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)

The urokinase-type plasminogen activator receptor (u-PAR) facilitates extracellular matrix degradation in part by accelerating plasmin formation at the cell surface. We previously reported that u-PAR expression is elevated in colon cancer cell lines characterized by their in vitro invasive capacity. Since, u-PAR expression is increased by a variety of growth factors, which signal through the extracellular signal-regulated kinases 1 and 2 (ERK1/ERK2), we determined if these mitogen-activated protein kinases (MAPKs) regulate u-PAR expression in two cultured colon cancer cell lines. An in-gel kinase assay showed that ERK1 activity was considerably higher in RKO cells, which display > or = 10(5) receptors/cell, than the GEO cells which have approximately 10(4) urokinase receptors per cell. The expression of either an ERK-inactivating phosphatase (CL100), or a kinase-defective ERK1, decreased the activity of a u-PAR promoter-driven CAT reporter in RKO cells. Immune complex kinase assays indicated that the constitutive ERK1 activity in RKO cells was largely a result of an activated MEK1. Further, treatment of RKO cells with a specific inhibitor (PD 098059) of MEK1 activation, which diminished ERK1 activity, reduced the amount of urokinase specifically bound to the cell surface and this was associated with reduced laminin degradation. The expression of a dominant negative c-Raf-1 also reduced u-PAR promoter activity suggesting that MEK1 activation involved an activator at, or upstream, of this serine-threonine kinase. Transfection of the u-PAR-deficient GEO cells with a constitutively activated MEK1 expression construct up-regulated u-PAR promoter activity. Similarly treatment of GEO cells with a phosphatase inhibitor (sodium vanadate) caused a dose-dependent increase in ERK1 activity which paralleled increased cell surface binding of urokinase. Taken together, these data suggest that elevated u-PAR expression, in at least a sub-population of colon cancer, is partly a consequence of a constitutively activated ERK-1-dependent signaling cascade.
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PMID:Elevated urokinase-type plasminogen activator receptor expression in a colon cancer cell line is due to a constitutively activated extracellular signal-regulated kinase-1-dependent signaling cascade. 919 Oct 56

Epidermal growth factor (EGF)-related proteins such as transforming growth factor alpha (TGF-alpha) control cancer cell growth through autocrine and paracrine pathways. Overexpression of TGF-alpha and/or its receptor (EGFR) has been associated with a more aggressive disease and a poor prognosis. The blockade of EGFR activation has been proposed as a target for anticancer therapy. Monoclonal antibody (MAb) C225 is an anti-EGFR humanized chimeric mouse MAb that is presently in Phase II clinical trials in cancer patients. Previous studies have suggested the potentiation of the antitumor activity of certain cytotoxic drugs, such as cisplatin and doxorubicin, in human cancer cell lines by treatment with anti-EGFR antibodies. We have evaluated in human ovarian, breast, and colon cancer cell lines, which express functional EGFR, the antiproliferative activity of MAb C225 in combination with topotecan, a cytotoxic drug that specifically inhibits topoisomerase I and that has shown antitumor activity in these malignancies. A dose-dependent supraadditive increase of growth inhibition in vitro was observed when cancer cells were treated with topotecan and MAb C225 in a sequential schedule. In this respect, the cooperativity quotient, defined as the ratio between the actual growth inhibition obtained by treatment with topotecan followed by MAb C225 and the sum of the growth inhibition achieved by each agent, ranged from 1.2 to 3, depending on drug concentration and cancer cell line. Treatment with MAb C225 also markedly enhanced apoptotic cell death induced by topotecan. For example, in GEO colon cancer cells, 5 nM topotecan, followed by 0.5 microg/ml MAb C225, induced apoptosis in 45% cells as compared with untreated cells (6%) or to 5 nM topotecan-treated cells (22%). Treatment of mice bearing established human GEO colon cancer xenografts with topotecan or with MAb C225 determined a transient inhibition of tumor growth because GEO tumors resumed the growth rate of untreated tumors at the end of the treatment period. In contrast, an almost complete tumor regression was observed in all mice treated with the two agents in combination. This determined a prolonged life span of the mice that was significantly different as compared with controls (P < 0.001), to MAb C225-treated group (P < 0.001), or to the topotecan-treated group (P < 0.001). All mice of the topotecan plus MAb C225 group were the only animals alive 14 weeks after tumor cell injection. Furthermore, 20% of mice in this group were still alive after 19 weeks. The combined treatment with MAb C225 and topotecan was well tolerated by mice with no signs of acute or delayed toxicity. These results provide a rationale for the evaluation of the anticancer activity of the combination of topoisomerase I inhibitors and anti-EGFR blocking MAbs in clinical trials.
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PMID:Antitumor activity of sequential treatment with topotecan and anti-epidermal growth factor receptor monoclonal antibody C225. 1021 28

A phase II trial evaluated the effectiveness and toxicity of combination paclitaxel (Taxol), gemcitabine (Gemzar), and trastuzumab (Herceptin) as first-line therapy for patients with newly diagnosed HER2-overexpressing metastatic breast cancer. To date, 27 patients have received paclitaxel at 175 mg/m2 over 3 hours on day 1, plus gemcitabine at 1,200 mg/m2 on days 1 and 8, plus trastuzumab at a 4-mg/kg loading dose on day 1, followed by 2 mg/kg weekly. Treatment cycles were repeated every 21 days. Responding or stable patients who had received six cycles of combination therapy continued single-agent trastuzumab weekly until disease progression. Treatment was generally well tolerated with grade 4 toxicity limited to myelosuppression. In all, 12 patients have achieved a partial remission and 1 patient had progressive disease; 14 patients continue treatment and have not yet been evaluated for response. Combination treatment with paclitaxel, gemcitabine, and trastuzumab is well tolerated and appears to be highly active. Accrual will continue to a total enrollment of 46 patients.
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PMID:Gemcitabine, paclitaxel, and trastuzumab in metastatic breast cancer. 1125 88

Current agents for the treatment of non-small-cell lung cancer include gemcitabine (Gemzar), paclitaxel (Taxol), docetaxel (Taxotere), vinorelbine (Navelbine), and irinotecan (CPT-11, Camptosar). Experimental agents include pemetrexed (LY231514, Alimta) and tirapazamine. Molecular and biological therapies include angiogenesis inhibitors, epidermal growth factor receptor inhibitors, HER2/neu inhibitors, and inhibitors of ras activation and function. Doublet chemotherapy is currently the standard treatment for advanced non-small-cell lung cancer. In the past 2 years, randomized trials have shown that many of the new two-drug combinations used to treat non-small-cell lung cancer have equivalent efficacy. These combinations produce 1-year survival rates of about 35% and 2-year survival rates of about 15%. Toxicity rates vary but are sufficiently low as to make the development of three-drug combinations feasible. Preliminary studies from several phase I and II trials suggest that triplet therapy can improve survival beyond that of double therapy regimens.
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PMID:Triplet combination chemotherapy and targeted therapy regimens. 1130 45

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

We have constructed a series of 22 phosphorothioate 20-mer antisense oligonucleotides directed against different regions of the human (EGFR) mRNA. Treatment with EGFR antisense oligonucleotides showed a dose-dependent inhibition of human GEO colon cancer cell growth in soft agar. Western blot analysis demonstrated a significant reduction in EGFR expression after treatment with each EGFR antisense oligonucleotide. The ability to inhibit GEO anchorage-independent growth, however, varied among the EGFR antisense sequences with an IC(50) ranging between 0.5 and 3.5 microM. Two of these antisense oligonucleotides targeting the regions between 2457-2476 and 614-4633 bases of the human EGFR mRNA have been modified as hybrid DNA/RNA mixed backbone oligonucleotides (MBO) to examine their anticancer properties in vivo. The 2 EGFR antisense MBOs retained the same biological properties of the fully phosphorothioate EGFR antisense oligonucleotides targeting the same EGFR mRNA sequences, such as blocking EGFR synthesis, inhibiting cell growth and enhancing programmed cell death in human cancer cell lines that express functional EGFRs. Furthermore, a potentiation in the growth inhibitory effect on GEO cancer cells was observed after treatment with these EGFR antisense MBOs in combination with cytotoxic drugs, including cisplatin, doxorubicin, paclitaxel, or topotecan. These results show the antiproliferative activity of specific EGFR antisense oligonucleotides and allow to identify novel EGFR antisense MBOs that deserve further evaluation as potential selective anticancer agents alone or in combination with cytotoxic drugs in human carcinomas that express functional EGFRs.
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PMID:Antisense oligonucleotides targeting the epidermal growth factor receptor inhibit proliferation, induce apoptosis, and cooperate with cytotoxic drugs in human cancer cell lines. 1141 Aug 62

The aim of this study was to determine whether constitutive ErbB2 activation controls growth and apoptosis in colon cancer cells. Growth arrested GEO cells showed constitutive activation of ErbB2 in the absence of exogenous growth factors or serum supplementation. Higher levels of heregulin and ErbB2 activation were observed in the growth-arrested state and cell cycle re-entry was independent of exogenous growth factors. Blockade of ErbB2 activation by heregulin neutralizing antibodies and by AG879 resulted in prevention of cell cycle re-entry. This indicated that autocrine heregulin activity was responsible for growth factor independence and for cell cycle re-entry. Activation of ErbB2 was the result of heregulin mediated interaction with ErbB3 and generated downstream activation of the ERK and the PI3K/AKT pathways. Heregulin neutralizing antibody treatment of growth arrested GEO cells also generated apoptosis as reflected by PARP cleavage and DNA fragmentation indicating a cell survival signal was also induced by the constitutively activated ErbB2. The activation of AKT but not the MAPK pathway was responsible for cell survival in these cells.
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PMID:Autocrine heregulin generates growth factor independence and blocks apoptosis in colon cancer cells. 1179 Nov 78

Docetaxel (Taxotere) has been intensively investigated for the treatment of metastatic breast cancer, where it has proved to be one of the most active agents. Initial phase II studies in anthracycline-resistant metastatic breast cancer demonstrated impressive response rates that have been confirmed in phase III randomized trials. Docetaxel remains the only single agent to demonstrate a survival benefit in anthracycline-resistant patients. More recently, the combination of docetaxel with capecitabine (Xeloda) has demonstrated additional improvement in survival over docetaxel alone in a randomized phase III trial. In patients previously treated with an alkylating agent, docetaxel is the only single drug to demonstrate improved efficacy over doxorubicin in a randomized trial. Docetaxel has been investigated in combination with the anthracyclines doxorubicin and epirubicin in randomized trials. The docetaxel-containing regimens have consistently demonstrated improvement over the non-docetaxel-containing regimens. The efficacy and safety of weekly docetaxel has extended the line of investigation for combinations with agents normally administered on a weekly basis, such as vinorelbine [Navelbine], gemcitabine [Gemzar], and trastuzumab [Herceptin], with promising findings. In addition, the results of the triple-drug combination of docetaxel, a platinum salt (cisplatin or carboplatin), and trastuzumab have resulted in impressive response rates and time to progression in a population of metastatic breast cancer patients with HER2/neu-positive tumors. The consistent demonstration of a high level of efficacy with manageable toxicity ensures the continued widespread investigation of docetaxel in metastatic breast cancer.
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PMID:The current status of docetaxel for metastatic breast cancer. 1210 94

Erlotinib (Tarceva) is an orally available selective small-molecule inhibitor of HER1/EGFR tyrosine kinase with a 50% inhibitory concentration of 2 nM for purified tyrosine kinase. This agent has been shown to produce stasis or regression of tumor growth in human cancer xenograft models, including non-small-cell lung cancer models. Ongoing preclinical investigations indicate that inhibition of the MAPK and Atk signaling pathways downstream of HER1/EGFR may be required for optimal antitumor effects. Erlotinib exhibits inhibition of MAPK and Atk kinases at concentrations higher than those required for HER1/EGFR tyrosine kinase inhibition; such findings suggest that maximal inhibition of HER1/EGFR, requiring high erlotinib doses, is necessary for optimum antitumor activity. These considerations are supported by tumor models, including non-small-cell lung cancer models, showing dose-related antitumor effects up to high doses of erlotinib. Erlotinib exhibits additive antitumor effects when combined with chemotherapeutic agents (cisplatin, doxorubicin, paclitaxel, gemcitabine [Gemzar], and capecitabine [Xeloda]), radiation therapy, and other targeted agents (e.g., bevacizumab [Avastin]). Recent studies indicate that erlotinib inhibits the EGFRvIII mutant at concentrations higher than those required for inhibition of wild-type receptor. Ongoing investigation will help to determine optimal dosing and dose frequency of erlotinib in various cancers in the clinical setting.
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PMID:Erlotinib: preclinical investigations. 1468 18

Gemcitabine (Gemzar) and paclitaxel show good activity as single agents and combined in metastatic breast cancer, and the combination of paclitaxel/trastuzumab (Herceptin) has been shown to prolong time to disease progression and survival significantly in this setting. Preclinical data indicate additive or synergistic effects of gemcitabine and trastuzumab in HER2-positive human breast cancer cell lines. In a phase II trial, patients with HER2-overexpressing metastatic breast cancer who had received no prior chemotherapy for metastatic disease received gemcitabine at 1,200 mg/m2 on days 1 and 8 and paclitaxel at 175 mg/m2 on day 1 every 21 days for six cycles plus trastuzumab at an initial loading dose of 4 mg/kg followed by 2 mg/kg weekly; patients without progressive disease after six cycles continued to receive trastuzumab until disease progression. Overall, objective response was observed in 28 (67%) of 42 evaluable patients, including complete response in 4 (10%) and partial response in 24 (57%); stable disease was observed in 7 (17%) and progressive disease was observed in 6 (14%). Median time to treatment failure was 9+ months. Median overall survival has not yet been reached, but is estimated at approximately 27 months. Significant toxicities apart from neutropenia were uncommon. The triplet combination of gemcitabine, paclitaxel, and trastuzumab is highly active and well tolerated in patients with HER2-overexpressing metastatic breast cancer.
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PMID:Gemcitabine, paclitaxel, and trastuzumab in metastatic breast cancer. 1476 3


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