Association of NOS2 and NOS3 gene polymorphisms with susceptibility to type 2 diabetes mellitus and diabetic nephropathy in the Chinese Han population.

Inducible nitric oxide synthase (NOS2) and endothelial nitric oxide synthase (NOS3) gene play important roles in the susceptibility to type 2 diabetes mellitus (T2DM). The present study aims to detect the potential association of NOS2 and NOS3 gene polymorphisms with the susceptibility toT2DM and diabetic nephropathy (DN) in the Chinese Han population. Four hundred and ninety T2DM patients and 485 healthy controls were enrolled in this case-control study. The genotypes of NOS2 and NOS3 gene polymorphisms were analyzed by the polymerase chain reaction (PCR)-ligase detection reaction (LDR) method. Our data demonstrated that the NOS2 rs2779248 and NOS2 rs1137933 genetic polymorphisms were significantly associated with the increased susceptibility to T2DM in the heterozygote comparison, dominant model, and allele contrast; and NOS3 rs3918188 genetic polymorphism was significantly associated with the increased susceptibility to T2DM in the homozygote comparison and recessive model. The allele-C and genotype-TC of NOS2 rs2779248, allele-A and genotype-GA of NOS2 rs1137933 and genotype-AA of NOS3 rs3918188 genetic polymorphisms might be the risk factors for increasing the susceptibility to T2DM. And a significant haplotype effect of NOS2 rs10459953/C- rs1137933/G- rs2779248/T was found between T2DM cases and controls. Moreover, NOS3 rs1800783 polymorphism was significantly associated with the increased susceptibility to DN in the heterozygote comparison, recessive model and allele contrast. At last, a positive correlation of family history of diabetes with NOS3 rs11771443 polymorphism was found in DN. These preliminary findings indicate that the NOS2 rs2779248, NOS2 rs1137933, and NOS3 rs3918188 genetic polymorphisms are potentially related to the susceptibility to T2DM, and the rs1800783 polymorphism might be considered as genetic risk factors for diabetic nephropathy, and family history of diabetes was closely associated with rs11771443 polymorphism in DN, and the genetic variants might be used as molecular markers for evaluating the risk of T2DM and diabetic nephropathy. © 2016 IUBMB Life, 68(7):516-525, 2016.

Repression of Biotin-Related Proteins by Benzo[a]Pyrene-Induced Epigenetic Modifications in Human Bronchial Epithelial Cells.

Benzo[a]pyrene (B[a]P) exposure has been associated with the alteration in epigenetic marks that are involved in cancer development. Biotinidase (BTD) and holocarboxylase synthetase (HCS) are 2 major enzymes involved in maintaining the homeostasis of biotinylation, and the deregulation of this pathway has been associated with a number of cancers. However, the link between B[a]P exposure and the dysregulation of BTD/HCS in B[a]P-associated tumorigenesis is unknown. Here we showed that the expression of both BTD and HCS was significantly decreased upon B[a]P treatment in human bronchial epithelial (16HBE) cells. Benzo[a]pyrene exposure led to the global loss of DNA methylation by immunofluorescence, which coincided with the reduction in acetylation levels on histones H3 and H4 in 16HBE cells. Consistent with decreased histone acetylation, histone deacetylases (HDACs) HDAC2 and HDAC3 were significantly upregulated in a dosage-dependent manner. When DNA methylation or HDAC activity was inhibited, we found that the reduction in BTD and HCS was separately regulated through distinct epigenetic mechanisms. Together, our results suggested the potential link between B[a]P toxicity and deregulation of biotin homeostasis pathway in B[a]P-associated cancer development.

[The profile of IGF2R gene expression and H3 histone modifications in replicative cell senescence].

OBJECTIVE: To study the profile of IGF2R expression and histone modifications in replicative cell senescence. METHODS: The changes of biological characteristics of young human pulmonary fibroblast (HPF) cells [at population doubling level (PDL) 23] and aging HPF cells (at PDL50) were observed and real-time quantitative PCR was utilized to investigate human IGF2R gene expressions profile during the process of cellular aging (at different PDL). Then chromatinimmunoprecipitation-real time quantitative PCR (CHIP-QPCR) methods were conducted to analyze histone modifications of the regions around the transcriptional start site of IGF2R (H3-Ac, H3K9-tri-Me, H3K9-Ac and H3K4-tri-Me). RESULTS: In contrast to young cells, the aging cells were bigger and less proliferative, their cell cycles arrest, and aging specific beta-galactosidase staining was positive. IGF2R gene expression was in positive correlation with PDL. H3-Ac, H3K9-Ac and H3K4-tri-Me were dominant in the upstream region (-0.6 kb) to the downstream region (+1.2 kb) of transcriptional start site (TSS). While in the downstream of TSS from +1.6 kb to +4.0 kb, H3K9-Ac was declined and H3K9-tri-Me was elevated in turn, but H3K4-tri-Me still prevailed in these areas. CONCLUSION: IGF2R is related to cell replicative senescence and its gene expression is regulated by histone modification of H3. Therefore, epigenetics may play a role in cell senescence.

[Effects of bisphenol A on OCT4 and SOX2 genes expression in mouse embryonic stem cells].

OBJECTIVE: To explore the effects of bisphenol A (BPA) exposure on toxicity characteristic and OCT4 and SOX2 gene expression of mouse embryonic stem cells (mESC). METHODS: mESC were cultured, and treated with the doses of 10(-8), 10(-7), 10(-6), 10(-5), 10(-4) mol/L respectively of BPA and DMSO (the solvent control group)for 24 hours, and three groups of cells were treated with the same method. The morphological changes of mESC in the control and exposure groups were observed through an inverted microscope. Cell counting kit 8 (CCK8) was used to detect the effects of BPA on proliferation of mESC, and based on the results, the half inhibitory concentration (IC50) was calculated. Real-time fluorescent quantitative polymerase chain reaction (RT-QPCR) and western blotting were used to detect the expression of OCT4 and SOX2. RESULTS: BPA had certain toxicity on mESC, the treatment of BPA significantly increased cell toxicity in a concentration-dependent manner, and the IC50 was 4.3×10(-4) mol/L, combined with the BPA exposure concentration of the environment and the related literature, eventually taking the five concentrations of 10(-8), 10(-7), 10(-6), 10(-5), 10(-4) mol/L as the experimental groups. The mESC morphology were effected after the treatment of BPA for 24 h, compared with the control group, the number of cells decreased, appearing some floating cells, and the cell cloning became irregular and differentiation in the higher concentration groups. The OCT4 mRNA expression level in the 10(-7) mol/L (1.146 ± 0.087), 10(-6) mol/L (1.156 ± 0.030), 10(-5) mol/L (1.158 ± 0.103) and the 10(-4) mol/L (1.374 ± 0.053) dose group were all significantly higher than the control group (1.000 ± 0.000) (t values were -2.384, -2.953, -3.203, -4.021 respectively, P value all < 0.05). Meanwhile, the SOX2 mRNA expression level in the 10(-4) mol/L (1.113 ± 0.052) were higher than the control group (1.000 ± 0.000) (t value was -2.765, P value < 0.05). Moreover, the OCT4 protein expression level in the 10(-5) mol/L (1.360 ± 0.168) and 10(-4) mol/L (1.602 ± 0.151) were all significantly higher than the control group (1.000 ± 0.000) (t values were -3.538, -4.002 respectively, P value all < 0.05), while no obvious change of the SOX2 protein expression level was detected in all treated groups. CONCLUSION: BPA in a certain dose range could upregulate the expression of OCT4 gene in mouse embryonic stem cells while had no significant effect on the expression of SOX2 gene.

[Study on sperm damage caused by trichloroethylene in male rats].

OBJECTIVE: To study in vitro sperm damage caused by trichloroethylene in male rats. METHODS: Sperms of Sprague-Dawley (SD) rats were collected 4 hours after being contaminated by trichloroethylene of 0, 2, 4, 6, 8, and 10 mmol/L in vitro. Giemsa staining was performed to observe the morphological changes of sperms, and flow cytometer was used to detect the changes in mitochondrial membrane potential. RESULTS: The sperm motilities in 6, 8, and 10 mmol/L trichloroethylene groups decreased significantly compared with that in control group (P <0.01); the sperm aberration rates in 8 and 10 mmol/L trichloroethylene groups were significantly higher than that in control group (P<0.01). With the increase in exposure dose, the proportion of sperms with reduced mitochondrial membrane potential increased, and there were significant differences in sperm apoptosis rate between the 4, 6, 8, and 10 mmol/L trichloroethylene groups and control group (P<0.01). CONCLUSION: In vitro exposure to trichloroethylene can reduce sperm motility and increase the aberration rate and apoptosis rate of sperms in male SD rats.

[Role of poly (ADP-ribose) polymerase 1 on DNA methylation variation induced by B(a)P in human bronchial epithelial cell].

OBJECTIVE: To investigate DNA methylation variation in human cells induces by B(a)P, and to explore the role of PARP1 during this process. METHODS: The 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. RESULTS: The 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). CONCLUSION: The 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.

[The effect of DNA methyltransferase 1 low expression on the global genome DNA methylation status of 16HBE cell].

OBJECTIVE: To construct DNA methyltransferase 1 (DNMT1) low expression 16HBE cell line and observe the variation of cell cycle and global genomic DNA methylation. METHODS: The method of Lenti-virus induced RNA interference was applied to introduce four different shRNA fragment into 16HBE cells. Flow cytometry and 5-mC immunofluorescence methods were used to observe the cell cycle and global DNA methylation status of DNMT1 low expression 16HBE cells. RESULTS: The DNMT1 protein relative expression level of 16HBE-shDNMT1-4 cell line was down regulated about 44% (P < 0.05) compared with the control. No obvious differences of cell cycle and global genome DNA methylation status were observed between the 16HBE and 16HBE-shDNMT1. CONCLUSION: The DNMT1 gene low expression cell is successfully constructed, and there are no obvious changes happened on the cell cycle and global genomic DNA methylation.

[Genome DNA hypomethylation in the process of crystalline nickel-induced cell malignant transformation].

OBJECTIVE: To observe the effect of crystalline NiS on genome DNA methylation profile in in vitro cultured cells. METHODS: 16HBE Cells were treated with crystalline NiS at 0.25, 0.50, 1.00 and 2.00 µg/cm(2) for 24 h and three times at total. DAC treatment was given at 3 µmol/L for 72 h.5-mC immunofluorescence and SssI methyltransferase assay methods were applied to investigate if the hypomethylation of genome DNA involved. RESULTS: The results of 5-mC immunofluorescence showed that the fluorescence intensity of NiS-treated cells were decreased in some degree, and transformed cells were decreased dramatically. By the SssI methylase assay, an average of (81.9 ± 7.3)% methylated CpG were found in negative control cells. By contrast, (77.9 ± 6.2)%, (75.3 ± 6.8)%, (59.5 ± 4.9)%, (67.4 ± 5.1)% methylated CpG were observed in cells treated with NiS for three times at dosage of 0.25, 0.50, 1.00 and 2.00 µg/cm(2) which were abbreviated as NiS0.25, NiS0.50, NiS1.00, NiS2.00 respectively. The ANOVA analysis results showed that there was a significant difference in the 5 groups above (F = 124.95, P < 0.01). The results of Dunnett-t test showed that the methylated CpG of both group NiS1.00 and NiS2.00 were significantly decreased compared with the negative control group (t values were 7.64, 4.89 respectively, P < 0.01). For methylated CpG, (46.2 ± 4.1)% and (43.6% ± 4.3)% were observed in NiS-transformed cells (NSTC1 and NSTC2) which were dramatically decreased compared with the negative control group (t values were 12.79, 13.56 respectively, P < 0.01). CONCLUSION: Genomic DNA methylation levels were decreased during NiS induced malignant transformation.

[Study on skin sensitization as well as liver and kidney impairment in guinea pigs treated with trichloroethylene].

OBJECTIVE: To study skin sensitization as well as liver and kidney impairment in guinea pigs treated with trichloroethylene (TCE). METHODS: Guinea pig maximization test (GPMT) was applied in this study, guinea pigs were divided into 3 groups, namely negative control, positive control and TCE treatment. Animals of 3 groups were administrated with olive oil, 2, 4-dinitrochlorobenzene (DNCB), and TCE, respectively, by intradermal injection. The animal skin was observed and blood was collected after various treatment, the liver function tests were conducted, including detection of activities of ALT, AST, LDH and levels of creatinine, uric acid, and urea with automatic biochemical analyzer. RESULTS: Obvious skin impairment was observed in the groups of positive control and TCE treatment, the skin impairment included erythema and edema, the sensitization rate was 100% in positive control and 83.3% in TCE treatment group. Additionally, the activities of ALT, AST and LDH increased significantly in the groups of positive control and TCE treatment when compared with the negative control. CONCLUSIONS: Trichloroethylene is one of the strong hypersensitizing substances, it could induce skin allergic reaction and liver impairment in guinea pigs.

An investigation of hormesis of trichloroethylene in L-02 liver cells by differential proteomic analysis.

Hormesis is the dose-response pattern of the biological responses to toxic chemicals, characterized by low-dose stimulation and high-dose inhibition. Although it is known that some cell types exhibit an adaptive response to low levels of cytotoxic agents, its molecular mechanism is still unclear and it has yet to be established whether this is a universal phenomenon that occurs in all cell types in response to exposure to every chemical. Trichloroethylene (TCE) is an organic solvent widely used and is released into the atmosphere from industrial degreasing operations. Acute (short-term) and chronic (long-term) inhalation exposure to trichloroethylene can affect the human health. In order to elucidate a cell-survival adaptive response of L-02 liver cells exposed to low dose of TCE, CCK-8 assay was used to assess cytotoxicity, and examined the possible mechanisms of hormesis by proteomics technology. We found that exposure of L-02 liver cells to low level of TCE resulted in adaptation to further exposure to higher level, about 1,000 protein-spots were obtained by two-dimensional electrophoresis (2-DE) and five protein spots were identified by matrix-assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry sequencing of tryptic peptides. Our results suggest that a relationship may exist between identified proteins and TCE-induced hormesis, which are very useful for further study of the mechanism and risk assessment of TCE.

Effect of PARP-1 deficiency on DNA damage and repair in human bronchial epithelial cells exposed to Benzo(a)pyrene.

Benzo[a]pyrene is a ubiquitously distributed environmental pollutant known to cause DNA damage, whereas PARP-1 is a nuclear enzyme that is activated by damaged DNA and plays an important role in base excision repair and genomic stability. Here, 16HBE and its PAPR1-deficient cells were exposed to BaP, and the DNA damage level and repair ability of both cell lines were measured by alkaline comet assay. The results showed that cell viability of both cell lines decreased in a dose-dependent manner when exposed to BaP, but there was no significant difference between two cell lines. Comet assay showed that BaP caused DNA damage in both cell lines at an obvious dose- and time-dependent manner. Compare with 16HBE, the PARP1-deficient cells were more sensitive to the damage caused by BaP. The results of DNA repair experiment showed that both cell lines can recover from the damage in a time-dependent pattern. The relative repair percentage of PARP1-deficient cells were generally lower than that of 16HBE at all exposed concentrations at the early stage of repair, but tended to be closer between two cell lines at the later period. According to results, we came to the conclusion that PARP1-deficient cells were more sensitive to BaP in contrast to normal 16HBE; DNA repair capacity in PARP1-deficient cells decreased significantly at the early stage of repair, but increased to the equivalent level of normal 16HBE in the later period. PARP-1 plays an important role in early repair of DNA damage caused by BaP in 16HBE notwithstanding the main repair work is taken by NER pathway.

[Relationship between polymerase eta expression and DNA damage-tolerance in human hepatic cells by hydroquinone].

OBJECTIVE: To investigate the effects of hydroquinone (HQ) on expression of Polymerase eta (Pol eta) and DNA damage in human hepatic cells (L-02), and to explore the role and possible mechanism of Pol eta involved in the process of DNA damage-tolerance. METHODS: After L-02 hepatic cells were exposed to HQ with various concentrations (0, 5, 10, 20, 40, 80 and 160 micromol/L) for 24 h, cell survival rate was detected by MTT assay; DNA impairment was detected by single cell gel electrophoresis (SCGE); Real-time fluorescent quantitative PCR and Western blotting methods were used to measure the expression of Pol eta at the mRNA and protein level in L-02 hepatic cells exposed to HQ with various concentrations (0, 5, 10, 20, 40, 80 and 160 micromol/L). RESULTS: MTT assay showed that HQ with concentrations from 0 to 80 micromol/L had little effect on the survival rate of L-02 (P>0.05); whereas the survival rate of the group of 160 micromol/Lwas significantly higher than that of the control (P<0.01) after being treated with HQ for 24 h; the higher dose of HQ presented, the more degrees of DNA damage were produced. It was found that HQ in a low concentration (1-80 micromol/L) could induce the expression of Pol eta which was in proportion to the increasements of HQ concentration; the expression levels of mRNA and protein were reached to the maximum when treated with 80 micromol/L; the expression of Pol eta decreased (the relative quantity values were 2.32 +/- 0.16 and 1.20 respectively) once the concentration of HQ exceeded 160 micromol/L as compared with the group of 80 micromol/L, but it was higher than that of the control. CONCLUSION: This study suggested that Pol eta might involve in the process of DNA damage-tolerance induced by HQ in the hepatic cells.

[Relationship between gene polymorphism of CYP2E1, CYP1A1, IL-4 and medicamentosa-like dermatitis induced by trichloroethylene].

OBJECTIVE: To investigate the relationship between gene polymorphism of CYP2E1, CYP1A1, IL-4 and susceptibility of medicamentosa-like dermatitis induced by trichloroethylene (TCE). METHODS: 35 patients with medicamentosa-like dermatitis induced by TCE were chosen as the patient group, and 35 healthy workers as control group. The real-time quantitative polymerase chain reaction (PCR) with TaqMan minor groove binding (MGB) probes was used to test single nucleotide polymorphisms (SNP) of CYP2E1, CYP1A1 and IL-4 in the patients with medicamentosa-like dermatitis as well as in the control. The genotypes and the frequency of genotype or allele were compared between the patients and control with statistical analysis. RESULTS: The frequency of allele G within CYP1A1 gene (rs1048943) was significantly higher in TCE patients (37.1%) than that in control (P<0.05); the frequency of allele T within CYP2E1-1053 C/T was significantly higher in TCE patients (41.4%) than that in control (P<0.01); the frequency of T/T within IL-4-588 C/T (rs2243250) was significantly higher in TCE patients (75.0%) than that in control (P<0.01), and the frequency of allele T within IL-4-588 C/T (rs2243250) was also significantly higher in TCE patients (87.5%) than that in control (P<0.01). CONCLUSION: The gene polymorphism of CYP2E1, CYP1A1, IL-4 is probably associated with hypersensitivity for the TCE patients with medicamentosa-like dermatitis, and could be one of the genetic factors related to the individual susceptibility to TCE exposure.

[Effect of hydroquinone on expression of ubiquitin-ligating enzyme Rad18 in human L-02 hepatic cells].

OBJECTIVE: To investigate the effects of hydroquinone (HQ) on expression of ubiquitin-ligating enzyme Rad18 in human hepatic cells (L-02), and to explore the role and possible mechanism of Rad18 involved in toxicity of HQ to hepatic cells. METHODS: After L-02 hepatic cells were exposed to HQ with various concentrations (0, 5, 10, 20, 40, 80 and 160 micromol/L) for 24 h, cell survival rate was measured by MTT assay; DNA impairment was evaluated by single cell gel electrophoresis (SCGE); The expression levels of Rad18 mRNA and protein were detected by Real-time fluorescent quantitative polymerase chain reaction (QPCR) technique and Western blot method respectively. RESULTS: HQ with concentration from 0 to 80 micromol/L had little effect on survival rate of L-02 (P > 0.05); Whereas the survival rate in the group of 160 micromol/L was significantly lower than in the control with the significant difference (P < 0.01) after treated with HQ for 24 h; The higher dose of HQ presented, the more degrees of olive tail moment (OTM) were produced and a dose-dependent relationship was shown. HQ in a low concentration (0 to approximately 40 micromol/L) could induce increase in the expression of Rad18 mRNA and protein which was in proportion to the increment of HQ concentration; the expression of Rad18 mRNA was enhanced increasingly, while the expression of Rad18 protein unchanged basically once the concentration of HQ exceeded 40 micromol/L; Besides, there was a positive correlation between OTM and the expression level of Rad18 mRNA (r = 0.919, P < 0.01). CONCLUSION: HQ could regulate up the expression of Rad18 in L-02 hepatic cells.

[Study on the relationship between breast cancer resistance protein expression and 5-fluorouracil resistance].

OBJECTIVE: To screen breast cancer resistance protein BCRP-mediated resistance agents and to investigate the relations between BCRP expression and drug resistance. METHODS: MT assay was performed to screen BCRP-mediated resistant agents with established BCRP expression cell model. While, the high performance liquid chromatography (HPLC) assay was administrated to measure the related dosage of intracellular retention resistant agents. The BCRP expression was investigated by both real-time RT-PCR and immunohistochemistry (IHC) assay in 140 clinical breast cancer tissue specimens. Chemosensitivity to resistant agents for clinical breast cancer tissue specimens was analyzed by MT assay. The Nonparametric variance statistics method was used to analyze the correlations between clinical breast cancer tissue of BCRP expression and drug resistance. RESULTS: MT assay showed that increasing resistance of 5-fluorouracil (5-Fu) climbed with the increases of the BCRP expressions by 10.58 times (P < 0.05, n = 3) in cell model. HPLC assay also proved that a significant negative correlation between the intracellular retention dose of 5-Fu with different expression of BCRP (r = -0.897, P < 0.05, n = 3). Forty-seven tissue specimens of BCRP-positive expression were rapidly determined by using both real-time RT-PCR and IHC in 140 clinical breast cancer tissue specimens. Subsequently, the resistance index (RI) for 47 BCRP-positive clinical breast cancer tissues to 5-Fu was shown from 7 to 12 times compared with normal cancer-side tissues through MT assay. The statistical correlation between BCRP expression and 5-Fu resistance was observed in clinical breast cancer tissue specimens (R2 = 0.8124, P < 0.01). CONCLUSION: This study results showed that there is a significant relationship between BCRP expression and 5-Fu resistance. Moreover, the results suggest that the chemotherapy scheme could be optimized on BCRP-positive expression breast cancer patients.

Piperine (PP) enhanced mitomycin-C (MMC) therapy of human cervical cancer through suppressing Bcl-2 signaling pathway via inactivating STAT3/NF-κB.

Piperine (PP), an alkaloid from black and long peppers (Piper nigrum Linn &Piper longum Linn), exhibits antitumor activities in vitro and in vivo. We investigated the ability of piperine (PP) to reverse the drug resistance of human cervical cancer cells. In our study, the cervica cancer cells resistant to mitomycin-C (MMC) treatment were used. We found the growth inhibitory effects of piperine on human cervical cancer cell, which were resistant to MMC. Piperine and MMC co-treatment resulted in a dose-dependent suppression of the cell proliferation. Decreasing of phosphorylated-signal transducer and activator of transcription (p-STAT3) was linked to the suppression of p65 by PP and MMC combinational treatment. Additionally, the presence of PP potentiated the effects of MMC on apoptosis induction in cervical cancer cells with drug resistance, which was dependent on Bcl-2 inhibition. The pro-apoptotic proteins of Bax and Bid were up-regulated, accompanied with Caspase cleavage. Moreover, in mice xenograft models, the combined therapy inhibited tumor growth compared to the PP or MMC mono-therapy group. Our data indicated a novel therapeutic strategy of PP to potentiate MMC-induced anti-tumor effect on cervical cancer cells with drug resistance through blocking p-STAT3/p65 and Bcl-2 activation.

Effect of hexavalent chromium on histone biotinylation in human bronchial epithelial cells.

Chromium is a potent human mutagen and carcinogen. The capability of chromium to cause cancers has been known for more than a century, and numerous epidemiological studies have been performed to determine its carcinogenicity. In the post-genome era, cancer has been found to relate to epigenetic mutations. However, very few researches have focused on hexavalent chromium (Cr(VI))-induced epigenetic alterations. The present study was designed to investigate whether Cr(VI) would affect the level of a newfound epigenetic modification: histone biotinylation. Histone acetylation and histone biotinylation were studied in detail using human bronchial epithelial (16HBE) cells as an in vitro model after Cr(VI) treatment. Our study showed that Cr(VI) treatment decreased histone acetylation level in 16HBE cells. In addition, low doses of Cr(VI) (≤0.6µM) elevated the level of histone biotinylation. Furthermore, immunoblot analysis of biotinidase (BTD), a major protein which maintains homeostasis of histone biotinylation, showed that the distribution of BTD became less even and more concentrated at the nuclear periphery in cells exposed to Cr(VI). Moreover, Cr(VI)-induced histone deacetylation may take part in the regulation of histone biotinylation. Together, our study provides new insight into the mechanisms of Cr(VI)-induced epigenetic regulation that may contribute to the chemoprevention of Cr(VI)-induced cancers and may have important implications for epigenetic therapy.

Proteome of melamine urinary bladder stones and implication for stone formation.

Melamine can cause urinary stones related to nephropathy of the kidney and hyperplasia or carcinoma of the bladder, but the mechanism of stone formation is not well understood. In this study, male rats were administered melamine for thirteen weeks to establish melamine bladder stone models and the stones were analysed by Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS) and western blot, respectively, for the composition and proteome, and to explore the implication of proteins for stone formation. The results showed bladder stones were composed of predominant melamine and a few amount of proteins. The proteins had a wide range of molecular weights and 1051 proteins were identified. Gene Ontology (GO) classification of the identified proteins showed most proteins were from injured cells, involved in various metabolic processes and had binding functions. Of the identified proteins, there were a few inflammatory proteins and urinary proteins. Physicochemical characteristics of the identified proteins showed that 67.1% proteins' isoelectric points (pI) value was below 7.0, 91.1% proteins' grand average of hydropathicity (GRAVY) scores were below 0 and nearly half of the proteins were stable. Our data indicated proteins might play an important role in melamine bladder stone formation.

Chromium(VI) causes down regulation of biotinidase in human bronchial epithelial cells by modifications of histone acetylation.

Hexavalent chromium (Cr(VI)), a commonly used industrial metal, is a well-known mutagen and carcinogen, and occupational exposure can induce a broad spectrum of adverse health effects, including cancers. Although Cr(VI)-induced DNA damage is thought to be the primary mechanism of chromate genotoxicity and mutagenicity, there is an increasing number of reports showing that epigenetic mechanisms of gene regulation might be a central target of Cr(VI) toxicity. Epigenetic changes, such as changes in phosphorylation, altered DNA methylation status, histone acetylation and signaling pathways, have been observed after chromium exposure. Nevertheless, to better demonstrate the roles of epigenetic modifications in Cr(VI)-induced carcinogenesis, more work needs to be carried out. This study is aimed to investigate changes in biotinidase (BTD) and holocarboxylase synthetase (HCS), two major proteins which maintain homeostasis of the newfound epigenetic modification: histone biotinylation, in cells exposed to Cr(VI). The data showed that Cr(VI) decreased BTD expression at the transcriptional level in human bronchial epithelial cells (16HBE). In addition, using the epigenetic modifiers, 5-Aza-2'-deoxycytidine (Aza) and Trichostatin A (TSA), we found that modifications of histone acetylation reversed the inhibition of BTD, suggesting that Cr(VI) may cause down regulation of BTD by modifications of histone acetylation.