Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P31749 (AKT)
 22,954 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Farnesyltransferase inhibitors (FTIs) are small-molecule inhibitors that selectivly inhibit farnesylation of a number of intracellular substrate proteins such as Ras. Preclinical work has revealed their ability to effectively inhibit tumor growth in vitro and in vivo in animal models across a wide range of malignant phenotypes. Acute myeloid leukemias (AMLs) are appropriate disease targets in that they express relevant biologic targets such as Ras, MEK, AKT, and others that may depend upon farnesyl protein transferase activity to promote cell proliferation and survival. Indeed, different intracellular proteins are substrates for prenylation. Interruption of prenylation may prevent substrates from undergoing maturation which may result in the inhibition of cellular events that depend on the function of those substrates. Phase I trials in AML and myelodysplasia have demonstrated biologic and clinical activities as determined by target enzyme inhibition, low toxicity, and both complete and partial responses. As a result, phase II trials have been initiated in order to further validate clinical activity and to identify downstream signal transduction targets that may be modified by these agents. It is anticipated that these studies will serve to define the optimal roles of FTIs in patients with these hematologic malignancies and provide insight into effective methods by which to combine FTIs with other agents.
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PMID:[Farnesyltransferase inhibitors: preliminary results in acute myeloid leukemia]. 1582 Sep 17

Combination studies of celecoxib and chemotherapeutic agents suggest that combining cyclooxygenase-2 inhibitors with other agents may have supra-additive or synergistic effects on tumor growth inhibition. Carboxyamido-triazole (CAI), a voltage-independent calcium channel inhibitor, has been shown to induce growth inhibition and apoptosis in cancer cells. We found that continuous exposure to cytostatic doses of CAI and LM-1685, a celecoxib analogue, reduced the proliferation and survival of seven human cancer cell lines by at least one log (P < or = 0.001) over either agent alone. To explore the mechanism of action of this combination, we further studied the effects of LM-1685/CAI on CCL-250 colorectal carcinoma cells. We found that the supra-additive antiproliferative effects occurred throughout a range of LM-1685 doses (5-25 micromol/L) and paralleled a decrease in COX-2 activity as measured by prostaglandin E2 production. In these cells, treatment with LM-1685/CAI suppressed the extracellular signal-regulated kinase pathway within the first hour but ultimately results in high, sustained activation of ERK over a 9-day period (P = 0.0005). Suppression of cyclin D1 and phospho-AKT, and cleavage of caspase-3 and PARP were concomitant with persistent ERK activation. Addition of PD98059, a MEK-1 inhibitor, suppressed ERK activation and significantly but incompletely reversed these signaling events and apoptosis. Flow cytometry experiments revealed that the CAI/LM-1685 combination induced a 3-fold increase in apoptosis over control (P = 0.005) in 3 days. We show that the combination of CAI and LM-1685 produces a cytotoxic effect by suppressing proliferation and triggering apoptosis.
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PMID:Supra-additive growth inhibition by a celecoxib analogue and carboxyamido-triazole is primarily mediated through apoptosis. 1586 84

Malignant melanoma is a highly aggressive tumor of the pigment-producing cells in the skin with a rapidly increasing incidence and a poor prognosis for patients with advanced disease that is resistant to current therapeutic concepts. Therefore, the development of novel strategies for treating melanoma are of utmost importance. In melanoma, both the Ras-Raf-MEK-ERK (MAPK) and the PI3K-AKT (AKT) signaling pathways are constitutively activated through multiple mechanisms, and thus exert several key functions in melanoma development and progression. Conversely, several molecules known to play key roles in melanoma development and progression such as the adhesion molecules E-/N-cadherin, MelCAM and alphavbeta3 integrin are regulated by these pathways and/or activate the same. The results of the research to date indicate that in melanoma both the MAPK and the AKT signaling pathways may represent promising therapeutic targets.
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PMID:The RAS/RAF/MEK/ERK and PI3K/AKT signaling pathways present molecular targets for the effective treatment of advanced melanoma. 1597 May 53

The establishment of metastatic bone lesions in prostate cancer (CaP) is a process partially dependent on angiogenesis. Previously we demonstrated that the stromal-derived factor-1 (SDF-1 or CXCL12)/CXCR4 chemokine axis is critical for CaP cell metastasis. In this investigation, cell lines were established in which CXCR4 expression was knocked down using siRNA technology. When CaP cells were co-transplanted with human vascular endothelial cells into SCID mice, significantly fewer human blood vessels were observed paralleling the reductions in CXCR4 levels. Likewise, the invasive behaviors of the CaP cells were inhibited in vitro. From these functional observations we explored angiogenic and signaling mechanisms generated following SDF-1 binding to CXCR4. Differential activation of the MEK/ERK and PI3K/AKT pathways that result in differential secretion IL-6, IL-8, TIMP-2 and VEGF were seen contingent on the cell type examined; VEGF and TIMP-2 expression in PC3 cells are dependent on AKT activation and ERK activation in LNCaP and LNCaP C4-2B cells leads to IL-6 or IL-8 secretion. At the same time, expression of angiostatin levels were inversely related to CXCR4 levels, and inhibited by SDF-1 stimulation. These data link the SDF-1/CXCR4 pathway to changes in angiogenic cytokines by different signaling mechanisms and, suggest that the delicate equilibrium between proangiogenic and antiangiogenic factors may be achieved by different signal transduction pathways to regulate the angiogenic phenotype of prostate cancers. Taken together, our results provide new information regarding expression of functional CXCR4 receptor-an essential role and potential mechanism of angiogenesis upon SDF-1 stimulation.
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PMID:Diverse signaling pathways through the SDF-1/CXCR4 chemokine axis in prostate cancer cell lines leads to altered patterns of cytokine secretion and angiogenesis. 1600 85

By using tissue microarrays and immunohisto-chemical analysis, we studied protein expression of genes in the erb-b signaling pathway (erb-b1; erb-b2; phosphoinositide-3-kinase, catalytic, a polypeptide [PIK3CA]; phosphatase and tensin homologue [PTEN]; phosphorylated AKT [p-AKT]; and phosphorylated extracellular signal-regulated kinase [p-ERK]) in 118 advanced ovarian carcinomas and related expression to clinicopathologic features and survival. High protein expression was seen in 15.3% of cases for erb-b2, 44.1% for erb-b1, 43.2% for PIK3CA, 51.6% for p-AKT, and 28.0% for p-ERK. Low protein levels of PTEN were seen in 41.5% of the cases and tended to be more common in well-differentiated tumors. In multivariate analysis, only high expression of both erb-b1 and erb-b2 was an independent factor in progression-free and disease-specific survival (P=.009, hazard ratio=2.46; P=.002, hazard ratio=3.023, respectively). The PI3K/AKT and RAS/MEK/ERK pathways seem to be activated in some cases of advanced ovarian carcinomas, although PIK3CA, p-AKT, p-ERK, and PTEN do not seem to be independent prognostic markers in this group of patients.
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PMID:Protein expression and prognostic value of genes in the erb-b signaling pathway in advanced ovarian carcinomas. 1619 7

Host defense against viruses probably depends on targeted death of infected host cells and then clearance of cellular corpses by macrophages. For this process to be effective, the macrophage must presumably avoid its own virus-induced death. Here we identify one such mechanism. We show that mice lacking the chemokine Ccl5 are immune compromised to the point of delayed viral clearance, excessive airway inflammation and respiratory death after mouse parainfluenza or human influenza virus infection. Virus-inducible levels of Ccl5 are required to prevent apoptosis of virus-infected mouse macrophages in vivo and mouse and human macrophages ex vivo. The protective effect of Ccl5 requires activation of the Ccr5 chemokine receptor and consequent bilateral activation of G(alphai)-PI3K-AKT and G(alphai)-MEK-ERK signaling pathways. The antiapoptotic action of chemokine signaling may therefore allow scavengers to finally stop the host cell-to-cell infectious process.
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PMID:CCL5-CCR5 interaction provides antiapoptotic signals for macrophage survival during viral infection. 1620 18

Dietary fats, which increase the risk of prostate cancer, stimulate release of intestinal neurotensin (NT), a growth-promoting peptide that enhances the formation of arachidonic acid metabolites in animal blood. This led us to use PC3 cells to examine the involvement of lipoxygenase (LOX) and cyclooxygenase (COX) in the growth effects of NT, including activation of EGF receptor (EGFR) and downstream kinases (ERK, AKT), and stimulation of DNA synthesis. NT and EGF enhanced [3H]-AA release, which was diminished by inhibitors of PLA2 (quinacrine), EGFR (AG1478) and MEK (U0126). NT and EGF phosphorylated EGFR, ERK and AKT, and stimulated DNA synthesis. These effects were diminished by PLA2 inhibitor (quinacrine), general LOX inhibitors (NDGA, ETYA), 5-LOX inhibitors (Rev 5901, AA861), 12-LOX inhibitor (baicalein) and FLAP inhibitor (MK886), while COX inhibitor (indomethacin) was without effect. Cells treated with NT and EGF showed an increase in 5-HETE levels by HPLC. PKC inhibitor (bisindolylmaleimide) blocked the stimulatory effects of NT, EGF and 5-HETE on DNA synthesis. We propose that 5-LOX activity is required for NT to stimulate growth via EGFR and its downstream kinases. The mechanism may involve an effect of 5-HETE on PKC, which is known to facilitate MEK-ERK activation. NT may enhance 5-HETE formation by Ca2+-mediated and ERK-mediated activation of DAG lipase and cPLA2. NT also upregulates cPLA2 and 5-LOX protein expression. Thus, the growth effects of NT and EGF involve a feed-forward system that requires cooperative interactions of the 5-LOX, ERK and AKT pathways.
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PMID:Involvement of arachidonic acid metabolism and EGF receptor in neurotensin-induced prostate cancer PC3 cell growth. 1633 Jan 12

We investigated the role of the MEK/MAPK pathway in the sensitivity/resistance of breast carcinoma cells to the EGFR tyrosine kinase inhibitor gefitinib (IRESSA). We assessed the effects of gefitinib on the growth of three breast cancer cell lines that showed high (SK-Br-3; IC50 4 microM), intermediate (MDA-MB-361; IC50 5.3 microM), and low (MDA-MB-468; IC50 6.8 microM) sensitivity to the drug. Although treatment with gefitinib inhibited EGFR activation in the three cell lines in a similar fashion, significant reduction of both p42/p44-MAPK and AKT phosphorylation was observed in SK-Br-3 and MDA-MB-361, but not in MDA-MB-468 cells. The growth of MDA-MB-468 cells was significantly inhibited by treatment with either the PI3K-inhibitor LY294002 or the MEK-inhibitor PD98059. In agreement with these findings, treatment of MDA-MB-468 cells with a combination of PD98059 and gefitinib produced a synergistic anti-tumor effect, whereas this combination was only additive in SK-Br-3 and MDA-MB-361 cells. The combination of gefitinib and PD98059 also produced a significant increase in the levels of apoptosis in MDA-MB-468 cells as compared with treatment with a single agent. This phenomenon was associated with a profound decrease in MAPK activation, reduction of BAD (ser112) phosphorylation and a paradoxical increase in the levels of AKT activation. Finally, overexpression of a constitutively activated form of p42-MAPK in MCF-10A non-transformed human mammary epithelial cells resulted in a two- to three-fold increase in the IC50 to gefitinib. Taken together, these data strongly support the role of the MEK/MAPK pathway in the resistance to gefitinib, and provide the rationale for novel therapeutic approaches based on combinations of signal transduction inhibitors.
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PMID:The MEK/MAPK pathway is involved in the resistance of breast cancer cells to the EGFR tyrosine kinase inhibitor gefitinib. 1641 29

Cathepsin B and uPAR play key roles in cancer cell migration and invasion. Here, we demonstrate that the simultaneous, siRNA-mediated down-regulation of uPAR and cathepsin B inhibits glioma cell migration and is accompanied by cytoskeletal condensation. We show that the dephosphorylation of cofilin is inhibited by the down-regulation of uPAR alone and, to a lesser extent, by the down-regulation of cathepsin B alone, and that the effect was much higher with the down-regulation of both molecules by pUC. Using FACS analysis and western blotting for the alphaVbeta3 integrin heterodimer, we determined that down-regulating uPAR subsequently causes the down-regulation of the alphaVbeta3 integrin heterodimer. As evidenced by western blot analysis of ERK1/2, pERK1/2, p38MAPK, p-p38MAPK, AKT, pAKT and PI3-k, the MEK and PI3-k pathways are inhibited. From cytoskeleton studies, we observed that the down-regulation of uPAR caused cytoskeletal condensation and that the simultaneous down-regulation of uPAR and cathepsin B was even more effective at inducing cytoskeletal condensation than uPAR alone. Our results demonstrate the relevance of uPAR in cytoskeletal dynamics and the potential of uPAR and cathepsin B as targets in the treatment of malignant gliomas.
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PMID:Down-regulation of uPAR and cathepsin B retards cofilin dephosphorylation. 1646 67

Insulin and moderate oxidative stress stimulate proliferation of ovarian theca-interstitial cells. The effects of these agents on selected signal transduction pathways were examined. PD98059 (inhibitor of MAP2K1, also known as MEK-1, upstream of extracellular signal-regulated protein kinases MAPK3/1, also known as ERK1/2), wortmannin (inhibitor of PIK3C2A, also known as PI3K), and rapamycin (inhibitor of FRAP1, also known as mTOR, upstream of RPS6KB1) each significantly decreased insulin and oxidative stress-induced proliferation of theca-interstitial cells. The greatest inhibition was observed in the presence of rapamycin; this effect occurred without a significant change in cell viability. Phosphorylation of AKT was stimulated by insulin only, while phosphorylation of MAPK3/1 and RPS6KB1 was increased by insulin and oxidative stress. Insulin-induced and oxidative stress-induced phosphorylation of RPS6KB1 was partly inhibited by wortmannin and partly by PD98059; the greatest inhibition was observed in the presence of a combination of wortmannin plus PD98059. Effects of insulin and oxidative stress on phosphorylation of RPS6KB1 were confirmed by kinase activity assays. These findings indicate that actions of insulin and oxidative stress converge on MAPK3/1 and RPS6KB1. Furthermore, we speculate that activation of RPS6KB1 may be in part induced via the MAPK3/1 pathway.
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PMID:Insulin and oxidative stress modulate proliferation of rat ovarian theca-interstitial cells through diverse signal transduction pathways. 1648 89


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