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)

We have investigated the role of a classical isoform of protein kinase C (PKCgamma) in promoting immortalized mammary cell tumorigenesis in vivo and the contribution of proteases and adhesion molecules to this process. We hypothesized that overexpression of PKCgamma in immortalized mammary epithelial cells may initiate, by activating the mitogenic ERK pathway, early changes in proteases, adhesion molecules, and markers of an epithelium-to-mesenchyme transition that may contribute to in vivo tumorigenesis. Here we show that compared to vector-transfected cells, immortalized murine mammary epithelial cells (NMuMG) overexpressing PKCgamma have stronger activation of (approximately 5-fold) ERK1/2 MAPKs, which results in a similar increase in cyclin D1. In addition, PKCgamma-expressing cells showed increased levels of vimentin, fibronectin (FN), beta1-integrins, enhanced adhesion to fibronectin, and its organization into fibrils. Concomitantly, PKCgamma induced a dramatic down-regulation of E-cadherin protein levels and its localization to cell-cell junctions. NMuMG cells expressing PKCgamma became resistant to death by anoikis and formed colonies in soft agar. This effect was dependent on ERK activation, because Mek1/2 inhibition with PD98059 abrogated anchorage-independent growth. Most importantly, unlike control NMuMG cells, PKCgamma-transfected cells inoculated s.c. into nude mice displayed tumorigenic and invasive capacity and were able to spontaneously metastasize. This behavior correlated with increased production of uPA and MMPs-9/-2 induced by PKCgamma. These results suggest that PKCgamma overexpression in immortalized mammary epithelial cells may generate, through an increase in ERK, signaling changes in the expression of genes associated with an epithelium-to-mesenchyme transition that may be sufficient to favor tumor growth in vivo.
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PMID:Immortalized mammary epithelial cells overexpressing protein kinase C gamma acquire a malignant phenotype and become tumorigenic in vivo. 1293 3

The urokinase-type plasminogen activator receptor (uPAR) is released from human cancers and is readily detected in blood. In animal models, soluble uPAR (SuPAR) antagonizes cancer progression; however, the mechanism by which SuPAR functions in vivo remains unclear. It is generally thought that SuPAR scavenges uPA and prevents its interaction with membrane-anchored uPAR. In this study, we demonstrate a novel molecular mechanism by which SuPAR may inhibit cancer progression. We show that SuPAR has the potential to directly and in a uPA-independent manner block the signaling activity of membrane-anchored uPAR. Whether SuPAR inhibits signaling is cell type-specific, depending on the state of the endogenous uPA-uPAR signaling system. In uPAR-deficient cells that lack endogenous uPAR signaling, including uPAR-/-murine embryonic fibroblasts and human embryonal kidney 293 cells, SuPAR functions as a partial signaling agonist that activates ERK/mitogen-activated protein kinase. By contrast, in cells with potent autocrine uPA-uPAR signaling systems, including MDA-MB 231 breast cancer cells and low density lipoprotein receptor-related protein-1-deficient murine embryonic fibroblasts, SuPAR substantially decreases ERK activation. The mechanism probably involves competitive displacement of membrane-anchored uPAR-uPA complex from signaling adaptor proteins. As a result of its effects on cell signaling, SuPAR blocks cell growth and inhibits cellular invasion of Matrigel. Cleavage of SuPAR by proteinases increases its signaling agonist activity and reverses its inhibitory effects on growth and invasion. Thus, proteolytic cleavage represents a molecular switch that neutralizes the anticancer activity of SuPAR.
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PMID:Soluble urokinase-type plasminogen activator receptor inhibits cancer cell growth and invasion by direct urokinase-independent effects on cell signaling. 1296 22

Mouse-transformed keratinocytes cultured in the presence of transforming growth factor beta1 (TGF-beta1) acquire an array of morphologic and functional properties that give rise to a migratory phenotype that expresses mesenchymal molecular markers. This cellular conversion involves activation of the Ras-ERK pathway, enhancement of urokinase (uPA) and matrix metalloproteinase-9 (MMP-9) expression and induction of invasiveness. In our present work, we demonstrate that cAMP and forskolin are able to prevent the expression of these mesenchymal properties, probably due to blockade of the Ras-ERK pathway. Our results also show that cAMP and forskolin are able to abolish the TGF-beta1-induced reorganization of the actin cytoskeleton that is characteristic of the mesenchymal phenotype and also inhibits the disruption of the E-cadherin cell to cell interactions. The latter responses seem to depend on the activity of protein kinase A, as demonstrated by the activation of the Ras-ERK pathway by specific protein kinase A inhibitors.
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PMID:Cyclic AMP inhibits TGFbeta1-induced cell-scattering and invasiveness in murine-transformed keratinocytes. 1456 20

VEGF-A is a major angiogenesis and permeability factor. Its cellular effects, which can be used as targets in anti-angiogenesis therapy, have mainly been studied in vitro using endothelial cell cultures. The purpose of the present study was to further characterize these effects in vivo in vascular endothelial cells and pericytes, in an experimental monkey model of VEGF-A-induced iris neovascularization. Two cynomolgus monkeys (Macaca fascicularis) received four injections of 0.5 microg VEGF-A in the vitreous of one eye and PBS in the other eye. After sacrifice at day 9, eyes were enucleated and iris samples were snap-frozen for immunohistochemistry (IHC) and stained with a panel of antibodies recognizing endothelial and pericyte determinants related to angiogenesis and permeability. After VEGF-A treatment, the pre-existing iris vasculature showed increased permeability, hypertrophy, and activation, as demonstrated by increased staining of CD31, PAL-E, tPA, uPA, uPAR, Glut-1, and alphavbeta3 and alphavbeta5 integrins, VEGF receptors VEGFR-1, -2 and -3, and Tie-2 in endothelial cells, and of NG2 proteoglycan, uPA, uPAR, integrins and VEGFR-1 in pericytes. Vascular sprouts at the anterior surface of the iris were positive for the same antigens except for tPA, Glut-1, and Tie-2, which were notably absent. Moreover, in these sprouts VEGFR-2 and VEGFR-3 expression was very high in endothelial cells, whereas many pericytes were present that were positive for PDGFR-beta, VEGFR-1, and NG2 proteoglycan and negative for alpha-SMA. In conclusion, proteins that play a role in angiogenesis are upregulated in both pre-existing and newly formed iris vasculature after treatment with VEGF-A. VEGF-A induces hypertrophy and loss of barrier function in pre-existing vessels, and induces angiogenic sprouting, characterized by marked expression of VEGFR-3 and lack of expression of tPA and Tie-2 in endothelial cells, and lack of alpha-SMA in pericytes. Our in vivo study indicates a role for alpha-SMA-negative pericytes in early stages of angiogenesis. Therefore, our findings shed new light on the temporal and spatial role of several proteins in the angiogenic cascade in vivo.
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PMID:In vivo angiogenic phenotype of endothelial cells and pericytes induced by vascular endothelial growth factor-A. 1468 16

Urokinase-type plasminogen activator receptor (uPAR) and epidermal growth factor receptor (EGFR) are ubiquitous receptors involved in the control of a variety of cellular processes frequently found altered in cancer cells. The EGFR has been recently described to play a transduction role of uPAR stimuli, mediating uPA-induced proliferation in highly malignant cells that overexpress uPAR. In the present work, we found for the first time that uPAR stimulation with the amino-terminal fragment (ATF) of urokinase devoid of proteolytic activity transactivates the EGFR in mammary MCF-7 cells through a mechanism involving Src and a metalloproteinase, as indicated by its sensitivity to selected inhibitors. In these cells, which express low levels of uPAR and malignancy, both ATF and EGF stimuli induced an interaction of the EGFR with uPAR and ERK activation. However, EGFR activation by uPAR stimuli mediated cellular invasion rather than proliferation, while EGFR activation by EGF led to a proliferative response. These results revealed a complex modulation of EGFR function toward different cellular responses according to the status of uPAR activity. On the other hand, we also found that MMP-mediated activation of EGFR can occur in an autocrine manner in cells which secrete uPA. All this reveals novel regulatory systems operating through autocrine loops involving uPAR stimuli, Src, MMP and EGFR activation which could mediate fine control of physiological processes as well as contribute to the expression of proliferative and invasive phenotypes of cancerous cells.
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PMID:EGF receptor transactivation by urokinase receptor stimulus through a mechanism involving Src and matrix metalloproteinases. 1472 May 19

Breast cancer represents a major health problem, with more than 1,000,000 new cases and 370,000 deaths yearly worldwide. In the last decade, in spite of an increasing incidence, breast cancer mortality has been declining in the majority of developed countries. This is the combined result of better education, widespread screening programmes and more efficacious adjuvant treatments. Better knowledge of breast cancer biology now allows the cosmetic, physical and psychological consequences of radical mastectomy to be spared in the majority of breast cancer patients. Use of the sentinel node technique is rapidly expanding and this will further reduce the extent and the consequences of surgery. Several clinico-pathological factors are used to discriminate between patients at low (<10%), average (10-40%) and high risk of relapse. Nodal status, tumour size, tumour grade and age are accepted universally as important factors to define risk categories. Newer factors such as uPA/PAI-1, HERer2-neu, proliferative indices and gene expression profile are promising and will allow better discrimination between patients at different risk. Endocrine manipulation with tamoxifen, ovarian ablation or both is the preferred option in the case of endocrine-responsive tumours. Tamoxifen administered for 5 years is the standard treatment for postmenopausal patients; tamoxifen plus ovarian ablation is more effective than tamoxifen alone for premenopausal women. Recent data demonstrate that, for postmenopausal patients, the aromatase inhibitors are superior to tamoxifen, with a different safety profile. At present, anastrozole can be used in the adjuvant setting in cases of tamoxifen intolerance or toxicity. Chemotherapy is the treatment of choice for steroid receptor-negative tumours. Polychemotherapy is superior to single agents and anthracycline-containing regimens are superior to CMF. Six courses of FEC or FAC or the sequential administration of four doses of anthracycline followed by four of CMF are the recommended regimens. New regimens including the taxanes have produced a further improvement in risk reduction and are reasonable therapeutic options. The taxanes have been approved for adjuvant therapy in the USA, while European approval is pending. Combined endocrine-chemotherapy is the standard adjuvant treatment in high-risk patients with endocrine-responsive tumours. Endocrine manipulation is usually administered after completion of the chemotherapy programme. For HER2-neu overexpressing tumours, several rapidly accruing trials are exploring the potential additive effect of trastuzumab, a monoclonal antibody directed against the extramembrane portion of the HER2 receptor. Primary chemotherapy is increasingly used in the treatment of locally advanced and operable breast cancer, with increased rates of breast-conserving surgery. A proportion of patients achieve a pathological complete response and these patients have significantly better long-term outcomes. Twenty-five to forty percent of breast cancer patients develop distant metastases. At this stage the disease is incurable; however, treatments can assure a significant prolongation of survival, symptomatic control and maintenance of quality of life. In the case of hormone receptor positivity and in the absence of visceral, life-threatening disease, endocrine manipulation is the treatment of choice. Active treatments include tamoxifen, ovarian ablation, aromatase inhibitors, pure anti-oestrogens and progestins. Aromatase inhibitors are the most active agents, but the choice and the sequence of endocrine therapies are also dictated by prior adjuvant treatment. Chemotherapy has to be preferred in cases of receptor-negative tumours, acquired resistance to hormones and aggressive visceral disease. Combination regimens are usually associated with higher response rates and sometimes survival prolongation, and this approach should be recommended in young patients with good performance status and visceral disease. On the other hand, single agents have a better tolerability profile and should be tand should be the treatment of choice when a careful balance between activity and tolerability is needed. For HER2-neu positive tumours, the combination of trastuzumab and chemotherapy is significantly superior to chemotherapy alone in terms of both response rates and survival. Other useful palliative treatments include bisphosphonates for the control of metastatic bone disease and radiotherapy for painful bone lesions or local relapses.
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PMID:The curability of breast cancer and the treatment of advanced disease. 1510 48

After therapeutic hormone deprivation, most prostate cancer (PrCa) cells develop androgen-independent (AI) growth. PrCa is highly heterogeneous and multifocal, suggesting that several molecular processes or pathways may be contributing to AI. The human LuCaP 23.1 xenograft model retains clinical hallmarks of PrCa, including heterogeneous growth, PSA production, androgen-responsiveness and progression to AI. In this work, we studied the effect of androgen depletion (castration) on the growth of LuCaP 23.1 xenografts. A total of 100 nude mice were implanted and analysed for their growth profiles before and after castration. By 11 and 15 weeks, tumours were harvested and assessed for molecular marker expression specific for PrCa. Prior to castration we found 37 fast growing (FG) tumours (948.9+/-76.9 mm(3)) and 63 slow growing (SG) tumours (229.6+/-18.4 mm(3)), a previously undescribed result for this PrCa model. Quantitative RT-PCR showed that in comparison to SGs, FGs contained high HER1, uPA and thymidilate synthetase (TS) expression with low levels of 5alpha-reductase 2 mRNA. All FG tumours progressed rapidly to AI growth 5 weeks after castration (FG-P). In SG castrated tumours, 66% of tumours (SG-P) showed retarded progression (by 12 weeks) to AI, whereas 34% responded to castration (SG-R). Molecular analysis permitted us to define distinct molecular profiles integrating different pathways associated with AI progression. FG-P, and a subgroup of SG-P tumours, presented significantly high levels of peptidylglycine alpha-amidating monooxygenase (PAM), HER1, HER2, TS, and uPA mRNA, all of which correlated with AR expression. The second subgroup of SG-P tumours showed overexpression of the antiapoptotic gene Bcl-2. A third subgroup of SG-P tumours showed significant expression of hypoxia-related gene (adrenomedullin) after castration. This work permitted to define distinct molecular profiles related to different AI growth in the LuCaP 23.1 xenograft.
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PMID:Molecular analysis integrating different pathways associated with androgen-independent progression in LuCaP 23.1 xenograft. 1548 89

Activation of nuclear factor-kappaB (NFkappaB) has been linked to the development of hormone-independent, estrogen receptor (ER)-negative human breast cancers. To explore the possibility that activated NFkappaB marks a subset of clinically more aggressive ER-positive breast cancers, NFkappaB DNA-binding was measured in ER-positive breast cancer cell lines and primary breast cancer extracts by electrophoretic mobility shift assay and ELISA-based quantification of specific NFkappaB p50 and p65 DNA-binding subunits. Oxidant (menadione 100 microMx30 min) activation of NFkappaB was prevented by pretreatment with various NFkappaB inhibitors, including the specific IkappaB kinase (IKK) inhibitor, parthenolide (PA), which was found to sensitize MCF-7/HER2 and BT474 but not MCF-7 cells to the antiestrogen tamoxifen. Early stage primary breast cancers selected a priori for lower ER content (21-87 fmol/mg; n=59) and known clinical outcome showed two- to four-fold increased p50 and p65 NFkappaB DNA-binding over a second set of primary breast cancers with higher ER content (>100 fmol/mg; n=22). Breast cancers destined to relapse (13/59) showed significantly higher NFkappaB p50 (but not p65) DNA-binding over those not destined to relapse (46/59; p=0.04). NFkappaB p50 DNA-binding correlated positively with several prognostic biomarkers; however, only NFkappaB p50 DNA-binding (p=0.04), Activator Protein-1 DNA-binding (AP-1; p<or=0.01) and urokinase-type plasminogen activator expression (uPA; p=0.0014) showed significant associations with metastatic relapse and disease-free patient survival. These clinical findings indicate that high-risk ER-positive breast cancers may be prognostically identified by increased NFkappaB p50 DNA-binding, and support preclinical models suggesting that therapeutic inhibition of NFkappaB activation may improve the endocrine responsiveness of high-risk ER-positive breast cancers.
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PMID:Activation of nuclear factor-kappaB (NFkappaB) identifies a high-risk subset of hormone-dependent breast cancers. 1574 83

We have established the well-defined cycling, pseudo-pregnant and pregnant rhesus monkey models, and used these to analyze expression of the common molecules specifically related to angiogenesis, apoptosis or proteolysis, such as vascular endothelial growth factor (VEGF) and its receptors KDR, flt-1, flt-4 and flk-1, basic fibroblast growth factor (bFGF) and its receptors Flg, transforming growth factor-alpha and beta1 (TGF-a/beta1), and TGF-beta1 receptor type I (TbetaR-I) and type II (TbetaR-II), as well as steroidogenic acute regulatory protein (StAR), tissue type plasminogen activator/urokinase plasminogen activator/plasminogen activator inhibitor type 1 (tPA/uPA/PAI-1) and matrix matalloproteinase type 1, -3/tissue inhibitor matalloproteinase type 1, -2, -3 (MMP-1, -3/TIMP-1, -2, -3), Fas/FasL, BcL-2/Bax, in the corpus luteum (CL), in the functional layer of the endometrium and in the materno-fetal boundary of the implantation site. We have demonstrated that: expression of these molecules in the monkey CL, endometrium and materno-fetal boundary of the implantation site is correlated well with CL functional and vascular development and with the processes involved in the establishment of the implantation window as well as with the early stages of placentation. A coordinated increase in tPA and its inhibitor PAI-1 expression in the monkey and rat CL may be instrumental in initiating luteal regression in both species, and correlated well with the timing of the closure of the implantation window, whereas high uPA activity in the CL is important for the early formation of the CL and for maintaining its function which is closely correlated to the period of establishment of the implantation window. Apoptosis, proteolysis and angiogenesis occur in the CL and in the endometrium during the time of establishment of the implantation window, as well as in the materno-fetal boundary of the implantation site at the early stages of placentation. It seems that these processes occur in these tissues in a coordinated and time- and cell-dependent manner, and are reliant on each other. Based on these observations, we have designed experiments to test the actions of some related available compounds on mouse implantation, used alone or in combination. The preliminary data showed that the compounds which could effectively affect apoptosis, angiogenesis or proteolysis in the implantation site were capable of effectively inhibiting implantation by acting on the endometrium and/or on the CL. Furthermore, the combined use of these compounds produced an obvious additive effect on inhibiting implantation. This finding suggested this may be a good approach for developing an anti-implantation agent.
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PMID:Involvement of molecules related to angiogenesis, proteolysis and apoptosis in implantation in rhesus monkey and mouse. 1579 44

The vectors PAI2, C595 and Herceptin target the membrane-bound uPA, MUC1 and HER2 antigens expressed by cancer cells, respectively. The expression of these receptors was tested in the ovarian cancer cell line OVCAR-3; MUC-1 was strongly expressed (3+), uPA moderately expressed (2+), but HER2 was negative (-). The alpha-emitting radionuclide Bismuth-213 was chelated with these targeting vectors to form alpha conjugates (ACs), the cytotoxicity of which were tested with OVCAR-3 cells. The PAI2 and C595 ACs are highly cytotoxic to the ovarian monolayer cancer cells and cell clusters in a concentration-dependent fashion and cause morphological changes of treated cancer cells, inducing apoptosis. These ACs are potential candidates for the control of ovarian cancer at the minimum residual disease (MRD) stage.
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PMID:Cytotoxicity of PAI2, C595 and Herceptin vectors labeled with the alpha-emitting radioisotope Bismuth-213 for ovarian cancer cell monolayers and clusters. 1596 Dec 20


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