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1.
BMC Oral Health ; 23(1): 200, 2023 04 03.
Article in English | MEDLINE | ID: mdl-37013557

ABSTRACT

BACKGROUND: Dyslipidaemia is associated with cancers. However, the specific expression of serum lipids in oral potentially malignant disorders (OPMD) and oral squamous cell carcinoma (OSCC) remains unclear, and it remains unknown whether serum lipids are associated with the development of OPMD and OSCC. This study investigated the serum lipid profiles of OPMD and OSCC patients, and the association of serum lipids with the occurrence of OPMD and OSCC. METHODS: A total of 532 patients were recruited from the Affiliated Hospital of Stomatology, Nanjing Medical University. Serum lipid parameters including total cholesterol (TC), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A (Apo-A), apolipoprotein B (Apo-B), and lipoprotein (a) (Lpa) were analysed, and clinicopathological data were collected for further analysis. Furthermore, a regression model was used to evaluate the relationship between serum lipids and the occurrence of OSCC and OPMD. RESULTS: After adjusting for age and sex, no significant differences were observed in serum lipid or body mass index (BMI) between OSCC patients and controls (P > 0.05). HDL-C, Apo-A, and Apo-B levels were lower in OSCC patients than in OPMD patients (P < 0.05); HDL-C and Apo-A levels were higher in OPMD patients than in controls (P < 0.05). Furthermore, female OSCC patients had higher Apo-A and BMI values than males. The HDL-C level was lower in patients under 60 years of age than in elders (P < 0.05); and age was related to a higher risk of developing OSCC. Female patients with OPMD had higher TC, HDL-C, and Apo-A levels than males (P < 0.05); OPMD patients over 60 years of age had higher HDL-C than youngers (P < 0.05), whereas the LDL-C level was lower in elders (P < 0.05). The HDL-C and BMI values of the patients with oral leukoplakia (OLK) with dysplasia were more elevated than those of the oral lichen planus group, and the LDL-C, and Apo-A levels in patients with OLK with dysplasia were decreased (P < 0.05). Sex, high HDL-C and Apo-A values were associated with the development of OPMD. CONCLUSION: Serum lipids exhibited certain differences according to the occurrence and development of OSCC; high levels of HDL-C and Apo-A might be markers for predicting OPMD.


Subject(s)
Carcinoma, Squamous Cell , Head and Neck Neoplasms , Mouth Neoplasms , Precancerous Conditions , Male , Humans , Female , Middle Aged , Aged , Lipids , Cholesterol, LDL , Cholesterol , Squamous Cell Carcinoma of Head and Neck , Clinical Relevance , Triglycerides , Cholesterol, HDL , Apolipoproteins A , Leukoplakia, Oral , Carcinogenesis , Apolipoproteins B
2.
Heliyon ; 9(3): e14047, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36938459

ABSTRACT

Regional economic power and local environmental policies have a substantial impact on pollution reduction in urban agglomerations (UAs); however, whether megacities in UAs exert spillover effects of pollution reduction on surrounding cities remains unknown. This study presents a causal analytic framework to evaluate the spillover effects of megacities on regional industrial pollution reduction in three major UAs in China between 2005 and 2016. The interaction between industrial pollution reduction and infrastructure investment indicators was also examined. Results indicated a good fit for spatial spillover of sulfur dioxide reduction (SR) in the Pearl River Delta (PRD) and Yangtze River Delta (YRD) but not in the Beijing-Hebei-Tianjin cluster (JJJ). Spatial spillover of dust reduction (DR) was evident in the PRD and JJJ but not the YRD. Spatial analysis showed that infrastructure investment indicators, at megacity and UA levels, had short-term spillover effects on surrounding cities for DR but not SR. However, spatial spillover effects, at both the city and UA levels, were substantial over the long term. In addition, the results of the spatial-time lag analysis suggest a linear relationship between pollution control-related infrastructure investment indicators and long-term pollution reduction. This study provides new information regarding the spatial spillover effects of megacities on regional industrial pollution reduction in UAs.

3.
Nat Hum Behav ; 5(1): 159-169, 2021 01.
Article in English | MEDLINE | ID: mdl-33398150

ABSTRACT

Over the past 10 years, Oosterhof and Todorov's valence-dominance model has emerged as the most prominent account of how people evaluate faces on social dimensions. In this model, two dimensions (valence and dominance) underpin social judgements of faces. Because this model has primarily been developed and tested in Western regions, it is unclear whether these findings apply to other regions. We addressed this question by replicating Oosterhof and Todorov's methodology across 11 world regions, 41 countries and 11,570 participants. When we used Oosterhof and Todorov's original analysis strategy, the valence-dominance model generalized across regions. When we used an alternative methodology to allow for correlated dimensions, we observed much less generalization. Collectively, these results suggest that, while the valence-dominance model generalizes very well across regions when dimensions are forced to be orthogonal, regional differences are revealed when we use different extraction methods and correlate and rotate the dimension reduction solution. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 5 November 2018. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.7611443.v1 .


Subject(s)
Social Perception/ethnology , Adolescent , Adult , Cross-Cultural Comparison , Emotions , Facial Expression , Humans , Judgment , Male , Models, Psychological , Social Perception/psychology , Young Adult
4.
Dig Dis Sci ; 66(8): 2627-2636, 2021 08.
Article in English | MEDLINE | ID: mdl-32920660

ABSTRACT

BACKGROUND: Long non-coding RNAs have been acknowledged as the crucial regulators in the progression of human cancers, including gastric cancer (GC). Small nucleolar RNA host gene 10 (SNHG10) has been identified as an oncogene in several cancer types. Nonetheless, it is unclear whether SNHG10 exerts functions in GC cells. AIMS: The aims of the current study were to explore the function and underlying mechanism of SNHG10 in GC. METHODS: The expression levels of SNHG10, miR-495-3p and catenin beta 1 (CTNNB1) were detected by RT-qPCR. Loss-of-function assays, including CCK-8, colony formation assay, flow cytometry analysis and transwell assays, were conducted to verify the effect of SHNG10 on the proliferation, apoptosis, migration and invasion of GC cells. Mechanism experiments were performed to identify the downstream molecular mechanism of SNHG10. RESULTS: SNHG10 was expressed at a high level in GC cells. Knockdown of SNHG10 inhibited the proliferation, migration and invasion of GC cells. Silencing of SNHG10 led to the downregulation of core factors of WNT signaling pathway. Knockdown of SNHG10 could decline the expression of CTNNB1 through sequestering miR-495-3p. CONCLUSIONS: SNHG10 promotes the procession of GC through targeting miR-495-3p/CTNNB1 and activating WNT signaling pathway.


Subject(s)
Cell Proliferation/physiology , MicroRNAs/metabolism , RNA, Long Noncoding/metabolism , Stomach Neoplasms/metabolism , beta Catenin/metabolism , Cell Line, Tumor , Gene Expression Regulation, Neoplastic , Gene Silencing , Humans , MicroRNAs/genetics , RNA, Long Noncoding/genetics , beta Catenin/genetics
5.
BMC Oral Health ; 20(1): 26, 2020 01 30.
Article in English | MEDLINE | ID: mdl-32000758

ABSTRACT

BACKGROUND: Vitamin D receptor (VDR) is involved in multiple immune-mediated disorders including oral lichen planus (OLP). This study investigated the association between VDR gene polymorphisms and the risk of OLP. METHODS: In total, 177 OLP patients and 207 healthy participants were recruited from the Affiliated Hospital of Stomatology, Nanjing Medical University. Eight single nucleotide polymorphisms (SNPs: rs731236, rs739837, rs757343, rs2107301, rs2239185, rs7975232, rs11574129 and rs11568820) in the VDR gene were selected and genotyped. RESULTS: The results showed that OLP risk was increased in subjects with the rs2239185 TT genotype (Recessive model: adjusted Odd ratio(OR) = 2.68, 95% Confidence interval(CI) = 1.28-5.62, P = 0.009) and rs7975232 CC genotype (Recessive model: adjusted OR = 2.25, 95% CI = 1.10-4.58, P = 0.026). Moreover, rs2239185 and rs7975232 (P < 0.01) showed significant cumulative effects on OLP risk.Haplotype analysis showed that the CC haplotype (rs2239185-rs7975232) was associated with an increased risk of OLP (OR = 3.11, 95% CI = 1.42-6.83, P = 0.005), compared with the AC haplotype. CONCLUSION: The rs2239185 and rs7975232 variants of VDR may influence OLP susceptibility, and VDR gene polymorphisms may be candidate susceptibility regions for OLP in a Chinese Han population.


Subject(s)
Asian People/genetics , Genetic Predisposition to Disease , Lichen Planus, Oral/genetics , Receptors, Calcitriol/genetics , Case-Control Studies , China , Female , Genotype , Humans , Lichen Planus, Oral/ethnology , Male , Polymorphism, Single Nucleotide
6.
ACS Cent Sci ; 3(11): 1208-1220, 2017 Nov 22.
Article in English | MEDLINE | ID: mdl-29202023

ABSTRACT

Targeted inhibition of anaplastic lymphoma kinase (ALK) dramatically improved therapeutic outcomes in the treatment of ALK-positive cancers, but unfortunately patients invariably progressed due to acquired resistance mutations in ALK. Currently available drugs are all type-I inhibitors bound to the ATP-binding pocket and are most likely to be resistant in patients harboring genetic mutations surrounding the ATP pocket. To overcome drug resistance, we rationally designed a novel kind of "bridge" inhibitor, which specially bind into an extended hydrophobic back pocket adjacent to the ATP-binding site of ALK. The novel type-I1/2 inhibitors display excellent antiproliferation activity against ALK-positive cancer cells and appear superior to two clinically used drugs, crizotinib and ceritinib. Structural and molecular modeling analyses indicate that the inhibitor induces dramatic conformational transition and stabilizes unique DFG-shifted loop conformation, enabling persistent sensitivity to different genetic mutations in ALK. These data highlight a rationale for further development of next-generation ALK inhibitors to combat drug resistance.

7.
J Mol Model ; 21(9): 242, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26311230

ABSTRACT

Mechanisms for the activation of water, ammonia, and other small molecules by the PCcarbeneP nickel pincer complex were studied computationally with the aid of density functional theory. The calculation results indicate that the strongly donating, nucleophilic carbene center can engage in a variety of heterolytic splitting of E-H (E=H, C, N, O) bonds, some of which are reversible. The cleavage of E-H bonds across the Ni=C bond represents a new mode of bond activation by ligand cooperativity in nickel pincer complex. On the basis of the calculations, we also demonstrate that reversible H2 activation across the Ir=C bond via the PCcarbeneP iridium pincer complex was observed in the experiments, while other E-H (E=C, N, O) bonds were not activated. Our calculations are in good agreement with experimental observations and could provide new insights into ligand cooperativity in nickel pincer complexes.

8.
PLoS One ; 10(3): e0120310, 2015.
Article in English | MEDLINE | ID: mdl-25790462

ABSTRACT

Porcine epidemic diarrhea (PED), caused by porcine epidemic diarrhea virus (PEDV), is a highly contagious, acute enteric viral disease of swine characterized by vomiting, watery diarrhea, dehydration and death. To identify and characterize the field PEDVs associated with the outbreaks of severe diarrhea in piglets in Jiangxi, 2013, the complete genome sequences of two representative strains of PEDV, designated CH/JX-1/2013 and CH/JX-2/2013, were determined and analyzed. The genome sequences of both emergent Jiangxi PEDV strains, CH/JX-1/2013 and CH/JX-2/2013, were 28,038 nucleotides in length excluding 3' poly (A) tail. Compared to the PEDV CV777 strain, CH/JX-1/2013 and CH/JX-2/2013 had some unique genetic characteristics in the proximal region of the 5´-UTRs. Phylogenetic analysis of the complete genomes and the structural proteins revealed that CH/JX-1/2013 and CH/JX-2/2013 had a close relationship with post-2010 Chinese PEDV strains and US strains identified in 2013. The nucleotide identity between the two Jiangxi strains (CH/JX-1/2013 and CH/JX-2/2013) and 30 strains of PEDV identified ante-2010 and post-2010 ranged from 96.3-97.0% and 97.3-99.7%, respectively. Multiple nucleotide and deduced amino acid mutations were observed in the ORF1a/b, S, ORF3, E, M and N genes among the current field PEDV strains when compared to the CV777 strain. Some of the mutations altered the amino acid charge and hydrophilicity, and notably, there was an amino acid substitution in the middle of one neutralizing epitope (L1371I) of the S gene of both CH/JX-1/2013 and CH/JX-2/2013. Taken together, the accumulated genetic variations of the current field PEDV strains might have led to antigenic changes of the viruses, which might confer the less effectiveness or failure of the CV777-based vaccines currently being widely used in Jiangxi, China.


Subject(s)
Coronavirus Infections/veterinary , Diarrhea/veterinary , Porcine epidemic diarrhea virus/genetics , Swine Diseases/virology , Animals , China/epidemiology , Coronavirus Infections/virology , Diarrhea/epidemiology , Diarrhea/virology , Disease Outbreaks , Genome, Viral , Mutation , Phylogeny , Porcine epidemic diarrhea virus/classification , Sequence Analysis, RNA , Swine , Swine Diseases/epidemiology
9.
Cell Logist ; 4(1): e27732, 2014 Jan 01.
Article in English | MEDLINE | ID: mdl-24843827

ABSTRACT

Brefeldin A (BFA) is a fungal metabolite best known for its ability to inhibit activation of ADP-ribosylation factor (Arf) and thereby inhibit secretory traffic. BFA also appears to regulate the trafficking of the GLUT4 glucose transporter by inducing its relocation from intracellular stores to the cell surface. Such redistribution of GLUT4 is normally regulated by insulin-mediated signaling. Hence, we tested whether BFA may intersect with the insulin pathway. We report that BFA causes the activation of the insulin receptor (IR), IRS-1, Akt-2, and AS160 components of the insulin pathway. The response is mediated through phosphoinositol-3-kinase (PI3K) and Akt kinase since the PI3K inhibitor wortmannin and the Akt inhibitors MK2206 and perifosine inhibit the BFA effect. BFA-mediated activation of the insulin pathway results in Akt-mediated phosphorylation of the insulin-responsive transcription factor FoxO1. This leads to nuclear exclusion of FoxO1 and a decrease in transcription of the insulin-responsive gene SIRT-1. Our findings suggest novel effects for BFA in signaling and transcription, and imply that BFA has multiple intracellular targets and can be used to regulate diverse cellular responses that include vesicular trafficking, signaling and transcription.

10.
Am J Physiol Endocrinol Metab ; 305(9): E1081-92, 2013 Nov 01.
Article in English | MEDLINE | ID: mdl-24022864

ABSTRACT

The purine anti-metabolite 6-mercaptopurine (6-MP) is widely used for the treatment of leukemia and inflammatory diseases. The cellular effects of 6-MP on metabolism remain unknown; however, 6-MP was recently found to activate the orphan nuclear receptor NR4A3 in skeletal muscle cell lines. We have reported previously that NR4A3 (also known as NOR-1, MINOR) is a positive regulator of insulin sensitivity in adipocytes. To further explore the role of NR4A3 activation in insulin action, we explored whether 6-MP activation of NR4A3 could modulate glucose transport system activity in L6 skeletal muscle cells. We found that 6-MP increased both NR4A3 expression and NR4A3 transcriptional activity and enhanced glucose transport activity via increasing GLUT4 translocation in both basal and insulin-stimulated L6 cells in an NR4A3-dependent manner. Furthermore, 6-MP increased levels of phospho-AS160, although this effect was not modulated by NR4A3 overexpression or knockdown. These primary findings provide a novel proof of principle that 6-MP, a small molecule NR4A3 agonist, can augment glucose uptake in insulin target cells, although this occurs via both NR4A3-dependent and -independent actions; the latter is related to an increase in phospho-AS160. These results establish a novel target for development of new treatments for insulin resistance.


Subject(s)
Antimetabolites/pharmacology , DNA-Binding Proteins/physiology , Glucose/metabolism , Mercaptopurine/pharmacology , Muscle Fibers, Skeletal/metabolism , Nerve Tissue Proteins/physiology , Receptors, Steroid/physiology , Receptors, Thyroid Hormone/physiology , 3T3 Cells , Animals , Cells, Cultured , DNA-Binding Proteins/drug effects , DNA-Binding Proteins/genetics , GTPase-Activating Proteins/metabolism , Glucose Transport Proteins, Facilitative/metabolism , Glucose Transporter Type 4/metabolism , Insulin Resistance , Mice , Muscle Fibers, Skeletal/drug effects , Nerve Tissue Proteins/drug effects , Nerve Tissue Proteins/genetics , RNA/biosynthesis , RNA/genetics , RNA, Small Interfering/biosynthesis , RNA, Small Interfering/genetics , Rats , Real-Time Polymerase Chain Reaction , Receptors, Steroid/drug effects , Receptors, Steroid/genetics , Receptors, Thyroid Hormone/drug effects , Receptors, Thyroid Hormone/genetics , Stimulation, Chemical , Translocation, Genetic
11.
Diabetes ; 62(12): 4192-200, 2013 Dec.
Article in English | MEDLINE | ID: mdl-23990361

ABSTRACT

In the current study, we investigated the role of tribbles homolog 3 (TRIB3) in glucose-induced insulin resistance and whether the induction of TRIB3 by glucose is dependent on the nutrient-sensing hexosamine biosynthetic pathway (HBP) known to mediate glucose toxicity in diabetes. In diabetic rats, TRIB3 expression in skeletal muscle was increased after 10 days of hyperglycemia, and glycemia and muscle TRIB3 were both restored toward normal by insulin therapy. In L6 myocytes, the induction of TRIB3 by high glucose or glucosamine was reversible upon removal of these substrates. To assess the role of HBP in the induction of TRIB3, we demonstrated that the ability of high glucose to augment TRIB3 expression was prevented by azaserine, an inhibitor of glutamine: fructose-6-phosphate amidotransferase (GFAT), which is the rate-limiting enzyme in the HBP pathway. TRIB3 expression was also substantially stimulated by glucosamine, which bypasses GFAT, accompanied by a decrease in the insulin-stimulated glucose transport rate, and neither response was affected by azaserine. Further, knockdown of TRIB3 inhibited, and TRIB3 overexpression enhanced, the ability of both high glucose and glucosamine to induce insulin resistance. These data provide the mechanistic link between the HBP flux and insulin resistance and point to TRIB3 as a novel target for treatment of glucose-induced insulin resistance.


Subject(s)
Biosynthetic Pathways/physiology , Glucose/metabolism , Hexosamines/biosynthesis , Hyperglycemia/metabolism , Insulin Resistance/physiology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Animals , Diabetes Mellitus, Experimental/metabolism , Insulin/metabolism , Male , Muscle, Skeletal/metabolism , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Rats , Rats, Sprague-Dawley , Up-Regulation/physiology
12.
Inflammation ; 36(2): 419-25, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23135214

ABSTRACT

Oral lichen planus (OLP) is generally accepted to be a T cell-mediated chronic inflammatory disease with an unclear pathogenesis. There have been numerous studies on the proliferation and apoptosis of T cells in situ. In contrast, research on the proliferation and apoptosis of peripheral blood mononuclear cells (PBMCs) in patients with OLP is rare. The aim of the present study was to investigate the proliferation and apoptosis of PBMCs in patients with OLP. PBMCs were isolated from 20 patients with reticular OLP, 20 patients with atrophic-erosive OLP, and 20 healthy volunteers. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2,5-tetrazolium bromide assays were performed to investigate the proliferation of PBMCs, and caspase-3 colorimetric assays were performed to investigate the apoptosis of PBMCs. The proliferation rate of PBMCs in atrophic-erosive OLP subjects was significantly higher than that in both healthy (P < 0.05) and reticular OLP (P < 0.05) subjects. In contrast, the proliferation rate of PBMCs in reticular OLP subjects was significantly lower than that in healthy subjects (P < 0.05). The apoptosis rates of PBMCs in OLP subjects (P < 0.05) and atrophic-erosive OLP subjects (P < 0.05) were significantly lower than the apoptosis rate in the healthy group. Our findings reinforce the view that T cell-mediated immune responses play a critical role in the pathogenesis of OLP. It can reasonably be concluded that these abnormalities are linked to the presence of inflammatory infiltrates.


Subject(s)
Apoptosis/immunology , Leukocytes, Mononuclear/metabolism , Lichen Planus, Oral/immunology , T-Lymphocytes/immunology , Adult , Aged , Caspase 3/immunology , Cell Proliferation , Female , Humans , Inflammation , Male , Middle Aged , Young Adult
13.
Aging Cell ; 9(2): 147-61, 2010 Apr.
Article in English | MEDLINE | ID: mdl-20047574

ABSTRACT

Aging or glucocorticoid excess decrease bone strength more than bone mass in humans and mice, but an explanation for this mismatch remains elusive. We report that aging in C57BL/6 mice was associated with an increase in adrenal production of glucocorticoids as well as bone expression of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1, the enzyme that activates glucocorticoids. Aging also decreased the volume of the bone vasculature and solute transport from the peripheral circulation to the lacunar-canalicular system. The same changes were reproduced by pharmacologic hyperglucocorticoidism. Furthermore, mice in which osteoblasts and osteocytes were shielded from glucocorticoids via cell-specific transgenic expression of 11beta-HSD type 2, the enzyme that inactivates glucocorticoids, were protected from the adverse effects of aging on osteoblast and osteocyte apoptosis, bone formation rate and microarchitecture, crystallinity, vasculature volume, interstitial fluid, and strength. In addition, glucocorticoids suppressed angiogenesis in fetal metatarsals and hypoxia inducible factor-1alpha transcription and vascular endothelial growth factor production in osteoblasts and osteocytes. These results, together with the evidence that dehydration of bone decreases strength, reveal that endogenous glucocorticoids increase skeletal fragility in old age as a result of cell autonomous effects on osteoblasts and osteocytes leading to interconnected decrements in bone angiogenesis, vasculature volume, and osteocyte-lacunar-canalicular fluid.


Subject(s)
Aging , Bone Density , Bone and Bones/metabolism , Glucocorticoids/metabolism , Neovascularization, Physiologic , Water/metabolism , 11-beta-Hydroxysteroid Dehydrogenase Type 2/metabolism , Animals , Bone Density/drug effects , Bone and Bones/cytology , Bone and Bones/drug effects , Female , Glucocorticoids/administration & dosage , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Male , Mice , Mice, Inbred C57BL , Stress, Mechanical , Vascular Endothelial Growth Factor A/metabolism
14.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 44(7): 392-4, 2009 Jul.
Article in Chinese | MEDLINE | ID: mdl-19957569

ABSTRACT

OBJECTIVE: To examine the effect of mouthwash Yupingfeng on the level of salivary epidermal growth factor (sEGF) in oral lichen planus (OLP). METHODS: The level of sEGF was measured by radioimmunoassay with ligand 125I-EGF. The saliva samples were taken from the normal control group and the OLP patients before and after treatment with Yupingfeng. RESULTS: The levels of sEGF in OLP patients before treatment with Yupingfeng were (4.09 +/- 3.64) microg/L, which was significantly higher than that in normal control [(2.15 +/- 1.62) microg/L, P = 0.013], and (2.57 +/- 1.19) microg/L after treatment,which was significantly lower than before treatment (P = 0.05). CONCLUSIONS: Yupingfeng can modulate the level of sEGF in OLP patients.


Subject(s)
Drugs, Chinese Herbal/pharmacology , Epidermal Growth Factor/metabolism , Lichen Planus, Oral/metabolism , Adult , Aged , Case-Control Studies , Female , Humans , Male , Middle Aged , Saliva/metabolism
15.
Cell Signal ; 19(11): 2255-63, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17716861

ABSTRACT

DNA methylation, which affects gene expression and chromatin stability, is catalyzed by DNA methyltransferases (DNMTs) of which DNMT1 possesses most abundant activity. PI3K/PKB pathway is an important pathway involved in cell proliferation, viability, and metabolism and often disrupted in cancer. Here we investigated the impact of PKB on DNMT1 and DNA methylation. Positive correlation between PKB-Ser473-phosphorylation and DNMT1 protein level in 17 human cell lines (p<0.01) and in 27 human bladder cancer tissues (p<0.05) was found. With activator, inhibitor, siRNA and constitutively active or dominant-negative plasmids of PKB, we found that PKB increased the protein level of DNMT1 without coordinate mRNA change, which was specific rather than due to cell-cycle change. PKB enhanced DNMT1 protein stability independent of de novo synthesis of any protein, which was attributed to down-regulation of N-terminal-120-amino-acids-dependent DNMT1 degradation via ubiquitin-proteasome pathway. Gsk3beta inhibitor rescued the decrease of DNMT1 by PKB inhibition, suggesting that Gsk3beta mediated the stabilization of DNMT1 by PKB. Then role of PKB regulating DNMT1 was investigated. Inhibition of PKB caused observable DNA hypomethylation and chromatin decondensation and DNMT1 overexpression partially reversed cell growth inhibition by PKB inhibition. In conclusion, our results suggested that PKB enhanced DNMT1 stability and maintained DNA methylation and chromatin structure, which might contribute to cancer cell growth.


Subject(s)
DNA (Cytosine-5-)-Methyltransferases/metabolism , DNA Methylation , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Cell Cycle , Cell Proliferation , Chromatin/metabolism , DNA (Cytosine-5-)-Methyltransferase 1 , DNA (Cytosine-5-)-Methyltransferases/genetics , Enzyme Stability , Epigenesis, Genetic , Gene Expression Regulation, Enzymologic , Glycogen Synthase Kinase 3/metabolism , Glycogen Synthase Kinase 3 beta , HeLa Cells , Humans , Mutant Proteins/metabolism , Phosphorylation , Proteasome Endopeptidase Complex/metabolism , Protein Processing, Post-Translational , RNA, Messenger/genetics , RNA, Messenger/metabolism , Structure-Activity Relationship , Ubiquitin/metabolism
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