Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The neu (c-erbB-2, HER2) proto-oncogene encodes a receptor tyrosine kinase that is a member of an important growth factor receptor family which includes the epidermal growth factor receptor (EGFR, ErbB1), ErbB3 and ErbB4. The neu is found over-expressed in 20-30% of human breast tumors. The c-erbB-2 is sufficient for the induction of mammary tumorigenesis in transgenic mice and the pathology of these mammary tumors strongly resembles human breast cancer. Murine transgenic models engineered to recapitulate human breast cancer provide an excellent and straightforward approach to dissect the molecular mechanisms governing the onset and progression of this disease. The molecular mechanisms by which ErbB-2 transforms cells involves direct effects on components of the cell-cycle regulatory apparatus. Recent studies have demonstrated a key role for components of the cell-cycle, in particular cyclin D1 and p27Kip1 (p27) in the onset and progression of ErbB-2-induced murine mammary tumorigenesis. Such studies have provided further impetus to therapeutics targeting these cell-cycle proteins.
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PMID:ErbB-2-induced mammary tumor growth: the role of cyclin D1 and p27Kip1. 1221 76

Advances in molecular and cell biology have led to further understanding of the mechanisms of malignant growth and metastasis in human breast cancer cells. Initiation and progression of breast cancer results from mutations and the abnormal expression of many genes that control cellular proliferation, differentiation, invasion, metastasis and sensitivity to therapy (chemotherapy and radiation therapy). Inhibition of host immunity also plays a role in breast cancer progression. Many genes have been selected as targets for antisense therapy, including HER-2/neu, PKA, TGF-alpha, EGFR, TGF-beta, IGFIR, P12, MDM2, BRCA, Bcl-2, ER, VEGF, MDR, ferritin, transferrin receptor, IRE, C-fos, HSP27, C-myc, C-raf and metallothionein genes. The strategy behind antisense therapy is the development of specific therapeutic agents that aim to correct the mutations and abnormal expression of cellular genes in breast tumour cells by decreasing gene expression, inducing degradation of target mRNA and causing premature termination of transcription. Many in vitro and in vivo studies have investigated the therapeutic efficacy of oligonucleotides and antisense RNAs. These studies have demonstrated specific inhibition of tumour cell growth by antisense therapy and have shown synergistic inhibitory effects between antisense oligonucleotides or antisense RNA and conventional chemotherapeutic drugs used in the treatment of breast cancer. Antisense oligonucleotides have been modified to improve their ability to penetrate cells, bind to gene sequences and downregulate target gene function. Many delivery systems for antisense RNA and antisense oligonucleotides have been developed, including virus vectors (retrovirus, adenovirus and adeno-associate virus) and liposomes, to carry the antisense RNA or oligonucleotides through the cell membrane into the cytoplasm and nucleus of the tumour cells. However, in order to determine their feasibility antisense therapies need to be further investigated to determine their antitumour activity, pharmacokinetics and toxicity in breast cancer patients.
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PMID:Gene targets of antisense therapies in breast cancer. 1222 74

The antiproliferative effects of (111)In-DTPA-hEGF on breast cancer cells expressing high levels of EGFR were compared with those of chemotherapeutic agents or gamma-radiation. MDA-MB-468 cells were cultured with (111)In-DTPA-hEGF (30 MBq/microg, 1.8 x 10(5) MBq/micromol), DTPA-hEGF, methotrexate, doxorubicin, paclitaxel or 5-fluorouracil. Cell growth was measured colorimetrically. The IC(50) for 111In-DTPA-hEGF was < 70 pM (11 kBq/mL) versus 500 pM for DTPA-hEGF. The IC(50) for paclitaxel, methotrexate, doxorubicin and 5-fluorouracil was 6 nM, 15 nM, 20 nM and 4 microM respectively. (111)In-DTPA-hEGF (70 pM, 11 kBq/mL) delivered approx. 6 Gy to breast cancer cells producing growth inhibition equivalent to 4 Gy of gamma-radiation. We conclude that (111)In-DTPA-hEGF exhibited potent antiproliferative effects towards breast cancer cells at concentrations much lower than chemotherapeutic agents and equivalent to those produced by several Gy of high dose rate gamma-radiation.
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PMID:Comparative antiproliferative effects of (111)In-DTPA-hEGF, chemotherapeutic agents and gamma-radiation on EGFR-positive breast cancer cells. 1223 95

In the multistep progressive pathogenesis of human breast cancer, comedo ductal carcinoma in situ (DCIS) represents a preinvasive precursor lesion for therapy resistant invasive cancer. Human tissue derived cell culture models exhibiting molecular similarities to clinical DCIS facilitate an important preclinical mechanistic approach for evaluation of preventive efficacy of natural and synthetic chemopreventive compounds. Natural phytochemicals present in fresh fruits, vegetables and grain products are likely to offer protection against cancer. The clinical efficacy of these natural phytochemicals, however, depends on extrapolation, and is therefore equivocal. The present study determined whether the natural soy isoflavone genistein (GEN) inhibited aberrant proliferation in 184-B5/HER cells (a model for human comedo DCIS) and identified possible mechanisms responsible for its efficacy. Human reduction mammoplasty derived HER-2/neu oncogene expressing preneoplastic 184-B5/HER cells represented the experimental system. Flow cytometry and cellular epifluorescence based assays were utilized to quantitate the alterations in cell cycle progression, cellular apoptosis, and in the status of cell cycle regulatory and apoptosis-associated gene product expression. The 184-B5/HER cells exhibited specific immunofluorescence to p185HER, p53, EGFR, but not to ERalpha, thus resembling comedo DCIS. Treatment of 184-B5/HER cells with GEN resulted in a dose-dependent decrease in the viable cell population, increase in the G0/G1:S + G2/M ratio and enhancement of sub G0/G1 (apoptotic population). Exposure to the maximum cytostatic 10 microM dose of GEN down-regulated HER-2/neu mediated signal transduction as evidenced by a 73.9% decrease (p=0.001) in p185HER specific, and a 89.8% decrease (p=0.001) in phosphotyrosine specific immunofluorescence. The increase in G0/G1:S + G2/M ratio in response to the treatment with 10 microM GEN was associated with a 85.5% decrease (p=0.001) in immunoreactivity to PCNA and a 128.6% increase (p=0.004) in immunoreactivity to the cyclin dependent kinase inhibitor p16INK4. The induction of apoptosis by GEN was associated with a 52.8% decrease (p=0.001) in the immunoreactivity to antiapoptotic Bcl-2 and with a 195.9% (p=0.001) increase in the immunoreactivity to proapoptotic Bax. Thus, preventive efficacy of GEN in HER-2/neu+/ER- 184-B5/HER cells may be due to its ability to down-regulate HER-2/neu mediated signal transduction, increase the expression of the cyclin dependent kinase inhibitor p16INK4, and induce Bcl-2 dependent apoptosis. These data provide evidence that GEN may be a potential chemopreventive lead compound for human comedo DCIS. The 184-B5/HER cells, may therefore, provide a high throughput mechanistic bioassay to identify new chemopreventive agents for human breast cancer.
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PMID:Soy isoflavone genistein modulates cell cycle progression and induces apoptosis in HER-2/neu oncogene expressing human breast epithelial cells. 1223 20

An expression vector (pJW4) for a human epidermal growth factor (hEGF)-CH1 fusion protein was constructed by fusing the gene for hEGF with the gene for CH1 of murine IgG1 with/without a peptide linker sequence [(GGGGS)3] and inserting the recombinant gene into vector pGEX2T. Expression vector pGEX2T was transfected into E. coli (BL-21) and hEGF-CH1 expressed by induction of the lac Iq promotor with 50 microM isopropyl beta-D-thiogalactopyranoside (IPTG). hEGF- CH1 fused to glutathione S-transferase (GST) was isolated and purified by affinity chromatography. GST was cleaved using thrombin. SDS-PAGE demonstrated a protein with the expected M(r) (18 kDa) positive for hEGF by Western blot. hEGF-linker-CH1 exhibited preserved binding to A431 (2-3 x 10(6) EGFR/cell) and MDA-MB-468 breast cancer cells (1-2 x 10(6) EGFR/cell). hEGF-CH1 without the linker exhibited poor receptor binding. hEGF-linker-CH1 also exhibited strong binding to soluble EGFR equivalent to that of hEGF. The tumor and normal tissue distribution of hEGF-linker-CH1 labeled with 123I was compared with 123 I-hEGF at 24 h after i.v. injection to mice implanted with s.c. MDA-MB-468 xenografts. Fusion of hEGF with CH1 increased its retention in the blood 14-fold but did not significantly increase tumor uptake. Tumor/blood ratios were higher for hEGF than for hEGF-linker-CH1. We conclude that hEGF is more attractive than hEGF-linker-CH1 for imaging EGFR-positive tumors.
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PMID:Fusion of the CH1 domain of IgG1 to epidermal growth factor (EGF) prolongs its retention in the blood but does not increase tumor uptake. 1253 70

HER2 (also known as Neu, ErbB2) is a member of the epidermal growth factor receptor (EGFR; also known as ErbB) family of receptor tyrosine kinases, which in humans includes HER1 (EGFR, ERBB1), HER2, HER3 (ERBB3) and HER4 (ERBB4). ErbB receptors are essential mediators of cell proliferation and differentiation in the developing embryo and in adult tissues, and their inappropriate activation is associated with the development and severity of many cancers. Overexpression of HER2 is found in 20-30% of human breast cancers, and correlates with more aggressive tumours and a poorer prognosis. Anticancer therapies targeting ErbB receptors have shown promise, and a monoclonal antibody against HER2, Herceptin (also known as trastuzumab), is currently in use as a treatment for breast cancer. Here we report crystal structures of the entire extracellular regions of rat HER2 at 2.4 A and human HER2 complexed with the Herceptin antigen-binding fragment (Fab) at 2.5 A. These structures reveal a fixed conformation for HER2 that resembles a ligand-activated state, and show HER2 poised to interact with other ErbB receptors in the absence of direct ligand binding. Herceptin binds to the juxtamembrane region of HER2, identifying this site as a target for anticancer therapies.
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PMID:Structure of the extracellular region of HER2 alone and in complex with the Herceptin Fab. 1261 Jun 29

Molecular imaging of the expression of key genes which determine the response to DNA damage following cancer treatment may predict the effectiveness of a particular treatment strategy. A prominent early response gene for DNA damage is the gene encoding p21(WAF-1/CIP-1), a cyclin-dependent kinase inhibitor that regulates progression through the cell cycle. In this study, we explored the feasibility of imaging p21(WAF-1/CIP-1) gene expression at the mRNA level using an 18-mer phosphorothioated antisense oligodeoxynucleotide (ODN) labeled with (111)In. The known induction of the p21(WAF-1/CIP-1) gene in MDA-MB-468 human breast cancer cells following exposure to epidermal growth factor (EGF) was used as an experimental tool. Treatment of MDA-MB-468 cells in vitro with EGF (20 n M) increased the ratio of p21(WAF-1/CIP-1) mRNA/beta-actin mRNA threefold within 2 h as measured by the reverse transcription polymerase chain reaction (RT-PCR). A concentration-dependent inhibition of EGF-induced p21(WAF-1/CIP-1) protein expression was achieved in MDA-MB-468 cells by treatment with antisense ODNs with up to a tenfold decrease observed at 1 microM. There was a fourfold lower inhibition of p21(WAF-1/CIP-1) protein expression by control sense or random sequence ODNs. Intratumoral injections of EGF (15 microg/dayx3 days) were employed to induce p21(WAF-1/CIP-1) gene expression in MDA-MB-468 xenografts implanted subcutaneously into athymic mice. RT-PCR of explanted tumors showed a threefold increased level of p21(WAF-1/CIP-1) mRNA compared with normal saline-treated tumors. Successful imaging of EGF-induced p21(WAF-1/CIP-1) gene expression in MDA-MB-468 xenografts was achieved at 48 h post injection of (111)In-labeled antisense ODNs (3.7 MBq; 2 microg). Tumors displaying basal levels of p21(WAF-1/CIP-1) gene expression in the absence of EGF treatment could not be visualized. Biodistribution studies showed a significantly higher tumor accumulation of (111)In-labeled antisense ODNs in the presence of EGF induction of the p21(WAF-1/CIP-1) gene (0.32%+/-0.06% injected dose/g) compared with normal saline-treated control mice (0.11%+/-0.07% injected dose/g). The tumor/blood ratio for antisense ODNs in the presence of EGF induction of the p21(WAF-1/CIP-1) gene (4.87+/-0.87) was also significantly higher than for control random sequence ODNs (2.14+/-0.69) or for mice receiving antisense ODNs but not treated with EGF (2.07+/-0.37). We conclude that antisense imaging of upregulated p21(WAF-1/CIP-1) gene expression is feasible and could represent a promising new molecular imaging strategy for monitoring tumor response in cancer patients. To our knowledge, this study also describes the first report of molecular imaging of the upregulated expression of a downstream gene target of the EGFR, a transmembrane tyrosine kinase receptor.
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PMID:Antisense imaging of epidermal growth factor-induced p21(WAF-1/CIP-1) gene expression in MDA-MB-468 human breast cancer xenografts. 1264 May 57

EGFRvIII is a tumor specific, ligand-independent, constitutively active variant of the epidermal growth factor receptor. Its expression has been detected in many human malignancies including breast cancer. No detectable level of EGFRvIII has, however, been observed in adult tissues, including normal breast tissues. These unique features of the EGFRvIII make it an excellent target for biologically based therapies. We have designed and generated a tumor specific ribozyme targeted to EGFRvIII. This specific EGFRvIII ribozyme is able to effectively cleave EGFRvIII mRNA under physiological conditions in a cell-free system, but does not cleave wild-type EGFR and other EGF-family receptors. While expressing this EGFRvIII-ribozyme in breast cancer cells, EGFRvIII-ribozyme is capable of downregulating endogenous EGFRvIII expression at the mRNA and protein levels. Inhibition of proliferation was observed in EGFRvIII-ribozyme transfectants. In addition, downregulation of EGFRvIII in breast cancer cells significantly inhibited tumor growth in athymic nude mice. Furthermore, this ribozyme has no effect on EGF-family receptor expression or the proliferation of breast cancer cells, which do not express EGFRvIII but express wild-type EGFR and other EGF-family receptors. These results suggest that we have generated a tumor-specific, biologically functional ribozyme and further demonstrate that EGFRvIII plays a significant role in breast cancer cell proliferation. The ultimate goal of this approach is to provide a potential treatment for breast cancer by specifically targeting this receptor.
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PMID:Suppression of EGFRvIII-mediated proliferation and tumorigenesis of breast cancer cells by ribozyme. 1264 Jun 78

Overexpression of the epidermal growth factor receptor (egfr) gene is a common feature in breast cancer. We demonstrated recently that the expression of EGFR in breast cancer strongly correlates with the length of a CA simple sequence repeat within the first 2000 bases in intron 1 of the egfr gene [CA simple sequence repeat (CA-SSR) I; H. Buerger et al., Cancer Res., 60: 854-857, 2000]. Using a standardized semiautomated method of microsatellite analysis for loss of heterozygosity detection, we identified an allelic imbalance (AI) at the egfr locus in 55 of 163 primary breast cancer cases. Fine mapping of the chromosomal region at 7p12-15 around the egfr gene using 10 CA-SSR markers showed that mutations of egfr in breast cancer are frequently restricted to the first intron of egfr. Thereby, the simple sequence repeat CA-SSR I in intron 1 was affected in 84% of the patients with AI. Reverse transcription-PCR analysis of 23 breast cancer tissues with AI excluded the presence of in-frame deletions between exon 2 and exon 7. For additional characterization of the underlying phenomenon leading to the detection of an AI in microsatellite analysis, a quantitative 5'-nuclease assay for the first CA-SSR I in intron 1 was established. In breast cancer cases with AI the presence of amplifications of this sequence was shown. Kaplan-Meier analysis revealed a statistically significant worse prognosis for patients with AI in the cancer tissue at the egfr locus compared with patients without AI. Interestingly, 75% of the patients bearing AI of CA-SSR I in the tumor also showed AI at normal, nontumorous breast tissue. Our data strongly support the assumption that distinct amplifications in intronic sequences of the egfr gene, which enhance the basic transcription activity of the gene, represent one of the first steps in breast carcinogenesis. Furthermore, they point to the presence of prognosis-associated markers for breast cancer already in morphological normal breast tissue.
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PMID:Distinct amplification of an untranslated regulatory sequence in the egfr gene contributes to early steps in breast cancer development. 1264 71

A case control study of pregnancy/lactation associated breast carcinoma (PAC) was conducted on 24 test cases with two controls per case, matching age, tumor grade, tumor size and axillary lymph nodes status. During seven years of this study, 6% of all patients with breast cancer had PAC. In this study, 67% of the test cases showed positive axillary lymph nodes compared to 49% in our series of 315 cases of non-pregnancy/non-lactating women with breast carcinoma (p < 0.05). The expression of nine prognostic markers, i.e. ER, PR, p53, C-erbB-2, EGFR, Cathepsin-D, PCNA, DNA ploidy and S-phase fraction, were studied by immunohistochemistry and flow cytometry. Hormone receptor status showed a statistically significant difference between the two groups, i.e. 29% immunoreactivity in test cases compared to 58% in controls with a p value of 0.007. Among p53, C-erbB-2, EGFR and Cathepsin-D in the test group, only EGFR showed a significant correlation, i.e. 33% immunoreactivity in test cases and 19% immunoreactivity in controls (p < 0.05). Higher PCNA positivity was seen in the test group compared to controls, i.e. 35% in test patients and 28% in controls (p < 0.05). Metastasis to bone and liver was a common feature of test patients as compared to controls (p < 0.05). After a median follow-up of 72 months, there was no significant difference in the overall survival (OS) of test cases and controls as 54% deaths were recorded in test patients and 44% in controls at the end of this study (p > 0.05). In summary, in spite of some significant differences in the expression of few prognostic markers, i.e. ER/PR, EGFR, PCNA and metastatic potential, there was no significant difference in the OS of PAC vs. control group if compared stage for stage.
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PMID:Case control study of novel prognostic markers and disease outcome in pregnancy/lactation-associated breast carcinoma. 1265 May 13


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