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:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rising incidence and poor prognosis of colorectal cancer have aroused substantial interest in novel chemopreventive strategies. Interestingly, treatment of ulcerative colitis with mesalazine, which displays few side effects during long-term treatment, is associated with a reduced incidence of colorectal cancer, but its molecular mechanism is not known. The effect of mesalazine on the Wnt/beta-catenin pathway was studied in colorectal cancer cell lines to find a molecular basis underlying its chemopreventive features. Mesalazine affects the Wnt/beta-catenin pathway in adenomatous polyposis coli mutated cells with intact beta-catenin, judged by luciferase reporter assays. Furthermore, mesalazine treatment reduced expression of nuclear beta-catenin and Wnt/beta-catenin target genes, and increased beta-catenin phosphorylation. This effect on the Wnt/beta-catenin pathway is mediated via protein phosphatase 2A (PP2A): increased phosphorylation of PP2A after mesalazine treatment is observed, which coincides with decreased PP2A enzymatic activity. The inhibition of PP2A enzymatic activity by mesalazine is essential for its effect on the Wnt/beta-catenin pathway, as shown by transient transfection with siPP2A and mutant PP2A. This study shows, using concentrations of mesalazine identical to concentrations seen in patients with inflammatory bowel disease, that mesalazine inhibits the Wnt/beta-catenin pathway via inhibition of PP2A.
Carcinogenesis 2006 Dec
PMID:Protein phosphatase 2A is required for mesalazine-dependent inhibition of Wnt/beta-catenin pathway activity. 1672 34

NFAT family is recognized as a transcription factor for inflammation regulation by inducing the expression of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), the key mediator of inflammation, which was reported to induce cell transformation in mouse epidermal Cl41 cells. In this study, we demonstrated that TNF-alpha was able to induce NFAT activation, as well as the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). The induction of COX-2 by TNF-alpha was abolished by knockdown of NFAT3 with its siRNA, while the induction of iNOS was not effected. Moreover, TNF-alpha-induced anchorage-independent cell growth was significantly inhibited by NFAT3 siRNA and cyclosporine A, a chemical inhibitor for the calcineurin/NFAT pathway, which suggests the importance of NFAT3 in regulating TNF-alpha-induced anchorage-independent cell growth. Consequently, impairment of COX-2 by its siRNA or selective inhibitor also inhibited TNF-alpha-induced anchorage-independent cell growth. Taken together, our results indicate that NFAT3 plays an important role in the regulation of TNF-alpha-induced anchorage-independent cell growth, at least partially, by inducing COX-2 expression in Cl41 cells. These findings suggest that NFAT3/cyclooxygenase-2 act as a link between inflammation and carcinogenesis by being involved in the tumor promotion stage.
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PMID:NFAT3 is specifically required for TNF-alpha-induced cyclooxygenase-2 (COX-2) expression and transformation of Cl41 cells. 1680 72

Wild-type p53-induced phosphatase (Wip1 or PPM1D) is a serine/threonine protein phosphatase expressed under various stress conditions, which selectively inactivates p38 MAPK. The finding that this gene is amplified in association with frequent gain of 17q21-24 in breast cancers supports its role as a driver oncogene. However, the pathogenetic mechanism of the wip1 gene expression in breast carcinogenesis remains to be elucidated. In this study, we examine Wip1 mRNA and protein expression in 20 breast cancer tissues and six cell lines. We additionally investigate the relationship among Wip1, active p38 MAPK, p53, and p16 proteins. In our experiments, Wip1 mRNA was significantly upregulated in 7 of 20 (35%) invasive breast cancer samples. Overexpression of Wip1 was inversely correlated with that of active (phosphor-) p38 MAPK (P = 0.007). Furthermore, Wip1-overexpressing tumors exhibited no or low levels of p16, which normally accumulates upon p38 MAPK activation (P = 0.057). Loss of p16 expression was not associated with hypermethylation of its promoter or loss of heterozygosity on 9p21. Among the 135 primary breast carcinomas further examined, a significant association was found between the Wip1 overexpression and negative staining for p53 (P value = 0.057), indicating that the tumors are wild-type for p53. This is first report showing that Wip1 overexpression abrogates the homeostatic balance maintained through the p38-p53-Wip1 pathway, and contributes to malignant progression by inactivating wild-type p53 and p38 MAPK as well as decreasing p16 protein levels in human breast tissues.
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PMID:Overexpression of the wip1 gene abrogates the p38 MAPK/p53/Wip1 pathway and silences p16 expression in human breast cancers. 1689 32

Many cellular signaling pathways share regulation by protein phosphatase-2A (PP2A), a widely expressed serine/threonine phosphatase, and the heterotrimeric G protein Galpha(12). PP2A activity is altered in carcinogenesis and in some neurodegenerative diseases. We have identified binding of Galpha(12) with the Aalpha subunit of PP2A, a trimeric enzyme composed of A (scaffolding), B (regulatory), and C (catalytic) subunits and demonstrated that Galpha(12) stimulated phosphatase activity (J Biol Chem 279: 54983-54986, 2004). We now show in substrate-velocity analysis using purified PP2A that V(max) was stimulated 3- to 4-fold by glutathione transferase (GST)-Galpha(12) with little effect on K(m) values. To identify the binding domains mediating the Aalpha-Galpha(12) interaction, an extensive mutational analysis was performed. Well-characterized mutations of Aalpha were expressed in vitro and tested for binding to GST-Galpha(12) in pull-down assays. Galpha(12) binds to Aalpha along repeats 7 to 10, and PP2A B subunits are not necessary for binding. To identify where Aalpha binds to Galpha(12), a series of 61 Galpha(12) mutants were engineered to contain the sequence Asn-Ala-Ala-Ile-Arg-Ser (NAAIRS) in place of 6 consecutive amino acids. Mutant Galpha(12) proteins were individually expressed in human embryonic kidney cells and analyzed for interaction with GST or GST-Aalpha in pull-down assays. The Aalpha binding sites were localized to regions near the N and C termini of Galpha(12). The expression of constitutively activated Galpha(12) (QLalpha(12)) in Madin Darby canine kidney cells stimulated PP2A activity as determined by decreased phosphorylation of tyrosine 307 on the catalytic subunit. Based on crystal structures of Galpha(12) and PP2A Aalpha, a model describing the binding surfaces and potential mechanisms of Galpha(12)-mediated PP2A activation is presented.
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PMID:Domains necessary for Galpha12 binding and stimulation of protein phosphatase-2A (PP2A): Is Galpha12 a novel regulatory subunit of PP2A? 1730

Protein phosphatase 2A (PP2A) holoenzyme plays a critical role in cell cycle control and growth factor signaling. The PPP2R1B gene encodes the beta isoforms of the subunit A of the PP2A. We aimed to evaluate the role of the PPP2R1B gene in the pathogenesis of cervical cancer. Twenty-four women with primary cervical cancer were included. All resected specimens were divided into two groups: (1) cervical cancers (n = 24), (2) nearby noncancerous tissues (n = 24). We performed nested reverse transcriptase-polymerase chain reaction analysis and complementary DNA sequencing on the genomic DNA samples of all specimens. The aberrant transcripts and gene mutation as well as the genotype and allele frequencies of codon 66 CTA/CTG of PPP2R1B genes in both groups were compared. The percentages of aberrant transcripts between both groups were nonsignificantly different (20.8% vs 33.3%). There was no mutation in all specimens. The genotype and allele frequencies between both groups were non-different. Proportions of CTA homozygote/heterozygote/CTG homozygote were (1) 66.7/8.3/25% and (2) 58.3/12.5/29.2%. Proportions of CTA/CTG alleles in both groups were (1) 70.8/29.2% and (2) 64.6/35.4%. We conclude that PPP2R1B genes may not play a role in the carcinogenesis of cervical cancer. Mutations of PPP2R1B gene are not frequent in cervical cancer.
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PMID:Mutation analysis of the tumor suppressor gene PPP2R1B in human cervical cancer. 1734 70

Tacrolimus is an ascomycin macrolactam derivative with immunomodulatory and anti-inflammatory activity that belongs to the class of calcineurin inhibitors. Tacrolimus in its topical formulation has been established as a safe and effective alternative to topical corticosteroids because of its mild side effects and its minimal systemic absorption. Topical tacrolimus has been approved for the treatment of atopic dermatitis in two concentrations, 0.03 and 0.1%. In a thorough research of literature the authors review all of the available data regarding the off-label uses of the medication in other dermatoses. It seems that compared to pimecrolimus, tacrolimus has proved to be a more effective treatment. There is no causal relationship that has been established between tacrolimus and carcinogenesis. Furthermore, the authors believe that, without any evidence, the theoretical concerns are not enough to produce warnings. Tacrolimus ointment 0.1% may be recommended as a first-line choice for seborrheic dermatitis of the face and trunk, facial and intertriginous psoriasis and probably for allergic contact dermatitis and Zoon's balanitis. It has been ineffective in numerous dermatoses such as alopecia areata, necrobiosis lipoidica, internal pruritus and in thick hyperkeratotic plaques of psoriasis when administered as the commercially available formulation without occlusion. There is yet unexploited therapeutic potential regarding the use of topical tacrolimus in dermatology. Isolated cases of successful administration of the medication in various cutaneous conditions require further large-scale studies to clarify the actual effectiveness.
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PMID:Assigning new roles to topical tacrolimus. 1768 74

The insulin-like growth factors (IGF-I and IGF-II), working through the type 1 IGF receptor (IGF-1R), are key mediators of skeletal muscle fiber growth and hypertrophy. These processes are largely dependent on stimulation of proliferation and differentiation of muscle precursor cells, termed myoblasts. It has not been rigorously determined whether the IGFs can also mediate skeletal muscle hypertrophy in a myoblast-independent fashion. Similarly, although the phosphatidylinositol 3-kinase (PI3K) and calcineurin signaling pathways have been implicated in skeletal muscle hypertrophy, these pathways are also involved in skeletal myoblast differentiation. To determine whether the IGFs can stimulate skeletal muscle hypertrophy in a myoblast-independent fashion, we developed and validated a retroviral expression vector that mediated overexpression of the human IGF-1R in rat L6 skeletal myotubes (immature muscle fibers), but not in myoblasts. L6 myotubes transduced with this vector accumulated significantly higher amounts of myofibrillar proteins, in a ligand- and receptor-dependent manner, than controls and demonstrated significantly increased rates of protein synthesis. Stimulation of myotube hypertrophy was independent of myoblast contributions, inasmuch as these cultures did not exhibit increased levels of myoblast proliferation or differentiation. Experiments with PI3K and calcineurin inhibitors indicated that myoblast-independent myotube hypertrophy was mediated by PI3K, but not calcineurin, signaling. This study demonstrates that IGF can mediate skeletal muscle hypertrophy in a myoblast-independent fashion and suggests that muscle-specific overexpression of the IGF-1R or stimulation of its signaling pathways could be used to develop strategies to ameliorate muscle wasting without stimulating proliferative pathways leading to carcinogenesis or other pathological sequelae.
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PMID:Muscle-specific overexpression of the type 1 IGF receptor results in myoblast-independent muscle hypertrophy via PI3K, and not calcineurin, signaling. 1794 Feb 16

Numerous studies have demonstrated the utility of topical tacrolimus ointment in atopic dermatitis. However, there is a concern that local immunosuppression by calcineurin inhibitors may enhance dermal photocarcinogenesis and carcinogenesis. Therefore, we investigated the influence of topical tacrolimus ointment on squamous cell carcinoma formation in hairless female C3.Cg/TifBomTac immunocompetent mice exposed to solar simulated radiation (SSR). In a first experiment, mice (n = 200) had tacrolimus applied on their dorsal skin three times weekly followed by SSR (2, 4 or 6 standard erythema doses, SED) 3-4 h later. Tacrolimus did not reduce the time to tumor development and in the group receiving 4 SED it even had a protective effect (156 days vs 170 days, P = 0.008). In a second experiment, mice (n = 50) were irradiated with 6 SED three times weekly for 3 months and subsequently treated five times weekly with topical tacrolimus to mimic the use of tacrolimus on sun-damaged skin. The median time to the first skin tumor was 234 days in SSR + tacrolimus group compared with 227 days in the only SSR-irradiated group (P = 0.160). In a third experiment, mice (n = 25) had tacrolimus applied on their dorsal skin every day for 1 month, thereafter the group was irradiated with 4 SED three times weekly. The median time to the first skin tumor was 142 days in tacrolimus + SSR group compared with 156 days in the only SSR-irradiated group from experiment 1 (P = 0.363). We conclude that tacrolimus ointment does not accelerate photocarcinogenesis or induce any dermal carcinogenicity in hairless mice.
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PMID:Topical tacrolimus in combination with simulated solar radiation does not enhance photocarcinogenesis in hairless mice. 1809 46

Protein phosphatase 2A (PP2A), an Akt pathway inhibitor, is considered to be activated by methylation of its catalytic subunit. Also PP2A downregulation was proposed to take part in carcinogenesis. Recently, PP2A activation was shown to be activated in response to DNA damage. To obtain further information on the role of PP2A in tumors and response to DNA damage, we investigated the relationship between PP2A methylation and activity, cell proliferation, Akt activation, c-Myc expression and PTEN activity in B16 melanoma cells untreated and after chloroethylnitrosourea (CENU) treatment. In untreated cells, okadaic acid, an antagonist of PP2A methylation, inhibited PP2A activity, stimulated cell proliferation, increased Akt activation and c-Myc expression. Xylulose-5-phosphate, an agonist of PP2A methylation, increased PP2A activity, decreased cell proliferation, Akt activation and c-Myc expression. However, both PP2A methylation modulators increased PTEN activity. During the response to CENU treatment, PP2A methylation and activity were strongly increased, Akt activation and c-Myc expression were decreased. However PTEN activity was increased. After tumor cell growth recovery, these modifications were moderately decreased. PP2A methylation was quantified and correlated positively with PP2A activity, and negatively with criteria for cell aggressiveness (cell proliferation, Akt activation, c-Myc expression). Based on these data, PP2A methylation status controls PP2A activity and oncoproteins expression and PP2A is strongly activated after CENU treatment thus partly explaining the growth inhibition in response to this agent. It follows that PP2A promethylating agents are potential candidates for anticancer drugs.
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PMID:PP2A activity is controlled by methylation and regulates oncoprotein expression in melanoma cells: a mechanism which participates in growth inhibition induced by chloroethylnitrosourea treatment. 1809 42

Ectopic expression of conditional murine p53 (p53val135) and oncogenic ras is enough to induce a senescent-like growth arrest at the restrictive temperature. We took advantage of this cellular system to identify new key players in the ras/p53-induced senescence. Applying a retroviral-based genetic screen, we obtained an antisense RNA fragment against PPP1CA, the catalytic subunit of protein phosphatase 1alpha, whose loss of function bypasses ras/p53-induced growth arrest and senescence. Expression of a specific short hairpin (sh)RNA against PPP1CA impairs the p53-dependent induction of p21 after DNA damage and blocks the subsequent pRb dephosphorylation, thus bypassing p53-induced arrest. We found that oncogenic ras promotes an increase in the intracellular level of ceramides together with an increase in the PPP1CA protein levels. Addition of soluble ceramide to the cells induced a senescence phenotype that is blocked through PPP1CA downregulation by specific shRNA. Analysis of human tumors suggests that one of the PPP1CA alleles might be lost in a high percentage of carcinomas such as kidney and colorectal. The overexpression of two out of five PPP1CA alternative spliced variants reduced tumor cell growth and the downregulation of the protein to hemizygosity increased the anchorage-independent growth. We propose that oncogenic stress induced by ras causes ceramide accumulation, therefore, increasing PPP1CA activity, pRb dephosphorylation and onset of the p53-induced arrest, contributing to tumor suppression.
Carcinogenesis 2008 Mar
PMID:PPP1CA contributes to the senescence program induced by oncogenic Ras. 1820 81


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