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:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ionizing radiation at 2 Gy activates the epidermal growth factor receptor (EGFR) kinase activity in A431 squamous carcinoma cells and as a consequence transiently activates a downstream effector, mitogen-activated protein kinase (MAPK). A dose-response analysis shows fourfold activation 3-5 min after irradiation at 0.5 Gy with no additional activation after doses up to 4 Gy. Activation is independent of protein kinase C as defined by marginal effects of protein kinase C down-regulation and the protein kinase C inhibitor, chelerythrine. In contrast, an intracellular Ca2+ chelator (BAPTA/AM), a Ca2+ antagonist (TMB-8) and a phospholipase C inhibitor (U73223), which inhibits radiation-induced Ca2+ oscillations, all block MAPK stimulation. The upstream component, Raf-1, is also activated through a mechanism that is dependent on EGFR and Ca2+. Activation of Raf-1, monitored by tyrosine phosphorylation and co-immunoprecipitation with Ras, was inhibited by BAPTA/AM and TMB-8, indicating that the Ca2+-dependent step occurs at or before the interaction of Ras and Raf-1. Neither the Ras guanosine triphosphate exchange protein, SOS, nor Ca2+-activated tyrosine kinases linked to the MAPK pathway, focal adhesion kinase and PYK2, were stimulated by radiation. In contrast, EGF activated SOS as shown by the enhanced association of SOS with EGFR in co-immunoprecipitation experiments. These results suggest that activation of EGFR-dependent downstream signaling induced by radiation differs from that induced by the natural ligands of EGFR.
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PMID:Calcium-dependent stimulation of mitogen-activated protein kinase activity in A431 cells by low doses of ionizing radiation. 961 Oct 96

To destroy both tumor blood vessels and adjacent tumor cells, an alpha-particle emitter, 213Bi, has been targeted with a monoclonal antibody (MAb) to vessels that feed lung tumors in mice. Animals, bearing approximately 100 EMT-6 carcinomas each of 50-400 cells in size in the lung, that were treated with 120 muCi of 213Bi-MAb 201B were all cured of their disease. Animals treated when tumors were larger (10(3)-10(4) cells) had extended life spans, but a small number of residual tumors eventually killed the animals. Significant extension of life span was also induced with another tumor model-rat tracheal carcinoma growing in the lungs of SCID mice that were then treated with 136 muCi 213Bi-MAb 201B. These studies indicate that attack of both blood vessels and tumor cells simultaneously is an effective mode of cancer treatment.
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PMID:Vascular targeted radioimmunotherapy with 213Bi--an alpha-particle emitter. 962 Jun 29

Integrin-basement membrane interactions provide essential signals that promote survival and growth of epithelial cells, whereas loss of such adhesions triggers programmed cell death. We found that HSC-3 human squamous carcinoma cells survived and grew readily as monolayers, but when they were suspended as single cells, they ceased proliferating and entered into the apoptotic death pathway, characterized by DNA fragmentation. In contrast, if the suspended carcinoma cells were permitted to form E-cadherin-mediated multicellular aggregates, they not only survived but proliferated. However, aggregated normal keratinocytes were unable to survive in suspension culture and rapidly became apoptotic. Anchorage independence and resistance to apoptosis of HSC-3 cell aggregates required high levels of extracellular Ca2+ and was inhibited with function-perturbing anti-E-cadherin antibody. Resistance to suspension-induced apoptosis in cell aggregates paralleled the up-regulation of Bcl-2 but occurred in the absence of focal adhesion kinase activation. Analysis of suspension-induced death in a set of cloned squamous epithelial cell lines with different levels of E-cadherin expression revealed that receptor-positive cell clones evaded apoptosis and proliferated in three-dimensional aggregate culture, whereas cadherin-negative clones failed to survive. Collectively, these observations indicate that cadherin-mediated intercellular adhesions generate a compensatory mechanism that promotes anchorage-independent growth and suppresses apoptosis.
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PMID:E-cadherin regulates anchorage-independent growth and survival in oral squamous cell carcinoma cells. 964 58

Recent studies have demonstrated the importance of E-cadherin, a homophilic cell-cell adhesion molecule, in contact inhibition of growth of normal epithelial cells. Many tumor cells also maintain strong intercellular adhesion, and are growth-inhibited by cell- cell contact, especially when grown in three-dimensional culture. To determine if E-cadherin could mediate contact-dependent growth inhibition of nonadherent EMT/6 mouse mammary carcinoma cells that lack E-cadherin, we transfected these cells with an exogenous E-cadherin expression vector. E-cadherin expression in EMT/6 cells resulted in tighter adhesion of multicellular spheroids and a reduced proliferative fraction in three-dimensional culture. In addition to increased cell-cell adhesion, E-cadherin expression also resulted in dephosphorylation of the retinoblastoma protein, an increase in the level of the cyclin-dependent kinase inhibitor p27(kip1) and a late reduction in cyclin D1 protein. Tightly adherent spheroids also showed increased levels of p27 bound to the cyclin E-cdk2 complex, and a reduction in cyclin E-cdk2 activity. Exposure to E-cadherin-neutralizing antibodies in three-dimensional culture simultaneously prevented adhesion and stimulated proliferation of E-cadherin transfectants as well as a panel of human colon, breast, and lung carcinoma cell lines that express functional E-cadherin. To test the importance of p27 in E-cadherin-dependent growth inhibition, we engineered E-cadherin-positive cells to express inducible p27. By forcing expression of p27 levels similar to those observed in aggregated cells, the stimulatory effect of E-cadherin-neutralizing antibodies on proliferation could be inhibited. This study demonstrates that E-cadherin, classically described as an invasion suppressor, is also a major growth suppressor, and its ability to inhibit proliferation involves upregulation of the cyclin-dependent kinase inhibitor p27.
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PMID:E-Cadherin-dependent growth suppression is mediated by the cyclin-dependent kinase inhibitor p27(KIP1). 967 52

We have previously demonstrated that vascular endothelial growth factor-165 (VEGF), a tumor-secreted angiogenic factor, can acutely and chronically induce fenestrations in microvascular endothelium (Cancer Res 1997, 57:765-772). Because the morphology and function of microvascular endothelium differs from tissue to tissue, we undertook studies to examine whether the neovasculature in tumors also differed depending upon tumor location. Four tumor types implanted in the brain or subcutis in nude mice were studied: a murine rhabdomyosarcoma (M1S), a murine mammary carcinoma (EMT), and two human glioblastomas (U87 and U251). In addition, we studied Chinese hamster ovary cells stably transfected with human VEGF165. As previously reported, tumors grown in the subcutaneous space had a microvasculature that was fenestrated and had open endothelial gaps. The identical tumors when grown in the brain also had fenestrated endothelium and vessels with open endothelial gaps, but they were drastically reduced in occurrence. Open endothelial gaps were not seen in all tumors implanted in the brain (EMT and M1S), although fenestrated endothelium was always seen. VEGF and VEGF receptors were measured in tumors from both locations by immunoblotting and competitive polymerase chain reaction, respectively. VEGF amount was not significantly different between the tumor locations. Interestingly, total tumor vascular mRNA expression of both Flk-1 and Flt-1 was greater in tumor vessels derived from the brain compared with tumor vessels derived from subcutaneous tissues. These results demonstrate that the host microvascular environment determines the morphology and function of the tumor vasculature and that endothelia from different tissues vary in their ability to express the VEGF receptors given identical stimuli.
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PMID:Host microvasculature influence on tumor vascular morphology and endothelial gene expression. 977 55

Overexpression and amplification of hepatocyte growth factor (HGF) receptor (Met) have been detected in many types of human cancers, suggesting a critical role for Met in growth and development of malignant cells. However, the molecular mechanism by which Met contributes to tumorigenesis is not well known. The tyrosine kinase c-Src has been implicated as a modulator of cell proliferation, spreading, and migration; these functions are also regulated by Met. To explore whether c-Src kinase is involved in HGF-induced cell growth, a mouse mammary carcinoma cell line (SP1) that co-expresses HGF and Met and a nonmalignant epithelial cell line (Mv1Lu) that expresses Met but not HGF were used. In this study, we have shown that c-Src kinase activity is constitutively elevated in SP1 cells and is induced in response to HGF in Mv1Lu cells. In addition, c-Src kinase associates with Met following stimulation with HGF. The enhanced activity of c-Src kinase also correlates with its ability to associate with Met. Expression of a dominant negative double mutant of c-Src (SRC-RF), lacking both kinase activity (K295R) and a regulatory tyrosine residue (Y527F), in SP1 cells significantly reduced c-Src kinase activity and strongly blocked HGF-induced motility and colony growth in soft agar. In contrast, expression of the dominant negative c-Src mutant had no effect on HGF-induced cell proliferation on plastic. Taken together, our data strongly suggest that HGF-induced association of c-Src with Met and c-Src activation play a critical role in HGF-induced cell motility and anchorage-independent growth of mammary carcinomas and further support the notion that the presence of paracrine and autocrine HGF loops contributes significantly to the transformed phenotype of carcinoma cells.
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PMID:c-Src kinase activity is required for hepatocyte growth factor-induced motility and anchorage-independent growth of mammary carcinoma cells. 983 58

Reactive oxygen species (ROS) play an important role in the pathogenesis of many human diseases, including the acute respiratory distress syndrome, Parkinson's disease, pulmonary fibrosis, and Alzheimer's disease. In mammalian cells, several genes known to be induced during the immediate early response to growth factors, including the protooncogenes c-fos and c-myc, have also been shown to be induced by ROS. We show that members of the STAT family of transcription factors, including STAT1 and STAT3, are activated in fibroblasts and A-431 carcinoma cells in response to H2O2. This activation occurs within 5 min, can be inhibited by antioxidants, and does not require protein synthesis. STAT activation in these cell lines is oxidant specific and does not occur in response to superoxide- or nitric oxide-generating stimuli. Buthionine sulfoximine, which depletes intracellular glutathione, also activates the STAT pathway. Moreover, H2O2 stimulates the activity of the known STAT kinases JAK2 and TYK2. Activation of STATs by platelet-derived growth factor (PDGF) is significantly inhibited by N-acetyl-L-cysteine and diphenylene iodonium, indicating that ROS production contributes to STAT activation in response to PDGF. These findings indicate that the JAK-STAT pathway responds to intracellular ROS and that PDGF uses ROS as a second messenger to regulate STAT activation.
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PMID:Activation of the JAK-STAT pathway by reactive oxygen species. 984 26

MCF-7 human breast carcinoma cultures grown in the presence of 17-beta estradiol form solid, multicellular nodules, a process that reflects changes in cell-substrate adhesions and loss of growth inhibition. We examined the effects of estradiol on the status of tyrosine phosphorylation in focal adhesion kinase (FAK) and the association of FAK with paxillin using immunoprecipitations and then probing western blots for FAK, phosphotyrosine, and paxillin. Culture of MCF-7 cells for seven days in the presence of 1 nM E2 resulted in decreased tyrosine phosphorylation of FAK compared to controls. The estradiol-induced effect was blocked by 100 nM of the estrogen receptor antagonist 4-hydroxytamoxifen, indicating dephosphorylation of FAK is an estrogen receptor-mediated event. FAK immunoprecipitated from either estradiol or DMSO-treated cells phosphorylated the exogenous substrate poly(Glu,Tyr), suggesting that the potential kinase activity of FAK was not changed by estradiol. Estradiol treatment also resulted in a reduced association between FAK and paxillin. The decreased phosphorylation levels and reduced association between FAK and paxillin may be important steps leading to the loss of stable focal contacts and loss of growth inhibition during MCF-7 nodulation.
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PMID:Decreased tyrosine phosphorylation of focal adhesion kinase after estradiol treatment of MCF-7 human breast carcinoma cells. 987 83

While cancer drug resistance has been extensively studied in cell culture, little is known about more clinically relevant in vivo resistance. The in vivo resistance of a murine mammary carcinoma EMT-6 to alkylating agents was demonstrated in the present study to be associated with multiple biochemical changes. These included an up to 1.5-fold increase in activity of phase II drug metabolizing enzymes (DMEs), such as glutathione (GSH), glutathione reductase (GR), glutathione S-transferase (GST), glutathione peroxidase (GPX) and aldehyde dehydrogenase (ALDH), and an up to 88% decrease of phase I DME activity [7-ethoxycumarin O-deethylase (ECOD), P450 reductase (PR)] in the resistant tumors compared with the parental tumor. Transplant of either parental or resistant tumors to mice was accompanied by a decrease of both phase I and phase II DME activity in the livers of female Balb/C mice compared with the non-tumor mice. Moreover, at the protein level, while cytochrome P450 (CYP) IIB1/2 in the liver of mouse bearing both the sensitive and the resistant tumor was significantly diminished compared to that in the liver of non-tumor control mouse in Western analysis, there was actually an increase of this protein in the liver of the host bearing either of the two resistant tumors compared to that of the sensitive tumor-bearing animal. Although this in vivo resistance phenotype is not expressed in cell culture, the profile of most of the enzyme changes in the resistant tumors remained similar in in vitro culture of the isolated tumor cells. Collectively, these results demonstrate that this in vivo alkylating agent resistance is associated with multiple changes of both phase I and phase II DMEs in the resistant tumors, and some of these, such as CYP IIB1/2 protein are further altered in the resistant tumor-bearing mouse liver, suggesting a potential role of systemic factors in this resistance phenotype.
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PMID:Biochemical characterization of in vivo alkylating agent resistance of a murine EMT-6 mammary carcinoma. Implication for systemic involvement in the resistance phenotype. 992 73

Granulocyte-colony-stimulating factor (G-CSF), a hematopoietic cytokine, regulates the proliferation and differentiation of granulocytic progenitor cells and functionally activated mature neutrophils. G-CSF also affects nonhematopoietic tumor cells by the binding of G-CSF to its specific receptor (G-CSFR) on the cells. In this study, we investigated the effect of G-CSF on the invasive potential of head-and-neck carcinoma cells, and explored the intracellular events initiated by the binding of G-CSF in tumor cells. In vitro treatment of head-and-neck-carcinoma cell lines, IMC-2, IMC-3, KB, Ca9-22, SCCKN and SCCTF, with recombinant G-CSF (rG-CSF) significantly augmented their invasive potential in dose- and time-dependent manners. Among these cancer cells, IMC-2, IMC-3, KB and Ca9-22 cells produced little G-CSF, while large amounts of G-CSF were produced by SCCKN and SCCTF cell lines. Anti-G-CSF antibody (Ab) abrogated the rG-CSF-enhanced invasiveness to the control level of that in untreated cancer cell lines. Immunocytochemical staining and Western blotting using anti-G-CSFR monoclonal antibody (MAb) revealed the expression of G-CSFR on head-and-neck-cancer cell lines exhibiting the enhancement of invasive activity by rG-CSF. IMC-2 cells, having the highest invasive ability among the cell lines used, showed augmentation of G-CSFR expression on stimulation with rG-CSF. Furthermore, stimulation of IMC-2 cells with rG-CSF induced rapid activation of tyrosine-phosphorylated JAK1, suggesting that the G-CSF signal may be transduced into the cells through G-CSFR. Moreover, the gelatinolytic activity of IMC-2 cells was enhanced by stimulation of rG-CSF, and the enhanced invasiveness was inhibited on addition of the tissue inhibitors of metalloproteinases (TIMPs). These results suggest that exogenous rG-CSF may increase the risk of metastasis and/or local recurrence in patients with G-CSFR-positive head-and-neck squamous-cell carcinoma, via an invasive mechanism.
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PMID:Granulocyte-colony-stimulating factor enhances invasive potential of human head-and-neck-carcinoma cell lines. 993 35


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