UNIPROT:P00750 - FACTA Search

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Query: UNIPROT:P00750 (PLA)
16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nuclear factor kappaB (NFkappaB) plays major role in regulating cellular responses as a result of environmental injuries. The molecular mechanism(s) by which hypoxia/reoxygenation (H/R) regulates p56lck-dependent activation of NFkappaB through tyrosine phosphorylation of IkappaBalpha and modulates the expression of downstream genes that are involved in cell migration in human breast cancer cells are not well defined. In this paper, we investigated the involvement of protein-tyrosine kinase p56lck in the redox-regulated activation of NFkappaB following H/R in highly invasive (MDA-MB-231) and low invasive (MCF-7) breast cancer cells. We demonstrated that H/R induces tyrosine phosphorylation of p56lck, nuclear translocation of NFkappaB, NFkappaB-DNA binding, and transactivation of NFkappaB through tyrosine phosphorylation of IkappaBalpha. Transfection of these cells with wild type Lck but not with mutant Lck F394 followed by H/R induces the tyrosine phosphorylation of inhibitor of nuclear factor kappaB (IkappaBalpha) and transcriptional activation of NFkappaB, and these are inhibited by Lck inhibitors. In vitro kinase assay demonstrated that immunoprecipitated p56lck but not Lyn or Fyn directly phosphorylate IkappaBalpha in presence of H/R. Pervanadate, H2O2, and H/R induce the interaction between Lck and tyrosine-phosphorylated IkappaBalpha, and this interaction is inhibited by Src homology 2 domain inhibitory peptide, suggesting that tyrosine-phosphorylated IkappaBalpha interacts with Src homology 2 domain of Lck. Luciferase reporter gene assay indicated that Lck induces NFkappaB-dependent urokinase type plasminogen activator (uPA) promoter activity in presence of H/R. Furthermore, H/R stimulates the cell motility through secretion of uPA. To our knowledge, this is the first report that p56lck in presence of H/R regulates NFkappaB activation, uPA secretion, and cell motility through tyrosine phosphorylation of IkappaBalpha and further demonstrates an important redox-regulated pathway for NFkappaB activation following H/R injury that is independent of IkappaB kinase/IkappaBalpha-mediated signaling pathways.
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PMID:Tyrosine kinase p56lck regulates cell motility and nuclear factor kappaB-mediated secretion of urokinase type plasminogen activator through tyrosine phosphorylation of IkappaBalpha following hypoxia/reoxygenation. 1453 91

BACKGROUND: Breast cancer cells frequently metastasize to the skeleton and induce extensive bone destruction. Cancer cells produce proteinases, including matrix metalloproteinases (MMPs) and the plasminogen activator system (PAS) which promote invasion of extracellular matrices, but whether these proteinases degrade bone matrix is unclear. To characterize the role that breast cancer cell proteinases play in bone degradation we compared the effects of three human breast cancer cell lines, MDA-MB-231, ZR-75-1 and MCF-7 with those of a normal breast epithelial cell line, HME. The cell lines were cultured atop radiolabelled matrices of either mineralized or non-mineralized bone or type I collagen, the principal organic constituent of bone. RESULTS: The 3 breast cancer cell lines all produced significant degradation of the 3 collagenous extracellular matrices (ECMs) whilst the normal breast cell line was without effect. Breast cancer cells displayed an absolute requirement for serum to dissolve collagen. Degradation of collagen was abolished in plasminogen-depleted serum and could be restored by the addition of exogenous plasminogen. Localization of plasmin activity to the cell surface was critical for the degradation process as aprotinin, but not alpha2 antiplasmin, prevented collagen dissolution. During ECM degradation breast cancer cell lines expressed urokinase-type plasminogen activator (u-PA) and uPA receptor, and MMPs-1, -3, -9,-13, and -14. The normal breast epithelial cell line expressed low levels of MMPs-1, and -3, uPA and uPA receptor. Inhibitors of both the PAS (aprotinin and PA inhibitor-1) and MMPs (CT1166 and tisue inhibitor of metalloproteinase) blocked collagen degradation, demonstrating the requirement of both plasminogen activation and MMP activity for degradation. The activation of MMP-13 in human breast cancer cells was prevented by plasminogen activator inhibitor-1 but not by tissue inhibitor of metalloproteinase-1, suggesting that plasmin activates MMP-13 directly. CONCLUSIONS: These data demonstrate that breast cancer cells dissolve type I collagen and that there is an absolute requirement for plasminogen activation and MMP activity in the degradation process.
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PMID:Human breast cancer cell-mediated bone collagen degradation requires plasminogen activation and matrix metalloproteinase activity. 1570 Nov 64

Cancer progression depends on an accumulation of metastasis supporting cell signaling molecules that target signal transduction pathways and ultimately gene expression. Osteopontin (OPN) is one such chemokine like metastasis gene which plays a key signaling event in regulating the oncogenic potential of various cancers by controlling cell motility, invasiveness and tumor growth. We have reported that OPN stimulates tumor growth and nuclear factor kappaB (NFkappaB)-mediated promatrix metalloproteinase-2 (pro-MMP-2) activation through IkappaBalpha/IKK (IkappaBalpha kinase) signaling pathway in melanoma cells. Urokinase type plasminogen activator (uPA), a widely acting serine protease degrades the ECM components and plays a pivotal role in cancer progression. However, the molecular mechanism by which upstream kinases regulate the OPN-induced NFkappaB activation and uPA secretion in human breast cancer cells is not well defined. Here we report that OPN induces the phosphatidylinositol 3'-kinase (PI 3'-kinase) activity and phosphorylation of Akt/PKB (protein kinase B) in highly invasive (MDA-MB-231) and low invasive (MCF-7) breast cancer cells. The OPN-induced Akt phosphorylation was inhibited when cells were transfected with dominant negative mutant of p85 domain of PI 3'-kinase (Deltap85) indicating that PI 3'-kinase is involved in Akt phosphorylation. OPN enhances the interaction between IkappaBalpha kinase (IKK) and phosphorylated Akt. OPN also induces NFkappaB activation through phosphorylation and degradation of IkappaBalpha by inducing the IKK activity. OPN also enhances uPA secretion, cell motility and ECM-invasion. Furthermore, cells transfected with Deltap85 or super-repressor form of IkappaBalpha suppressed the OPN-induced uPA secretion and cell motility. Pretreatment of cells with PI 3'-kinase inhibitors or NFkappaB inhibitory peptide (SN50) reduced the OPN-induced uPA secretion, cell motility and ECM-invasion. Taken together, OPN induces NFkappaB activity and uPA secretion by activating PI 3'-kinase/Akt/IKK-mediated signaling pathways and further demonstrates a functional molecular link between OPN induced PI 3'-kinase dependent Akt phosphorylation and NFkappaB-mediated uPA secretion, and all of these ultimately control the motility and invasiveness of breast cancer cells.
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PMID:Osteopontin: it's role in regulation of cell motility and nuclear factor kappa B-mediated urokinase type plasminogen activator expression. 1601 53

The principal secreted estrogen, 17beta-estradiol rapidly activates signaling cascades that regulate important physiological processes including ion transport across membranes, cytosolic pH and cell proliferation. These effects have been extensively studied in the MCF-7 estrogen-responsive human breast carcinoma cell line. Here, we demonstrate that a physiological concentration of 17beta-estradiol caused a rapid, synchronous and transient increase in intracellular calcium concentration in a confluent monolayer of MCF-7 cells 2-3 min after treatment. This response was abolished when cells were pre-incubated with the phospholipase A(2) (PLA(2)) inhibitor quinacrine or with the cyclooxygenase inhibitor indomethacin. The translocation of GFP-cPLA(2)alpha to perinuclear membranes occurred 1-2 min after 17beta-estradiol treatment; this translocation was concurrent with the transient phosphorylation of cPLA(2)alpha at serine residue 505. The phosphorylation and translocation of cPLA(2) were sensitive to inhibition of the extracellular signal regulated kinase (ERK) signaling cascade and occurred simultaneously with a transient activation of ERK. The phosphorylation of cPLA(2) could be stimulated by membrane impermeable 17beta-estradiol conjugated to bovine serum albumen and was blocked by an antagonist of the classical estrogen receptor. Here we show, for the first time, that PLA(2) and the eicosanoid biosynthetic pathway are involved in the 17beta-estradiol induced rapid calcium responses of breast cancer cells.
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PMID:Estrogen induces phospholipase A2 activation through ERK1/2 to mobilize intracellular calcium in MCF-7 cells. 1637 35

Many advanced human tumors including breast cancer overproduce plasmin that is known to promote angiogenesis and metastasis. The mechanism of this effect is poorly understood. Here we report that annexin II, an endothelial co-receptor for tPA (tissue-type plasminogen activator) and plasminogen, was undetectable in normal and hyperplastic ductal epithelial cells and ductal complexes. By contrast, it was consistently expressed in invasive breast cancer and ductal carcinoma in situ (DCIS) indicating its involvement in breast cancer. Using the well established invasive/metastatic MDA-MB231 cell line and the noninvasive/nonmetastatic MCF-7 human breast cancer cell line, we investigated the mechanism by which annexin II regulates breast cancer progression and metastasis. Western and Northern blot analyses demonstrate selective expression of annexin II in MDA-MB231 cells but not in poorly invasive MCF-7 cells suggesting its participation in invasive breast cancer. Since annexin II is a receptor for plasminogen, we tested whether MDA-MB231 cells are capable of producing plasmin in vitro. MDA-MB231 cell membranes induced plasmin generation in a time-dependent manner while those from MCF-7 cells failed to convert plasminogen to plasmin. The generated plasmin is capable of degrading ECM consequently facilitating cell invasion and migration, biological functions required for angiogenesis and metastasis. Plasmin generation and its dependent invasion and migration can be blocked by a monoclonal antibody to annexin II or angiostatin, potent inhibitors of angiogenesis, breast cancer, and metastasis. Our findings indicate that annexin II-dependent localized plasmin generation by human breast cancer cells could contribute to angiogenesis and metastasis. These results suggest that annexin II may be an attractive target for new anti-angiogenic and anti-breast cancer therapies.
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PMID:Angiogenesis-associated protein annexin II in breast cancer: selective expression in invasive breast cancer and contribution to tumor invasion and progression. 1664 92

Methoxy polyethylene glycol-polylactide (MPEG-PLA) nanoparticles (NPs) were prepared by the nanoprecipitation method with particle size of 140+/-21nm in diameter and drug encapsulation efficiency of 87.6+/-3.1%. In vitro cytotoxicity of the drug formulated in the NPs was investigated with MCF-7 cancer cells in close comparison with that of Taxol((R)). The in vitro cytotoxicity with MCF-7 cells showed that the NP formulation could be 33.3, 10.7, 7.7 times more effective than Taxol((R)) after 24, 48, 72h culture at the same drug concentration of 1microg/ml. Confocal laser scanning microscopy (CLSM) visualized cellular internalization of the coumarin 6-loaded MPEG-PLA NPs. The in vitro results were further confirmed by the in vivo pharmacokinetic analysis with SD rats. The total area-under-the-curve (AUC(0-infinity)), which determines the therapeutic effects of a dose, was found to be 29,600+/-1,690ng-h/ml for the NP formulation, which is 3.09 times of 9,570+/-1,480ng-h/l for Taxol((R)) with 10mg/kg dose i.v. injection. The half-life (t(1/2)) of the drug formulated in the NPs was found to be 18.80+/-3.14h, which is 2.75 times of 6.84+/-1.39h for Taxol((R)). The distribution volume at steady state for the drug loaded in the NPs was 7.21+/-2.17l/kg, which was 2.93 times of 2.46+/-1.41l/kg for Taxol((R)). Our proof-of-concept in vitro and in vivo valuation shows that our MPEG-PLA NP formulation could have great advantages versus the original drug in small-molecule drug chemotherapy as well as in various applications in nanomedicine.
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PMID:In vitro and in vivo evaluation of methoxy polyethylene glycol-polylactide (MPEG-PLA) nanoparticles for small-molecule drug chemotherapy. 1757 4

We synthesized nanoparticles (NPs) of the blend of two-component copolymers for targeted chemotherapy with paclitaxel used as model drug. One component is poly(lactide)-D-alpha-tocopheryl polyethylene glycol succinate (PLA-TPGS), which is of desired hydrophobic-lipophilic balance, and another is TPGS-COOH, which facilitates the folate conjugation for targeting. The nanoparticles of the two-copolymer blend at various component ratio were prepared by the solvent extraction/evaporation single emulsion method and then decorated by folate, which were characterized by laser light scattering (LLS) for particles' size and size distribution, zeta potential analyzer for surface charge, and X-ray photoelectron spectroscopy (XPS) for surface chemistry. The drug encapsulation efficiency (EE) and in vitro drug release were measured by high performance liquid chromatography (HPLC). The targeting effect was investigated in vitro by cancer cell uptake of coumarin-6-loaded NPs and further confirmed by cytotoxicity of cancer cells treated with the drug formulated in the NPs. We showed that the NP formulation has great advantages vs the pristine drug in achieving better therapeutic effect, which increased 8.68% for MCF-7 breast cancer cells, and that the folate-decoration can significantly promote targeted delivery of the drug into the corresponding cancer cells and thus enhance its therapeutic effect, which increased 24.4% for the NP formulation of 16.7% TPGS-COOH component and 31.1% for the NP formulation of 33.3% TPGS-COOH component after 24h treatment at the same 25 microg/ml paclitaxel concentration. The experiments on C6 glioma cells further confirmed these advantages.
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PMID:Targeted delivery of paclitaxel using folate-decorated poly(lactide)-vitamin E TPGS nanoparticles. 1839 33

We developed a novel system of poly(lactide acid)-d-alpha-tocopheryl polyethylene glycol 1000 succinate (PLA-TPGS) nanoparticles (NPs) for quantum dots (QDs) formulation to improve imaging effects and reduce side effects as well as to promote a sustainable imaging. The QDs-loaded PLA-TPGS NPs were prepared by a modified solvent extraction/evaporation method, which were then characterized by laser light scattering (LLS) for size and size distribution; field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and transmission electron microscope (TEM) for surface morphology. Surface chemistry of the QDs-loaded PLA-TPGS NPs was analyzed by X-ray photoelectron microscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR). Encapsulation efficiency of the QDs in the polymeric nanoparticles was measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The photostability of the QDs formulated in the PLA-TPGS nanoparticles was investigated as changes in the florescence intensity versus the irradiation time. Confocal laser scanning microscopy (CLSM) was used to image the cellular uptake of the QDs-loaded NPs by MCF-7 cells. Methylthiazolyldiphenyl-tetrazolium (MTT) assay was employed to assess the viability of MCF-7 cells incubated with the QDs formulated by the PLA-TPGS NPs versus the mercaptoacetic acid (MAA)-coated QDs. It was found that the QDs formulated in the PLA-TPGS NPs can result in higher fluorescence intensity and higher photostability than the bare QDs as well as lower cytotoxicity than the MAA-coated QDs.
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PMID:Formulation, characterization, and in vitro evaluation of quantum dots loaded in poly(lactide)-vitamin E TPGS nanoparticles for cellular and molecular imaging. 1872 31

To gain further insight into how estrogens modulate cell function, the effects of estrogen on cell proliferation were studied in human breast cancer cells. We examined the effects of estrogen on the proliferation of three human breast cancer cell lines that differed in their estrogen receptor contents. Ten nM estradiol markedly stimulated the proliferation of MCF-7 human breast cancer cells that contained high levels of estrogen receptor (1.15+/-0.03 pmole/mg protein) over that of control. In T47D cells that contained low levels of estrogen receptor (0.23+/-0.05 pmole/mg protein), Ten nM estrogen slightly stimulated the proliferation over that of control. MDA-MB-231 cells, that contained no detectable levels of estrogen receptors, had their growth unaffected by estrogen. These results showed their sensitivity to growth stimulation by estrogen correlated well with their estrogen receptor content. Also we examined the effect of estrogen on cellular progesterone receptor level as well as plasminogen activator activity in MCF-7 cells. Ten nM estradiol showed maximal stimulation of progesterone receptor level as well as plasminogen activator activity in MCF-7 cells. It is not clear whether these stimulations of progesterone receptor and plasminogen activator activity by estrogen are related to the estrogen stimulation of cell proliferation of MCF-7 cells. Studies with estrogen in human breast cancer cells in culture indicate that sensitivity to growth stimulation by estrogen correlates well with estrogen receptor contents.
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PMID:Estrogen modulation of human breast cancer cell growth. 1898 61

To gain further insight into how antiestrogens modulate cell function, the effects of antiestrogen on cell proliferation were studied in human breast cancer cells. We examined the effects of trans-tamoxifen on the proliferation of three human breast cancer cell lines that differed in their estrogen receptor contents. Trans-tamoxifen (1 muM) markedly inhibited the estrogen stimulated proliferation of MCF-7 human breast cancer cells that contained high levels of estrogen receptor (1.15+/-0.03 pmole/mg protein) over that of control. In T47D cells that contained low levels of estrogen receptor (0.23+/-0.05 pmole/mg protein), trans-tamoxifen (1 muM) showed minimal inhibition of estrogen stimulated cell proliferation over that of control. MDA-MB-231 cells, that contained no detectable levels of estrogen receptors, had their growth unaffected by trans-tamoxifen treatment. These results showed their sensitivity to growth inhibition by antiestrogen correlated well with their estrogen receptor content. Also we activator activity in MCF-7 cells. Trans-tamoxifen (1 muM) showed maximal inhibition of estrogen stimulated progestrone receptor level as well as plasminogen activator activity in MCF-7 cells that were stimulated by estrogen. It is not clear whether these inhibitions of progestrone receptor and plasminogen activator activity by estrogen are related to the antiestrogen inhibition of cell proliferation of MCF-7 cells. From the results of this study, it is clearly demonstrated that trans-tamoxifen is an antiestrogen in MCF-7 human breast cancer cells. Our data suggest that the biological effectiveness of trans-tamoxifen appear to result from its affinity of interaction with the estrogen receptor.
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PMID:Antiestrogen, trans-tamoxifen modulation of human breast cancer cell growth. 1898 62

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