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)

Tumor growth and metastasis are dependent on angiogenesis. Vascular endothelial growth factor (VEGF) plays an important role in the angiogenesis of numerous solid malignancies including colon cancer. Evidence from preclinical and clinical studies indicates VEGF is the predominant angiogenic factor in human colon cancer and is associated with formation of metastases and poor prognosis. Based on these results, it was hypothesized that inhibition of VEGF receptor activity could inhibit colon cancer liver metastasis. To test this hypothesis, the authors evaluated the ability of a small molecule inhibitor specific for the tyrosine kinase VEGF receptor Flk-1/KDR (SU5416) or multiple tyrosine kinase receptors (SU6668) to inhibit tumor angiogenesis and metastasis in a model of colon cancer hepatic metastasis. Both SU5416 and SU6668 inhibited metastases, microvessel formation, and cell proliferation while increasing tumor cell and endothelial cell apoptosis. These results showed that targeting the VEGF receptor/ligand system is a rational approach to inhibiting tumor growth and prolonging survival.
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PMID:Vascular endothelial growth factor in human colon cancer: biology and therapeutic implications. 1080 85

Kaposi's sarcoma (KS) is the most common neoplasm associated with human immunodeficiency virus-1 (HIV-1) infection. KS involves the skin and mucous membranes as well as other organs and can lead to tumor-associated edema and ulcerations. Despite therapy with highly active antiviral agents, most patients with HIV-1-related KS eventually develop disseminated disease. In the treatment of KS, a strong rationale exists for the use of agents that inhibit vascular endothelial growth factor (VEGF). Angiogenesis appears to be an important feature of this disease, and recent experimental studies have demonstrated the role of VEGF and its receptors in the pathogenesis of KS. Thus, therapeutic agents that target the VEGF pathway may be an effective strategy in reducing the tumor growth and edema associated with KS. Phase I study results with SU5416, a synthetic low molecular-weight inhibitor of the VEGF-Flk-1/KDR receptor tyrosine kinase, demonstrate that this agent is well tolerated. Preliminary results show that in a majority of patients with autoimmune deficiency syndrome (AIDS)-related disease, SU5416 clearly has biological activity (it flattens, shrinks, or dissolves lesions and reduces or resolves edema) or stabilizes the disease. Angiogenesis inhibition with SU5416 is a promising therapeutic approach in treating patients with KS, and further clinical evaluation is currently under way.
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PMID:The role of vascular endothelial growth factor (VEGF) in AIDS-related Kaposi's sarcoma. 1080 88

HER2/neu oncogene encodes a 185 kDa trans-membrane protein which is overexpressed in 20-30% of breast and ovarian cancers and portends a poor prognosis. We have studied the targeting and therapy of this oncoprotein with 4D5, a murine monoclonal antibody which recognizes a distinct epitope on the extracelluar domain of HER2/neu. We conjugated the antibody with an active ester of the macrocyclic chelating agent DOTA, radiolabeled the conjugate with either (111)In or (90)Y, and studied the antibody distribution and therapy, respectively, in athymic mice bearing xenografts of MCF7/HER2/neu, a human breast cancer cell line transfected with the HER2/neu oncogene. For the biodistribution of (111)In-labeled DOTA-4D5, a high specificity of tumor localization (30% ID/g) was seen with a tumor-to-blood ratio of greater than 2 at 48 h postinjection. Compared to a previously published study with (125)I-labeled 4D5 in beige nude mice bearing NIH3T3/HER2/neu xenografts [De Santes et al. (1992) Cancer Res. 52, 1916-1923], (111)In-labeled 4D5 antibody gave superior antibody uptake in tumor (30% ID/g vs 17% ID/g at 48h). In the therapy study, treatment of the nude mice bearing MCF7/HER2/neu xenografts with 100 microCi (3 microg) of (90)Y-labeled DOTA-4D5 caused a 3-fold reduction of tumor growth compared to untreated controls (injected with human serum albumin) in 40 days. Treatment of animals with 100 microCi of nonspecific antibody (90)Y-labeled DOTA-Leu16 (3 microg) had no tumor growth inhibition. Treatment with unlabeled DOTA-4D5 (3 microg) had a slight effect on tumor growth compared to untreated controls. When analyzed at the level of single animals, no effect was seen in seven of nine animals; however, in two of the animals, tumor growth inhibition was observed. Although a cold antibody therapeutic effect was unexpected at this dose level (3 microg), it may be possible that in some animals that 3 microg of antibody of (90)Y-labeled DOTA-4D5 augmented tumor growth reduction. To further explore the effects of cold antibody treatment alone, animals were treated with 100 or 400 microg of unlabeled 4D5 administered in two doses. These animals showed a 1.7-1.8-fold reduction in tumor growth over 28 days, a result less than that obtained with RIT only.
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PMID:Biodistribution and radioimmunotherapy of human breast cancer xenografts with radiometal-labeled DOTA conjugated anti-HER2/neu antibody 4D5. 1082 48

To understand the molecular mechanisms by which anti-p185HER2 antibody and the ligand heregulin inhibit tumor growth, we have investigated several signaling proteins and pathways. We report here that anti-p185HER2 monoclonal antibody ID5 induced tyrosine phosphorylation of HER2 in SKBr3 breast cancer cells that overexpress p185HER2. Heregulin beta1 induced phosphorylation of both HER3 and HER2. ID5 produced a greater association of phospholipase C (PLC)-gamma1 with HER2 than did heregulin. Concordantly, ID5, but not heregulin, increased PLC-gamma1 activity. However, the G1 cell cycle arrest and induction of p27Kip1 produced by ID5 were not affected by the inhibition of PLC-gamma. ID5 preferentially induced binding of the Mr 46,000 isoform of SHC to HER2, whereas heregulin preferentially induced binding of the Mr 52,00 isoform of SHC to HER3. Heregulin, but not ID5, induced the p85 subunit of phosphatidylinositol 3'-kinase (PI3-K) to interact with HER3. Heregulin induced sustained activation of P13-K signaling, whereas ID5 had only a transient effect. Heregulin, but not ID5, activated the c-Jun-NH2-terminal kinase cascade. Pretreatment of SKBr3 cells with ID5 decreased heregulin-induced association of HER2 with HER3 as well as the activation of c-Jun-NH2-terminal kinase and PI3-K activities. Inhibition of the mitogen-activated protein kinase pathway in SKBr3 cells did not affect heregulin-induced G2-M-phase arrest, apoptosis, and differentiation. Heregulin-induced apoptosis could be blocked by inhibition of p70s6k, but not by inhibition of PI3-K. Heregulin-induced differentiation could be eliminated by inhibition of PI3-K. We conclude that ID5 and heregulin signal via different pathways, although both agents can inhibit the clonogenic growth of cells that overexpress HER2.
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PMID:Differential signaling by an anti-p185(HER2) antibody and heregulin. 1091 64

The analysis of the genetic causes of tumor development led to the identification of many genes affected in these diseases, which play a role in the control of cell proliferation and apoptosis. However, these studies also suggested that not all alterations are equal with regard to their effect on tumor growth, and they demonstrated that the deregulation of the classical cytoplasmic cascade made up by Ras-Raf-MEK and ERK plays a critical role in tumor development. These findings also raise the hope that via interference with a single pathway growth of a tumor carrying multiple genetic alterations will be affected.
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PMID:[Deregulation of intracellular signal pathways in colorectal carcinoma]. 1092 40

Vascular endothelial growth factor (VEGF) plays a fundamental role in mediating tumor angiogenesis and tumor growth. Here we investigate the direct effect of a novel small molecule inhibitor of the Flk-1-mediated signal transduction pathway of VEGF, SU5416, on tumor angiogenesis and microhemodynamics of an experimental glioblastoma by using intravital multifluorescence videomicroscopy. SU5416 treatment significantly suppressed tumor growth. In parallel, SU5416 demonstrated a potent antiangiogenic activity, resulting in a significant reduction of both the total and functional vascular density of the tumor microvasculature, which indicates an impaired vascularization as well as significant perfusion failure in treated tumors. This malperfusion was not compensated for by changes in vessel diameter or recruitment of nonperfused vessels. Analyses of the tumor microcirculation revealed significant microhemodynamic changes after angiogenesis blockage such as a higher red blood cell velocity and blood flow in remnant tumor vessels when compared with controls. Our results demonstrate that the novel antiangiogenic concept of targeting the tyrosine kinase of Flk-1/KDR by means of a small molecule inhibitor represents an efficient strategy to control growth and progression of angiogenesis-dependent tumors. This study provides insight into microvascular consequences of Flk-1/KDR targeting in vivo and may have important implications for the future treatment of angiogenesis-dependent neoplasms.
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PMID:Inhibition of tumor growth, angiogenesis, and microcirculation by the novel Flk-1 inhibitor SU5416 as assessed by intravital multi-fluorescence videomicroscopy. 1093 68

Intravenously administered anti-tumor single-chain Fv (scFv) and diabody molecules exhibit rapid clearance kinetics and accumulation in tumors that express their cognate antigen. In an attempt to fit the rate of isotope decay to the timing of delivery and duration of tumor retention, anti-HER2/neu CHX-A" DTPA-C6.5K-A scFv and diabody conjugates were labeled with the alpha-particle emitter (213)Bi (t(1/2) = 47 min). Radioimmunotherapy studies employing 0.64, 0.35, or 0.15 microCi of (213)Bi-labeled C6.5K-A diabody or 1.1, 0.6, or 0. 3 microCi of (213)Bi-labeled C6.5K-A scFv were performed in nude mice bearing early, established SK-OV-3 tumors. Only the 0.3 microCi dose of (213)Bi-labeled C6.5K-A scFv resulted in both acceptable toxicity and a reduction in tumor growth rate. The specificity of the anti-tumor effects was determined by comparing the efficacy of treatment with 0.3 and 0.15 microCi doses of (213)Bi-labeled C6.5K-A scFv and (213)Bi-labeled NM3E2 (an irrelevant scFv) in nude mice bearing large established tumors. The 0.3 microCi dose of (213)Bi on both the C6.5K-A and NM3E2 scFvs resulted in similar anti-tumor effects (p = 0.46) indicating that antigen-specific targeting was not a factor. This suggests that the physical half-life of (213)Bi may be too brief to be effectively paired with systemically-administered diabody or scFv molecules.
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PMID:Delivery of the alpha-emitting radioisotope bismuth-213 to solid tumors via single-chain Fv and diabody molecules. 1093 67

Poly(ethylene glycol) (PEG) modification of substances with antitumor activity was shown to enhance penetration into growing solid tumors and extend antitumor effects. Accordingly, PEG was introduced as a modifier to two types of monoclonal antibodies (N12 and L26) specific to the ErbB2 (HER2) oncoprotein. These antibodies suppress the growth of tumors overexpressing ErbB2 (e.g. N87 human tumor) and the effect of PEG on their antitumor activity was evaluated. Methoxy-PEG-maleimide conjugated to sulfhydryl groups at the hinge region of the antibodies impaired their antibody binding to N87 tumor cells and did not enhance the antitumor inhibitory activity in tumor-bearing mice. A branched N-hydroxysuccinimide-activated PEG (PEG2), conjugated through amino groups of the protein, was used for binding to the whole antibody (Ab) or to its monomeric Fab' fragment. When tested against N87 cells in vitro, the binding activity and antitumor cytotoxic effects of Ab-PEG2 were mostly preserved. PEG2 modification did not seem to alter the tumor-inhibitory activity of the antibodies in vivo and the same pattern of tumor development was observed during the first few weeks following administration. However, the stimulating effects of PEG were observed at later stages of tumor growth since tumor development was either slowed down or completely arrested. Furthermore, a second tumor implanted into the same mice during this later stage was significantly or completely inhibited, as compared to results in mice injected with the unmodified antibody. The Fab'-PEG2 monomeric derivative was also shown to be effective in inhibiting the growth of a second tumor. The extended and prolonged enhancing effect of PEG on the antitumor activity of antibodies or Fab' fragments directed against ErbB2 may be of importance in the treatment of ErbB2-overexpressing neoplasms.
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PMID:Inhibition of tumor growth by poly(ethylene glycol) derivatives of anti-ErbB2 antibodies. 1094 5

Antiangiogenic therapy is a promising new strategy to inhibit tumor growth and formation of metastases. Vascular endothelial growth factor (VEGF) and its receptors, VEGF-receptor 1 (VEGF-R1; FLT-1) and VEGF-R2 (KDR), have been shown to play a major role in tumor angiogenesis. PTK787/ZK 222584, a specific inhibitor of both VEGF-receptor tyrosine kinases, was investigated for its antitumoral and antiangiogenic activity in a murine renal cell carcinoma model. After intrarenal application of the renal carcinoma cells, mice develop a primary tumor and metastases to the lung and to the abdominal lymph nodes. Daily oral therapy with PTK787/ZK 222584 at a dose of 50 mg/kg resulted in a significant decrease of 61 and 67% in primary tumors after 14 and 21 days, respectively. The occurrence of lung metastases was significantly inhibited at both time points (98% reduction and 78% reduction, respectively). After 14 days, no lymph node metastases developed in the PTK787/ZK 222584-treated group, whereas after 21 days of treatment, the lymph node metastases were reduced by 87%. Vessel density in tumor tissues, detected by immunohistochemistry with an anti-CD31 antibody, was significantly decreased by PTK787/ZK 222584. Using color Doppler imaging ultrasound, significant changes in blood flow in the tumor feeding renal artery were found under treatment with PTK787/ZK 222584. Blood flow changes correlated with changes in vessel density but not with tumor volume. The compound was well tolerated in all in vivo experiments and had no significant effects on body weight or general well-being of the animals. This was in contrast to the animals treated with the antiangiogenic agent TNP-470. s.c. therapy with 30 mg/kg TNP-470 every other day had to be discontinued after 13 days because of animal weight loss (>20%) and ataxia. These results demonstrate that PTK787/ZK 222584 is a potent inhibitor of tumor growth, metastases formation, and tumor vascularization in murine renal cell carcinoma. Furthermore, we have been able to demonstrate that color Doppler imaging ultrasound can be used to measure blood flow to a tumor and that flow correlates with vessel density. Thus, this may be a valuable noninvasive method for monitoring the effects of antiangiogenic agents such as PTK787/ZK 222584 on tumor vasculature.
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PMID:Effects of PTK787/ZK 222584, a specific inhibitor of vascular endothelial growth factor receptor tyrosine kinases, on primary tumor, metastasis, vessel density, and blood flow in a murine renal cell carcinoma model. 1098 92

Angiogenesis is essential for tumor growth and metastasis. It is regulated by numerous angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF). Recently, VEGF-C, a new VEGF family member, has been identified that binds to the tyrosine kinase receptors flt-4 [VEGF receptor (VEGFR) 3] and KDR (VEGFR2). Although the importance of VEGF has been shown in many human tumor types, the contribution of VEGF-C and its primary receptor flt-4 to tumor progression is less well understood. We have therefore measured the level of VEGF-C, flt-4, and KDR mRNA by RNase protection assay and the pattern of VEGF-C expression by immunohistochemistry in 11 normal breast tissue samples and 61 invasive breast cancers. No significant difference in VEGF-C expression was observed between normal and neoplastic breast tissues (P = 0.11). There was a significant correlation between VEGF-C and both flt-4 (P = 0.02) and KDR (P = 0.0002), but no association was seen between VEGF-C and either lymph node status (P = 0.66) or number of involved nodes (P = 0.88), patient age (P = 0.83), tumor size (P = 0.20), estrogen receptor status (P = 0.67), or tumor grade (P = 0.35). No significant relationship was present between VEGF-C and vascular invasion (P = 0.30), tumor vascularity (P = 0.21), VEGF-A (P = 0.62), or thymidine phosphorylase expression (P = 1.00). VEGF-C was expressed predominantly in the cytoplasm of tumor cells, although occasional stromal components including fibroblasts were also positive. We could demonstrate no association between lymph node metastasis and either VEGF-C (P = 0.66) or flt-4 (P = 0.4). However, we did observe a significant loss of the long but not the short isoform of flt-4 in tumors compared with normal tissues (P = 0.02 and P = 0.25, respectively), and this difference was largely accounted for by the reduction of long flt-4 in node-positive tumors. These findings strongly support a role for VEGF-C/flt-4 signaling in tumor growth by enhancement of angiogenesis and/or lymphangiogenesis and suggest that differential regulation of these processes may be controlled via flt-4 isoform transcription. They further suggest that the measurement of flt-4 isoform expression may identify a patient group that is likely to have node-positive disease and therefore benefit from additional treatment and also emphasize an additional ligand interaction that could be exploited by anti-VEGFR therapy.
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PMID:The short form of the alternatively spliced flt-4 but not its ligand vascular endothelial growth factor C is related to lymph node metastasis in human breast cancers. 1110 44


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