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: UMLS:C0178874 (tumor progression)
40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The process of tumor cell invasion of the basement membrane is proposed to consist of three steps: attachment, local proteolysis and migration. 12-(S)-HETE, a 12-lipoxygenase metabolite of arachidonic acid, upregulates surface expression of integrin cytoadhesins and an autocrine motility factor receptor, suggesting that this metabolite may play an important regulatory function in tumor cell invasion. In the present study, we determined whether 12-(S)-HETE affects surface expression and/or release of cathepsin B, a cysteine protease that has been implicated in focal degradation of basement membrane. Secretion and distribution of cathepsin B was evaluated in two model systems for various stages of neoplastic progression: (i) murine B16 melanoma lines of low (B16-F1) and high (B16a) lung colonization potential, and (ii) immortalized and ras-transfected MCF-10 human breast epithelial cells that differ in their invasive capacities in vitro. In the B16a cells, 12-(S)-HETE induced release of native and latent cathepsin B activity and concomitantly reduced cell-associated cathepsin B immunoreactivity. In contrast, 12-(S)-HETE did not induce the release of cathepsin B from B16-F1 cells, suggesting that there may be an enhanced response to 12-(S)-HETE in more malignant cells. This was confirmed in the MCF-10 system, in which 12-(S)-HETE was able to induce the release of cathepsin B from the ras-transfected cells, but not from the immortal cells. A simultaneous reduction in staining for cathepsin B was observed in the ras-transfected cells, but not in their immortal counterparts. The release of cathepsin B may be mediated by PKC as pretreatment of B16a cells with the selective PKC inhibitor calphostin C, but not with the PKA inhibitor H8, prevented the stimulated release of cathepsin B. In B16a cells, the release of cathepsin B was accompanied by a translocation toward the cell periphery of vesicles staining for cathepsin B, resulting in focal areas of accumulation of cathepsin B. After 12-(S)-HETE stimulation of the ras-transfected MCF-10 cells, cathepsin B was distributed homogeneously on the apical surface. Thus, 12-(S)-HETE can upregulate the surface expression on tumor cells of proteins able to mediate each of the three steps of tumor cell invasion: adhesion, degradation, and migration.
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PMID:A lipoxygenase metabolite, 12-(S)-HETE, stimulates protein kinase C-mediated release of cathepsin B from malignant cells. 752 40

Tea polyphenols are known to inhibit a wide variety of enzymatic activities associated with cell proliferation and tumor progression. The molecular mechanisms of antiproliferation are remained to be elucidated. In this study, we investigated the effects of the major tea polyphenol (-)-epigallocatechin gallate (EGCG) on the proliferation of human epidermoid carcinoma cell line, A431. Using a [3H]thymidine incorporation assay, EGCG could significantly inhibit the DNA synthesis of A431 cells. In vitro assay, EGCG strongly inhibited the protein tyrosine kinase (PTK) activities of EGF-R, PDGF-R, and FGF-R, and exhibited an IC50 value of 0.5-1 microgram/ml. But EGCG scarcely inhibited the protein kinase activities of pp60v-src, PKC, and PKA (IC50 > 10 micrograms/ml). In an in vivo assay, EGCG could reduce the autophosphorylation level of EGF-R by EGF. Phosphoamino acid analysis of the EGF-R revealed that EGCG inhibited the EGF-stimulated increase in phosphotyrosine level in A431 cells. In addition, we showed that EGCG blocked EGF binding to its receptor. The results of further studies suggested that the inhibition of proliferation and suppression of the EGF signaling by EGCG might mainly mediate dose-dependent blocking of ligand binding to its receptor, and subsequently through inhibition of EGF-R kinase activity.
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PMID:Suppression of extracellular signals and cell proliferation through EGF receptor binding by (-)-epigallocatechin gallate in human A431 epidermoid carcinoma cells. 932 39

Expression of the RI alpha subunit of the cAMP-dependent protein kinase type I (PKA-I) is enhanced in human cancer cell lines, in primary tumors, in transformed cells, and in cells upon stimulation of growth. Signaling via the cAMP pathway may be complex, and the biological effects of the pathway in normal cells may depend upon the physiological state of the cells. However, results of different experimental approaches such as antisense exposure, 8-Cl-cAMP treatment, and gene overexpression have shown that the inhibition of RI alpha/PKA-I exerts antitumor activity in a wide variety of tumor-derived cell lines examined in vitro and in vivo. cDNA microarrays have further shown that in a sequence-specific manner, RI alpha antisense induces alterations in the gene expression profile of cancer cells and tumors. The cluster of genes that define the "proliferation-transformation" signature are down-regulated, and those that define the "differentiation-reverse transformation" signature are up-regulated in antisense-treated cancer cells and tumors, but not in host livers, exhibiting the molecular portrait of the reverted (flat) phenotype of tumor cells. These results reveal a remarkable cellular regulation, elicited by the antisense RI alpha, superimposed on the regulation arising from the Watson-Crick base-pairing mechanism of action. Importantly, the blockade of both the PKA and PKC signaling pathways achieved with the CRE-transcription factor decoy inhibits tumor cell growth without harming normal cell growth. Thus, a complex circuitry of cAMP signaling comprises cAMP growth regulatory function, and deregulation of the effector molecule by this circuitry may underlie cancer genesis and tumor progression.
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PMID:Dissecting the circuitry of protein kinase A and cAMP signaling in cancer genesis: antisense, microarray, gene overexpression, and transcription factor decoy. 1211 65

Angiogenesis, the development of new blood vessels from preexisting vessels, is a key step in tumor growth, invasion and metastasis formation. Inhibition of tumor angiogenesis is considered as an attractive approach to suppress cancer progression and spreading. Adhesion receptors of the integrin family promote tumor angiogenesis by mediating cell migration, proliferation and survival of angiogenic endothelial cells. Integrins up regulated and highly expressed on neovascular endothelial cells, such as alphaVbeta3 and alpha5beta1, have been considered as relevant targets for anti-angiogenic therapies. Small molecular integrin antagonists or blocking antibodies suppress angiogenesis and tumor progression in many animal models, and some of them are currently being tested in cancer clinical trials as anti-angiogenic agents. COX-2 inhibitors exert anti-cancer effects, at least in part, by inhibiting tumor angiogenesis. We have recently shown that COX-2 inhibitors suppress endothelial cell migration and angiogenesis by preventing alphaVbeta3-mediated and cAMP/PKA-dependent activation of the small GTPases Rac and Cdc42. Here we will review the evidence for the involvement of vascular integrins in mediating angiogenesis and the role of COX-2 metabolites in modulating the cAMP/Protein Kinase A pathway and alphaVbeta3-dependent Rac activation in endothelial cells.
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PMID:Regulation of endothelial cell integrin function and angiogenesis by COX-2, cAMP and Protein Kinase A. 1451 76

GEM 231 is a second-generation antisense oligonucleotide targeted against the RIalpha regulatory subunit of cAMP-dependent protein kinase type I (PKA-I). Excessive expression of PKA-I is associated with cell proliferation and transformation, and increased levels of secreted extracellular PKA (ECPKA) are found in the serum of cancer patients. Preclinical studies have demonstrated single-agent antitumor activity of GEM 231 in a variety of human cancer xenograft models, and additive or synergistic antitumor activity has been observed with taxane and/or camptothecin-based combinations. Based on prior safety (MTD) data demonstrating dose-dependent, reversible, and cumulative transaminitis, and high peak plasma concentration (Cmax)-dependent changes in activated partial thromboplastin time (aPTT) with GEM 231 2-h twice-weekly infusions, an alternative schedule of GEM 231 given as a single agent was evaluated in patients with advanced solid tumors. Fourteen patients (median age approximately 60 yrs) with advanced solid malignancies received a total of 78 weeks of therapy. GEM 231 was infused via a CADD pump at 80 mg/m2/day (d) for 3 d/wk (n = 1), then for 5 d/wk at 80 (n = 3), 120 (n = 8), and 180 mg/m2/d (n = 2). One cycle was defined as 4 weeks of therapy. Apparent dose dependency for the occurrence of transaminitis was readily reversible. At 180 mg/m2/d, 2 of 2 patients had cycle 1 dose-limiting toxicity (DLT) transaminitis. One patient treated at 120 mg/m2/d experienced grade 3 transaminase elevations after 8 weeks of therapy, but when serum transaminase values rapidly improved he resumed treatment at 80 mg/m2/d for 6 weeks until tumor progression was documented. Another patient at 120 mg/m2/d developed grade 3 esophagitis after 3 weeks, limiting further dosing. One patient (lung cancer) demonstrated stable disease for 9 weeks. Overall, plasma aPTT was minimally prolonged and changes were transient, peaked at the end of each infusion, and were not associated with spontaneous bleeding. A constitutive symptom (e.g., low-grade fatigue) was common, cumulative, and reversible following discontinuation of therapy. Serum ECPKA was measured by enzymatic assay and Western blotting from blood drawn at the beginning and end of each infusion. Serum ECPKA levels demonstrated a trend to decline with the treatment. In addition to single agent schedules, combination trials were undertaken to assess safety and possible interaction of GEM 231 with taxanes (paclitaxel, docetaxel), given once every 3 weeks (one cycle). While trials using the 2-h twice-weekly GEM 231 infusions are ongoing, preliminary results from both studies show that it is safe to combine paclitaxel or docetaxel with GEM 231. Overall, it is also feasible to administer GEM 231 in combination with taxane or nontaxane chemotherapy (e.g., camptothecins). Phase I combination studies are currently underway to further explore the clinical, pharmacokinetic, and biologic profile of GEM 231 with chemotherapy.
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PMID:Clinical studies in patients with solid tumors using a second-generation antisense oligonucleotide (GEM 231) targeted against protein kinase A type I. 1475 40

Vascular integrins are essential regulators and mediators of physiological and pathological angiogenesis, including tumor angiogenesis. Integrins provide the physical interaction with the extracellular matrix (ECM) necessary for cell adhesion, migration and positioning, and induce signaling events essential for cell survival, proliferation and differentiation. Integrins preferentially expressed on neovascular endothelial cells, such as alphaVbeta3 and alpha5beta1, are considered as relevant targets for anti-angiogenic therapies. Anti-integrin antibodies and small molecular integrin inhibitors suppress angiogenesis and tumor progression in many animal models, and are currently tested in clinical trials as anti-angiogenic agents. Cyclooxygense-2 (COX-2), a key enzyme in the synthesis of prostaglandins and thromboxans, is highly up-regulated in tumor cells, stromal cells and angiogenic endothelial cells during tumor progression. Recent experiments have demonstrated that COX-2 promotes tumor angiogenesis. Chronic intake of nonsteroidal anti-inflammatory drugs and COX-2 inhibitors significantly reduces the risk of cancer development, and this effect may be due, at least in part, to the inhibition of tumor angiogenesis. Endothelial cell COX-2 promotes integrin alphaVbeta3-mediated endothelial cell adhesion, spreading, migration and angiogenesis through the prostaglandin-cAMP-PKA-dependent activation of the small GTPase Rac. In this article, we review the role of integrins and COX-2 in angiogenesis, their cross talk, and discuss implications relevant to their targeting to suppress tumor angiogenesis.
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PMID:Endothelial cell integrins and COX-2: mediators and therapeutic targets of tumor angiogenesis. 1498 67

The La protein interacts with a variety of small RNAs as well as certain growth-associated mRNAs such as Mdm2 mRNA. Human La (hLa) phosphoprotein is so highly conserved that it can replace the tRNA processing function of the fission yeast La protein in vivo. We used this system, which is based on tRNA-mediated suppression (TMS) of ade6-704 in S. pombe, to compare the activities of mouse and human La proteins. Prior studies indicate that hLa is activated by phosphorylation of serine-366 by protein kinase CK2, neutralizing a negative effect of a short basic motif (SBM). First, we report the sequence mapping of the UGA stop codon that requires suppressor tRNA for TMS, to an unexpected site in S. pombe ade6-704. Next, we show that, unlike hLa, native mLa is unexpectedly inactive for TMS, although its intrinsic activity is revealed by deletion of its SBM. We then show that mLa is not phosphorylated by CK2, accounting for the mechanistic difference between mLa and hLa. We found a PKA/PKG target sequence in mLa (S199) that is not present in hLa, and show that PKA/PKG efficiently phosphorylates mLa S199 in vitro. A noteworthy conclusion that comes from this work is that this fission yeast system can be used to gain insight into differences in control mechanisms used by La proteins of different mammalian species. Finally, RNA binding assays indicate that while mutation of mLa S199 has little effect on pre-tRNA binding, it substantially decreases binding to a probe derived from Mdm2 mRNA. In closing, we note that species-specific signaling through La may be relevant to the La-dependent Mdm2 pathways of p53 metabolism and cancer progression in mice and humans.
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PMID:Mouse and human La proteins differ in kinase substrate activity and activation mechanism for tRNA processing. 1825 91

Phylogenetic studies had shown that evolution of mitochondria occurred in parallel with the maturation of kinases implicated in growth and final size of modern organisms. In the last years, different reports confirmed that MAPKs, Akt, PKA and PKC are present in mitochondria, particularly in the intermembrane space and inner membrane where they meet mitochondrial constitutive upstream activators. Although a priori phosphorylation is the apparent aim of translocation, new perspectives indicate that kinase activation depends on redox status as determined by the mitochondrial production of oxygen species. We observed that the degree of mitochondrial oxidation of ERK Cys(38) and Cys(214) discriminates the kinase to be phosphorylated and determines translocation to the nuclear compartment and proliferation, or accumulation in mitochondria and arrest. Otherwise, transcriptional gene regulation by Akt depends on Cys(60) and Cys(310) oxidation to sulfenic and sulfonic acids. It is concluded that the interactions between kinases and mitochondria control cell signaling pathways and participate in the modulation of cell proliferation and arrest, tissue protection, tumorigenesis and cancer progression.
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PMID:Mitochondrial kinases in cell signaling: Facts and perspectives. 1973 3

Myc is a transcription factor that significantly contributes to cancer progression by modulating the expression of important genes through binding to a DNA sequence, CACGTG, called E-box. We find that on Myc binding to chromatin, the lysine-demethylating enzyme, LSD1, triggers a transient demethylation of lysine 4 in the histone H3. In addition, we demonstrate that Myc binds and recruits LSD1 to the E-box chromatin and the formation of this complex is stimulated by cAMP-PKA. Demethylation by LSD1 produces H(2)O(2), which locally oxidizes guanine and induces the recruitment of 8-oxoguanine-DNA glycosylase (OGG1) and of the nuclease Ape1 on the E-box chromatin. Inhibition of oxidation or silencing of LSD1, OGG1 or Ape1 significantly reduce transcription and inhibit mRNA accumulation of Myc-target genes. Collectively, these data highlight the role of transient LSD1-mediated demethylation of H3K4 leading to local DNA oxidation as driving force in the assembly of the Myc-induced transcription initiation complex.
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PMID:LSD1-mediated demethylation of histone H3 lysine 4 triggers Myc-induced transcription. 2041 16

RAB25 plays an important role in tumor progression and aggressiveness; altered RAB25 expression may cause human cancer. As the underlying mechanism of RAB25-mediated carcinogenesis in various tumor types progressively comes to light, RAB25 is expected to represent a novel therapeutic target. However, the regulation of RAB25 expression per se has not yet been described. Here we have firstly identified and characterized the human RAB25 promoter. Using PCR-based chromatin accessibility and chromatin immunoprecipitation (ChIP) assays, an open chromatin conformation (-173/+17) was detected around the transcription start site of the RAB25 gene. Deletion constructs of the 5' flanking region were fused to a luciferase reporter gene. After transient transfection in gastric cancer cell line AGS, a CRE (-67/-58) binding CREB was identified in the core promoter region. Electrophoretic mobility shift (EMSA) and ChIP assays demonstrated that CREB binds to the core promoter. Deletion of CREB consensus sequence resulted in the total loss of the promoter activity. Moreover, we have also found forskolin, PKA activator, could enhance open chromatin accessibility, by which to expose the CRE and facilitate phosphorylation of CREB, which in turn recruits co-factor CBP and Brg I and then results in a more open chromatin configuration associated with local histone modification, finally heightening RAB25 expression and strengthening its promoter activity. Therefore, the present study delineates the fundamental elements of a core promoter structure that will be helpful for future studies regarding the regulation of RAB25 gene.
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PMID:A CRE that binds CREB and contributes to PKA-dependent regulation of the proximal promoter of human RAB25 gene. 2107 12


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