Phosphorylation Of P53 Protein Research Articles

Dynamic p53 protein expression and phosphorylation in the kidneys of rats that experienced intrauterine growth restriction

Aim: This study investigated the mechanisms involved in intrauterine growth restriction (IUGR). Methods: The IUGR model was established by feeding pregnant SD rats a low-protein diet. Protein expression and phosphorylation were detected using Western blot and/or immunohistochemistry. Cell apoptosis was detected by TUNEL staining. The MDM2 mRNA expression was measured by real-time PCR. Results: Pups from the IUGR group had significantly lower body (7th day, 2 months) and kidney weights (1st day, 7th day, 2 months) compared to pups from the control group (p < 0.01). The glomeruli number in IUGR pups was significantly less than that in the control pups at 2 and 3 months after birth (p < 0.01). p53 protein level and p53 phosphorylation at Ser15 were time-dependently decreased in the kidney at 1st day, 7th day, 21st day, 2 months and 3 months, but their levels in the kidney of the IUGR pups was significantly higher than that in control pups at each time point (p < 0.05, p < 0.01, or p < 0.001). Significantly more positive p21 staining was observed in IUGR pups than in control pups at each time point. Real-time PCR of MDM2 mRNA expression showed no significant difference between IUGR and control pups (p > 0.05). Significant apoptosis was observed in the kidneys of IUGR pups compared to control pups. Conclusion: Malnutrition-induced IUGR may be associated with the activation of p53–p21 signaling in the kidney.

BAY 61-3606, CDKi, and Sodium Butyrate Treatments Modulate p53 Protein Level and Its Site-Specific Phosphorylation in Human Vestibular Schwannomas In Vitro

This study is done to evaluate the effect of spleen tyrosine kinase inhibitor (BAY 61-3606), cyclin-dependent kinase inhibitor (CDKi), and sodium butyrate (Na-Bu) on the level and phosphorylation of p53 protein and its binding to murine double minute 2 (MDM2) homologue in human vestibular schwannomas (VS). Primary cultures of the tumor tissues were treated individually with optimum concentrations of these small molecules in vitro. The results indicate modulation of p53 protein status and its binding ability to MDM2 in treated samples as compared to the untreated control. The three individual treatments reduced the level of total p53 protein. These treatments also decreased Ser392 and Ser15 phosphorylated p53 in tumor samples of young patients and Ser315 phosphorylated p53 in old patients. Basal level of Thr55 phosphorylated p53 protein was present in all VS samples and it remained unchanged after treatments. The p53 protein from untreated VS samples showed reduced affinity to MDM2 binding in vitro and it increased significantly after treatments. The MDM2/p53 ratio increased approximately 3-fold in the treated VS tumor samples as compared to the control. The differential p53 protein phosphorylation status perhaps could play an important role in VS tumor cell death due to these treatments that we reported previously.

Ibuprofen supplementation and its effects on NF-κB activation in skeletal muscle following resistance exercise.

Resistance exercise triggers a subclinical inflammatory response that plays a pivotal role in skeletal muscle regeneration. Nuclear factor‐κB (NF‐κB) is a stress signalling transcription factor that regulates acute and chronic states of inflammation. The classical NF‐κB pathway regulates the early activation of post‐exercise inflammation; however there remains scope for this complex transcription factor to play a more detailed role in post‐exercise muscle recovery. Sixteen volunteers completed a bout of lower body resistance exercise with the ingestion of three 400 mg doses of ibuprofen or a placebo control. Muscle biopsy samples were obtained prior to exercise and at 0, 3 and 24 h post‐exercise and analysed for key markers of NF‐κB activity. Phosphorylated p65 protein expression and p65 inflammatory target genes were elevated immediately post‐exercise independent of the two treatments. These changes did not translate to an increase in p65 DNA binding activity. NF‐κB p50 protein expression and NF‐κB p50 binding activity were lower than pre‐exercise at 0 and 3 h post‐exercise, but were elevated at 24 h post‐exercise. These findings provide novel evidence that two distinct NF‐κB pathways are active in skeletal muscle after resistance exercise. The initial wave of activity involving p65 resembles the classical pathway and is associated with the onset of an acute inflammatory response. The second wave of NF‐κB activity comprises the p50 subunit, which has been previously shown to resolve an acute inflammatory program. The current study showed no effect of the ibuprofen treatment on markers of the NF‐κB pathway, however examination of the within group effects of the exercise protocol suggests that this pathway warrants further research.

Abstract 5138: Histone deacetylase 2 and N-Myc reduce p53 protein phosphorylation at serine 46 by repressing gene transcription of tumor protein 53-induced nuclear protein 1

Abstract Myc oncoproteins and histone deacetylases (HDACs) exert oncogenic effects by modulating gene transcription. Paradoxically, N-Myc induces p53 gene expression. Tumor protein 53-induced nuclear protein 1 (TP53INP1) phosphorylates p53 protein at serine 46, leading to enhanced p53 activity, transcriptional activation of p53 target genes and programmed cell death. We aimed to identify the mechanism through which N-Myc overexpressing p53 wild-type neuroblastoma cells acquired resistance to apoptosis.Gene and protein expression was analysed by real-time RT-PCR and immunoblot. Cell survival/death was examined by flow cytometry study of Annexin V-staining. The prognostic value of TP53INP1 expression in tumor tissues was investigated in three independent cohorts of neuroblastoma patients. TP53INP1 was one of the genes most significantly repressed by HDAC2 and N-Myc according to Affymetrix microarray gene expression datasets. HDAC2 and N-Myc reduced TP53INP1 gene expression by direct binding to the TP53INP1 gene promoter, leading to transcriptional repression of TP53INP1, p53 protein de-phosphorylation at serine 46, neuroblastoma cell proliferation and survival. Moreover, low levels of TP53INP1 expression in human neuroblastoma tissues correlated with high levels of N-Myc expression and poor patient outcome, and the BET bromodomain inhibitors JQ1 and I-BET151 reduced N-Myc expression and reactivated TP53INP1 expression in neuroblastoma cells. These findings identify TP53INP1 repression as an important co-factor for N-Myc oncogenesis, and provide further evidence for the potential application of BET bromodomain inhibitors in the therapy of N-Myc-induced neuroblastoma. Citation Format: Jeyran Shahbazi, Christopher J. Scarlett, Murray Norris, Bing Liu, Michelle Haber, Andrew E. Tee, Alice Carrier, Andrew V. Biankin, Wendy B. London, Glenn M. Marshall, Richard Lock, Tao Liu. Histone deacetylase 2 and N-Myc reduce p53 protein phosphorylation at serine 46 by repressing gene transcription of tumor protein 53-induced nuclear protein 1. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5138. doi:10.1158/1538-7445.AM2014-5138

Jungia sellowii suppresses the carrageenan-induced inflammatory response in the mouse model of pleurisy.

This study was conducted to explore the anti-inflammatory effect of Jungia sellowii (Asteraceae) using a murine model of pleurisy induced by carrageenan (Cg). This plant is used in southern Brazil to treat inflammatory diseases. J. sellowii leaves were extracted with ethanol/water to obtain the crude extract (CE), which was fractionated with different solvents, yielding n-hexane (Hex), dichloromethane (DCM), ethyl acetate (EtOAc) and n-butanol (BuOH) fractions, and aqueous fraction (Aq). The major compounds succinic acid (SA) and lactic acid (LA) were isolated from Aq fraction, and their structures were determined by (1)H and (13)C NMR. Pleurisy was induced by Cg (Saleh et al. 1996). The leukocytes, exudation, myeloperoxidase (MPO) and adenosine-deaminase (ADA) activities, metabolites of nitric oxide (NO x ) levels, protein levels and mRNA expression for interleukin 1 beta (IL-1β), tumour necrosis factor alpha (TNF-α), interleukin 17A (IL17A) and inducible of nitric oxide synthase (iNOs), and p65 protein phosphorylation (NF-κB) were analysed 4h after pleurisy induction. Animals pre-treated with CE, BuOH, Aq, SA, or LA inhibited leukocytes, exudation, MPO and ADA activities, NO x , IL-1β, TNF-α, and IL-17A levels, and the mRNA expression for IL-1β, TNF-α, IL-17A, iNOS, and p65 protein phosphorylation (NF-κB) (p<0.05). Our study demonstrated that J. sellowii can protect against inflammation induced by Cg by decreasing the leukocytes and exudation. Its effects are related to the decrease of either proinflammatory cytokines and/or NO x . The isolated compounds SA and LA may play an important role in this anti-inflammatory action by inhibiting all the studied parameters. The anti-inflammatory properties of these compounds are due to the downregulation of NF-κB.

Guanylyl cyclase-G modulates jejunal apoptosis and inflammation in mice with intestinal ischemia and reperfusion.

BackgroundMembrane bound guanylyl cyclase-G (mGC-G), a novel form of GC mediates ischemia and reperfusion (IR)-induced renal injury. We investigated the roles of mGC-G in intestinal IR-induced jejunal damage, inflammation, and apoptosis.Materials and methodsMale C57BL/6 wild-type (WT) and mGC-G gene knockout (KO) mice were treated with a sham operation or 45 min of superior mesenteric arterial obstruction followed by 3, 6, 12, or 24 h of reperfusion.ResultsSham-operated KO mice had significantly lower plasma nitrate and nitrite (NOx) levels and jejunal villus height, crypt depth, and protein expression of phosphorylated-nuclear factor-kappa-B (NF-κB), phosphorylated-c-Jun N-terminal kinases (JNK) 2/3, phosphorylated-p38, and B-cell lymphoma-2 (Bcl-2). They had significantly greater jejunal interleukin-6 mRNA, cytochrome c protein, and apoptotic index compared with sham-operated WT mice. Intestinal IR significantly decreased plasma NOx in WT mice and increased plasma NOx in KO mice. The jejunal apoptotic index and caspase 3 activities were significantly increased, and nuclear phosphorylated-NF-κB and phosphorylated-p38 protein were significantly decreased in WT, but not KO mice with intestinal IR. After reperfusion, KO mice had an earlier decrease in jejunal cyclic GMP, and WT mice had an earlier increase in jejunal proliferation and a later increase in cytosol inhibitor of kappa-B-alpha. Intestinal IR induced greater increases in plasma and jejunal interleukin-6 protein in WT mice and a greater increase in jejunal interleukin-6 mRNA in KO mice.ConclusionsmGC-G is involved in the maintenance of jejunal integrity and intestinal IR-induced inflammation and apoptosis. These results suggest that targeting cGMP pathway might be a potential strategy to alleviate IR-induced jejunal damages.

Histone deacetylase 2 and N-Myc reduce p53 protein phosphorylation at serine 46 by repressing gene transcription of tumor protein 53-induced nuclear protein 1.

Myc oncoproteins and histone deacetylases (HDACs) exert oncogenic effects by modulating gene transcription. Paradoxically, N-Myc induces p53 gene expression. Tumor protein 53-induced nuclear protein 1 (TP53INP1) phosphorylates p53 protein at serine 46, leading to enhanced p53 activity, transcriptional activation of p53 target genes and programmed cell death. Here we aimed to identify the mechanism through which N-Myc overexpressing p53 wild-type neuroblastoma cells acquired resistance to apoptosis. TP53INP1 was found to be one of the genes most significantly repressed by HDAC2 and N-Myc according to Affymetrix microarray gene expression datasets. HDAC2 and N-Myc reduced TP53INP1 gene expression by direct binding to the TP53INP1 gene promoter, leading to transcriptional repression of TP53INP1, p53 protein de-phosphorylation at serine 46, neuroblastoma cell proliferation and survival. Moreover, low levels of TP53INP1 expression in human neuroblastoma tissues correlated with high levels of N-Myc expression and poor patient outcome, and the BET bromodomain inhibitors JQ1 and I-BET151 reduced N-Myc expression and reactivated TP53INP1 expression in neuroblastoma cells. These findings identify TP53INP1 repression as an important co-factor for N-Myc oncogenesis, and provide further evidence for the potential application of BET bromodomain inhibitors in the therapy of N-Myc-induced neuroblastoma.

P330 ACTIVATION OF INTERFERON AND NF-κB PATHWAYS IN EARLY HUMAN ALCOHOLIC LIVER DISEASE DEVELOPMENT

Background and aims : Animal data suggest a pathogenic role for TLR4 with subsequent activation of NFkB in alcohol liver injury. Here, we assessed cytokines, TLR and TLR-dependent pathways expressions in human ALD. Methods : Liver biopsies from 41 actively drinking ALD patients were compared with normal liver tissue (n=6) and with liver biopsies from ALD patients after 2 weeks of alcohol abstinence (n=27). Quantitative PCR and Western blotting were used for mRNA and protein analysis, respectively, immunohistochemistry for cellular localization of inflammatory processes. The study was approved by our local ethics committee. Results : Compared with normal livers, already early ALD (with minimal fibrosis) showed a significant activation of NFkB with increased total and phosphorylated p65 protein expression and up-regulation of NFkB responsive genes mRNA levels TNFalphaand IL-1beta. P65 immunohistochemistry evidenced positive staining mainly in inflammatory cells in ALD patients. Interestingly, TLR4 mRNA expression remained unchanged whereas CD14 and TNF receptor 1 mRNA were down-regulated in active ALD. Only IL-1beta returned to control levels after abstinence. STAT3 phosphorylation was also significantly induced in early ALD patients. Intriguingly, STAT3 mRNA expression as well as STAT3 responsive genes SOCS3, IL-6 and MCP-1 were significantly downregulated in ALD patients suggesting an overall inhibition of the STAT3 pathway. STAT3 inhibition did not recover following 2 weeks of alcohol abstinence. The interferon pathway was strongly activated in early ALD with significant increase in total and phosphorylated interferon regulatory factor-3, up-regulation of interferon-beta and interferon responsive genes ISG6-16 and OAS-1 mRNA levels. Interferon-beta levels significantly correlated with up-regulation of TLR3 and 7 mRNA. Activation of the interferon pathway was not reversed after abstinence. CD68 mRNA was significantly increased and both CD68 and CD163 immunohistochemistry revealed enlarged, aggregated Kupffer cells and small inflammatory cells in early ALD compared to scattered Kupffer cells in normal liver. Conclusions: Besides NFkB, early activation of the interferon pathway could play an important role in human ALD pathogenesis. Inhibition of the STAT3 pathway could contribute to impaired regenerative capacity in ALD.

Vitamin B6 activates p53 and elevates p21 gene expression in cancer cells and the mouse colon

Increasing evidence indicates vitamin B6 acts as a protective factor against colon cancer. However, the mechanisms of the effect of vitamin B6 are poorly understood. The present preliminary study using DNA microarray and real-time PCR indicates p21 mRNA is upregulated in human colon carcinoma (HT29) cells exposed to pyridoxal (PL, 500 µM). A similar effect was observed in human epithelial colorectal adenocarcinoma (Caco2) cells, human colon adenocarcinoma (LoVo) cells, human embryonic kidney (HEK293T) cells, and human hepatoma (HepG2) cells. Adding other B6-vitamers such as pyridoxal 5'-phosphate (PLP), pyridoxine (PN), and pyridoxamine (PM) caused no such effect. In order to understand the mechanism of higher mRNA expression of p21 by PL, effect of PL on the p53 activation was examined (the upstream factor for p21 mRNA transcription) in HT29 cells, LoVo cells, and HepG2 cells. PL increased the phosphorylated p53 protein levels (active form) in whole-cell lysates and the nuclei of the cells. Noteworthy, the consumption of a vitamin B6-deficient diet for 5 weeks significantly reduced p21 mRNA levels and tended to reduce phosphorylated p53 protein levels (P=0.053) in the colons of mice compared to a diet with adequate vitamin B6. Thus, these results suggest vitamin B6 plays a role in increasing p21 gene expression via p53 activation in several cancer cells and the mouse colon.

Deficiency of Ataxia Telangiectasia Mutated Kinase Modulates Cardiac Remodeling Following Myocardial Infarction: Involvement in Fibrosis and Apoptosis

Ataxia telangiectasia mutated kinase (ATM) is a cell cycle checkpoint protein activated in response to DNA damage. We recently reported that ATM plays a protective role in myocardial remodeling following β-adrenergic receptor stimulation. Here we investigated the role of ATM in cardiac remodeling using myocardial infarction (MI) as a model. Methods and Results: Left ventricular (LV) structure, function, apoptosis, fibrosis, and protein levels of apoptosis- and fibrosis-related proteins were examined in wild-type (WT) and ATM heterozygous knockout (hKO) mice 7 days post-MI. Infarct sizes were similar in both MI groups. However, infarct thickness was higher in hKO-MI group. Two dimensional M-mode echocardiography revealed decreased percent fractional shortening (%FS) and ejection fraction (EF) in both MI groups when compared to their respective sham groups. However, the decrease in %FS and EF was significantly greater in WT-MI vs hKO-MI. LV end systolic and diastolic diameters were greater in WT-MI vs hKO-MI. Fibrosis, apoptosis, and α-smooth muscle actin staining was significantly higher in hKO-MI vs WT-MI. MMP-2 protein levels and activity were increased to a similar extent in the infarct regions of both groups. MMP-9 protein levels were increased in the non-infarct region of WT-MI vs WT-sham. MMP-9 protein levels and activity were significantly lower in the infarct region of WT vs hKO. TIMP-2 protein levels similarly increased in both MI groups, whereas TIMP-4 protein levels were significantly lower in the infarct region of hKO group. Phosphorylation of p53 protein was higher, while protein levels of manganese superoxide dismutase were significantly lower in the infarct region of hKO vs WT. In vitro, inhibition of ATM using KU-55933 increased oxidative stress and apoptosis in cardiac myocytes.

Codon 72 Polymorphism Of TP53 Gene Is a Novel Prognostic Marker For Thalidomide Therapy In Multiple Myeloma

Backgrounds and purposeRecently, newly developed drugs such as thalidomide, lenalidomide and bortezomib have significantly improved survival of the patients with multiple myeloma (MM). However, certain group of the patients who have characteristic high-risk cytogenetic changes such as deletion of TP53 tumor suppressor gene revealed significantly shorter survival. In patients with deletion of TP53 gene, the somatic point mutation in the residual TP53 gene has been reported to be rare. Thus, the exact role of alteration of TP53 gene in high-risk myeloma remains unclear. Polymorphism of TP53 gene at codon 72 in exon 4, CGC to CCC transition, leads to arginine (Arg) to proline (Pro) amino-acid substitution. Biological analyses showed that the Arg variant more efficiently induces expression of P21 and apoptosis via Ser-6 and 20 phosphorylation of p53 protein. In contrast the Pro variant is less resistant to MDM-2-mediated degradation and more potently induced cell-cycle arrest and DNA damage repair. Recently, clinical significance of this polymorphism has been extensively studied in solid tumors as well as hematological malignancies including non-Hodgkin lymphoma and leukemia. However, consistent association of the polymorphism with cancer risk has not been elucidated.The purpose of this study is to examine codon 72 polymorphism in patients with refractory multiple myeloma (MM) treated with thalidomide, and to elucidate its association with myeloma risk and outcome of thalidomide-therapy. Patients & methodsA total of 37 Japanese patients with refractory or relapsed MM who were treated with thalidomide monotherapy were included in this study. Three cases showed deletion of TP53 gene by fluorescence in situ hybridization (FISH) analyses. The codon 72 polymorphism was evaluated in the rest of 34 patients. Genomic DNA was isolated from bone marrow mononuclear cells. The genomic TP53 gene was amplified by polymerase chain reaction, and the amplified DNAs were directly sequenced. ResultsDirect DNA sequence showed that the Pro/Pro homozygote was observed in six patients (18%), Pro/Arg heterozygote in 12 (35%) and Arg/Arg homozygote in 16 (47%). There was no significant difference in the frequency of the polymorphism between the 34 Japanese MM patients and the healthy Japanese individuals (P=0.44). Thus, association of codon 72 polymorphism with myeloma risk has failed to be elucidated. The response rate to thalidomide therapy was 33% in the patients with Pro/Pro, 27% in Pro/Arg and 44% in Arg/Arg (P=0.49), respectively. Other clinical backgrounds including age, sex, Durie-Salomon stage, ISS stage, serum creatinine, albumin, b2M, calcium, hemoglobin levels and M-protein type were not correlated with TP53 codon 72 polymorphism, either.Progression free survival (PFS), overall survival (OS) and post-relapse survival were shown in Figure 1. The patients with Pro allele tended to show shorter PFS; 5 weeks for the patients with Pro/Pro versus 32 weeks for those with Pro/Arg plus Arg/Arg (P=0.07) (Figure 1). Overall survival (OS) of the patients with Pro/Pro, Pro/Arg and Arg/Arg allele was 18 weeks, 49 weeks and 133 weeks, respectively (P=0.027). Especially, the patients with Pro/Pro allele revealed significantly shorter OS compared with those with Pro/Arg plus Arg/Arg (18 weeks versus 100 weeks, P=0.023) (Figure 1). Significant difference of OS in patients with Pro/Pro+Pro/Arg vs Arg/Arg (P= 0.032) suggested the dominant effect of Pro allele for poorer prognosis. Post-relapse survival of the patients with Pro/Pro, Pro/Arg and Arg/Arg allele was 11, 42 and 64 weeks, respectively (P=0.054). Post-relapse survival for Pro/Pro versus Pro/Arg plus Arg/Arg were 11 weeks versus 64 weeks (P=0.029). ConclusionThese results indicated that codon 72 polymorphism did not correlated with myeloma risk, but significantly associated with therapeutic outcome. Namely, the patients with Pro allele revealed earlier relapse and shorter post-relapse survival, resulted in shorter OS in thalidomide therapy. Further evaluation is needed to clarify whether the codon 72 polymorphism will be a new prognostic marker for the treatment with novel drugs. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Effects and mechanisms of ceramide signaling pathway in gastrin-inhibited cell apoptosis of large intestinal cancer

Objective To investigate the effects and mechanisms of ceramide signaling pathway in gastrin-inhibited cell apoptosis of large intestinal cancer.Methods Gastrin group and proglumide group were divided into five different densities with concentration gradient of gastrin and proglumide being 6.25,12.50,25.00,50.00,100.00 mg/L and 8.00,16.00,32.00,64.00,128.00 mg/L,respectively.The changes of proliferation of the HT-29 cells were detected by methyl thiazol tetrazolium (MTT) assay,and the optimal concentrations of gastrin and proglumide were determined.The changes of apoptosis rate of HT-29 cells were detected by using flow cytometry.The mRNA expression levels of gastrin receptor/cholecystokinin-B receptor (CCK-BR),ceramide,p38,B lymphocytes/leukemia-2 (bcl-2) and bcl-2 associated X protein (bax) were detected by using reverse transcriptase-polymerase chain reaction (RT-PCR).The protein expression levels of bcl-2,bax and ceramide,and p38 phosphorylation levels were detected by using Western blotting.Results Gastrin could promote the proliferation of HT-29 cells,and the optimal concentration was 25 mg/L (F =31.36,P ＜ 0.05).Proglumide could significantly inhibit the proliferation of HT-29 cells stimulated by gastrin,and the optimal concentration was 32 mg/L (F =24.31,P ＜ 0.05).The apoptosis rate of the gastrin group was significantly lower than in the control group and the gastrin + proglumid group (q =4.23,4.06,P ＜0.05).The mRNA and protein expression of bax and the levels of phosphorylated ceramide protein and phosphorylated p38 protein in the gastrin group were significantly lower than in the control group,the proglumid group,and the gastrin + proglumid group (q =5.50,6.00,7.50; 6.50,7.00,8.50; 8.00,8.50,10.00; 4.60,4.90,6.53,P＜0.05).On the contrary,the mRNA and protein expression of bcl-2 in the gastrin group was significantly higher than in the control group,the proglumid group,and the gastrin + proglumid group (q =4.95,4.24,7.07; 7.07,6.36,7.78,P ＜ 0.05).Conclusion Gastrin could inhibit the apoptosis of HT-29 cells by down-regulate the phosphorylation levels of ceramide and p38 protein,thus up-regulate bcl-2 and down-regulate bax through the ceramide signaling transduction pathway,while the effect can be restrained by gastrin receptor antagonist proglumide. Key words: Colorectal cancer; Gastrin ; Ceramide ; p38 ; B lymphocytes/leukemia-2 ; Bcl-2 associated X protein

Intestinal Inflammatory Biomarkers and Outcome in Pediatric Clostridium difficile Infections

To identify specific fecal biomarkers for symptomatic Clostridium difficile infection and predictors of poor outcomes. We enrolled 65 children with positive C difficile testing (cases) and 37 symptomatic controls. We also analyzed stool samples from colonized and non-colonized asymptomatic children. We performed enzyme immunoassays to determine fecal interleukin (IL)-8, lactoferrin, and phosphorylated-p38 protein concentrations, and quantitative polymerase chain reaction to determine IL-8 and chemokine ligand (CXCL)-5 RNA relative transcript abundances, and C difficile bacterial burden. Of 68 asymptomatic controls, 16 were colonized with C difficile. Phosphorylated-p38 was specific for C difficile infection but lacked sensitivity. Fecal cytokines were elevated in samples from symptomatic children, whether cases or controls. In children with C difficile infection, fecal CXCL-5 and IL-8 messenger RNA abundances at diagnosis correlated with persistent diarrhea after 5 days of C difficile infection therapy and with treatment with vancomycin. When children with concomitant viral gastroenteritis were excluded, these correlations persisted. Time-to-diarrhea resolution was significantly longer in patients with elevated fecal cytokines at diagnosis. A logistic regression model identified high CXCL-5 messenger RNA abundance as the only predictor of persistent diarrhea. Conversely, fecal C difficile bacterial burden was not different in symptomatic and asymptomatic children and did not correlate with any clinical outcome measure. Fecal inflammatory cytokines may be useful in distinguishing C difficile colonization from disease and identifying children with C difficile infection likely to have prolonged diarrhea.

Abstract 3199: Ceramide restores the expression of wild-type p53 tumor suppressor in mRNA splicing through PP1 and ASF/SF2.

Abstract p53 mutants that have been detected in approximately 50% of tumors loss the activity in stabilizing the genome and tumor suppression, and further exhibit oncogenic function in cancer cells. Most tumors that exhibit disrupted p53 signaling pathways remain addicted to p53 mutants, and p53 mutants have emerged as perhaps the most important target to improve cancer treatment. Most works in restoring p53 activity focus on either altering protein conformations of the mutants or introducing foreign p53 gene into cells. Using gene silencing strategy and mass spectrometry, here we demonstrated that ceramide modulates the RNA splicing to restore the expression of wild-type p53 in p53 deletion-mutant ovarian cancer cells. Enhanced endogenous long-carbon chain ceramide species (C16- to C24-ceramides) and exogenous C6-ceramide, but not other sphingolipids, restored wild-type p53 mRNA (intact exon-5), phosphorylated p53 protein (Ser15 in exon-5) and p53-responsive proteins (p21, Bax) in cells that dominantly expressed a deleted p53-mRNA and protein in exon-5. Thus, the restored p53 sensitized the cells to induced apoptosis. Furthermore, ceramide activated protein phosphatase 1 (PP1), rather than PP2a, increased the translocation of alternative splicing factor ASF/SF2 from cytoplasm to nucleus and thus determined the pre-mRNA splicing for wild-type p53. Alternative pre-mRNA splicing not only generates more than one protein isoform from single gene, it also results in gene mutants in cancer and other diseases. Our study elucidates a previous unrecognized mechanism in regulating the expression of wild-type versus mutant protein of p53 and indicates mutants can be restored in posttranscriptional levels by using an epigenetic approach. Citation Format: Yong-Yu Liu, Gauri A. Patwardhan. Ceramide restores the expression of wild-type p53 tumor suppressor in mRNA splicing through PP1 and ASF/SF2. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3199. doi:10.1158/1538-7445.AM2013-3199

A Novel Interleukin 33/ST2 Signaling Regulates Inflammatory Response in Human Corneal Epithelium

Interleukin (IL) 33, a member of IL-1 cytokine family, is well known to promote Th2 type immune responses by signaling through its receptor ST2. However, it is not clear whether ST2 is expressed by mucosal epithelium, and how it responds to IL-33 to induce inflammatory mediators. This study was to identify the presence and function of ST2 and explore the role of IL-33/ST2 signaling in regulating the inflammatory cytokine production in corneal epithelial cells. Human corneal tissues and cultured primary human corneal epithelial cells (HCECs) were treated with IL-33 in different concentrations without or with different inhibitors to evaluate the expression, location and signaling pathways of ST2 in regulating production of inflammatory cytokine and chemokine. The mRNA expression was determined by reverse transcription and real time PCR, and protein production was measured by enzyme-linked immunosorbent assay (ELISA), immunohistochemical and immunofluorescent staining. ST2 mRNA and protein were detected in donor corneal epithelium and cultured HCECs, and ST2 signal was enhanced by exposure to IL-33. IL-33 significantly stimulated the production of inflammatory cytokines (TNF-α, IL-1β and IL-6) and chemokine IL-8 by HCECs at both mRNA and protein levels. The stimulated production of inflammatory mediators by IL-33 was blocked by ST2 antibody or soluble ST2 protein. Interestingly, the IκB-α inhibitor BAY11-7082 or NF-κB activation inhibitor quinazoline blocked NF-κB p65 protein phosphorylation and nuclear translocation, and also suppressed the production of these inflammatory cytokines and chemokine induced by IL-33. These findings demonstrate that ST2 is present in human corneal epithelial cells, and IL-33/ST2 signaling plays an important role in regulating IL-33 induced inflammatory responses in ocular surface.

Activation of Lung p53 by Nutlin-3a Prevents and Reverses Experimental Pulmonary Hypertension

Induction of cellular senescence through activation of the p53 tumor suppressor protein is a new option for treating proliferative disorders. Nutlins prevent the ubiquitin ligase MDM2 (murine double minute 2), a negative p53 regulator, from interacting with p53. We hypothesized that cell senescence induced by Nutlin-3a exerted therapeutic effects in pulmonary hypertension (PH) by limiting the proliferation of pulmonary artery smooth muscle cells (PA-SMCs). Nutlin-3a treatment of cultured human PA-SMCs resulted in cell growth arrest with the induction of senescence but not apoptosis; increased phosphorylated p53 protein levels; and expression of p53 target genes including p21, Bax, BTG2, and MDM2. Daily intraperitoneal Nutlin-3a treatment for 3 weeks dose-dependently reduced PH, right ventricular hypertrophy, and distal pulmonary artery muscularization in mice exposed to chronic hypoxia or SU5416/hypoxia. Nutlin-3a treatment also partially reversed PH in chronically hypoxic or transgenic mice overexpressing the serotonin-transporter in SMCs (SM22-5HTT+ mice). In these mouse models of PH, Nutlin-3a markedly increased senescent p21-stained PA-SMCs; lung p53, p21, and MDM2 protein levels; and p21, Bax, PUMA, BTG2, and MDM2 mRNA levels; but induced only minor changes in control mice without PH. Marked MDM2 immunostaining was seen in both mouse and human remodeled pulmonary vessels, supporting the use of Nutlins as a PH-targeted therapy. PH prevention or reversal by Nutlin-3a required lung p53 stabilization and increased p21 expression, as indicated by the absence of Nutlin-3a effects in hypoxia-exposed p53(-/-) and p21(-/-) mice. Nutlin-3a may hold promise as a prosenescence treatment targeting PA-SMCs in PH.

Inhibitory effect of ARHI on pancreatic cancer cells and NF-κB activity

The aim of this study was to investigate the effect of aplasia ras homolog member I (ARHI) on proliferation, apoptosis and the cell cycle in the pancreatic cancer cell line PANC-1. The study also aimed to examine the effect of ARHI on the activity of the nuclear factor (NF)-κB and to determine whether ARHI acts as a tumor suppressor in the development of pancreatic cancer by inhibiting the activity of NF-κB. A pIRES2‑EGFP‑ARHI vector, constructed by reverse transcrition (RT)‑PCR, was transiently transfected into the PANC-1 cells and analyzed for the expression of the ARHI protein by western blotting. A MTT assay was used to quantify cell proliferation, and apoptosis was analyzed by flow cytometry. The NF‑κB signaling pathway, specifically the pathway using the nuclear phosphorylated p65 isoform, was analyzed by western blotting. Expression of the ARHI protein was detected by western blotting subsequent to the PANC-1 cells being transiently transfected with the pIRES2‑EGFP‑ARHI construct. Cell proliferation was strongly inhibited in the PANC-1 cells transfected with pIRES2‑EGFP‑ARHI. The cell cycle assays indicated an increase in the number of cells at the G0/G1 phase and a decrease in the cells at the S phase, but the difference was not significant (P>0.05). Time course studies also indicated a marked increase in the apoptotic index following transient transfection, as well as a gradual decrease in the expression of the nuclear phosphorylated p65 protein. ARHI acts as a tumor suppressor by downregulating the NF‑κB signaling pathway, which results in the inhibition of cell proliferation, apoptosis and the cell cycle in the pancreatic tumor PANC-1 cell line.

The effect of sodium nitroprusside on survival and stress signaling in PC12 rat phaeochromocytoma cells expressing a dominant negative RasH mutant protein

Toxic concentrations of the second messenger nitric oxide cause cellular stress leading to cell death. Ras proteins, possible targets of nitric oxide-induced nitrosylation, may act as mediators in nitrosative stress. To analyze the possible involvement of Ras proteins in nitric oxide cytotoxicity, a PC12 rat phaeochromocytoma cell line expressing a dominant negative Ras mutant protein was used in this study. Cytotoxic concentrations of the nitric oxide donor sodium nitroprusside activated several proapoptotic mechanisms, including stimulation of the stress kinase pathways mediated by c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), inhibition of the translation initiation factor eIF2α, induction and phosphorylation of the p53 protein, and inhibited Akt-mediated antiapoptotic signaling, independent of Ras function. Simultaneously, Ras-dependent stimulation of the prosurvival ERK pathway was also observed, followed by an increased activation of the caspase-9/caspase-3 cascade in cells with impaired Ras function. It is concluded that nitric oxide stimulation of multiple signaling pathways contributes to the cell death program, whereas concomitant activation of the Ras/ERK pathway provides a certain degree of protection.

Small molecule inhibitor SB203580 enhances the antitumor effect of gefitinib in PC-9 and A549 lung cancer cell lines

To detect the inhibitory effect of a p38MAPK inhibitor SB203580 in combination with gefitinib on lung adenocarcinoma cell line PC-9 cells and A549 cells, and its cellular and molecular mechanisms of action. MTT test was used to detect the growth inhibition of PC-9 and A549 cells by SB203580 alone and in combination with gefitinib. Cell apoptosis and cell cycles were determined by flow cytometry. The expressions of p38 and phosphorylated -p38 proteins in the two cell lines were analyzed by immunofluorescence microscopy. The associated protein expression was determined by Western-blot. Compared with the SB203580 group and gefitinib group, the growth inhibition and cell apoptosis of PC-9 cells in the SB203580 + gefitinib group were significantly increased (P < 0.05). The inhibition rate of PC-9 cells of 2 µmol/L SB203580 + 0.01 µmol/L gefitinib group was (46.6 ± 2.4)%, significantly higher than that induced by 0.01 µmol/L gefitinib (12.7 ± 1.5%) (P < 0.05). Immunofluorescence microscopy showed a low expression of phosphorylated-p38 protein in A549 cells and high expression in PC-9 cells. Flow cytometry showed that PC-9 cells in the SB203580 + gefitinib group were (77.35 ± 2.83)% at G0/G1 phase, (3.38 ± 0.84)% at S phase, and (19.56 ± 1.99)% at G2/M phase. Western-blotting showed that compared with the control group, the expression of phosphorylated Akt and phospho-p38 proteins in PC-9 cells of the SB203580 + gefitinib group was almost completely suppressed. The results indicate that the small molecular inhibitor SB203580 can effectively enhance the inhibitory effect of gefitinib on lung adenocarcinoma PC-9 cells. The enhanced inhibitory effect of SB203580 may be correlated with the blockage of p38MAPK signal transduction pathway.

Mechanisms of action of naturally occurring antibodies against β-amyloid on microglia

BackgroundNaturally occurring autoantibodies against amyloid-β (nAbs-Aβ) have been shown to exert beneficial effects on transgenic Alzheimer’s disease (AD) animals in vivo and on primary neurons in vitro. Not much is known about their effect on microglial cells. Our aim was to investigate the effect of nAbs-Aβ on amyloid-β (Aβ)-treated microglial cells in vitro with respect to cell viability, stress pathways, cytokine production and phagocytotic abilities and whether these effects can be conveyed to neurons.MethodsPrimary microglial cells isolated from Swiss Webster mouse mesencephalons on embryonic day 13.5 were pretreated with nAbs-Aβ and then treated with Aβ oligomers. After 3 hours, phagocytosis as well as western blot analysis were evaluated to measure the amount of phagocytized Aβ. Cell viability was analyzed using an MTT assay 24 hours after treatment. Pro-inflammatory cytokines in the supernatants were analyzed with ELISAs and then we treated primary neuronal cells with these conditioned microglia supernatants. Twenty-four hours later we did a MTT assay of the treated neurons. We further investigated the effect of a single nAbs-Aβ administration on Tg2576 mice in vivo.ResultsUpon co-administration of Aβ and nAbs-Aβ no change in microglia viability was observed. However, there was an increase in phosphorylated p38 protein level, an increase in the pro-inflammatory cytokines TNF-α and IL-6 and an increase in Aβ uptake by microglial cells. Treatment of primary neurons with conditioned microglia medium led to a 10% improvement in cell viability when nAbs-Aβ were co-administered compared to Aβ-treated cells alone. We were unable to detect changes in cytokine production in brain lysates of Tg2576 mice.ConclusionsWe provide evidence on the mechanism of action of nAbs-Aβ on microglia in vitro. Interestingly, our in vivo data indicate that nAbs-Aβ administration should be considered as a therapeutic strategy in AD, since there is no inflammatory reaction.