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: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HER2 is an attractive immunotherapeutic target for neoplastic disease because this cell surface molecule is overexpressed on a large fraction of malignant tumor cells. To directly assess therapeutic responses to targeted therapy by noninvasive in vivo imaging in small animals, human HER2-expressing ovarian carcinoma cells were genetically modified with a firefly luciferase gene, and light emission was used for visualization of tumor growth and response to therapy. This imaging approach was able to demonstrate in real-time tumor regression in a HER2 xenograft mouse model by adoptive transfer of in vitro induced and expanded cytotoxic CD8+ natural killer T (NKT) cells retargeted with a humanized bispecific antibody F(ab')(2)HER2xCD3. Immunotherapy with effector cells alone or a humanized monoclonal antibody anti-p185(HER2) (4D5-8) resulted in significant but slower reduction in tumor burden. Long-term survival of tumor xenografts correlated inversely with visible residual tumor burden. In vitro, F(ab')(2)HER2xCD3 substantially augmented cytotoxic activity of CD8+ NKT cells. By flow-sorting, CD8+ NKT cells coexpressing CD56 were found to have the highest redirected killing ability. Treatment with concanamycin A or EGTA abrogated CD8+ NKT cytotoxicity indicating that perforin is a major pathway of tumor cell lysis. In contrast, when CD8+ NKT cell were cross-linked with F(ab')(2)HER2xCD3 neither the immunosuppressants cyclosporine A and FK506, nor the increase of intracellular cyclic AMP by dibutyryl cyclic AMP were able to inhibit cytotoxicity demonstrating that signaling via the CD3 antigen changes the biological activity of non-MHC-restricted effector cells. These studies have demonstrated that CD8+ NKT cells can be successfully redirected to tumor cells using bispecific antibodies and offer a promising strategy for adoptive immunotherapy of neoplastic diseases.
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PMID:Visualization of effective tumor targeting by CD8+ natural killer T cells redirected with bispecific antibody F(ab')(2)HER2xCD3. 1238 39

It is known that the HER2/neu proto-oncogene is associated with a wide variety of human cancers and considered to be an attractive target for developing anti-cancer agents. We report here for the first time that the Epstein-Barr virus nuclear antigen-1 (EBNA1) suppresses the HER2/neu oncogene expression at the transcriptional level. Recombinant clones of EBNA1 were subcloned and stably transfected into HER2/neu-overexpressing human ovarian cancer SKOV3.ip1 cells. These EBNA1-containing clones down-regulated the endogenous production of p185(HER2/neu). In addition, the EBNA1-expressing stable transfectants showed reduced growth rate, low soft agarose colony-forming ability and tumorigenic potential as compared with the parental line. These data suggest that EBNA1 may act as a transforming suppressor of the HER2/neu oncogene.
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PMID:The Epstein-Barr virus nuclear antigen-1 may act as a transforming suppressor of the HER2/neu oncogene. 1245 78

The development and the effect of immunoliposomes directed against human breast cancer cells overexpressing p185/HER2 are described. These immunoliposomes carry an antisense oligonucleotide directed toward the translational start site of dihydrofalate reductase (DHFR) RNA, which causes high cytotoxicity. To prepare the immunoliposomes, we followed two methodologies based on the high affinity between streptavidin and biotin and the use of biotinylated antibodies. In the first approach, the streptavidin molecule is covalently attached to the phospholipid DOPE, which is mixed with the cationic liposome DOTAP complexed with the antisense oligonucleotide. The second approach, which is much easier to perform, involves the binding of streptavidin to antibody and oligonucleotide, both biotinylated, and the latter complexed with DOTAP. The formation of the intermediary complexes of this immunoliposome was studied sequentially by gel electrophoresis. The uptake of the oligonucleotide carried by the immunoliposome was monitored by flow cytometry and confocal microscopy. As a model, we used SKBR3 cells that overexpress p185. The full immunoliposomes were more toxic than the antisense oligonucleotide in the absence of the antibody, thus increasing the sensitivity of the treatment.
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PMID:Development and effects of immunoliposomes carrying an antisense oligonucleotide against DHFR RNA and directed toward human breast cancer cells overexpressing HER2. 1247 81

Our previous work showed that, compared with parental U87MG human glioblastoma cells, vascular endothelial growth factor (VEGF) mRNA levels are decreased in U87/T691, a derivative line in which epidermal growth factor receptor (EGFR) signaling is inhibited by introduction of a truncated p185(Neu) protein (A. Maity et al., Cancer Res., 60: 5879-5886, 2000). The effect of EGFR activation on VEGF was mediated at the level of transcription via a phosphatidylinositol 3'-kinase (PI3K)-dependent pathway. In the current study we investigated the effect of PTEN, a negative regulator of PI3K signaling commonly mutated in glioblastoma cells, on VEGF expression. Several glioblastoma cell lines containing mutant PTEN, including U87MG, U87/T691, and U251MG, were infected with adenovirus expressing wild-type PTEN. This led to a decrease in the levels of both VEGF mRNA and phosphorylated Akt, a marker for PI3K activation. Treatment of U87MG cells with LY294002, a PI3K inhibitor, or cotransfection with a vector expressing wild-type PTEN decreased VEGF promoter activity using reporters containing either 1.5 kb of the promoter or a fragment extending from -88 to +54 bp. Activity of the -88/+54 VEGF promoter was down-regulated by dominant negative Akt and up-regulated by constitutively active myristoylated Akt. Introduction of wild-type PTEN and pharmacological inhibition of EGFR decreased VEGF mRNA expression and VEGF promoter activity in U87MG cells to a greater extent that did either manipulation by itself. Therefore, in human glioblastoma cells, PTEN mutation can cooperate with EGFR activation to increase VEGF mRNA levels by transcriptionally up-regulating the proximal VEGF promoter via the PI3K/Akt pathway.
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PMID:PTEN mutation and epidermal growth factor receptor activation regulate vascular endothelial growth factor (VEGF) mRNA expression in human glioblastoma cells by transactivating the proximal VEGF promoter. 1251 3

The ERBB2 gene is overexpressed in 30% of breast cancers and this has been correlated with poor prognosis. ERBB2 is upregulated in other cancers such as prostate, pancreas, colon and ovary. In breast cancer cells, the mechanisms leading to ERBB2 gene overexpression are increased transcription and gene amplification. In these cancers, AP-2 transcription factors are involved in ERBB2 overexpression, and AP-2 levels are correlated with p185(c-)(erbB-2) levels. In this work, we wanted to know if the same molecular mechanisms are responsible for the ERBB2 upregulation in non-breast cancers. We compared ERBB2 gene copy number, p185(c-)(erbB-2) and mRNA levels with AP-2 levels in several ovary, prostate, colon and pancreas cancer cells. A moderate expression of erbB-2 mRNA and protein were observed in some cells without gene amplification. In contrast to breast cancer cells, AP-2 factors were absent or low in some non-breast cells which did express ERBB2. It is thus likely that AP-2 is not a major player in the increased levels of erbB-2 transcripts in non-breast cancer cells. The transcriptional activity of the ERBB2 promoter in colon and ovary cancer cells was estimated using reporter vectors. The results showed that the promoter regions involved in ERBB2 gene overexpression in breast cancer cells are different from those that lead to the gene upregulation in colon and ovary cancers. In conclusion, our results indicate that different transcriptional and post-transcriptional mechanisms are responsible for the increased levels of erbB-2 transcript and protein in breast and non-breast cancer cells.
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PMID:Different mechanisms are implicated in ERBB2 gene overexpression in breast and in other cancers. 1294 24

In a screening for new growth factors released by melanoma cells, we found that the p185-phosphorylating capacity of a medium conditioned by a melanoma cell line was due to the secretion of heregulin, a ligand for the human epidermal growth factor receptor (HER) family of receptor tyrosine kinases. Expression of heregulin, including a new isoform, and secretion of functionally active protein was found in several cell lines. Receptor activation by heregulin, either autocrine or paracrine, resulted in a potent growth stimulation of both melanocytes and melanoma cells. Heregulin receptor HER3 and coreceptor HER2 were the main receptors expressed by these cells. Nevertheless, none of the cell lines in our panel overexpressed HER2 or HER3. In contrast, loss of HER3 was found in two cell lines, whereas one cell line showed loss of functional HER2, both types of deregulations resulting in unresponsiveness to heregulin. This implies the heregulin/HER system as a possible important physiologic growth regulatory system in melanocytes in which multiple deregulations may occur during progression toward melanoma, all resulting in, or indicating, growth factor independence.
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PMID:The heregulin/human epidermal growth factor receptor as a new growth factor system in melanoma with multiple ways of deregulation. 1609 54

The ribonuclease barnase (12 kDa) and its inhibitor barstar (10 kDa) form a very tight complex in which all N and C termini are accessible for fusion. Here we exploit this system to create modular targeting molecules based on antibody scFv fragment fusions to barnase, to two barnase molecules in series and to barstar. We describe the construction, production and purification of defined dimeric and trimeric complexes. Immobilized barnase fusions are used to capture barstar fusions from crude extracts to yield homogeneous, heterodimeric fusion proteins. These proteins are stable, soluble and resistant to proteolysis. Using fusions with anti-p185(HER2-ECD) 4D5 scFv, we show that the anticipated gain in avidity from monomer to dimer to trimer is obtained and that favorable tumor targeting properties are achieved. Many permutations of engineered multispecific fusion proteins become accessible with this technology of quasi-covalent heterodimers.
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PMID:Design of multivalent complexes using the barnase*barstar module. 1463 68

Major prognostic factors for early-stage non-small-cell lung cancer (NSCLC) are tumor size and nodal status. It has been suggested that HER2/neu overexpression may be related to poor prognosis in NSCLC. We evaluated the significance of HER2/neu overexpression on survival in patients with NSCLC. Data were collected on 239 patients treated surgically for stage I/II NSCLC between 1987 and 1996. None of the patients received adjuvant chemotherapy or radiation. Formalin-fixed, paraffin-embedded tumor tissue samples were stained with p185/HER2 receptor antibody. Results were reported as positive (2+, 3+) or negative (0, 1+) (Group A). A separate analysis considered only 3+ as positive (Group B). HER2/neu overexpression was seen in 18% in Group A (43 of 239) and 6% in Group B (15 of 239). HER2/neu overexpression was highest in bronchoalveolar cell carcinoma and adenocarcinoma. More stage I tumors were positive than stage II in both groups, but this was significant only in Group A (21% vs. 7%, P = 0.02). No difference was seen with age, gender, or grade for either group. In Group A, the relapse rate was 55% for HER2/neu-overexpressing tumors and 31% for HER2/neu-negative tumors (P = 0.003). Median time to relapse in patients with HER2/neu-positive tumors was 2.9 years; it was not reached in patients with HER2/neu-negative tumors. Median survival of patients with HER2/neu-positive tumors was 3.6 years compared to 5 years in patients with HER2/neu-negative tumors (P = 0.66). In Group B, the relapse rate was 60% for HER2/neu-overexpressing tumors and 33% for negative tumors (P = 0.036). Median time to relapse was 3.4 years in HER2/neu positive and had not been reached in negative tumors. There was no difference in 5-year survival rates for both groups (47% for HER2/neu positive and 50% for negative, P = 0.66).
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PMID:Effect of HER2/neu expression on survival in non-small-cell lung cancer. 1470 Apr 81

Oncogenes, the abnormal forms of proto-oncogenes, were shown to be involved in malignant transformation and in tumor progression. c-erbB2/HER2/neu is member of EGFR family and encodes the p185 protein, which functions as a tyrosine-kinase. Gene amplification and/or p185 overexpression were reported to be associated with poor prognostic in cancer. Our purpose was to investigate p185 immunohistochemical expression in breast carcinomas and in the corresponding axillary lymph nodes metastases and to identify possible correlation between p185 and other factors of poor prognostic, such as loss of hormonal receptors expression. In our study, 40.91% of cases were erbB-2 positive, p185 expression being maintained from the primary tumors to axillary metastases and associated with positive nodal status and with the absence of hormonal receptors expression (p < 0.05). These findings support the hypothesis the c-erbB2 is an advantageous acquisition for the aggressive behavior of the tumor cell and for its ability to invade and metastasize.
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PMID:[Overexpression of c-erbB-2 gene product is associated with poor prognosis factors in breast carcinoma]. 1475 39

An engineered antibody fragment (minibody; scFv-C(H)3gamma(1) dimer, M(r) 80 000) specific for carcinoembryonic antigen (CEA) has previously demonstrated excellent tumor targeting coupled with rapid clearance in vivo. In this study, variable (V) genes from the anti- p185(HER-2) 10H8 antibody were similarly assembled and expressed. Four constructs were made: first, the V genes were assembled in both orientations (V(L)-linker-V(H) and V(H)-linker-V(L)) as single chain Fvs (scFvs). Then each scFv was fused to the human IgG1 C(H)3 domain, either by a two amino acid linker (ValGlu) that resulted in a non-covalent, hingeless minibody, or by IgG1 hinge and a GlySer linker peptide to produce a covalent, hinge-minibody. The constructs, expressed in NS0 mouse myeloma cells at levels of 20-60 mg/l, demonstrated binding to the human p185(HER-2) overexpressing breast cancer cell line, MCF7/HER2. Binding affinities (K(D) approximately 2-4 nM) were equivalent to that for the parental 10H8 mAb (K(D) approximately 1.6 nM). Radioiodinated 10H8 hinge-minibody was evaluated in athymic mice, bearing MCF7/HER2 xenografts. Maximum tumor uptake was 5.6 (+/-1.65)% injected dose/g (ID/g) at 12 h, which was lower than that of the anti-CEA minibody, whereas the blood clearance (beta-phase, 5.62 h) was similar. Thus, minibodies with different specificities display similar pharmacokinetics, while tumor uptake may vary depending on the antigen-antibody system.
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PMID:Characterization of engineered anti-p185HER-2 (scFv-CH3)2 antibody fragments (minibodies) for tumor targeting. 1518 22


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