Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0276241 (MCF)
28,353 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mouse monoclonal antibody (mAb) 225 IgG1 against the epidermal growth factor (EGF) receptor has been investigated for its capacity to localize in human tumor xenografts. The EGF receptor is the product of the c-erb-B proto-oncogene (also known as EGFR). Elevated expression of EGF receptors has been demonstrated in many human tumors and tumor cell lines. We studied A431 human vulvar squamous cell carcinoma cells, with 2 X 10(6) receptors per cell; MDA-MB-468 (MDA 468) human breast adenocarcinoma cells, with 3 X 10(5) receptors per cell; and MCF-7 human breast adenocarcinoma cells, with 5 X 10(3) receptors per cell. The 111In-labeled pentetic acid (DTPA), derivative of mAb 225 (111In-DTPA-225) was injected intraperitoneally into nude mice bearing subcutaneous tumor xenografts. We measured uptake by quantifying radioactivity in tumor and normal tissues and by obtaining gamma camera images. Uptake in A431 xenografts was 28% +/- 2.4% of the injected dose per gram of tumor on day 3 and 12.4% +/- 3.0% on day 7. Distribution ratios comparing uptake in the tumor with that in normal tissues were consistently greater than 4. In contrast, there was far less uptake of the control mAb KS1/4S-1 labeled with 111In. This conjugate, 111In-DTPA-KS1/4S-1, has an IgG1 isotype but does not bind to human or murine cells. Imaging of the tumor with mAb 225 was excellent, especially on days 3-7. MDA 468 xenografts exhibited reduced localization of mAb 225 in the tumor. For MCF-7 xenografts, the tumor uptake of mAb 225 after 7 days was only 0.70% +/- 0.10% of the injected dose per gram of tumor, which was comparable to the uptake of the KS1/4S-1 control mAb. The ratio of the concentration of radioactivity in the tumor to that in normal tissue (distribution ratio) showed poor selectivity of uptake, and imaging was not obtained. These observations suggest that labeled mAb can target the product of a proto-oncogene, the EGF receptor, when it is expressed at high levels in human tumor xenografts.
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PMID:Imaging of human tumor xenografts with an indium-111-labeled anti-epidermal growth factor receptor monoclonal antibody. 279 90

The EGF-like domains of heregulin alpha, beta 1, beta 2, and beta 3 were fused to a truncated form of Pseudomonas exotoxin (PE38KDEL), which contains a modified carboxyl-terminal sequence, KDEL, that increases that toxin activity. The resulting chimeric toxins were produced in Escherichia coli, purified to near homogeneity, and shown to be cytotoxic to target cells with very high activity on HTB20, N-87 MCF-7, and HepG2 cells; high activity on A431 and MDA-MB468 cells; and low activity toward SK-OV3, L929, and KB cells. The fact that cytotoxicity did not correlate with the levels of erbB2 expression indicated that another receptor in the erb family might be involved. Accordingly, cytotoxicity assays were performed on NIH/3T3 cell lines transfected with EGFR, ErbB2, ErbB3, or ErbB4. The results indicate that the heregulin toxins target ErbB4 or possibly ErbB3 but not ErbB2.
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PMID:Cytotoxic activity of chimeric toxins containing the epidermal growth factor-like domain of heregulins fused to PE38KDEL, a truncated recombinant form of Pseudomonas exotoxin. 780 44

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

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

Hydroxylated styrenes (tyrphostins) undergo oxidation by hypervalent iodine oxidants such as [(diacetoxy)iodo]benzene (DAIB) to give a range of products depending on the structure of the phenolic substrate, the solvent, the oxidant stoichiometry, and the purification strategy. Conditions have been developed to modify the phenolic component of the tyrphostin without affecting the appended substituted-vinyl moiety. Novel products include: unstable 2-acyloxy-2-methoxy-4-(substituted-vinyl)cyclohexadienones and their rearrangement products 2-acyloxy-4-hydroxy-3-methoxy-1-(substituted-vinyl)benzenes; phenyliodoniophenolates and their rearrangement products iodophenoxytyrphostins; and 3,3'-dialkoxy-2,2'-dihydroxy-5, 5'-di(substituted-vinyl)biphenyls. None of these oxidation products displayed enhanced activity in vitro in the NCI 60-cell line panel or in a panel of human breast cancer cell lines, compared to their tyrphostin precursors. The inhibitory activity of three representative tyrphostins (3e,n, 28) was not modulated by aerobic/anaerobic conditions in MCF-7 and MDA 468 cells and was independent of EGFR status in clones of ZR75B cells transfected with this receptor. Basal growth of MCF-7 cells was unaffected by co-administration of the growth factors EGF, TGF-alpha, IGF-I, and IGF-II, and the new agents did not inhibit EGFR and c-erbB2 autophosphorylation in cell lysates from MDA 468 or SkBr3 cells, respectively, suggesting that receptor tyrosine kinases are not targets for these compounds. Growth stimulation by the tyrphostin 3n in the ER(+) breast cell lines MCF-7, T47D, and ZR75-1 was abolished by 1 microM tamoxifen, suggesting that this compound has estrogen agonist activity.
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PMID:Structural studies on bioactive compounds. 32. Oxidation of tyrphostin protein tyrosine kinase inhibitors with hypervalent iodine reagents. 1078 Sep 12

The neu differentiation factors/heregulins (HRGs) comprise a family of polypeptide growth factors that activate p185(erbB-2) through direct binding to either erbB-3 or erbB-4 receptor tyrosine kinases. We have previously shown that HRG-beta is mitogenic for various human mammary epithelial cell lines that coexpress c-erbB-2 and c-erbB-3. Phosphatidylinositol 3-kinase (PI3K) is activated by p185(erbB-2) /erbB-3 heterodimers in cells stimulated by HRG, and PI3K is constitutively activated by p185(erbB-2) /erbB-3 in breast carcinoma cells that overexpress c-erbB-2. To better understand the relative abilities of HRGs, epidermal growth factor (EGF), or insulin to activate PI3K under normal physiological conditions, we compared the levels of recruitment of the 85-kDa regulatory subunit of PI3K when activated by the type I (erbB) or type II [insulin-like growth factor (IGF)] receptor tyrosine kinases in two different nontransformed human mammary epithelial cell lines. The nontransformed H16N-2 cells isolated from normal tissue express EGFR, p185(erbB-2), and erbB-3, and are highly responsive to the mitogenic effects of HRG-beta as well as to the combination of EGF and insulin in serum-free culture. We measured the stoichiometry of p85 recruited by tyrosine-phosphorylated proteins induced in H16N-2 cells by either the alpha or the beta isoform of HRG. HRG-beta was greater than 10-fold more potent in inducing p85 recruitment than was the less biologically active HRG-alpha isoform. HRG-beta was also a more potent inducer of p85 recruited by tyrosine-phosphorylated proteins than was either EGF, insulin, or EGF and insulin combined. Furthermore, erbB-3 principally mediated the direct recruitment of p85 in cells stimulated by HRG or EGF, indicating that, in addition to the high-level activation of PI3K by p185(erbB-2) / erbB-3, EGFR/erbB-3 heterodimer interaction is essential for the weak but significant level of PI3K activated by EGF in cells that express normal EGFR levels. Studies using the PI3K inhibitor wortmannin also indicated that PI3K activation was required for the proliferation of H16N-2 cells induced by either HRG-beta or EGF and insulin in serum-free culture. Finally, HRG-beta was also an especially potent inducer of PI3K in the nontransformed MCF-10A cells, which were derived spontaneously from normal reduction mammoplasty tissue. These data show, for the first time, a side-by-side quantitative comparison of the relative degree of PI3K activated by different growth factors in nontransformed growth factor-dependent cells under precisely defined conditions in culture.
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PMID:Heregulin-beta is especially potent in activating phosphatidylinositol 3-kinase in nontransformed human mammary epithelial cells. 1079 4

Epidermal growth factor receptor vIII (EGFRvIII) is a tumor-specific, ligand-independent, constitutively active variant of the EGFR. Its expression has been detected in gliomas and various other human malignancies. To more fully characterize the function and potential biological role of EGFRvIII in regulating cell proliferation and in tumorigenesis, we transfected EGFRvIII cDNA into a nontumorigenic, interleukin 3 (IL-3)-dependent murine hematopoietic cell line (32D cells). We observed 32D cells expressing high levels of EGFRvIII (32D/EGFRvIII P5) to be capable of abrogating the IL-3-dependent pathway in the absence of ligands. In contrast, the parental cells, 32D/EGFR, 32D/ErbB-4, and 32D/ErbB-2+ErbB-3 cells, all depended on IL-3 or EGF-like ligands for growth. 32D/EGFRvIII P5 cells subjected to long-term culture conditions in the absence of IL-3 revealed further elevation of EGFRvIII expression levels. These results suggested that the IL-3-independent phenotype is mediated by EGFRvIII. The level of expression is a critical driving force for the IL-3-independent phenotype. Dose-response analysis revealed 32D/EGFRvIII cells to require 500-fold higher concentrations (50 ng/ml) of EGF to further stimulate the EGF-mediated proliferation than in the 32D/EGFR cells (100 pg/ml). Similar effects were also observed in beta-cellulin-mediated proliferation. Moreover, 32D cells expressing high levels of EGFRvIII formed large tumors in nude mice, even when no exogenous EGF ligand was administered. In contrast, no tumors grew in mice injected with 32D/EGFR, 32D/ErbB-4, and 32D/ErbB-2+ErbB-3 cells or low-expressing clone 32D/EGFRvIII C2 cells or the parental 32D cells. The changes of the ligand specificity support the notion for an altered conformation of EGFRvIII to reveal an activated ligand-independent oncoprotein with tumorigenic activity analogous to v-erbB. These studies clearly demonstrate that EGFRvIII is capable of transforming a nontumorigenic, IL-3-dependent murine hematopoietic cell line (32D cells) into an IL-3-independent and ligand-independent malignant phenotype in vitro and in vivo. To delineate the biological significance of EGFRvIII in human breast cancer, we expressed EGFRvIII in the MCF-7 human breast cancer cell line. Expression of EGFRvIII in MCF-7 cells produced a constitutively activated EGFRvIII receptor. Expression of EGFRvIII in MCF-7 cells also elevated ErbB-2 phosphorylation, presumably through heterodimerization and cross-talk. These MCF-7/EGFRvIII transfectants exhibited an approximately 3-fold increase in colony formation in 1% serum with no significant effect observed at higher percentages of serum. A similar result was also seen in anchorage-dependent assays. Furthermore, EGFRvIII expression significantly enhanced tumorigenicity of MCF-7 cells in athymic nude mice with P < 0.001. Collectively, these results provide the first evidence that EGFRvIII could play a pivotal role in human breast cancer progression.
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PMID:Epidermal growth factor receptor vIII enhances tumorigenicity in human breast cancer. 1085 Apr 60

The transforming growth factor-alpha/epidermal growth factor receptor (TGF-alpha-EGFR) autocrine pathway, which is involved in the development and the progression of human epithelial cancers, controls, in part, the production of angiogenic factors. These angiogenic factors, including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), are secreted by cancer cells to stimulate normal endothelial cell growth through paracrine mechanisms. ZD1839 (Iressa) is a p.o.-active, selective EGFR-tyrosine kinase inhibitor (TKI) in clinical trials in cancer patients. In this study, we evaluated the antiangiogenic and antitumor activity of ZD1839 in human colon (GEO, SW480, and CaCo2), breast (ZR-75-1 and MCF-7 ADR), ovarian (OVCAR-3), and gastric (KATO III and N87) cancer cells that coexpress TGF-alpha and EGFR. ZD1839 treatment determined a dose- and time-dependent growth inhibition accompanied by the decrease of VEGF, bFGF and TGF-alpha production in vitro. Treatment of immunodeficient mice bearing well-established, palpable GEO xenografts with ZD1839 determined a cytostatic dose-dependent tumor growth inhibition. Immunohistochemical analysis of GEO tumor xenografts after ZD1839 treatment revealed a significant dose-dependent reduction of TGF-alpha, bFGF, and VEGF expression in cancer cells and of neoangiogenesis, as determined by microvessel count. Furthermore, the antitumor activity of ZD1839 was potentiated in combination with the cytotoxic drug paclitaxel in GEO tumor xenografts. Tumor regression was observed in all mice after treatment with ZD1839 plus paclitaxel, and it was accompanied by a significant potentiation in inhibition of TGF-alpha, VEGF, and bFGF expression with a few or no microvessels. Furthermore, 6 of 16 mice bearing well-established, palpable GEO xenografts had no histological evidence of GEO tumors at the end of treatment with ZD1839 plus paclitaxel. These results demonstrate that the antitumor effect of ZD1839 is accompanied by inhibition in the production of autocrine and paracrine growth factors that sustain autonomous local growth and facilitate angiogenesis, and that this effect can be potentiated by the combined treatment with certain cytotoxic drugs, such as paclitaxel.
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PMID:Inhibition of growth factor production and angiogenesis in human cancer cells by ZD1839 (Iressa), a selective epidermal growth factor receptor tyrosine kinase inhibitor. 1135 Sep 18

4-Anilinoquinazoline- and 4-anilinopyrido[3,4-d]pyrimidine-6-acrylamides are potent pan-erbB tyrosine kinase inactivators, and one example (CI-1033) is in clinical trial. A series of analogues with a variety of Michael acceptor units at the 6-position were prepared to define the structural requirements for irreversible inhibition. A particular goal was to determine whether additional functions to increase solubility could be appended to the Michael acceptor. Substituted acrylamides were prepared by direct acylation of the corresponding 6-amines with the requisite acid or acid chloride. Vinylsulfonamide derivatives were obtained by acylation of the amines with chloroethylsulfonyl chloride followed by base-promoted elimination. Vinylsulfone and vinylsulfine derivatives were prepared by oxidation and base elimination of a hydroxyethylthio intermediate. The compounds were evaluated for their inhibition of phosphorylation of the isolated EGFR enzyme and for inhibition of EGF-stimulated autophosphorylation of EGFR in A431 cells and of heregulin-stimulated autophosphorylation of erbB2 in MDA-MB 453 cells. Substitution at the nitrogen of the acrylamide was tolerated only with a methyl group; larger substituents were dystherapeutic, and no substitution at all was tolerated at the acrylamide alpha-carbon. In contrast, while electron-donating groups at the acrylamide beta-carbon were not useful, even quite large electron-withdrawing groups (which increase its electrophilicity) were tolerated. A series of derivatives with solubility-enhancing substituents linked to the acrylamide beta-carbon via amides were potent irreversible inhibitors of isolated EGFR (IC50s = 0.4-1.1 nM), with weakly basic morpholine and imidazole derivatives being the best. Vinylsulfonamides were also potent and irreversible inhibitors, but vinylsulfones and vinylsulfines were reversible and only poorly active. Two compounds were evaluated against A431, H125, and MCF-7 xenografts in nude mice but were inferior in these assays to the clinical trial compound CI-1033.
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PMID:Tyrosine kinase inhibitors. 18. 6-Substituted 4-anilinoquinazolines and 4-anilinopyrido[3,4-d]pyrimidines as soluble, irreversible inhibitors of the epidermal growth factor receptor. 1146 82


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