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:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphodiesterase I (EC 3.1.4.1) activity was detected in normal human blood serum. The enzyme is stable at laboratory temperature for three days, but is inactivated at pH less than 7. The pH for optimum activity increases with the substrate concentration (under the conditions used, from pH 9.0 to 10.2) and, conversely, the Km increases with pH and buffer concentration. The enzyme is inhibited by ethylenediaminetetraacetate but not by phosphate (0.1 mol/liter). We developed a simple quantitative method for its determination, based on hydrolysis of the p-nitrophenyl ester of thymidine 5'-monophosphate and subsequent measurement of the liberated p-nitrophenol at 400 nm in NaOH (0.1 mol/liter). Normal values (mean +/- 2 SD) were determined to be 33 +/- 6.4 U/liter. Preliminary studies indicate that phosphodiesterase I activity is greater than normal in serum of patients with necrotic changes in the liver or kidney or in cases of breast cancer, but not in that of patients with myocardial infarction, bone cancer, lung cancer, or chronic liver cirrhosis.
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PMID:Determination of phosphodiesterase I activity in human blood serum. 16 91

The antitumor activity of the antineoplastic agent, tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide), has previously been shown to require intracellular anabolism of the drug to a nicotinamide adenine dinucleotide (NAD) analog (2-beta-D-ribofuranosylthiazole-4-carboxamide adenine dinucleotide or "tiazofurin adenine dinucleotide"), which then acts as a potent inhibitor of the target enzyme inosine monophosphate (IMP) dehydrogenase. Inhibition of the latter enzyme in turn brings about a profound depletion of intracellular guanosine nucleotides essential for tumor cell growth and replication. In the present study, the cytotoxicity and metabolism of tiazofurin have been examined in six human lung cancer cell lines. At the pharmacologically attainable drug concentration of 100 microM, colony survival was less than 1.5% in three cell lines ("sensitive"), while survival in the remaining three was greater than 50% ("resistant"). The metabolism of tritiated tiazofurin was examined at concentrations ranging from 0.5 to 100 microM following both brief (6 h) and protracted (14 d) exposures. The sensitive lines accumulated concentrations of tiazofurin adenine dinucleotide that were approximately 10 times those achieved by the resistant lines at both time points. We also observed tendencies for the sensitive cell lines to exhibit: (a) higher specific activities of NAD pyrophosphorylase, the enzyme required for the synthesis of tiazofurin adenine dinucleotide, (b) significantly lower levels of a phosphodiesterase which degrades the latter dinucleotide, (c) greater inhibition of the target enzyme IMP dehydrogenase, and (d) greater depressions of guanosine nucleotide pools after drug treatment. By contrast, the basal levels of IMP dehydrogenase and purine nucleotides in these six lines did not correlate in any obvious way with their responsiveness or resistance. The accumulation and monophosphorylation of parent drug were also not prognostic variables. These studies thus suggest that the extent of accumulation of tiazofurin adenine dinucleotide, as regulated by its synthetic and degradative enzyme activities, is the single most predictive determinant of the responsiveness of cultured human lung tumor cells to tiazofurin.
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PMID:Relationships between the cytotoxicity of tiazofurin and its metabolism by cultured human lung cancer cells. 285 24

Type I and type II cAMP receptor proteins participate in cell growth regulation, differentiation and neoplastic transformation of neoplasms. In this paper the growth regulatory effects of cAMP analogs, DBcAMP (non-site-selective) and 8-Cl-cAMP (site-selective) on a highly metastatic human lung cancer cell line PG were studied. By MTT assay, DBcAMP at 1mmol/L was found to inhibit PG growth by 30% on the day 8, while 8-CL-cAMP at 10-20 mumol/L inhibited the growth by 75%-80%. When phosphodiesterase inhibitor isobutyl-1-methyl-xanthine (IBMX) was added the inhibitory effect of 8-Cl-cAMP was not enhanced, whereas that of DBcAMP was significantly enhanced. The invasiveness and colony-forming ability of the treated cells decreased. The cAMP level as determined by RIA was much more increased in DBcAMP-treated than in 8-Cl-cAMP-treated PG cells. The result suggests that 8-Cl-cAMP and DBcAMP exert their effects on tumor cell growth and invasion by defferent mechanisms.
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PMID:[Effects of site-selective 8-Cl-cAMP on the growth regulation of human lung giant cell cancer]. 765 98

In order to study the role of calmodulin (CaM) in the proliferation of lung cancer cells, the CaM level of the specimens of 40 cases of primary lung cancers and the DNA content of the specimens of 35 cases of primary lung cancers were determined with phosphodiesterase assay and flow cytometry respectively. It was found that the CaM level of lung cancers was significantly higher than that of host lungs, benign lung diseases and normal lungs (p<0.001) and that it was significantly correlated with the histopathological grading and TNM staging of the lung cancers. It was also found that the cellular DNA content of lung cancers, like the CaM level, was also significantly higher than that of benign lung diseases and normal lungs (p<0.001). There was a significant positive correlation between the cellular DNA content and tissue CaM level in lung cancers (r=0.885). It is believed that CaM plays an important role in the proliferation of lung cancer cells through the mechanism of the promotion of an uncontrolled synthesis of DNA in the cells. Consequently, it is inferred that CaM antagonists may be tried as a chemotherapeutic agent for lung cancer.
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PMID:A study on the levels of calmodulin and DNA in human lung cancer cells. 861 3

Autotaxin (ATX) is one of the newly discovered autocrine motility-stimulating factors with peptide sequences identical to those of the brain-type phosphodiesterase I (PD-Ialpha). Although ATX/PD-Ialpha is believed to play a role in tumor progression, its expression in various human cancers has not been extensively studied. We have studied the expression of ATX messenger RNA (mRNA) in normal human bronchial epithelial cell (HBEC) and non-small-cell lung cancer (NSCLC) cell lines, and in primary NSCLC with their corresponding normal lung tissues, using reverse transcription-polymerase chain reaction, Northern blot analysis, and in situ hybridization. ATX mRNA was commonly expressed in these cell lines and tissues. The predominantly expressed mRNA species corresponded to the ATX complementary DNA isolated from a human teratocarcinoma cell line. Overexpression of ATX mRNA was detected in seven of 12 (58%) tumor cell lines; however, there was no correlation between the levels of expression of ATX mRNA and the spontaneous motility of these cells. In situ hybridization localized ATX mRNA expression to the basal cells of normal bronchial epithelium, stromal B lymphocytes, and tumor cells. An overexpression of ATX mRNA as compared with its expression in normal bronchial epithelium was mainly found in poorly differentiated carcinomas. Our findings suggest that ATX may have roles additional to its motility-stimulating function in undifferentiated NSCLC.
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PMID:Autotaxin expression in non-small-cell lung cancer. 1042 4

Docetaxel, a semisynthetic taxane, improves the survival of stage IIIB and IV non-small cell lung cancer patients. However, the 5-year survival remains poor, and few patients experience a complete remission. In this report, we evaluated the effects of exisulind, a novel proapoptotic agent that is a sulfone metabolite of sulindac, in combination with docetaxel on the growth of the human non-small cell lung cancer cell line A549 in vitro and in vivo. Exisulind is a novel sulindac metabolite in that it does not inhibit cyclooxygenase enzymes and has been shown to induce apoptosis in a variety of human cancers by inhibiting cyclic GMP-dependent phosphodiesterase. Exisulind alone increased the fraction of cells in the G(1) phase of the cell cycle from 46% to 65%, whereas it decreased the fraction of cells in the S phase from 38% to 14%. Docetaxel increased the fraction of cells in the S phase from 17% to 19%, and 10 nM docetaxel increased the G2-M phase by 23%. Docetaxel alone induced apoptosis from 11% to 64% at 12-24 h after incubation. The combination of exisulind with concentrations of docetaxel (in concentrations that alone did not alter cell cycle distribution) reduced the G(1) accumulation induced by exisulind, increased the fraction of cells in G(2)-M (9-17%), and increased apoptosis (5-62%). The IC(50) for in vitro growth inhibition by exisulind alone was approximately 200 microM and 2.5 nM for docetaxel. The in vitro combination of exisulind and docetaxel produced an additive to synergistic growth inhibition. In athymic nude rats with A549 orthotopic lung cancers, both exisulind and docetaxel alone moderately prolonged survival, inhibited tumor growth and metastases, and increased apoptosis compared with control animals treated with a carrier. However, the combination of exisulind with docetaxel significantly prolonged survival (P = < 0.0004), inhibited tumor growth and metastases (P = < 0.0001), and increased apoptosis (P = < 0.001) when compared with control animals. These results provide rationale for conducting clinical trials using the combination of exisulind and docetaxel in patients with advanced lung cancer.
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PMID:Exisulind in combination with docetaxel inhibits growth and metastasis of human lung cancer and prolongs survival in athymic nude rats with orthotopic lung tumors. 1189 25

It is well known that high intracellular levels of cAMP can effectively kill cancer cells in vitro. Unfortunately substances elevating cAMP such as forskolin, 8-bromo-cAMP, 8-chloro-cAMP, monobutiryl or dibutiryl cAMP are not recommended to be used as anti-cancer drugs because of their high cytotoxicity. In contrast blockers of phosphodieterases such as theophylline and aminophylline, which could elevate intracellular cAMP, are commonly used as anti-asthma drugs reaching concentrations in the blood of 10-20 microg/ml. We tested the effectiveness of theophylline and aminophylline to induce cell death alone or in combination with common anti-cancer drugs such as cisplatin and gemcitabine (gemzar). We examined such drug combinations in the induction of cell death in a variety of carcinoma cell lines derived from human ovarian, prostate and lung cancer and in granulosa cell line transformed by SV40 and Ras oncogene. While theophylline could induce moderate cell death alone, at 20-25 microg/ml concentrations, aminophylline was ineffective at this concentration. Theophylline (at 15-25 ng/ml) was found in all four representative cell lines to synergize with gemcitabine or cisplatin to induce programmed cell death, which permits a reduction in the effective doses of cisplatin and gemcitabine by 2-3-fold. The effect of theophylline in induction of apoptosis involved reduction of intracellular levels of Bcl2. Such a reduction was proportional to the extent of apoptosis induced by theophylline as well as by the combined drug treatments. Therefore, we propose that theophylline should be considered as a potential anti-cancer drug in combination with other chemotherapeutic drugs. Screening of other phosphodiesterase blockers, which are not severely toxic, could open a possibility to improved chemotherapeutic cancer treatments with reduced undesired side-effects. A clinical trial, using theophylline as an anti-cancer drug, is currently being conducted in lung cancer patients.
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PMID:Phosphodiesterase inhibitors as anti-cancer drugs. 1531 91

Purine bases and their bioisosteric analogs are widely used as building blocks in combinatorial chemistry. Recently a great number of fused pyrimidine derivatives became known as potential drug molecules against various types of proliferative diseases, caused by over-expression of protein kinases. One of the most important compound families are quinazolines : e.g. the best inhibitor of EGFR tyrosine kinase is PD153035 (6,7-dimethoxy-4-(3'-bromophenyl)amino-quinazoline) and IRESSA (gefitinib, ZD1839), developed from this compound family, is presently the only one approved and granted drug by the FDA for the treatment of advanced non-small-cell lung cancer (NSCLC). KF31327 (3-ethyl-8-[2-(4-hydroxymethylpiperidino)benzylamino]-2,3-dihydro-1H-imidazo[4,5-g]-quinazoline-2-thione dihydrochloride) from this group, showed significantly higher inhibitory activity on cyclic GMP-specific phosphodiesterase compared with those of sildenafil (Viagra). The synthetic procedures of the example compounds are based on imidoyl chloride intermediates that were prepared from the appropriate 3H-quinazoline-4-ones. Although the key intermediates, quinazoline-4-ones, have been known since more than hundred years, their synthetic procedures have been improved much only in the past ten years. In this paper we reviewed the efficient synthetic methods of quinazolin-4-ones, and presented a novel, reliable method for their synthesis. There was no considerable effect of microwave-, or traditional thermal activation on the yield and compound purity.
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PMID:Improved, high yield synthesis of 3H-quinazolin-4-ones, the key intermediates of recently developed drugs. 1554 62

Gemcitabine and cisplatin are commonly used in chemotherapy, however, these drugs may cause severe cytotoxic side effects. Theophylline and aminophylline are commonly used as anti-asthma drugs and can block anti-phosphodiesterase activity. We examined whether these methylxanthins could effect lung cancer cell survival and synergise with gemcitabine and cisplatin to induce apoptosis. We found that theophylline induced apoptosis in the cultured H1299 cell line already at concentrations of 30 microg/ml, reaching an ED50% at 100 microg/ml. In contrast, aminophylline induced apoptosis at concentrations of 300 microg/ml and 17% apoptosis was evident at concentrations as high as 900 microg/ml, which is a lethal dose for in vivo treatment. Cisplatin induced apoptosis with ED50% of 0.8 microg/ml, while gemcitabine induced apoptosis with ED50% of 20 ng/ml. Using a combination of 20 microg/ml of theophylline (calculated as an effective but not toxic anti-asthma drug) with 10 ng/ml gemcitabine or with 0.3 microg/ml cisplatin significantly elevated incidence of apoptosis compared to gemcitabine or cisplatin alone at similar concentrations. In contrast, an observed synergistic effect between aminophylline and gemcitabine was evident only at concentrations of 80 microg/ml and 10 ng/ml respectively. However, no effect was apparent in combination doses of aminophylline (80 microg/ml) with cisplatin (0.3 microg/ml). The combined treatments involved reduction in the intracellular level of the anti-apoptotic Bcl-2 gene product. This corresponded with the extent of apoptosis induced by the various drug combinations. Thus, theophylline is significantly more effective than aminophylline in increasing the sensitivity of the H1299 lung cancer cells to the induction of cell death by gemcitabine and cisplatin. Thus, combination of theophylline with these drugs may permit a reduction in the effective dose needed in chemotherapy treatment of lung cancer patients.
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PMID:Induction of apoptosis in non-small lung carcinoma cell line (H1299) by combination of anti-asthma drugs with gemcitabine and cisplatin. 1564 33

The methylxanthine theophylline is contained in tea and in numerous asthma and cold medications. Theophylline inhibits the enzyme phosphodiesterase, thereby preventing the intracellular break-down of cAMP. The resulting increase in intracellular cAMP reduces smooth muscle tone, thus dilating the airways. Epidemiologic studies on preventive effects of tea on the development of lung cancer have yielded mixed results, with some studies demonstrating a reduction in lung cancer risk whereas others showed evidence for cancer promotion. On the other hand, preclinical studies in mouse models of lung cancer or in vitro systems have consistently demonstrated strong cancer preventive effects of tea and of polyphenols contained in tea. Investigations conducted in our laboratory have recently shown that cell lines derived from human pulmonary adenocarcinomas of Clara cell lineage (PACC) and experimentally induced PACCs in a hamster model are under beta-adrenergic growth control. beta-adrenergic agonists as well as forskolin, which activates cAMP, had strong growth-promoting effects on human PACC cells and on the hamster PACCs. The current project therefore tests the hypothesis that theophylline activates growth-stimulating signaling in human PACC cells and their normal cells of origin, small airway epithelial cells (SAEC). Using assays for the assessment of intracellular cAMP, activated PKA, phosphorylated CREB, ERK1/2 and cell numbers, our data provide evidence for a significant stimulation of cell proliferation in both cell systems via activation of these signaling components.
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PMID:Theophylline stimulates cAMP-mediated signaling associated with growth regulation in human cells from pulmonary adenocarcinoma and small airway epithelia. 1594 55


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