Molecular and enzymatic profiles of mammalian DNA methyltransferases: structures and targets for drugs

DNA methylation is an epigenetic event involved in a variety array of processes that may be the foundation of genetic phenomena and diseases. DNA methyltransferase is a key enzyme for cytosine methylation in DNA, and can be divided into two functional families (Dnmt1 and Dnmt3) in mammals. All mammalian DNA methyltransferases are encoded by their own single gene, and consisted of catalytic and regulatory regions (except Dnmt2). Via interactions between functional domains in the regulatory or catalytic regions and other adaptors or cofactors, DNA methyltransferases can be localized at selective areas (specific DNA/nucleotide sequence) and linked to specific chromosome status (euchromatin/heterochromatin, various histone modification status). With assistance from UHRF1 and Dnmt3L or other factors in Dnmt1 and Dnmt3a/Dnmt3b, mammalian DNA methyltransferases can be recruited, and then specifically bind to hemimethylated and unmethylated double-stranded DNA sequence to maintain and de novo setup patterns for DNA methylation. Complicated enzymatic steps catalyzed by DNA methyltransferases include methyl group transferred from cofactor Ado-Met to C5 position of the flipped-out cytosine in targeted DNA duplex. In the light of the fact that different DNA methyltransferases are divergent in both structures and functions, and use unique reprogrammed or distorted routines in development of diseases, design of new drugs targeting specific mammalian DNA methyltransferases or their adaptors in the control of key steps in either maintenance or de novo DNA methylation processes will contribute to individually treating diseases related to DNA methyltransferases.

Activity identification of chimeric anti-caspase-3 mRNA hammerhead ribozyme in vitro and in vivo

To study the expression activity of various vectors containing anti-caspase-3 ribozyme cassettes in vivo, and to further study the role of caspas-3 in the apoptotic pathway, we constructed anti-caspase-3 hammerhead ribozyme embedded into the human snRNA U6, and detected the activity of the ribozyme in vitro and in vivo. Meanwhile we compared it with the self-cleaving hammerhead ribozymes that we previously studied, and with the general ribozyme, cloned into RNA polymerase II expression systems. The results showed that the three ribozymes, p1.5RZ107, pRZ107 and pU6RZ107 had the correct structure, and that they could cleave caspase-3 mRNA exactly to produce two fragments: 143nt/553nt. p1.5RZ107 has the highest cleavage efficiency in vitro, almost 80%. However, the U6 chimeric ribozyme, pU6RZ107, has the highest cleavage activity in vivo, almost to 65%, though it has lower cleavage activity in vitro. The cleavage results demonstrated that the pU6RZ107, the U6 chimeric ribozyme, could more efficiently express and downregulate the level of caspase-3 in vivo, and the ribozyme could provide an alternative approach to the research into the mechanism of apoptosis and human gene therapy also.

A cross-sectional study of dentine hypersensitivity in China

OBJECTIVE

To carry out a cross-sectional study of the prevalence of dentine hypersensitivity and related risk factors in Chengdu City, China.

METHODS

A total of 1,320 subjects were distributed equally in six communities in Chengdu City and of all age groups (10 years for an age group) including the same number of male and female subjects in each community. Each subject completed a structured interview and the subjects who reported hypersensitivity were examined further using a triple syringe to administer a blast of cold air to confirm the diagnosis of dentine hypersensitivity. Periodontal attachment loss and gingival recession of all sensitive teeth were measured.

RESULTS

The prevalence of dentine hypersensitivity was 25.5% in the oral test. Only 16.6% of subjects who reported hypersensitivity symptoms had received desensitising treatment. 50-59 year age group was the cohort with the greatest number of subjects with DH and the premolar was the most commonly affected tooth. Low education level, gingival recession, and attachment loss were related to dentine hypersensitivity.

CONCLUSIONS

The prevalence of dentine hypersensitivity in an urban adult population in Chengdu City was 25.5%.

Characterization of mouse IFT complex B

The primary cilium plays a key role in the development of mammals and in the maintenance of health. Primary cilia are assembled and maintained by the process of intraflagellar transport (IFT). In this work, we characterize mouse IFT complex B by identifying all of the mammalian orthologues of complex B and B-associated proteins previously identified in Chlamydomonas and Caenorhabditis and also identify a new component (IFT25/Hspb11) of complex B by database analysis. We tagged each of these proteins with the FLAG epitope and show that all except IFT172 and IFT20 localize to cilia and the peri-basal body or centrosomal region at the base of cilia. All of the proteins except IFT172 immunoprecipitate IFT88 indicating that they are co-assembled into a complex. IFT20 is the only complex B protein that localizes to the Golgi apparatus. However, overexpression of IFT54/Traf3ip1, the mouse orthologue of Dyf-11/Elipsa, displaces IFT20 from the Golgi apparatus. IFT54 does not localize to the Golgi complex nor does it interact with GMAP210, which is the protein that anchors IFT20 to the Golgi apparatus. This suggests that IFT54s effect on IFT20 is a dominant negative phenotype caused by its overexpression. Cell Motil. Cytoskeleton 2009. (c) 2009 Wiley-Liss, Inc.

Functional gene silencing mediated by chitosan/siRNA nanocomplexes

Chitosan/siRNA nanoparticles to knock down FHL2 gene expression were reported in this work. The physicochemical properties such as particle size, surface charge, morphology and complex stability of chitosan nanoparticle-incorporated siRNA were evaluated. Nanoparticles which were formulated with chitosan/siRNA exhibited irregular, lamellar and dendritic structures with a hydrodynamic radius size of about 148 nm and net positive charges with zeta-potential value of 58.5 mV. The knockdown effect of the chitosan/siRNA nanoparticles on gene expression in FHL2 over-expressed human colorectal cancer Lovo cells was investigated. The result showed that FHL2 siRNA formulated within chitosan nanoparticles could knock down about 69.6% FHL2 gene expression, which is very similar to the 68.8% reduced gene expression when siRNA was transfected with liposome Lipofectamine. Western analysis further showed significant FHL-2 protein expression reduced by the chitosan/siRNA nanoparticles. The results also showed that blocking FHL2 expression by siRNA could also inhibit the growth and proliferation of human colorectal cancer Lovo cells. The current results demonstrated that chitosan-based siRNA nanoparticles were a very efficient delivery system for siRNA in vivo as previously reported.

CIGARETTE SMOKE-INDUCED HYPERCAPNIC EMPHYSEMA IN C3H MICE IS ASSOCIATED WITH INCREASES OF MACROPHAGE METALLOELASTASE AND SUBSTANCE P IN THE LUNGS

The authors tested whether macrophage metalloelastase (MMP-12) and substance P (SP) were increased in the cigarette smoke (CS)-exposed female C3H/HeN mice with hypercapnic emphysema. The authors found that as compared to control (filtered air), 16 weeks of CS exposure significantly up-regulated mRNA and protein levels of MMP-12, the ratio of MMP-12/tissue inhibitor of matrix metalloproteinase-1, and SP/preprotachykinin-A (a precursor to SP) in the lungs. Importantly, a significant correlation was found between MMP-12 and SP, and between MMP-12/SP and the degrees of hypoxemia/hypercapnia denoted in CS-exposed mice. These data suggest a possible involvement of SP and MMP-12 in the pathogenesis of severe COPD.

Final STEPP results of prophylacatic versus reactive skin toxicity (ST) treatment (tx) for panitumumab (pmab)-related ST in patients (pts) with metastatic colorectal cancer (mCRC)

CRA4027

Background: Pmab, a fully human monoclonal antibody targeting the epidermal growth factor receptor (EGFR), is approved as monotherapy in the US for mCRC following disease progression (PD) and in the EU and Canada for tumors bearing wild-type (WT) KRAS. The most common toxicity with anti-EGFR inhibitors are ST. This study of pmab+ chemotherapy (CT) estimates the difference in the incidence of specific ≥ grade 2 ST of interest between pts receiving prophylactic (P) or reactive (R) skin tx. Methods: Pts had unresectable mCRC after PD with 1st-line fluoropyrimidine and oxaliplatin-based CT ± bevacizumab. Pts received either pmab 6.0mg/kg/FOLFIRI Q2W or pmab 9 mg/kg/irinotecan Q3W. Within each stratum, pts were randomized 1:1 to either P ST tx 24 hrs before the 1st dose daily for 6 wks or R ST tx after ST occurred. Tx for ST included: moisturizers, sunscreen, topical steroid, and doxycycline. Efficacy and safety were evaluated by P vs R tx groups, KRAS status (mutant [MT] vs WT), and chemotherapy status. Responses were assessed using modified RECIST with confirmation. Quality of life was assessed using the Dermatology Life Quality Index at screening, wks 2–7, and follow-up. Results: 95 pts were enrolled and randomized: 48 pts to P and 47 pts to R. During the 6 wk ST tx period, 29% of pts in the P group vs 62% of pts in the R group had protocol-specified ≥grade 2 ST. Of the 87 KRAS evaluable pts, 49 (56%) pts had WT KRAS and 38 (44%) pts had MT KRAS. Efficacy and safety are shown. Mean (SD) change in DLQI from baseline was 1.3 (2.6) for P and 4.2 (5.8) for R at wk 3 (when the median time to 1st ≥grade 2 ST was reached in the R group) and was 2.0 (2.8) for P and 2.6 (4.4) for R at wk 7. Conclusions: Prophylactic use of the skin tx regimen resulted in >50% reduction in the rate of specific ≥ grade 2 STs and improved QOL during the 6-week skin tx period vs R use. Numerical differences in favor of the P group were observed for all endpoints.

[Table: see text]

[Table: see text]

Thermally-Induced Change in the Relaxation Behavior of Skin Tissue

Skin biothermomechanics is highly interdisciplinary, involving bioheat transfer, burn damage, biomechanics, and physiology. Characterization of the thermomechanical behavior of skin tissue is of great importance and can contribute to a variety of medical applications. However, few quantitative studies have been conducted on the thermally-dependent mechanical properties of skin tissue. The aim of the present study is to experimentally examine the thermally-induced change in the relaxation behavior of skin tissue in both hyperthermal and hypothermic ranges. The results show that temperature has great influence on the stress-relaxation behavior of skin tissue under both hyperthermal and hypothermic temperatures; the quantitative relationship that has been found between temperature and the viscoelastic parameter (the elastic fraction or fractional energy dissipation) was temperature dependent, with greatest dissipation at high temperature levels.

Final STEPP results of prophylacatic versus reactive skin toxicity (ST) treatment (tx) for panitumumab (pmab)-related ST in patients (pts) with metastatic colorectal cancer (mCRC)

CRA4027

The full, final text of this abstract will be available in Part II of the 2009 ASCO Annual Meeting Proceedings, distributed onsite at the Meeting on May 30, 2009, and as a supplement to the June 20, 2009, issue of the Journal of Clinical Oncology.

[Table: see text]

Safety summary of panitumumab (pmab) in combination with chemotherapy (ctx) from four clinical trials in patients (pts) with metastatic colorectal cancer (mCRC)

e15005

Background: Pmab is a fully human anti-epidermal growth factor receptor (EGFR) monoclonal antibody approved in the US and EU (wild-type KRAS) as monotherapy for pts with mCRC. Safety data from 4 studies (Siena et al ASCO 2008; Peeters et al ASCO 2008; Cohn et al ASCO 2008; Mitchell et al WORLD GI 2008) of pmab in combination with ctx are summarized. Methods: Two studies are single-arm, phase II trials and two are randomized, phase III trials with pooled, blinded safety data that include ctx-controls. All studies were multicenter. Common pt eligibility criteria included: diagnosis of mCRC with measurable disease per modified RECIST criteria, age ≥ 18 years, and adequate hematologic, renal, hepatic, and metabolic function. All studies required pts to receive FOLFOX, FOLFIRI, or irinotecan ctx in combination with pmab. Pts received pmab 6.0 mg/kg Q2W with FOLFOX Q2W or FOLFIRI Q2W, or pmab 9.0 mg/kg Q3W with irinotecan Q3W. Results from planned interim analyses are available for 3 studies, and results from the final analysis are available for one study. Results: Among the 4-study safety data, 1213 pts received pmab + ctx; 703 pts received pmab + FOLFIRI, 455 pts received pmab + FOLFOX, and 55 pts received pmab + irinotecan. Approximately 1,200 pts were enrolled in each phase III study, and data are available from 1,003 pts who received pmab + ctx and 997 pts who received ctx alone. All pts in the phase III studies, regardless of treatment group, were included in the pooled, blinded interim analysis sets monitored by the data monitoring committee for each study. Safety results for the two phase II studies of pmab + ctx and two phase III studies of pmab ± ctx are summarized (Table). Conclusions: Phase II data are consistent with expectations, and phase III trials are ongoing. A consistent safety profile was observed across studies.

[Table: see text]

[Table: see text]

Equilibrium of adsorption of mixed milk protein/surfactant solutions at the water/air interface

Ellipsometry and surface profile analysis tensiometry were used to study and compare the adsorption behavior of beta-lactoglobulin (BLG)/C10DMPO, beta-casein (BCS)/C10DMPO and BCS/C12DMPO mixtures at the air/solution interface. The adsorption from protein/surfactant mixed solutions is of competitive nature. The obtained adsorption isotherms suggest a gradual replacement of the protein molecules at the interface with increasing surfactant concentration for all studied mixed systems. The thickness, refractive index, and the adsorbed amount of the respective adsorption layers, determined by ellipsometry, decrease monotonically and reach values close to those for a surface covered only by surfactant molecules, indicating the absence of proteins from a certain surfactant concentration on. These results correlate with the surface tension data. A continuous increase of adsorption layer thickness was observed up to this concentration, caused by the desorption of segments of the protein and transforming the thin surface layer into a rather diffuse and thick one. Replacement and structural changes of the protein molecules are discussed in terms of protein structure and surface activity of surfactant molecules. Theoretical models derived recently were used for the quantitative description of the equilibrium state of the mixed surface layers.

AttenuatedSalmonellaandShigellaas Carriers for DNA Vaccines

The discovery that genes can be functionally transferred from bacteria to mammalian cells has suggested the possible use of bacterial vectors as gene delivery vehicles for vaccines. Attenuated invasive human intestinal bacteria, such as Salmonella and Shigella, have been used as plasmid DNA vaccine carriers and their potency has been evaluated in several animal models. This delivery system allows the administration of DNA vaccines together with associated bacterial immunostimulators directly to professional antigen presenting cells via human mucosal surfaces. Various strategies have been taken to improve the use of this delivery system to achieve robust immune responses at both mucosal and systemic sites of the immunized animals.

Effect of early insulin therapy on nuclear factor kappaB and cytokine gene expressions in the liver and skeletal muscle of high-fat diet, streptozotocin-treated diabetic rats

To clarify the effect of early insulin therapy on nuclear factor kappaB (NFkappaB) pathway and inflammatory cytokine responses in the liver and skeletal muscle in type 2 diabetes. High-fat diet and low dose streptozotocin (STZ) induced diabetic rats were given NPH insulin or gliclazide for 3 weeks initiated at the 3rd day after STZ injection as early treatment and NPH for 3 weeks at 1 month as late treatment. Intraperitoneal glucose tolerance test (IPGTT) was performed at 3rd day after the end of treatment. Early interventions caused a decrease in glucose-insulin index in IPGTT, promoted glucose transporter 4 (Glut4) gene and protein expressions in muscle and reduced phosphoenolpyruvate carboxykinase (PEPCK) protein levels in the liver. There was an increase in inhibitor kappaB (IkappaBalpha) protein and a decrease in NFkappaB p65 DNA binding activity. A decreased level in mRNAs encoding tumor necrosis factor (TNF)alpha in the liver and muscle and interleukin (IL)-1beta in the liver were observed. Our results suggested that early insulin treatment inhibits NFkappaB activity and inflammatory cytokine responses in the liver and skeletal muscle that were involved in the amelioration of insulin resistance in type 2 diabetic rats.

Treatment with anti-CC chemokine receptor 3 monoclonal antibody or dexamethasone inhibits the migration and differentiation of bone marrow CD34 progenitor cells in an allergic mouse model

BACKGROUND

The migration and in situ differentiation of CD34(+) progenitors contribute to inflammatory eosinophilia in asthma and corticosteroids have been widely used in asthma. However, little is know about whether and how corticosteroids modulate the migration and differentiation of CD34(+) progenitors. This study was aimed to investigate the impact of anti-CC chemokine receptor 3 (CCR3) or dexamethasone on inflammatory eosinophilia in asthma and possible mechanism(s) underlying the action of dexamethasone or anti-CCR3 on migration and differentiation of CD34(+) progenitors in asthmatic context.

METHODS

Using an asthmatic mouse model, airway inflammation of anti-CCR3- or dexamethasone-treated mice and that of controls were characterized. And the migration and differentiation of CD34(+) progenitor cells were analyzed in vivo, ex vivo or in vitro.

RESULTS

Treatment with anti-CCR3 or dexamethasone significantly inhibited allergen-induced eosinophilia and CD34(+) progenitor cell infiltration in the lung, which was accompanied by lower levels of airway hyper-responsiveness and mucus production. Moreover, anti-CCR3 inhibited the eotaxin-mediated migration and IL-5/eotaxin-induced differentiation of CD34(+) progenitors in vitro. Dexamethasone was also shown to mitigate eotaxin-mediated migration and IL-5 or eotaxin-promoted differentiation of CD34(+) progenitor cells ex vivo, which were associated with the down-regulation of CCR3 expression on bone marrow progenitor cells.

CONCLUSIONS

Treatment with anti-CCR3 or dexamethasone can inhibit the migration and differentiation of CD34(+) progenitor cells by regulating the eotaxin/CCR3 axis in asthmatic mice. Our findings provide new insights into understanding the mechanism(s) underlying the action of dexamethasone and CCR3-mediated signaling in allergic inflammation and aid in the design of new immunotherapy for intervention of human asthma.