Animals ; DNA Methylation ; DNA-Cytosine Methylases ; chemistry ; metabolism ; physiology ; Embryonic Development ; physiology ; Humans ; Mice ; Site-Specific DNA-Methyltransferase (Adenine-Specific) ; chemistry ; metabolism ; physiology

OBJECTIVE: To analyze the effect of DNA hypermethylation on NOR1 promoter activity and expression. METHODS: NOR1 promoter plasmids were treated with SssI methyltransferase. The plasmids were modified by sodium bisulfite and purified. Sodium bisulfite-modified plasmids were subjected to PCR with primers designed to analyze the methylation status of 26 CpG sites in a 311-bp region of the NOR1 promoter. Cells were transfected by methylated or mock-methylated promoter plasmids. The promoter activities were assessed by the luciferase levels of cell lysates or by directly observing GFP expression under fluorescence microscope. HL60 cells were treated with different concentrations of 5-aza-dC. Total RNA was isolated from harvested cells. Real-time RT-PCR was used to measure the expression level of NOR1 mRNA. RESULTS: Bisulfite sequencing confirmed that SssI methyltransferase treatment successfully resulted in intensive hypermethylation of the NOR1 promoter plasmids. The promoter activity of NOR1 promoter plasmids was totally blocked by SssI methyltransferase treatment. NOR1 expression levels in HL60 cells were restored by 5-aza-dC treatment. CONCLUSION NOR1 promoter plasmids are intensively hypermethylated by SssI methyltransferase treatment. The promoter activity of NOR1 promoter plasmids are totally blocked by SssI methyltransferase treatment. The 5-aza-dC treatment may restore the endogenous NOR1 mRNA level in HL60 cells.
Azacitidine ; analogs & derivatives ; pharmacology ; Base Sequence ; Cell Line, Tumor ; CpG Islands ; DNA Methylation ; DNA Modification Methylases ; antagonists & inhibitors ; DNA-Cytosine Methylases ; pharmacology ; Decitabine ; Epigenesis, Genetic ; Gene Silencing ; HL-60 Cells ; Humans ; Membrane Transport Proteins ; genetics ; metabolism ; Molecular Sequence Data ; Nasopharyngeal Neoplasms ; pathology ; Promoter Regions, Genetic ; genetics ; RNA, Messenger ; genetics ; metabolism

OBJECTIVETo explore the regulatory effect of CpG methyltransferase (M.SssI) on expression of claudin-7 and claudin-8, promoting apoptosis and inhibiting proliferation of human colorectal cancer HT-29 cells.

METHODSHT-29 cells were treated with M.SssI (50 U/ml) for 24 hours. The methylation status of claudin-7 and claudin-8 gene promoters was assayed by bisulfite sequencing PCR (BSP). Real-time PCR with SYBR green I technique was used to detect the relative expression of claudin-7 and -8 mRNA, and claudin-7 and claudin-8 proteins were tested by cell immunofluorescence and Western blotting, while the effect on cell apoptosis was assessed by Hoechst 33342 fluorescence and flow cytometry. Inhibition of cell proliferation was measured by MTT assay.

RESULTSThe amounts of methylated claudin-7 and claudin-8 gene CpGs were 25, 10 in the M.SssI group, 9 and 5 in the PBS group, 0 and 3 in the 5-azacytidine group, respectively. Compared with the PBS group, Claudin-7 and -8 were significantly reduced by M.SssI (P < 0.05), but increased by 5-azacytidine (P < 0.05) at both mRNA and protein levels. Hoechst 33342 staining revealed that HT-29 cells treated with PBS and 5-azacytidine were not significantly different, showing even blue fluorescence, round shape and same cell volume. But the M.SssI group presented more apoptotic cells with intensive white fluorescence intensity. Cytometry indicated that early apoptotic index of the M.SssI group was increased by 84.7%, compared with that of the PBS group (P = 0.002). Measurement of MTT optical density demonstrated that cell growth of the M.SssI group was significantly lower than that of the PBS group (P = 0.002), with an inhibition rate of 32.1%, whereas the proliferation of 5-azacytidine group was similar to that of the PBS group (P = 0.084).

CONCLUSIONSOur findings suggest that M.SssI can down-regulate claudin-7, -8 mRNA and proteins in the human colon cancer HT-29 cells by up-regulating methylation status of claudin-7 and -8 gene promoters, and finally induce apoptosis and inhibit proliferation of the tumor cells.

Apoptosis ; physiology ; Cell Proliferation ; Claudins ; metabolism ; Colonic Neoplasms ; DNA-Cytosine Methylases ; metabolism ; Down-Regulation ; physiology ; Flow Cytometry ; Gene Expression Regulation ; HT29 Cells ; Humans ; RNA, Messenger ; Real-Time Polymerase Chain Reaction

OBJECTIVETo explore the polymorphism of low density lipoprotein receptor (LDL-R) genes Pvu II and Ava II in a population with phlegm-dampness constitution (PDC).

METHODSPolymorphism of LDL-R genes at Pvu II and Ava II of 48 persons with gentle constitution (GC) and 61 with PDC were analyzed with PCR-RELP technique, and their serum contents of lipids and glucose were determined and compared as well.

RESULTSThe A+ allelic and P-allelic frequency were higher and the P+ allelic frequency was lower in subjects with PDC than those in subjects with GC, which were 0.3083 vs 0.1771, 0.9098 vs 0.7708 and 0.0902 vs 0.2292, respectively, all showing significant difference between the two groups (P<0.05). Comparison of the two groups in serum levels of triglyceride (TG), fasting blood glucose, 2 h postprandial blood glucose, and 2 h postprandial insulin showed that all the parameters were higher in subjects with PDC than in subjects with GC respectively, showing significant difference (P<0.05).

CONCLUSIONPDC is related with the P- and A+ allelic frequency of higher LDL-R genes at Pvu II and Ava II, therefore, the polymorphism of LDL-R genes could be taken as one of the genetic markers for PDC, and humans with PDC are more liable to suffer from blood lipids and glucose disorder than those with GC.

Adult ; Aged ; Aged, 80 and over ; Blood Glucose ; C-Peptide ; DNA-Cytosine Methylases ; metabolism ; Deoxyribonucleases, Type II Site-Specific ; metabolism ; Female ; Genetic Predisposition to Disease ; Humans ; Lipids ; blood ; Male ; Middle Aged ; Polymorphism, Genetic ; Polymorphism, Restriction Fragment Length ; Receptors, LDL ; genetics ; Tongue Diseases ; genetics

OBJECTIVETo compare the DNA methylation-related alteration induced by trichloroethylene (TCE) in human hepatic L-02 cells (L-02 cells) and SET deficient cells, and reveal the role of SET on the mechanisms in TCE-induced epigenetic pathway.

METHODSThe L-02 cells and pre-established SET deficient cells were treated with different TCE concentrations, and the changes of total cell viability, DNA methylation level and DNA methyltransferases (DNMTs) activity were measured, respectively. In addition, the TCE-induced alteration in the protein expression of DNMT1, DNMT3a and DNMT3b were analyzed by Western blotting.

RESULTSAfter treatment with TCE for 24 h, the cell proliferation level was significantly decreased in both cell lines. When concentrations of TCE were 0, 1.0, 2.0, 4.0 and 8.0 mmol/L, the proliferation levels of L-02 cells were 100.00±2.70, 83.34±2.38, 75.56±4.51, 71.67±2.77 and 66.67±1.63, respectively (F = 58.29, P < 0.001); the cell proliferation levels of SET deficient cells were 101.12±1.67, 85.01±2.33, 79.44±1.67, 78.337±3.89 and 76.11±3.33, respectively (F = 42.41, P < 0.001). When concentration of TCE reached 4.0 mmol/L, the difference of cell proliferation level between two groups was statistically significant (t = -3.51; P = 0.013). After treated by TCE for 24 h, the global DNA methylation significantly decreased in both cell lines (F value was 212.87 and 79.32, respectively, P < 0.001). The difference between two groups was not statistically significant. After treated by TCE for 24 h, the methyltransferases activities were significantly decreased in both cell cells (F values were 77.92 and 113.80, respectively, P-0.001). The SET deficiency could inhibit the decrease of methyltransferases activity under TCE treatment. When the concentration of TCE reached 8.0 mmol/L, the enzymatic activity of L-02 cells and SET deficient cells decreased to 67.61%±2.85% and 72.97%± 1.94%, respectively. The difference between two groups was statistically significant (t = -3.94, P = 0.008). After treated with TCE for 24 h, concentrations of TCE were 0, 1.0, 2.0, 4.0 and 8.0 mmol/L, and the relative protein levels of DNMT1 in normal L-02 cells increased significantly to 1.00±0.03, 1.28±0.04, 1.20±0.04, 1.62±0.05, 1.43±0.04 (F = 103.00, P < 0.001); In SET deficient cells, the expressions of DNMT1 were 1.00±0.04, 0.96±0.02, 1.19±0.05, 0.85±0.03, 0.83±0.03, which was significantly down-regulated under TCE treatment (F = 44.18, P < 0.001).

CONCLUSIONSET deficiency can significantly attenuate the TCE-induced decreases of cell viability and DNMTs activity, as well as alteration of protein expression of DNMT1 in L-02 cells, which indicated that SET was involved in the mechanism of TCE-induced cytotoxicity and epigenetic pathway in L-02 cells.

Cell Line ; Cell Survival ; DNA (Cytosine-5-)-Methyltransferase 1 ; DNA (Cytosine-5-)-Methyltransferases ; DNA Methylation ; Humans ; Liver ; Trichloroethylene

OBJECTIVE: To examine the expression of DNMT1, DNMT3a, and DNMT3b in the eutopic and ectopic endometrium in women with endometriosis. METHODS: RT-PCR and real-time RT-PCR were used to examine the expression of DNMT1, DNMT3a, and DNMT3b in the eutopic and ectopic endometrium in 20 women with endometriosis and the endometrium in 20 women without endometriosis. Immunofluorescene staining was used to detect the expression of DNMT1 in these tissues. RESULTS: The expression levels of DNMT1, DNMT3a, and DNMT3b were significantly lower in the ectopic endometrium and eutopic endometrium than those of the control endometium (P<0.05). The changes in the ectopic endometium compared with the control endometium were 0.44, 0.12, and 0.27 folds for DNMT1, DNMT3a, and DNMT3b, respectively, and these in the eutopic endometrium were 0.27, 0.13, and 0.15 folds for DNMT1,DNMT3a, and DNMT3b, respectively. The expression level of DNMT1, DNMT3a, and DNMT3b between the ectopic endometrium and eutopic endometrium was not significantly different (P>0.05 ). Immunofluorescence staining that DNMT1 protein level significantly decreased in the ectopic endometrium and eutopic endometrium of endometriosis patients. CONCLUSION Decreased expression levels of DNMT1, DNMT3a, and DNMT3b in the ectopic endometrium and eutopic endometrium may play a role in patients with abnormal epigenetics which may lead to endometriosis.
Adult ; DNA (Cytosine-5-)-Methyltransferase 1 ; DNA (Cytosine-5-)-Methyltransferases ; metabolism ; Endometriosis ; enzymology ; genetics ; Endometrium ; enzymology ; Epigenomics ; Female ; Humans

OBJECTIVETo investigate the correlation of genomic DNA methylation level with unexplained early spontaneous abortion and analyze the role of DNMT1, DNMT3A and DNMT3B.

METHODSForty-five villus samples from spontaneous abortion cases (with 33 maternal peripheral blood samples) and 44 villus samples from induced abortion (with 34 maternal peripheral blood samples) were examined with high-pressure liquid chromatography (HPLC) to measure the overall methylation level of the genomic DNA. The expressions of DNMT mRNAs were detected using fluorescence quantitative-PCR in the villus samples from 33 induced abortion cases and 30 spontaneous abortion cases.

RESULTSGenomic DNA methylation level was significantly lower in the villus in spontaneous abortion group than in induced abortion group (P<0.01), but similar in the maternal blood samples between the two groups (P>0.05). The mean mRNA expression levels of DNMT1 and DNMT3A in the villus were significantly lower in spontaneous abortion group than in induced abortion group (P<0.05), but DNMT3B expression showed no significant difference between them (P>0.05).

CONCLUSIONInsufficient genomic DNA methylation in the villus does exist in human early spontaneous abortion, and this insufficiency is probably associated with down-regulated expressions of DNMT1 and DNMT3A.

Abortion, Spontaneous ; genetics ; DNA (Cytosine-5-)-Methyltransferase 1 ; DNA (Cytosine-5-)-Methyltransferases ; metabolism ; DNA Methylation ; Female ; Genomics ; Humans ; Pregnancy ; RNA, Messenger

In order to study the activity and gene expression of DNA methyltransferase (DNMT) on U266 myeloma cells and to analyze their significance, the activity of DNMT was detected by ELISA, and the expressions of DNMT1, DNMT3a and 3b were analyzed by RT-PCR. U266 cells were treated by phenylhexyl isothiocyanate (PHI), and the change of activity and gene expression of DNMT were determined. The results indicated that the activity and expression of DNMT in U266 myeloma cells were higher, compared with normal control. After being treated by different concentration of PHI, U266 cells were driven into apoptosis and the activity of DNMT decreased obviously and the mRNA level of DNMT declined. It is concluded that the activity and gene expression of DNMT on U266 myeloma cells are higher, and DNMT may be a new therapeutic target of multiple myeloma.
Cell Line, Tumor ; DNA (Cytosine-5-)-Methyltransferase 1 ; DNA (Cytosine-5-)-Methyltransferases ; metabolism ; DNA Methylation ; Humans ; Multiple Myeloma ; metabolism ; RNA, Messenger ; genetics

Hypermethylation in the promoter region is an important epigenetic mechanism for the transcriptional repression of a number of cancer-associated genes, and over-expression and/or increased activity of DNA methyltransferases are considered to be the main cause of promoter hypermethylation. In order to explore the roles of two methyltransferase members (DNMT1 and DNMT3b) in the cholangiocarcinoma tumorigenesis, antisense eukaryotic expression plasmid of DNMT1 and DNMT3b gene was constructed respectively, and were co-transfected into the human cholangiocarcinoma cell line QBC-939 to observe their biological effects on the cell growth and proliferation ability, apoptosis, cell cycle alteration, and the tumorigenesis ability in the subcutaneous tissue of nude mouse. The results demonstrated that co-transfection with antisense eukaryotic expression plasmid of DNMT1 and DNMT3b gene and single transfection with antisense eukaryotic expression plasmid of DNMT1 gene can suppress the growth and proliferation of QBC-939, block the cell cycle at G1 phase, increase the apoptosis rate, minimize the tumor size in the subcutaneous tissue of nude mouse. The suppressing biological effect of co-transfection is stronger than single transfection with antisense DNMT1. Meanwhile, single transfection with antisense eukaryotic expression plasmid of DNMT3b gene has no effects on the biological characteristics of QBC-939. This study suggests that DNMT1 gene plays a key role in DNA methylation and DNMT3b gene may act as an accessory to support its function in inactivation of tumor suppressor genes. Combination DNMT1 and DNMT3b will increase their biological effects and have the synergistic effect on suppressing the growth of human cholangiocarcinoma cell line QBC-939.
Apoptosis ; Biliary Tract Neoplasms/*metabolism ; Cell Line, Tumor ; Cell Proliferation ; Cholangiocarcinoma/*metabolism ; DNA (Cytosine-5-)-Methyltransferase/*biosynthesis ; DNA (Cytosine-5-)-Methyltransferase/genetics ; Down-Regulation ; Gene Expression Regulation, Neoplastic ; Genetic Vectors ; Mice, Nude ; Neoplasm Transplantation

OBJECTIVETo investigate DNA methylation variation in human cells induces by B(a)P, and to explore the role of PARP1 during this process.

METHODSThe changes of DNA methylation of 16HBE and its PARP1-deficient cells exposed to B(a)P (1.0, 2.0, 5.0, 10.0, 15.0, 30.0 µmol/L) were investigated by immunofluorescence and high performance capillary electrophoresis, and simultaneously, the expression level of PARP 1 and DNMT 1 were monitored dynamically.

RESULTSThe percentage of methylated DNA of overall genome (mCpG%) in 16HBE and 16HBE-shPARP1 cells were separately (4.04 ± 0.08)% and (9.69 ± 0.50)%. After being treated by 5-DAC for 72 hours, mCpG% decreased to (3.15 ± 0.14)% and (6.07 ± 0.54)%. After both being exposed to B(a)P for 72 hours, the mCpG% in 16HBE group (ascending rank) were separately (5.10 ± 0.13), (4.25 ± 0.10), (3.91 ± 0.10), (4.23 ± 0.27), (3.70 ± 0.15), (3.08 ± 0.07); while the figures in 16HBE-shPARP1 group (ascending rank) were respectively (10.63 ± 0.60), (13.08 ± 0.68), (9.75 ± 0.55), (7.32 ± 0.67), (6.90 ± 0.49) and (6.27 ± 0.21). The difference of the results was statistically significant (F values were 61.67 and 60.91, P < 0.01). For 16HBE group, expression of PARP 1 and DNMT 1 were 141.0%, 158.0%, 167.0%, 239.0%, 149.0%, 82.9% and 108.0%, 117.0%, 125.0%, 162.0%, 275.0%, 233.0% comparing with the control group, whose difference also has statistical significance (t values were 11.45, 17.32, 32.24, 33.44, 20.21 and 9.87, P < 0.01). For 16HBE-shPARP1 group, expression of PARP 1 and DNMT 1 were 169.0%, 217.0%, 259.0%, 323.0%, 321.0%, 256.0% and 86.0%, 135.0%, 151.0%, 180.0%, 229.0%, 186.0% comparing with the control group, with statistical significance (t values were 9.06, 15.92, 22.68, 26.23, 37.19 and 21.15, P < 0.01). When the dose of B(a)P reached 5.0 µmol/L, the mRNA expression of DNMT 1 in 16HBE group (ascending rank) were 125.0%, 162.0%, 275.0%, 233.0% times of it in control group, with statistical significance (t values were 12.74, 24.92, 55.11, 59.07, P < 0.01); while the dose of B(a)P reached 2.0 µmol/L, the mRNA expression of DNMT 1 in 16HBE-shPARP1 group were 135.0%, 151.0%, 180.0%, 229.0%, 186.0% of the results in control group, and the differences were statistically significant (t values were 23.82, 40.17, 32.69, 74.85, 46.76, P < 0.01).

CONCLUSIONThe hypomethylation of 16HBE cells induced by B(a)P might be one important molecular phenomenon in its malignant transformation process. It suggests that PARP1 could regulate DNA methylation by inhibiting the enzyme activity of DNMT1, and this effect could be alleviated by PARP1-deficiency.

Benzo(a)pyrene ; adverse effects ; Cell Line ; DNA (Cytosine-5-)-Methyltransferase 1 ; DNA (Cytosine-5-)-Methyltransferases ; genetics ; metabolism ; DNA Damage ; DNA Methylation ; Epithelial Cells ; drug effects ; metabolism ; Humans ; Poly (ADP-Ribose) Polymerase-1 ; Poly(ADP-ribose) Polymerases ; genetics ; metabolism