[A case-control study on the relationship between food preference and lung cancer and mesothelioma in a rural area with naturally occurring asbestos].

OBJECTIVE: To understand the relationship between food preference and lung cancer or malignant pleural mesothelioma and the interactive effect between food preference and asbestos exposure in a rural area with naturally occurring asbestos. METHODS: At the basis of the cohort of Dayao in Yunnan, we performed a 1 ∶ 2 casecontrol study including 53 cases( 23 cases for lung cancer and 26 cases for mesothelioma)and 106 age-and sex-matched normal healthy controls. In order to study the protective effect of food preference and the interactive effect between food preference and asbestos exposure, conditional logistic regression was used to estimate adjusted odds ratios( OR)and their 95% confidence intervals( CI) in both unvaried and multivariate analyses. RESULTS: Both green tea and wild mushroom were inversely associated with lung cancer ormalignant pleural mesothelioma, and the adjusted ORs were: 0. 88( 95% CI 0. 66-0. 87) for green tea, 0. 85( 95% CI 0. 23- 0. 95) for wild mushroom intake. Food preference to wild mushroom modified the associations of Crocidolite ' s contacting, Respectively, relative excess risk due to interaction( RERI), attributable proportion due to interaction( API), synergy index( S) were 0. 86, 0. 26 and 0. 61. CONCLUSION: Both green tea and wild mushroom might serve as protective factors on lung cancer or malignant pleural mesothelioma.

Increased damage of exon 5 of p53 gene in workers from an arsenic plant.

Mutagenesis is a multistage process. Substitution mutations can be induced by base modified through alteration of pairing property. Mutations of exon 5 and 8 of p53 gene have been found in most arsenicosis patients with precarcinomas and carcinomas, but never in arsenicosis individuals without precarcinomas and carcinomas. This study investigates whether base modification exists in exon 5 and 8 of p53 gene, and explores the dose-effect relationship between damage of exon 5 of p53 gene and urinary arsenic. Concentrations of urinary 8-hydroxydeoxyguanine (8-OHdG) are analyzed to identify the occurrence of DNA damage. The real-time PCR developed by Sikorsky et al. is applied to detect base modification in exon 5 and 8 of p53 gene for apparently healthy participants. Our results show that the mean total arsenic concentrations of two exposed groups from an arsenic plant are significantly elevated compared with the control group, and the damage level of exon 5 of the high-exposed group is significantly higher than that of the control group, but which does not happen in exon 8. The closely correlation between the damage index of exon 5 and urinary organic arsenic concentration are found. Concentration of 8-OHdG of the high-exposed group is significantly higher than that of the control group. These results imply that base modification in exon 5 of p53 gene can be induced by arsenic. In addition, our study suggests that the damage level of exon 5 is a useful biomarker to assess adverse health effect levels caused by chronic exposure to arsenic.

[Study on the association between urinary organic arsenic and 8-hydroxydeoxyguanine in workers exposed to arsenic].

OBJECTIVE: To evaluate the association between metabolism of arsenic and DNA oxidative damage in workers in a arsenic mill. METHODS: Urinary organic arsenic and 8-hydroxydeoxyguanine were detected in 37 workers highly exposed to arsenic and 16 administrative and logistic staff with mild exposure in a arsenic mill in Yunnan province, and also 28 local people who did not have the exposure in the near past time. The correlation between metabolism of arsenic and DNA oxidative damage was evaluated. RESULTS: The urinary organic arsenic concentration was respectively (0.48 +/- 0.37) mg/L and (0.08 +/- 0.05) mg/L for men with high and low exposure, and was respectively 0.11 mg/L and (0.30 +/- 0.24) mg/ L for women with high and low exposure, while it was lower than 0.02 mg/L in the controls. Urinary 8-hydroxydeoxyguanine concentration was (18.07 +/- 11.68) micromol/mol creatinine, (11.79 +/- 8.25) micromol/mol creatinine, (10.07 +/- 3.04) micromol/mol creatinine for the males with high and low exposure and of controls, respectively, (P < 0.05), and it was 84.35 micromol/mol creatinine, (21.27 +/- 5.89) micromol/mol creatinine, (14.43 +/- 2.58) micromol/mol creatinine for females with high and low exposure and of controls, respectively. The female workers exposed to arsenic had higher urinary 8-hydroxydeoxyguanine levels than males did (P < 0.05). The increased tendencies of urinary 8-hydroxydeoxyguanine levels with the organic arsenic concentration were found in workers (r(s) = 0.279, P = 0.019). CONCLUSION: Occupational individuals exposed to arsenic have obvious DNA oxidative damage, which is more severe in females. The difference of metabolism of arsenic may play a key role.

LincRNAs and base modifications of p53 induced by arsenic methylation in workers.

Arsenic (As) metabolites could induce methylation changes of DNA and base modifications of p53, which play role in the toxicity of As. LincRNAs should play a key regulatory role in the p53 transcriptional response. There were 43 workers producing As trioxide, 36 workers who stopped exposure to As trioxide about 85 days ago, and 24 individuals as control group. Three As species in urine were measured, and primary and secondary methylation indexes, iAs%, MMA% and DMA% were calculated. RT-PCR was performed to detect the expression of 7 LincRNAs and the base modifications of exon 5, 6, 7, and 8 of p53. The concentrations of urinary As were high in workers. Compared to control group, significant changes for 5 LincRNAs in workers producing As trioxide were found (P < 0.05), and there were significant base modifications of p53 in workers came from the two plants (P < 0.05). There exist various correlations between different exon base modifications of p53 and expressions of LincRNAs (P < 0.05). The closely positive correlations between MMA/DMA and MEG3/TUG1/HOTAIR/MALAT1 were found, but negative correlation between DMA/MALAT1 and the base modifications of exon 7 and 8 of p53 were found also (P < 0.05). LincRNAs and base modifications of p53 could be induced by As, MALAT1 and the base modifications of exon 7 and 8 of p53 could play unique roles in epigenic changes. These findings suggest potentially widespread roles of p53 and relative RNAs in arsenic workers, which may be caused by As metabolism.