Chien Tien Su

Polymorphisms in one-carbon metabolism pathway genes, urinary arsenic profile, and urothelial carcinoma

BackgroundGene polymorphisms in the one-carbon metabolism pathway could contribute to arsenic methylation capability through plasma folate and homocysteine metabolism, thereby increasing the susceptibility to urothelial carcinoma (UC) risk.ObjectivesThe goal of our study was to evaluate the roles of gene polymorphisms in the one-carbon metabolism pathway in the carcinogenesis of UC.MethodsA hospital-based case–controlled study was conducted. The urinary arsenic profile was examined using high-performance liquid chromatography and hydride generator-atomic absorption spectrometry. Folate levels were measured using a competitive immunoassay kit. Genotyping was conducted using polymerase chain reaction-restriction fragment length polymorphism technique.ResultsPatients with UC had higher urinary total arsenic, inorganic arsenic percentage (InAs%) and monomethylarsenic acid percentage (MMA%), and lower dimethylarsenic acid percentage (DMA%), plasma folate and homocysteine levels than controls. The correlations between folate and DMA%, and folate and homocysteine, were significant according to Pearson’s correlation coefficients. Subjects carrying the 5,10-methylenetetrahydrofolate reductase (MTHFR) CT or TT genotype had a lower DMA% and lower folate levels than those carrying the CC genotype. Participants with the methionine synthase (MS) AA genotype had higher homocysteine levels than those with the AG or GG genotype. However, neither MTHFR nor MS gene polymorphisms were associated with UC risk.ConclusionsEnvironmental factors played a more important role in UC carcinogenesis than MTHFR or MS gene polymorphism.

The relationship between obesity, insulin and arsenic methylation capability in Taiwan adolescents.

PURPOSE This study evaluated the arsenic methylation profile of adolescents and explored the influence of body mass index (BMI) on the arsenic methylation profile of adolescents in an area of Taiwan with no-obvious arsenic exposure. METHODS This study evaluated 202 normal weight students and 101 obese students from eight elementary schools, recruited from September 2009 to December 2009. Concentrations of urinary arsenic species, including inorganic arsenic, monomethylarsonic acid (MMA(5+)) and dimethylarsinic acid (DMA(5+)) were determined by a high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. RESULTS Urinary total arsenic was significantly decreased with increasing BMI, indicating that obese children may retain higher levels of arsenic in the body, as compared to normal weight children. Participants with obesity accompanied by high insulin levels had higher inorganic arsenic, significantly higher MMA percentage and significantly lower DMA percentage than those with obesity and low insulin levels. It seems children with obesity and high insulin levels had lower arsenic methylation capacity than those with obesity and low insulin. CONCLUSIONS This is the first study to demonstrate that total urinary arsenic is negatively associated with the BMI in adolescents in Taiwan, adjusted for age and sex. Obese adolescents with high insulin levels had significantly higher MMA% and significantly lower DMA% than obese adolescents with low insulin.

Gene polymorphisms of glutathione S-transferase omega 1 and 2, urinary arsenic methylation profile and urothelial carcinoma

Genetic polymorphisms in arsenic-metabolizing enzymes may be involved in the biotransformation of inorganic arsenic and may increase the risk of developing urothelial carcinoma (UC). The present study evaluated the roles of glutathione S-transferase omega 1 (GSTO1) and GSTO2 polymorphisms in UC carcinogenesis. A hospital-based case-control study was conducted. Questionnaire information and biological specimens were collected from 149 UC cases and 251 healthy controls in a non-obvious inorganic arsenic exposure area in Taipei, Taiwan. The urinary arsenic profile was determined using high-performance liquid chromatography and hydride generator-atomic absorption spectrometry. Genotyping for GSTO1 Ala140Asp and GSTO2 Asn142Asp was conducted using polymerase chain reaction-restriction fragment length polymerase. GSTO1 Glu208Lys genotyping was performed using high-throughput matrix-assisted laser desorption and ionization time-of-flight mass spectrometry. A significant positive association was found between total arsenic, inorganic arsenic percentage and monomethylarsonic acid percentage and UC, while dimethylarsinic acid percentage was significantly inversely associated with UC. The minor allele frequency of GSTO1 Ala140Asp, GSTO1 Glu208Lys and GSTO2 Asn142Asp was 18%, 1% and 26%, respectively. A significantly higher MMA% was found in people who carried the wild type of GSTO1 140 Ala/Ala compared to those who carried the GSTO1 140 Ala/Asp and Asp/Asp genotype (p=0.02). The homogenous variant genotype of GSTO2 142 Asp/Asp was inversely associated with UC risk (OR=0.17; 95% CI, 0.03 - 0.88; p=0.03). Large-scale studies will be required to verify the association between the single nucleotide polymorphisms of arsenic-metabolism-related enzymes and UC risk.

Polymorphisms in cell cycle regulatory genes, urinary arsenic profile and urothelial carcinoma

INTRODUCTION Polymorphisms in p53, p21 and CCND1 could regulate the progression of the cell cycle and might increase the susceptibility to inorganic arsenic-related cancer risk. The goal of our study was to evaluate the roles of cell cycle regulatory gene polymorphisms in the carcinogenesis of arsenic-related urothelial carcinoma (UC). METHODS A hospital-based case-controlled study was conducted to explore the relationships among the urinary arsenic profile, 8-hydroxydeoxyguanosine (8-OHdG) levels, p53 codon 72, p21 codon 31 and CCND1 G870A polymorphisms and UC risk. The urinary arsenic profile was determined using high-performance liquid chromatography (HPLC) and hydride generator-atomic absorption spectrometry (HG-AAS). 8-OHdG levels were measured by high-sensitivity enzyme-linked immunosorbent assay (ELISA) kits. Genotyping was conducted using polymerase chain reaction-restriction fragment length polymerase (PCR-RFLP). RESULTS Subjects carrying the p21 Arg/Arg genotype had an increased UC risk (age and gender adjusted OR=1.53; 95% CI, 1.02-2.29). However, there was no association of p53 or CCND1 polymorphisms with UC risk. Significant effects were observed in terms of a combination of the three gene polymorphisms and a cumulative exposure of cigarette smoking, along with the urinary arsenic profile on the UC risk. The higher total arsenic concentration, monomethylarsonic acid percentage (MMA%) and lower dimethylarsinic acid percentage (DMA%), possessed greater gene variant numbers, had a higher UC risk and revealed significant dose-response relationships. However, effects of urinary 8-OHdG levels combined with three gene polymorphisms did not seem to be important for UC risk. CONCLUSIONS The results showed that the variant genotype of p21 might be a predictor of inorganic arsenic-related UC risk.

The polymorphisms of P53 codon 72 and MDM2 SNP309 and renal cell carcinoma risk in a low arsenic exposure area

Our recent study demonstrated the increased risk of renal cell carcinoma (RCC) associated with high urinary total arsenic levels among people living in a low arsenic exposure area. Genomic instability is important in arsenic carcinogenesis. This study evaluated the relationship between the polymorphisms of p53, p21, and MDM2, which plays a role in gene stability, and the arsenic-related RCC risk. Here, we found that p53 Pro/Pro genotype and MDM2 SNP309 GG genotype significantly increased RCC risk compared to the p53 Arg/Arg genotype and MDM2 SNP309 TT genotype. RCC patients with the p53Arg/Arg genotype had a signicantly low percentage of inorganic arsenic, a low percentage of monomethylarsonic acid (MMA), and a high percentage of dimethylarsinic acid (DMA), which indicates efcient arsenic methylation capacity. Subjects with the p53 Arg/Pro + Pro/Pro genotype or MDM2 SNP309 TG+GG genotype, in conjunction with high urinary total arsenic (≥14.02μg/L), had a signicantly higher RCC risk than those with the p53 Arg/Arg or MDM2 SNP309 TT genotypes and low urinary total arsenic. Taken together, this is the first study to show that a variant genotype of p53 Arg(72)Pro or MDM2 SNP309 may modify the arsenic-related RCC risk even in a non-obvious arsenic exposure area.

Urinary total arsenic and 8-hydroxydeoxyguanosine are associated with renal cell carcinoma in an area without obvious arsenic exposure.

8-Hydroxydeoxyguanosine (8-OHdG) is one of the most reliable and abundant markers of DNA damage. The study was designed to explore the relationship between urinary 8-OHdG and renal cell carcinoma (RCC) and to investigate whether individuals with a high level of 8-OHdG would have a modified odds ratio (OR) of arsenic-related RCC. This case-control study was conducted with 132 RCC patients and 245 age- and sex-matched controls from a hospital-based pool between November 2006 and May 2009. Pathological verification of RCC was completed by image-guided biopsy or surgical resection of renal tumors. Urinary 8-OHdG levels were determined using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Concentrations of urinary arsenic species, including inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), were determined by a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Level of urinary 8-OHdG was significantly associated with the OR of RCC in a dose-response relationship after multivariate adjustment. Urinary 8-OHdG was significantly related to urinary total arsenic. The greatest OR (3.50) was seen in the individuals with high urinary 8-OHdG and high urinary total arsenic. A trend test indicated that the OR of RCC was increased with one of these factors and was further increased with both (p=0.002). In conclusion, higher urinary 8-OHdG was a strong predictor of the RCC. High levels of 8-OHdG combined with urinary total arsenic might be indicative of arsenic-induced RCC.

Protective effects of plasma alpha-tocopherols on the risk of inorganic arsenic-related urothelial carcinoma

Arsenic plays an important role in producing oxidative stress in cultured cells. To investigate the interaction between high oxidative stress and low arsenic methylation capacity on arsenic carcinogenesis, a case-control study was conducted to evaluate the relationship among the indices of oxidative stress, such as urinary 8-hydroxydeoxyquanine (8-OHdG), as well as plasma micronutrients and urinary arsenic profiles on urothelial carcinoma (UC) risk. Urinary 8-OHdG was measured using high-sensitivity enzyme-linked immunosorbent assay kits. The urinary arsenic species were analyzed using high-performance liquid chromatography and hydride generator-atomic absorption spectrometry. Plasma micronutrient levels were analyzed using reversed-phase high-performance liquid chromatography. The present study showed a significant protective effect of plasma alpha-tocopherol on UC risk. Plasma alpha-tocopherol levels were significantly inversely related to urinary total arsenic concentrations and inorganic arsenic percentage (InAs%), and significantly positively related to dimethylarsinic acid percentage (DMA%). There were no correlations between plasma micronutrients and urinary 8-OHdG. Study participants with lower alpha-tocopherol and higher urinary total arsenic, higher InAs%, higher MMA%, and lower DMA% had a higher UC risk than those with higher alpha-tocopherol and lower urinary total arsenic, lower InAs%, lower MMA%, and higher DMA%. These results suggest that plasma alpha-tocopherol might modify the risk of inorganic arsenic-related UC.

Genetic polymorphisms of myeloperoxidase and their effect on hypertension.

Abstract Myeloperoxidase (MPO) is a member of the mammalian peroxidase superfamily and plays specific roles in host defense. This study aimed to explore the association between one polymorphism of MPO and hypertension risk. Study subjects were recruited from Taipei City Hospital, Zhongxiao Branch, Taipei Medical University Hospital and Taipei Municipal WanFang Hospital. Participants completed questionnaires and provided blood samples. In this study we considered hypertension to be present among subjects that had blood pressures above 140/90 mmHg, or who had previously received treatment for hypertension. The polymorphism of MPO investigated in this study was constructed by performing a restriction fragment length polymorphism following polymerase chain reaction. This study found the odds ratio and 95% confidence interval for hypertension among subjects with the MPO -463 GA/AA genotype to be 1.97 (1.23–3.16) when compared with those with the GG genotype after multivariate adjustment. Participants with a body mass index (BMI) ≥ 24 kg/m2 and with MPO -463 GA/AA genotype had a 4.60-fold increased risk of hypertension compared with those with a BMI < 24 kg/m2 and with the GG genotype. This is the first study to conclude that the MPO -463 GA/AA genotype was associated with hypertension. In addition, we also detected that subjects with the MPO -463 GA/AA genotype that had higher BMIs and positive diabetes status tended to have higher risks of hypertension than subjects with the MPO -463 GA/AA genotype that had normal BMIs and were not diabetic.

Relation of polymorphism of arsenic metabolism genes to arsenic methylation capacity and developmental delay in preschool children in Taiwan

ABSTRACT Inefficient arsenic methylation capacity has been associated with developmental delay in children. The present study was designed to explore whether polymorphisms and haplotypes of arsenic methyltransferase (AS3MT), glutathione‐S‐transferase omegas (GSTOs), and purine nucleoside phosphorylase (PNP) affect arsenic methylation capacity and developmental delay. A case‐control study was conducted from August 2010 to March 2014. All participants were recruited from the Shin Kong Wu Ho‐Su Memorial Teaching Hospital. In total, 179 children with developmental delay and 88 children without delay were recruited. Urinary arsenic species, including arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) were measured using a high‐performance liquid chromatography‐linked hydride generator and atomic absorption spectrometry. The polymorphisms of AS3MT, GSTO, and PNP were performed using the Sequenom MassARRAY platform with iPLEX Gold chemistry. Polymorphisms of AS3MT genes were found to affect susceptibility to developmental delay in children, but GSTO and PNP polymorphisms were not. Participants with AS3MT rs3740392 A/G + G/G genotype, compared with AS3MT rs3740392 A/A genotype, had a significantly lower secondary methylation index. This may result in an increased OR for developmental delay. Participants with the AS3MT high‐risk haplotype had a significantly higher OR than those with AS3MT low‐risk haplotypes [OR and 95% CI, 1.59 (1.08–2.34)]. This is the first study to show a joint dose‐response effect of this AS3MT high‐risk haplotype and inefficient arsenic methylation capacity on developmental delay. Our data provide evidence that AS3MT genes are related to developmental delay and may partially influence arsenic methylation capacity. HIGHLIGHTSAS3MT genotypes were found to affect susceptibility to developmental delay.AS3MT rs3740392 A/G and G/G genotype had a significantly low SMI (DMA/MMA) index.AS3MT high‐risk haplotype was significantly associated with developmental delay.

The joint effects of arsenic and risk diplotypes of insulin-like growth factor binding protein-3 in renal cell carcinoma.

The association between renal cell carcinoma (RCC) and diabetes mellitus (DM), alcohol consumption, insulin-like growth factor binding protein-3 (IGFBP-3) gene, and arsenic exposure, has been the subject of independent studies. However, few studies have examined the combined effect of these factors on RCC risk. The aim of this study was to examine the association between these risk factors and the odds ratio (OR) of RCC. A hospital-based case-control study was conducted in 398 RCC patients and 756 age- and gender-matched non-cancer controls. Genomic DNA was used to examine the genotype of IRS-1 (Gly972Arg), PI3-K (Met362Ile), IGFBP-3 (A[-202]C), and IGFBP-3 (C[-1590]A) by PCR-RFLP. Profiles of urinary arsenic were measured by high performance liquid chromatography linked with hydride generator and atomic absorption spectrometry. Participants who had never consumed alcohol and who had high total levels of urinary arsenic and DM had a high OR of RCC. IGFBP-3 (A[-202]C) and IGFBP-3 (C[-1590]A) were in linkage disequilibrium. Participants carrying high-risk IGFBP-3 diplotypes A-C/C-C, A-A/A-C, and C-A/C-A had a significantly higher odds ratio (OR) and 95% confidence interval (2.80, 1.91-4.12) of RCC compared to those carrying other IGFBP-3 diplotypes. This is the first study to show that borderline significant interaction of high total levels of urinary arsenic and IGFBP-3 high-risk diplotypes significantly enhanced the OR of RCC. Our data also provide evidence that subjects with more risk factors (e.g., high total levels of urinary arsenic, never consumed alcohol, IGFBP-3 high-risk diplotypes) may experience a higher OR of RCC.