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)

The bioreductive alkylating agent mitomycin C (mitomycin) has been shown to have greater activity under hypoxic than oxic conditions on murine cell lines such as the EMT-6 fibrosarcoma cell line. Solid tumors are known to contain hypoxic cells and are relatively resistant to ionizing radiation and some chemotherapeutic agents. We tested the cytotoxicity of mitomycin against fresh biopsies of human carcinomas under both hypoxic and oxic conditions in the human tumor clonogenic assay (HTCA). Additionally, we examined the metabolism of mitomycin by sonicates of the murine EMT-6 cells and the human WiDR colon carcinoma cells. We confirmed that under our clonogenic assay conditions the EMT-6 cell line was more sensitive to mitomycin under hypoxic than oxic conditions. Additionally, we established that EMT-6 cells also metabolize mitomycin at a more rapid rate under hypoxic than oxic conditions. However, these effects of hypoxia on mitomycin activity were not demonstrable for the human WiDR colon cancer cell line. In addition to these findings, the cytotoxicity of mitomycin was either unchanged or reduced under hypoxic conditions for ten fresh human tumors tested for mitomycin sensitivity in HTCA. Based on these observations, we conclude that the potentiating effect of hypoxia on mitomycin metabolism and biological activity may be peculiar to the murine EMT-6 and S-180 cell lines and that mitomycin C is not likely to have differential efficacy against hypoxic human carcinoma cells.
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PMID:Cytotoxicity of mitomycin C on clonogenic human carcinoma cells is not enhanced by hypoxia. 642 4

Activated pp60c-src has been implicated in a number of human malignancies including colon carcinoma and breast adenocarcinoma. Association of the src SH2 domain with tyrosine-phosphorylated proteins plays a role in src-mediated signal transduction. Inhibitors of src SH2 domain-phosphoprotein interactions are, thus, of great interest in defining the role(s) of src in signal transduction pathways. To facilitate such studies, an enzyme-linked immunosorbent assay (ELISA) was developed to detect inhibitors of src SH2-phosphoprotein interactions. This assay measures inhibition of binding of a fusion construct (glutathione S-transferase src SH3-SH2) with autophosphorylated epidermal growth factor receptor tyrosine kinase domain. Activities of phosphopeptide segments derived from potential src SH2 cognate phosphoprotein partners were determined, with the focal adhesion kinase-derived segment VSETDDY*AEIIDE yielding the highest inhibitory activity. Structure activity studies starting from acetyl (Ac)-Y*EEIE have identified Ac-Y*Y*Y*IE as the most active compound screened in the ELISA. This compound is at least 20-fold more active than the parent peptide Ac-Y*EEIE. A high resolution (2 A) crystal structure of human src SH2 complexed with Ac-Y*EEIE was obtained and provided a useful framework for understanding the structure-activity relationships. Additionally, Ac-Y*EEIE was able to block interactions between src and its cellular phosphoprotein partners in vanadate-treated cell lysates from MDA-MB-468 breast carcinoma cells. However, it is unable to abrogate proliferation of MDA-MB-468 cells in culture, presumably because of poor cell penetration and/or lability of the phosphate group on tyrosine.
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PMID:Peptide inhibitors of src SH3-SH2-phosphoprotein interactions. 752 93

We have previously reported on the expression of interleukin-4 receptors (IL-4R) on many human epithelial cancer cells; however, the binding characteristics, structure, function, and signal transduction through the IL-4R in cancer cells is not known. IL-4 binding characteristics were determined in human colon carcinoma cell lines by a 125I-IL-4 binding assay, which demonstrated that the HT-29 and WiDr colon cancer cell lines expressed high affinity IL-4R (Kd = 200 pM). Cross-linking experiments revealed a major band of 140 kDa and a broad band at 70 kDa. While the common gamma chain of IL-2R is associated with IL-4R in immune cells and is similar in size to the 70-kDa protein, this chain was not expressed in these colon cancer cells. Interestingly, IL-13, which has many functions similar to IL-4, inhibited 125I-IL-4 binding to both the 140- and 70-kDa molecules. Next, we investigated the mechanism of IL-4-induced signal transduction in colon cancer cells. After stimulation with IL-4, a 170-kDa band was primarily phosphorylated within 1 min of exposure and was identified as insulin receptor substrate-1. In addition, by immunoprecipitation assay, three other phosphorylated bands were identified as JAK1, JAK2, and Tyk2 tyrosine kinases. The phosphorylation of JAK1 and JAK2 was induced by IL-4 stimulation; however, Tyk2 was constitutively phosphorylated, and IL-4 treatment further augmented this phosphorylation. The kinetics and in vitro kinase assays demonstrated that JAK1, JAK2, and Tyk2 were phosphorylated within minutes and that JAK1 and JAK2 were activated after IL-4 exposure. Contrary to observations in immune cells. JAK3 mRNA was neither detected in colon cancer cells nor did IL-4 treatment cause phosphorylation of JAK3. These data indicate that in colon carcinoma cells JAK1, JAK2, Tyk2, and insulin receptor substrate-1 are phosphorylated after IL-4 stimulation. In addition, as is the case in lymphoid cells, IL-4 activated and phosphorylated signal transducers and activators of transcription (IL-4-STAT or STAT-6) protein in both colon cancer cell lines. These results indicate that the IL-4R complex is composed of different subunits in different tissues and shares a component with the IL-13R complex. In addition, we demonstrate for the first time that like its family members (e.g. IL-3 and GM-CSF), IL-4 can phosphorylate and activate JAK-2 kinase.
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PMID:Receptors for interleukin (IL)-4 do not associate with the common gamma chain, and IL-4 induces the phosphorylation of JAK2 tyrosine kinase in human colon carcinoma cells. 853 May 27

We have recently reported that IL-13R may share a component with IL-4R. Here we report that both IL-4 and IL-13 share signaling events in human colon carcinoma cell lines (HT-29 and WiDr). IL-13 caused rapid phosphorylation of the three out of four members of the known Janus family of kinases (JAKs). We show that JAK2 kinase is rapidly phosphorylated and activated in response to IL-13. Within 1 min of activation, JAK2 was phosphorylated, and peaked in 10 min. In addition, IL-13 phosphorylated insulin response substrate-1, IL-4R p140, JAK1, and Tyk2, but not JAK3 kinase. IL-4 also stimulated all three kinases and substrates, but unlike in immune cells, IL-4 did not involve JAK3 activation for its signaling in colon cancer cell lines. Furthermore, JAK2 associated with the IL-4R p140 before and after stimulation with IL-13. Both IL-13 and IL-4 induced phosphorylation of IL-4 STAT (STAT6) but not STAT1, STAT3, or STAT5. 125I-IL-13 did not bind to colon cancer cell lines, but unlabeled IL-13 competed for the binding of 125I-IL-4. Our data suggest that IL-13 utilizes IL-4R and its signaling pathway, and JAK2 may play an important role in the function of IL-4R and IL-13R in colon cancer cells.
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PMID:IL-13 induces phosphorylation and activation of JAK2 Janus kinase in human colon carcinoma cell lines: similarities between IL-4 and IL-13 signaling. 860 18

Detachment of basal keratinocytes from basement membrane signals a differentiation cascade. Two integrin receptors alpha6beta4 and alpha3beta1 mediate adhesion to laminin 5 (epiligrin), a major extracellular matrix protein in the basement membrane of epidermis. By establishing a low temperature adhesion system at 4 degrees C, we were able to examine the exclusive role of alpha6beta4 in adhesion of human foreskin keratinocyte (HFK) and the colon carcinoma cell LS123. We identified a novel 80-kD membrane-associated protein (p80) that is tyrosine phosphorylated in response to dissociation of alpha6beta4 from laminin 5. The specificity of p80 phosphorylation for laminin 5 and alpha6beta4 was illustrated by the lack of regulation of p80 phosphorylation on collagen, fibronectin, or poly-L-lysine surfaces. We showed that blocking of alpha3beta1 function using inhibitory mAbs, low temperature, or cytochalasin D diminished tyrosine phosphorylation of focal adhesion kinase but not p80 phosphorylation. Therefore, under our assay conditions, p80 phosphorylation is regulated by alpha6beta4, while motility via alpha3beta1 causes phosphorylation of focal adhesion kinase. Consistent with a linkage between p80 dephosphorylation and alpha6beta4 anchorage to laminin 5, we found that phosphatase inhibitor sodium vanadate, which blocked the p80 dephosphorylation, prevented the alpha6beta4-dependent cell anchorage to laminin 5 at 4degreesC. In contrast, adhesion at 37 degrees C via alpha3beta1 was unaffected. Furthermore, by in vitro kinase assay, we identified a kinase activity for p80 phosphorylation in suspended HFKs but not in attached cells. The kinase activity, alpha6beta4, and its associated adhesion structure stable anchoring contacts were all cofractionated in the Triton-insoluble cell fraction that lacks alpha3beta1. Thus, regulation of p80 phosphorylation, through the activities of p80 kinase and phosphatase, correlates with alpha6beta4-SAC anchorage to laminin 5 at 4 degrees C in epithelial cells of the skin and intestine. Transmembrane signaling through p80 is an early tyrosine phosphorylation event responsive to and possibly required for anchorage to laminin 5 by HFK and LS123 epithelial cells.
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PMID:Anchorage mediated by integrin alpha6beta4 to laminin 5 (epiligrin) regulates tyrosine phosphorylation of a membrane-associated 80-kD protein. 864 1

Members of the integrin family manifest considerable overlap in ligand specificity, and many cells have the capacity to express multiple integrin receptors for the same ligand. For example, at least 5 different integrins recognize tenascin as a ligand, and 4 of these bind to the same region of the protein, the third fibronectin type III repeat (TNfn3). We utilized colon carcinoma cells (SW480) that do not normally attach to TNfn3 to examine the possibility that ligation of different integrin receptors for this ligand would induce different effects on cell behavior and intracellular signaling. Heterologous expression of the tenascin receptors alphavbeta3 and alpha9beta1 produced comparable effects on cell adhesion and spreading on TNfn3, but alphavbeta3-transfectants proliferated considerably better on each concentration examined. alphavbeta6-transfectants attached (although less avidly), but completely failed to spread or proliferate. Expression of a chimeric beta subunit composed of the beta3 extracellular domain fused to the beta6 transmembrane and cytoplasmic domains resulted in adhesion and spreading similar to that seen with beta3-transfectants, but considerably less proliferation. When the same cell lines were plated on fibronectin, alphavbeta6-transfectants spread and proliferated as well as cells transfected with the chimeric beta3/beta6 subunit, but, again, neither cell line proliferated as well as cells expressing alphavbeta3. Cell proliferation was always associated with spreading and with phosphorylation of the focal adhesion kinase, paxillin, and the mitogen-activated kinase, Erk2, but cell attachment in the absence of spreading or proliferation was not associated with phosphorylation of any of these proteins. These data suggest that different integrin receptors for a single ligand can produce markedly different effects on cell proliferation, and that both the extracellular and cytoplasmic domains of integrin beta subunits contribute to these differences.
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PMID:Differential effects of the integrins alpha9beta1, alphavbeta3, and alphavbeta6 on cell proliferative responses to tenascin. Roles of the beta subunit extracellular and cytoplasmic domains. 879 54

A case of catheter-related fungemia due to Hansenula anomala is reported. A 61-year-old male was diagnosed as having stage 3 ascending colon carcinoma stenosing the colon severely and was admitted to our hospital to receive an operation of the carcinoma. Just after admission, an intravenous hyperalimentation (IVH) catheter was inserted and IVH was started to prevent development of ileus and to prepare for laparotomy. Nine days later, he developed a fever. On the next day, the IVH catheter was removed and cultures of blood and the catheter revealed the presence of yeast-like organisms that were identified as H. anomala. Laboratory data showed hypogranulocytemia, slight disturbances of liver and kidney, a prolongation of PT, an increase of FDP and positive reaction of candida antigen by CAND-TEC. He improved after the removal of the catheter, and treatment with intravenous infusion of fluconazole 2 days after the removal was thought to be useful for recovery and to prevent the reappearance of infection though susceptibility to fluconazole was not good. Human infections due to H. anomala are rare and this is the 8th case of H. anomala fungemia in Japan. From this report and a review of the literature, risk factors for developing this fungemia include the use and abuse of central venous catheters such as IVH-catheter. It appears that H. anomala has recently emerged as a potential pathogen in the immunocompromised hosts and patients after insertion of central venous catheters and that these organisms should be added to the growing list of unusual fungal pathogens in these patients.
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PMID:[Hansenula anomala fungemia in a patient undergoing IVH-treatment with ascending colon carcinoma]. 885 93

Lck protein is expressed in some colon carcinoma cell lines but its expression in colon cancer cells in vivo has not been clarified. LCK transcription is regulated from two distinct promoters and initiated exclusively from the downstream promoter in colon carcinoma cell lines in contrast to peripheral lymphocytes. We investigated the expression of the downstream promoter-initiated LCK transcript in 18 colorectal primary cancer and normal mucosae, and two hepatic metastases, using a RNase protection assay with the EcoRI-BglII fragment of human LCK cDNA, YT16. In normal tissues, only traces of the LCK transcript were detected. The expression of the LCK transcript was augmented in 3/18 cancer specimens. The relative level of the LCK transcript in the cancer tissue compared to the average value of normal adjacent tissue was 10-60 in 3 cases, and 3-10 in 7 cases. One hepatic metastasis expressed more LCK message than the primary lesion. Our results indicate that the LCK message is strongly expressed in some colorectal cancers.
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PMID:Augmented expression of LCK message directed from the downstream promoter in human colorectal cancer specimens. 886 6

p53 is a pivotal regulator of apoptosis but its mechanism of action is obscure. We report that the polyproline (PP) region located between p53's transactivation and DNA binding domains is necessary to induce apoptosis but not cell growth arrest. The PP region was dispensable for DNA binding, inhibition of SAOS-2 tumor cell growth, suppression of E1A + RAS cell transformation, and cell cycle inhibition. A temperature-sensitive dominant inhibitory p53 mutant lacking PP (p53ts deltaPP) retained its ability to cooperate with adenovirus E1A in transformation of primary BRK cells. However, while activation of wt p53 induced apoptosis in E1A + p53ts-transformed cells, activation of p53 deltaPP induced cell cycle arrest but not apoptosis in E1A + p53ts deltaPP-transformed cells. Similarly, PP deletion abolished apoptosis in LoVo colon carcinoma cells, which are killed by wt p53 overexpression. Transactivation was largely unaffected by PP deletion. Significantly, BAX induction was intact, indicating that additional events are required for p53 to induce apoptosis. As a recently described site for familial mutation in at least one breast cancer family, the PP region represents a domain that may be altered in human tumors. We concluded that p53's ability to induce apoptosis is dispensable for inhibiting cell growth and transformation and that the PP region plays a crucial role in apoptotic signaling.
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PMID:The polyproline region of p53 is required to activate apoptosis but not growth arrest. 928 84

We examined alterations in cell morphology and expression of adhesion molecules in response to a general protein kinase inhibitor K252a treatment of non-adherent colon adenocarcinoma Colo201 cells. K252a induced rapid cell adhesion and spreading with concomitant formation of actin stress fibers. A protein kinase A inhibitor KT5720 also induced cell adhesion, but the rate of spread was slower than that seen with K252a. These adhesions were mediated by integrin molecules since cell adhesion required Mg2+, Mn2+ or Ca2+, and was inhibited by monoclonal antibodies for integrins alpha2 and beta1. Indirect immunofluorescence microscopic observations revealed that integrin alpha2 and beta1 molecules in K252a-treated cells were concentrated at sites of focal adhesion, but expressions of integrin molecules were not modulated. Tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin increased during K252a- or KT5720-induced cell adhesion. Immunosuppressants FK506 and cyclosporin A suppressed the K252a-induced cell adhesion and abolished tyrosine phosphorylation of cellular proteins including FAK and paxillin. Furthermore, W7 and calmidazolium, inhibitors of calmodulin, also inhibited the cell adhesion. Based on findings that FK506 and cyclosporin A are inhibitors of the calcium calmodulin-dependent protein phosphatase, calcineurin, this phosphatase may regulate integrin-dependent cell adhesion and spread of Colo201 cells. This Colo201 cell model provides a pertinent system for studying molecules involved in signal transduction pathways and can shed light on mechanisms of metastasis and invasion of colon carcinoma cells.
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PMID:Rapid adhesion and spread of non-adherent colon cancer Colo201 cells induced by the protein kinase inhibitors, K252a and KT5720 and suppression of the adhesion by the immunosuppressants FK506 and cyclosporin A. 987 66


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