Self-catalyzed Co, N-doped carbon nanotubes-grafted hollow carbon polyhedrons as efficient trifunctional electrocatalysts for zinc-air batteries and self-powered overall water splitting.

It is still essential and challenging to explore inexpensive and versatile electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER), for the development of rechargeable zinc-air batteries (ZABs) and overall water splitting. Herein, a rambutan-like trifunctional electrocatalyst is fabricated by re-growth of secondary zeolitic imidazole frameworks (ZIFs) on ZIF-8-derived ZnO and the following carbonization treatment. Co nanoparticles (NPs) are encapsulated into N-doped carbon nanotubes (NCNT) grafted N-enriched hollow carbon (NHC) polyhedrons to form the Co-NCNT@NHC catalyst. The strong synergy between the N-doped carbon matrix and Co NPs endows Co-NCNT@NHC with trifunctional catalytic activity. The Co-NCNT@NHC displays a half-wave potential of 0.88 V versus RHE for ORR in alkaline electrolyte, an overpotential of 300 mV at 20 mA cm-2 for OER, and an overpotential of 180 mV at 10 mA cm-2 for HER. Impressively, a water electrolyzer is successfully powered by two rechargeable ZABs in series, with Co-NCNT@NHC as the 'all-in-one' electrocatalyst. These findings are inspiring for the rational fabrication of high-performance and multifunctional electrocatalysts intended for the practical application of integrated energy-related systems.

Interface Engineering with Quaternary Ammonium-Based Ionic Liquids toward Efficient Blue Perovskite Light-Emitting Diodes.

Perovskite light-emitting diodes (PeLEDs) have become a hot research topic in recent years and can now achieve an external quantum efficiency (EQE) of over 22% for green and red devices. However, the efficiency of blue PeLEDs, which are essential for display applications, lags far behind their green and red counterparts. The interface of the PeLEDs has a critical influence on the carrier transport and exciton recombination dynamics, and interface engineering is considered to be an effective strategy to improve the device performance. Herein, quaternary ammonium-based ionic liquids serve as an interfacial modification layer to significantly improve the device efficiency and stability. The interaction of quaternary ammonium cations with Pb(Br/Cl)6 octahedra promotes nucleation sites, which significantly improves the morphology of perovskite films and reduces the formation of defects in films. In addition, ion migration is also effectively suppressed in the device. As a result, with tributylmethylammonium bromide (TMAB) used as the interface layer, the EQE of the device is successfully increased from 3.5 to 6.7%, and the operational stability with a half-lifetime (T50) is increased by over 12 times. Our work provides a new class of interface modification materials toward high-performance blue PeLEDs.

Hierarchical multi-yolk-shell copper oxide@copper-1, 3, 5-benzenetricarboxylate as an ultrastable anode for lithium ion batteries.

The capacity attenuation of transition metal oxides (TMOs) and metal-organic frameworks (MOFs) is the obstacle for practical application in lithium ion batteries, due to the extensive volume variation upon charge/discharge cycles. Herein, a hierarchical composite material with copper oxide (CuO) multi-yolks and copper-1, 3, 5-benzenetricarboxylate (Cu-BTC) shell is synthesized by a facile method to study the effect of the hierarchical structure on the electrochemical performance. The porosity and pore volume of CuO@Cu-BTC composites are optimized to buffer the volume change and facilitate the infiltration of electrolytes by altering reaction conditions. The CuO@Cu-BTC (20 h) with the largest surface area and pore volume delivers an excellent reversible capacity of 780.7 mAh g-1 at 200 mA g-1 after 100 cycles, and ultrastable long-term performance with a specific capacity of 569 mAh g-1 at a current density of 1000 mA g-1 after 900 cycles. The corresponding full battery shows moderate capacity retention from 149.4 to 125.8 mAh g-1 after 70 cycles, with a specific capacity retention of 84.2%, based on the mass of lithium iron phosphate (LiFePO4) at 0.2 C (1 C = 170 mA g-1). This strategy applies copper oxide as the metal source of the coordination compound, as well as the internal yolks, which can be extended to the in-situ construction of other hierarchical composites, providing a new avenue for practical application of TMOs and MOFs as anode materials.

Preparation of Room Temperature Vulcanized Silicone Rubber Foam with Excellent Flame Retardancy.

To retard the spread of fire in many cases with sealing materials is significant. A series of silicone rubber foam materials were prepared with room temperature vulcanization and foaming reactions. The morphology, chemical structure, cell structure, and thermal stability were investigated and results proved that the synthesis of silicone rubber was successful in a wide range of feed ratios. The fire-retardant tests were carried out to study the fire-proof property of the composite materials, and the excellent performance showed a promising prospect for wide application in sealing materials.

2D conductive MOFs with sufficient redox sites: reduced graphene oxide/Cu-benzenehexathiolate composites as high capacity anode materials for lithium-ion batteries.

As a superconductive metal-organic framework (MOF) material, Cu-BHT (BHT: benzenehexathiol) can exhibit outstanding electrochemical properties owing to the potential redox reactions of the cuprous ions, sulfur species and benzene rings of Cu-BHT, but its compact texture limits the specific capacity of Cu-BHT. To improve the dense feature of Cu-BHT, rGO/Cu-BHT (rGO: reduced graphene oxide) composite materials are fabricated via a facile route and they exhibit applicable conductivities, improved lithium ion diffusion kinetics compared to pristine Cu-BHT, and sufficient redox sites. The rGO/Cu-BHT composite materials maximize the potential capacity of Cu-BHT, and the rGO/Cu-BHT 1 : 1 material achieves outstanding reversible specific capacities of 1190.4, 1230.8, 1131.4, and 898.7 mA h g-1, at current densities of 100, 200, 500, and 1000 mA g-1, respectively, superior to those of pristine Cu-BHT and rGO. These results present the promising future of 2D conductive MOFs as functional materials for energy storage, based on the regulation of electronic conductivity, redox sites, and lithium ion diffusion kinetics.

Factors Influencing Administration, Recognition, and Compliance of Medicine among Community Residents from Jilin Province, China: A Questionnaire Study.

INTRODUCTION: To identify and analyze factors that influence administration, recognition, and compliance of medicine among community residents in Jilin Province, China. METHODS: A survey was carried out among 2417 community residents in Jilin Province, China, to study their administration (CRA), recognition (CRR), and compliance (CRC) of medicine. Multivariate logistic regression analyses and chi-squared tests were performed to assess factors influencing CRA, CRR, and CRC. RESULTS: Logistic analyses showed that gender, educational level, and occupation were influencing factors on CRA; age, educational level, smoking status, and health condition were influencing factors on CRR; and gender, age, occupation, and health condition were influencing factors on CRC. CONCLUSIONS: CRA, CRR, and CRC are associated with specific lifestyles and social economic statuses of community residents. Attention should be paid to influencing factors in order to facilitate community pharmaceutical care, promote the rational use of drugs, and ensure the safe use of medications. This study explores the type and extent of professional services provided through community pharmacies in Jilin Province, China, and provides evidence for optimizing the quality of community pharmacy services.

Tailoring the Vertical Morphology of Organic Films for Efficient Planar-Si/Organic Hybrid Solar Cells by Facile Nonpolar Solvent Treatment.

The optical and electrical properties of the blending organic film poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) are strongly affected by its morphology, resulting in the performance variation in Si/organic hybrid solar cells. Here, a facile postsolvent treatment is used to tailor the vertical morphology of PEDOT:PSS by introducing a nonpolar solvent. X-ray photoelectron spectroscopy depth-profiling measurements show that the distribution of PEDOT and PSS on the surface of n-type Si can be changed by nonpolar solvent n-hexane (NHX) treatment, where more PSS aggregate at the bottom of the blend film and more PEDOT float up to the top, as compared with the reference sample. As a result, after NHX treatment, the average lifetime of the Si/organic films is increased from 152 µs for untreated samples to 248 µs for NHX-treated ones because of the better passivation effect of PSS on Si. Moreover, the transmission line model measurements indicate that the contact resistance (RC) of PEDOT:PSS film and the Ag electrode is decreased for better charge collection after NHX treatment. Eventually, the best power conversion efficiency (PCE) of 13.78% for NHX-treated planar solar cells is obtained, much higher than the PCE (with best of 12.78%) of reference devices without nonpolar solvent treatment. Our results provide a facile method to tailor the vertical morphology of the PEDOT:PSS in Si/organic hybrid solar cells.

Multiple Active Sites: Lithium Storage Mechanism of Cu-TCNQ as an Anode Material for Lithium-Ion Batteries.

Recently, carboxylate metal-organic framework (MOF) materials were reported to perform well as anode materials for lithium-ion batteries (LIBs); however, the presumed lithium storage mechanism of MOFs is controversial. To gain insight into the mechanism of MOFs as anode materials for LIBs, a self-supported Cu-TCNQ (TCNQ: 7,7,8,8-tetracyanoquinodimethane) film was fabricated via an in situ redox routine, and directly used as electrode for LIBs. The first discharge and charge specific capacities of the self-supported Cu-TCNQ electrode are 373.4 and 219.4 mAh g-1 , respectively. After 500 cycles, the reversible specific capacity of Cu-TCNQ reaches 280.9 mAh g-1 at a current density of 100 mA g-1 . Mutually validated data reveal that the high capacity is ascribed to the multiple-electron redox conversion of both metal ions and ligands, as well as the reversible insertion and desertion of Li+ ions into the benzene rings of ligands. This work raises the expectation for MOFs as electrode materials of LIBs by utilizing multiple active sites and provides new clues for designing improved electrode materials for LIBs.

MOF-Derived CuS@Cu-BTC Composites as High-Performance Anodes for Lithium-Ion Batteries.

The CuS(x wt%)@Cu-BTC (BTC = 1,3,5-benzenetricarboxylate; x = 3, 10, 33, 58, 70, 99.9) materials are synthesized by a facile sulfidation reaction. The composites are composed of octahedral Cu3 (BTC)2 ·(H2 O)3 (Cu-BTC) with a large specific surface area and CuS with a high conductivity. The as-prepared CuS@Cu-BTC products are first applied as the anodes of lithium-ion batteries (LIBs). The synergistic effect between Cu-BTC and CuS components can not only accommodate the volume change and stress relaxation of electrodes but also facilitate the fast transport of Li ions. Thus, it can greatly suppress the transformation process from Li2 S to polysulfides by improving the reversibility of the conversion reaction. Benefiting from the unique structural features, the optimal CuS(70 wt%)@Cu-BTC sample exhibits a remarkably improved electrochemical performance, showing an over-theoretical capacity up to 1609 mAh g-1 after 200 cycles (100 mA g-1 ) with an excellent rate-capability of ≈490 mAh g-1 at 1000 mA g-1 . The outstanding LIB properties indicate that the CuS(70 wt%)@Cu-BTC sample is a highly desirable electrode material candidate for high-performance LIBs.

Distribution, source, and environmental risk assessment of phthalate esters (PAEs) in water, suspended particulate matter, and sediment of a typical Yangtze River Delta City, China.

Phthalates (PAEs) in drinking water sources such as the Yangtze River in developing countries had aroused widespread concern. Here, the water, suspended particulate matter (SPM), and sediment samples were collected from 15 sites in wet and dry seasons in Zhenjiang, for the determination of six PAEs (DMP, DEP, DIBP, DBP, DEHP, and DOP) using the solid-phase extraction (SPE) or ultrasonic extraction coupled with gas chromatography-mass spectrometry (GC-MS). The total concentrations of six PAEs (Σ6PAEs) spanned a range of 2.65-39.31 µg L-1 in water, 1.97-34.10 µg g-1 in SPM, and 0.93-34.70 µg g-1 in sediment. The partition coefficients (Kd1) of PAEs in water and SPM phase ranged from 0.004 to 3.36 L g-1 in the wet season and from 0.12 to 2.84 L g-1 in the dry season. Kd2 of PAEs in water and sediment phase was 0.001-9.75 L g-1 in the wet season and 0.006-8.05 L g-1 in the dry season. The dominant PAEs were DIBP, DBP, and DEHP in water and SPM, DIBP, DEHP, and DOP in sediment. The concentration of DBP in water exceeded the China Surface Water Standard. The discharge of domestic sewage and industrial wastewater might be the main potential sources of PAEs. The risk quotient (RQ) method used for the risk assessment revealed that DBP (0.01 < RQ < 1) posed a medium risk, while DIBP and DEHP (RQ > 1) posed a high environmental risk in water, DIBP (RQ > 1) also showed a high risk in sediment.

Saccharopolyspora qinghaiensis sp. nov., a novel actinobacterium isolated from a salt lake.

A novel halophilic, Gram-positive and aerobic actinobacterium, designated strain AFM 20147T, was isolated from a sediment sample collected from Xiaochaidan Salt Lake of Qinghai, China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain AFM 20147T belongs to the genus Saccharopolyspora, shows high sequence similarities to Saccharopolyspora griseoalba AFM 10238T (99.41%) and Saccharopolyspora halophila YIM 90500T (98.20%), and has low similarities (below 98.0%) with other members of the genus. The DNA-DNA relatedness values of strain AFM 20147T with S. griseoalba AFM 10238T and S. halophila YIM 90500T were 40 ± 1.7% and 37 ± 2.3%, respectively. Optimal growth was found to occur at 28 °C, pH 7.5 and in the presence of 7.5% (w/v) NaCl. Strain AFM 20147T was found to contain meso-diaminopimelic acid as the cell wall diamino acid, and galactose and arabinose as the whole cell sugars. The major fatty acids were identified as iso-C15:0, iso-C16:0 and anteiso-C17:0. The major polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylinositol and phosphatidylcholine. MK-9(H4) was found to be the predominant menaquinone and the DNA G+C content was determined to be 67.8 mol%. DNA-DNA relatedness data, together with phenotypic and chemotaxonomic differences, clearly distinguish the isolate from its close neighbours. On the basis of the data from this polyphasic analysis, a novel species Saccharopolyspora qinghaiensis sp. nov. is proposed. The type strain is S. qinghaiensis AFM 20147T (=KCTC 49190T =CGMCC 4.7556T).

Seed-mediated synthesis of Au@PtCu nanostars with rich twin defects as efficient and stable electrocatalysts for methanol oxidation reaction.

Pt-based nanocrystals with a twinned structure are highly desirable to achieve high performances in both catalytic activity and durability for methanol oxidation reaction (MOR). However, it still remains great challenge for producing such twinned nanocrystals due to the high internal strain energy of Pt. Here we present a seed-mediated approach to generate Au@PtCu nanostars with a five-fold twinned structure using Au decahedra as seeds. The composition of Pt/Cu in the nanocrystals was tuned by varying the molar ratio of Pt to Cu salt precursors with the amount of Au seeds being the same. Through composition optimization, Au@Pt1.2Cu nanostars achieved the highest specific (1.06 mA cm-2) and mass (0.18 mA mgPt -1) activities for MOR, which were about 5.9 and 1.6 times higher than those of commercial Pt/C, respectively. After accelerated stability test (ADT) for 1500 cycles, such nanostars remained ∼95% of specific activity compared to a loss of ∼28% for commercial Pt/C, indicting their superior durability for MOR. We believed that this enhancement may arise from the unique twinned structure and possible synergetic effect between Pt and Cu components.

Silent pelvic splenosis: Case report.

INTRODUCTION: Splenosis is a benign, usually asymptomatic, condition involving autotransplantation of splenic tissue that occurs frequently after splenic rupture caused by trauma or surgery [1]. Up to 67% of the patients presenting splenic rupture may develop splenosis [2]. The interval of time between the initial trauma and the diagnosis varies from 3 to 45 years with an average interval of 21 years [3]. Since the finding of this entity is usually accidental, the real incidence is not well known. Although splenosis following traumatic splenectomy after traffic accidents is well-documented in the literature, there do not seem to be many reported cases where splenosis produced gynecological complications [4]. There were fewer than 100 cases of splenosis reported since the first report of Buchbinder and Lipkoff in 1939 [5] in the English language medical literature of which only a minority appeared in the gynecological literature. PRESENTATION OF CASE: A case of pelvic and omentum majus splenosis in a patient is presented. DISCUSSION: Pelvic splenosis remains a rare finding in clinical practice. In most reported cases in the literature, the diagnosis was not considered before surgery. This approach may obviate the need for invasive evaluation for a primary or secondary neoplasm, and thus unnecessary surgery, and therefore preserve probable functional splenic tissue. Our case was diagnosed using non-surgical modalities. CONCLUSION: Our case emphasizes the rare diagnosing of pelvic splenosis in the evaluating pelvic mass with the tissue evidence instead of surgery.

Study on the condensed state physics of poly(ε-caprolactone) nano-aggregates in aqueous dispersions.

Narrowly size distributed spherical, ellipsoid-like and lamellae stacked poly(ε-caprolactone) (PCL) nano-aggregates in aqueous dispersions with a diameter ranging from about (∼) 50 to 330 nm were prepared via nanoprecipitation method in the present study. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to characterize the morphology and size of the PCL nano-aggregates. We investigated the melt behaviors of the original (without any thermal treatment after preparation) PCL nano-aggregates in aqueous dispersions by nano differential scanning calorimetry (nano-DSC). In particular, the condensed state of the original ∼50 nm PCL nanospheres was demonstrated to be amorphous as a result of exhibiting no melting peak in the first nano-DSC heating scan. Furthermore, the rubbery↔flow condensed state transition of the amorphous PCL nanospheres was explored by fluorescence measurements. Moreover, the confined crystallization of the ∼50 nm PCL nanospheres from rubbery state in aqueous dispersions was investigated via isothermal crystallization process. Enormous supercooling was observed during crystallization due to nanoconfinement effect. In addition, when the diameter of the original PCL aggregates was increased to more than 150 nm, PCL is in semi-crystalline state and the crystallinity increases with the diameter.

DNA demethylation is superior to histone acetylation for reactivating cancer-associated genes in ovarian cancer cells.

To investigate the contributions of histone H3 lysine 9 acetylation and DNA methylation to p16, hMLH1 and MGMT silencing in ovarian cancer cells, we treated three ovarian cancer cell lines with Trichostatin A (TSA) and 5-aza-2'-deoxycytidine and examined the status of mRNA expression, DNA methylation and histone H3 lysine 9 acetylation at the promoter of p16, hMLH1 and MGMT. The results showed that the hypermethylated silenced tumor-related genes in the ovarian cancer cells were characterized by hypoacetylated histone H3 lysine 9. Treatment with TSA resulted in the increase of histone H3 lysine 9 acetylation at the hypermethylated promoter, but with little effects on gene expression. TSA did not contribute to DNA demethylation. 5-aza-2'-deoxycytidine treatment caused DNA demethylation, increased histone H3 lysine 9 acetylation at the hypermethylated promoter and resulted in reactivation of p16, hMLH1 and MGMT. Combined treatments synergistically increased histone H3 lysine 9 acetylation accompanied by the re-expression of the hypermethylated genes. To conclude, in ovarian cancer cells, DNA methylation and histone deacetylation act synergistically for the silencing of cancer-associated genes. DNA demethylation is superior to histone acetylation for reactivating cancer-associated genes.

Role of histone modifications and DNA methylation in the regulation of O6-methylguanine-DNA methyltransferase gene expression in human stomach cancer cells.

To determine a possible function of histone modifications in stomach carcinogenesis, we analyzed global and MGMT-promoter levels of di-methyl-H3-K9, di-methyl-H3-K4 and acetyl-H3-K9, as well as MGMT DNA methylation and mRNA expression following treatment with 5-aza-2' -deoxycytidine and/or Trichostatin A. We found that histone H3-K9 di-methylation, H3-K4 di-methylation, H3-K9 acetylation and DNA methylation work in combination to silence MGMT. The results indicate that histone modifications as well as DNA methylation may be involved in stomach carcinogenesis. In addition to its effect on DNA methylation, 5-aza-2' -deoxycytidine can act at histone modification level to reactivate MGMT expression in a region-specific and DNA methylation-dependent manner.

[Effects of 5-Aza-2'-deoxycytidine and trichostatin A on P16, hMLH1 and MGMT genes and DNA methylation in human gastric cancer cells].

OBJECTIVE: To investigate the effects of 5-Aza-2'-deoxycytidine (5-Aza-dC) and trichostatin A (TSA) on DNA methylation and expression of P16, hMLH1 and MGMT genes in the human gastric cancer cell line MGC-803, and to explore the mechanism of P16, hMLH1 and MGMT gene silencing in human gastric cancer cells. METHODS: MGC-803 cells were cultured in RPMI-1640 medium and were treated with 5-Aza-dC or TSA. Methylation-specific polymerase chain reaction (MS-PCR) was used to detect the promoter methylation status of P16, hMLH1 and MGMT genes. RT-PCR was used to detect the mRNA expressions of P16, hMLH1 and MGMT. RESULTS: Promoter hypermethylation of P16, hMLH1 and MGMT genes were detected in MGC-803 cells, and mRNA expressions of P16, hMLH1 and MGMT were absent before treatment. After treatment with 5-Aza-dC, the promoter region of the P16, hMLH1 and MGMT gene exhibited a demethylation status, and their mRNA expressions were increased. The treatment with TSA had no effects on DNA demethylation or restoration of P16 or hMLH1 expression. P16, hMLH1 and MGMT mRNA relative expression levels after treatment with a combination of 5-Aza-dC and TSA were 0.412+/-0.030, 0.397+/-0.024 and 0.553+/-0.043 respectively, which were higher than those after 5-Aza-dC treatment alone (0.221+/-0.022, 0.214+/-0.018 and 0.156+/-0.017, all P<0.05). CONCLUSIONS: Promoter hypermethylation is a major mechanism of P16, hMLH1 and MGMT gene silencing in human gastric cancer cells. Treatment with 5-Aza-dC alone or the combination of 5-Aza-dC and TSA can reactivate the expressions of these genes.

Promoter histone H3 lysine 9 di-methylation is associated with DNA methylation and aberrant expression of p16 in gastric cancer cells.

In the course of gastric cancer development, gene silencing by DNA hypermethylation is an important mechanism. While DNA methylation often co-exists with histone modifications to regulate gene expression, the function of histone modifications in gene silencing in gastric cancer has not been evaluated in detail. p16, a well-known tumor suppressor gene, is frequently silenced in DNA hypermethylation manner in gastric cancer. Accordingly, we chose p16 to clarify whether there is a correlation among histone H3 lysine 9 (H3-K9) di-methylation, H3-K9 acetylation, DNA methylation and p16 expression in human gastric cancer. Three gastric cancer cells, MKN-45, SGC-7901 and BGC-823, were treated with 5-aza-2'-deoxycytidine (5-Aza-dC) and/or trichostatin A (TSA). We investigated p16 promoter DNA methylation status, p16 mRNA levels, regional and global levels of di-methyl-H3-K9 and acetyl-H3-K9 in four groups: i) 5-Aza-dC, ii) TSA, iii) the combination of 5-Aza-dC and TSA and iv) control group with no treatments. p16 silencing is characterized by DNA hypermethylation, H3-K9 hypoacetylation and H3-K9 hypermethylation at the promoter region. Treatment with TSA, increased H3-K9 acetylation at the hypermethylated promoter, but did not affect H3-K9 di-methylation or p16 expression. By contrast, treatment with 5-Aza-dC, reduced H3-K9 di-methylation, increased H3-K9 acetylation at the hypermethylated promoter and reactivated the expression of p16. Combined treatment restored the expression of p16 synergistically. In addition, 5-Aza-dC and the combined treatment did not result in global alteration of H3-K9 di-methylation. These results suggest that H3-K9 di-methylation, H3-K9 acetylation and DNA methylation work in combination to silence p16 in gastric cancer. The decreased H3-K9 di-methylation correlates with DNA demethylation and reactivation of p16. H3-K9 di-methylation as well as DNA methylation related to p16 silencing is limited to the promoter region. In addition to its effect on DNA methylation, 5-Aza-dC can act at histone modification levels to reactivate p16 expression in region-specific and DNA methylation-dependent manner.

[Effects of 5-Aza-2'-deoxycytidine and trichostatin A on DNA methylation and expression of hMLH1 in ovarian cancer cell line COC1/DDP].

BACKGROUND & OBJECTIVE: Cisplatin (DDP) can cause DNA damage in cells. DNA mismatch repair proteins serve to detect DDP-caused DNA damage and generate an injury signal that eventually contributes to the triggering of tumor cell apoptosis. As a member of the mismatch repair system, the absence of hMLH1 expression contributes to the resistance of tumor cells to DDP. This study was to explore the role of hMLH1 expression and DNA methylation in DDP-resistance of human ovarian cancer, and to evaluate the reversal effects of 5-aza-2'-deoxycytidine (5-Aza-dC) and trichostatin A (TSA) on DDP-resistance. METHODS: We cultured human ovarian cancer cell line COC1 and its DDP-resistant subline, COC1/DDP. We treated the two cell lines with 5-Aza-dC and TSA. DNA methylation at hMLH1 gene promoter was detected by methylation-specific polymerase chain reaction (MSP). The expression of hMLH1 was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The inhibition rate of cell proliferation was detected by MTT assay. RESULTS: In COC1 cells, both hMLH1 mRNA and protein were detected, while no DNA methylation of hMLH1 gene was detected. 5-Aza-dC and TSA used alone or in combination had no effects on DNA methylation, hMLH1 mRNA or protein expression (P>0.05), and cell proliferation. In COC1/DDP cells, DNA hypermethylation of hMLH1 gene was detected, while no hMLH1 mRNA or protein was detected. 5-Aza-dC resulted in DNA demethylation and restoration of hMLH1 expression. TSA had no effect on DNA demethylation or restoration of hMLH1 expression. 5-Aza-dC plus TSA also resulted in DNA demethylation, restored hMLH1 expression more obviously than 5-Aza-dC did (P<0.05), and restricted the proliferation of COC1/DDP cells. CONCLUSIONS: Hypermethylation of DNA promoter is related to the silencing of hMLH1 in ovarian cancer COC1/DDP cells. 5-Aza-dC alone or in combination with TSA results in DNA demethylation of hMLH1 gene, restoration of hMLH1 expression and reversal of DDP-resistance of COC1/DDP cells.

[Histone H3 lysine 9 methylation is associated with the expression of hMLH1 and DNA methylation in gastric cancer cells].

OBJECTIVE: To identify the association of his tone H3 lysine 9 (H3-K9) methylation with DNA methylation and the expression of the mismatch repair gene hMLH1 in human gastric cancer cells. METHODS: Gastric cancer cells of the lines BGC-823 and MGC-803 were cultured and treated with 5-Aza-2'-deoxycytidine (5-Aza-dC), a demethylation agent, for 72 hour. Chromatin immunoprecipitation (ChIP) assay was used to assess the status of histone H3 lysine 9 methylation in the promoter regions of hMLH1 gene. Methylation-specific PCR (MSP) was used to evaluate the effect of 5-Aza-dC on DNA methylation status. RT-PCR was used to examine the hMLH1 gene expression. RESULTS: In the MGC-803 cells, silenced hMLH1 gene was characterized by DNA methylation and histone H3-K9 hypermethylation; 5-Aza-dC demethylated the DNA and reduced the histone H3-K9 methylation at silenced loci and resulted in reactivation of hMLH1 gene therein. Contrary to the MGC-803 cells, BGC-823 cells expressed hMLH1 gene with DNA demethylation and histone H3-K9 hypomethylation; and 5-Aza-dC had no effects on the gene expression, DNA methylation, and histone H3-K9 methylation therein. CONCLUSION: Hypermethylation of DNA in the promoter region is related to transcriptional silencing of hMLH1 gene. Histone H3-K9 methylation in different regions of the promoter studied correlates with DNA methylation status of hMLH1 gene in gastric cancer cells. Alteration of DNA methylation affects histone H3-K9 methylation. 5-Aza-dC can control hMLH1 expression, DNA methylation, and histone H3-K9 methylation in the promoter.