in ER-positive breast cancer cell lines, MCF-7, T47D, and BT474, 17 beta-estradiol (E2) transiently induced EGFR messenger RNA (mRNA) levels 2- to 3-fold; this induction was prevented by the presence of the antiestrogen ICI 164,384 and was also reflected in the level of EGFR protein. Up-regulation of EGFR mRNA is most likely due to a direct effect of ER on the EGFR gene, with no involvement of protein synthesis, as it was not inhibited in the presence of cycloheximide; however, the subsequent down-regulation of EGFR required de novo protein synthesis. E2 had no effect on EGFR mRNA stability, and EGFR transcript levels were found to parallel EGFR mRNA levels, further supporting a direct transcriptional mechanism in the regulation of EGFR expression by estrogens. Additionally, sequencing of the EGFR promoter revealed putative imperfect estrogen-responsive elements that were capable of binding human ER. The transient nature of EGFR induction by E2, with a rapid return to a basal level that is dependent on protein synthesis, suggests that breast cancer cells possess active mechanisms to maintain low levels of EGFR expression in the presence of estrogen and a functional ER.
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PMID:Bimodal regulation of epidermal growth factor receptor by estrogen in breast cancer cells. 877 Aug 93


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