Association between heat-shock protein 70 gene polymorphisms and DNA damage in peripheral blood lymphocytes among coke-oven workers

Effect of heat stress on DNA damage: a systematic literature review

Thermal stress has a direct effect on various types of DNA damage, which depends on the stage of the cell cycle when the cell is exposed to different climate conditions. A literature review was conducted to systematically investigate and assess the overall effect of heat stress and DNA damage following heat exposure. In this study, electronic databases including PubMed, Scopus, and Web of Science were searched to find relevant literature on DNA damage in different ambient temperatures. Outcomes included (1) measurement of DNA damage in heat exposure, (2) three different quantification methods (comet assay, 8-hydroxy-2-deoxyguanosine (8-OHdG), and γ-H2AX), and (3) protocols used for moderate (31) and high temperatures (42). The evidence shows that long exposure and very high temperature can induce an increase in DNA damage through aggregate in natural proteins, ROS generation, cell death, and reproductive damage in hot-humid and hot-dry climate conditions. A substantial increase in DNA damage occurs following acute heat stress exposure, especially in tropical and subtropical climate conditions. The results of this systematic literature review showed a positive association between thermal stress exposure and inhibition of repair of DNA damage.

Extracellular Heat Shock Proteins as Therapeutic Targets and Biomarkers in Fibrosing Interstitial Lung Diseases

Interstitial lung diseases (ILDs) include a large number of diseases and causes with variable outcomes often associated with progressive fibrosis. Although each of the individual fibrosing ILDs are rare, collectively, they affect a considerable number of patients, representing a significant burden of disease. Idiopathic pulmonary fibrosis (IPF) is the typical chronic fibrosing ILD associated with progressive decline in lung. Other fibrosing ILDs are often associated with connective tissues diseases, including rheumatoid arthritis-ILD (RA-ILD) and systemic sclerosis-associated ILD (SSc-ILD), or environmental/drug exposure. Given the vast number of progressive fibrosing ILDs and the disparities in clinical patterns and disease features, the course of these diseases is heterogeneous and cannot accurately be predicted for an individual patient. As a consequence, the discovery of novel biomarkers for these types of diseases is a major clinical challenge. Heat shock proteins (HSPs) are molecular chaperons that have been extensively described to be involved in fibrogenesis. Their extracellular forms (eHSPs) have been recently and successfully used as therapeutic targets or circulating biomarkers in cancer. The current review will describe the role of eHSPs in fibrosing ILDs, highlighting the importance of these particular stress proteins to develop new therapeutic strategies and discover potential biomarkers in these diseases.

Heat-shock protein 70 (HSP70) polymorphisms affect the risk of coke-oven emission-induced neurobehavioral damage

OBJECTIVES

Epidemiology studies indicated that coke-oven workers with long-term exposure to polycyclic aromatic hydrocarbons (PAHs) often have some neurobehavioral abnormalities especially impairment for cognitive function, while the underlying mechanisms are not fully understood. Numerous studies have indicated the antioxidant and anti-apoptosis roles of heat shock protein 70 (Hsp70). The genetic polymorphisms in HSP70 genes are associated with multiple diseases including neurotoxicity. However, it is unclear whether HSP70 polymorphisms are related to the neurotoxicity of PAH. We, therefore, investigate the possible association between HSP70 polymorphisms and neurobehavioral abnormalities.

METHODS

188 coke-oven workers and 137 control workers were recruited in this study. Emotional and cognitive function was assessed using the WHO/NCTB. HSP70 polymorphisms (HSP70-1 G190C, HSP70-2 G1267 A and HSP70-hom T2437C) were checked by PCR-RFLP.

RESULTS

The results indicated that HSP70-1 CC genotypes in coke-oven workers were associated with poor neurobehavioral performance such as the attention /response speed and visual perception/memory, while the HSP70-2 AA genotypes were associated with lower short-term auditory memory.

CONCLUSIONS

HSP70-1 CC and HSP70-2 AA genotypes in coke-oven workers may increase the risk for neurobehavioral damage, especially attention, learning and memory.

Interaction of heat shock protein 70 (HSP70) polymorphisms and occupational hazards increases the risk of hypertension in coke oven workers

OBJECTIVES

The interaction between genetic, epigenetic inheritance and environmental factors determines susceptibility to hypertension. Previous epidemiology studies have shown that coke oven workers who are frequently exposed to various occupational hazards have remarkable increase in the risk for hypertension. Among many genetic variants identified in hypertension, heat shock protein 70 (HSP70) was found to play important roles in the pathogenesis of hypertension and associated diseases. We therefore explore the possible role of HSP70 polymorphisms and their interaction with occupational environment in hypertension risk.

METHODS

We carried out a case-control study among 367 coke oven workers in northwest China, focused on three common HSP70 polymorphisms (HSP70-1 G190C, HSP70-2 A1267G and HSP70-hom T2437C), and evaluated the association of HSP70 gene polymorphisms with work sites for high risk of hypertension.

RESULTS

The results indicated that HSP70-1 GC and CC genotype had 2.73-fold and 4.26-fold increased relative risk (95% CI 1.33 to 5.55 and 1.17 to 15.53), respectively, comparing with HSP70-1 GG genotype. HSP70-2 AG and GG conferred a 47% and 36% reduced risk (95% CI 0.23 to 0.99 and 0.14 to 0.92) comparing with HSP70-2 AA genotype. Further analysis of the interaction of HSP70 polymorphisms with occupational environment indicated a strong positive interaction between HSP70 genotype (HSP70-1 GC+CC, HSP70-2 AA and HSP70-hom TC+CC) and oven top workplace.

CONCLUSIONS

Collectively, these data indicate that HSP70 polymorphisms interact with occupational hazards might increase the risk of hypertension in coke oven workers.

Effects of coke oven emissions and benzo[a]pyrene on blood pressure and electrocardiogram in coke oven workers

Objective:

To evaluate the effects of occupational exposures to coke oven emissions (COEs) and benzo[a]pyrene (B[a]P) on the prevalence of hypertension and abnormal electrocardiogram (ECG) in coke oven workers.

Methods:

We included 880 coke oven workers and 710 oxygen employees in the exposed and control groups, respectively. Blood pressure (BP), ECG, blood lipid levels, and glucose levels of all subjects were measured. COE and B[a]P concentrations at the bottom, side, and top of the oven and control plants were estimated by weighing and high-performance liquid chromatography.

Results:

The COE concentration at the top and side was higher than that at the bottom (P < 0.05). The levels of B[a]P at the top and side significantly exceeded the limit value. Abnormal BP, ECG, the detection ratio of hypertension and left ventricular high voltage were significantly greater in the exposed group than in the control group (P < 0.05). The logistic regression analysis results revealed that age and B[a]P exposure were risk factors for hypertension in coke oven workers (P < 0.05) and both were risk factors for abnormal ECG (P < 0.05). Moreover, B[a]P exposure, age, and gender were risk factors for impaired fasting glucose in coke oven workers (P < 0.05).

Conclusions:

B[a]P and COE exposures are risk factors for hypertension and abnormal ECG in coke oven workers.

In vitro assessment of anticytotoxic and antigenotoxic effects of CANOVA(®)

BACKGROUND

CANOVA(®) (CA) is a homeopathic immunomodulator. It contains several homeopathic medicines prepares according to the Brazilian Pharmacopoeia. CA is indicated in clinical conditions in which the immune system is impaired and against tumors. N-methyl-N-nitrosourea (NMU) is an N-nitroso compound, with genotoxic/mutagenic properties. Although several studies have shown promising results in the use of CA, there are no studies reporting possible antigenotoxic effects.

METHOD

This study evaluated the in vitro antigenotoxic and anticytotoxic effects of CA in human lymphocytes exposed to NMU. Samples of human lymphocytes that were subjected to different concentrations of a mixture containing CA and NMU were used. The genotoxicity/antigenotoxicity of CA was evaluated by the comet assay, anticytotoxicity was assessed by quantification of apoptosis and necrosis using acridine orange/ethidium bromide.

RESULTS

CA significantly reduced DNA damage induced by NMU and reduced significantly the frequency of NMU-induced apoptosis after 24 h of treatment.

CONCLUSION

CA has an important cytoprotective effect significantly reducing the DNA damage and apoptosis induced by the carcinogen NMU.

The chaperone balance hypothesis: the importance of the extracellular to intracellular HSP70 ratio to inflammation-driven type 2 diabetes, the effect of exercise, and the implications for clinical management

Recent evidence shows divergence between the concentrations of extracellular 70 kDa heat shock protein [eHSP70] and its intracellular concentrations [iHSP70] in people with type 2 diabetes (T2DM). A vital aspect regarding HSP70 physiology is its versatility to induce antagonistic actions, depending on the location of the protein. For example, iHSP70 exerts a powerful anti-inflammatory effect, while eHSP70 activates proinflammatory pathways. Increased eHSP70 is associated with inflammatory and oxidative stress conditions, whereas decreased iHSP70 levels are related to insulin resistance in skeletal muscle. Serum eHSP70 concentrations are positively correlated with markers of inflammation, such as C-reactive protein, monocyte count, and TNF-α, while strategies to enhance iHSP70 (e.g., heat treatment, chemical HSP70 inducers or coinducers, and physical exercise) are capable of reducing the inflammatory profile and the insulin resistance state. Here, we present recent findings suggesting that imbalances in the HSP70 status, described by the [eHSP70]/[iHSP70] ratio, may be determinant to trigger a chronic proinflammatory state that leads to insulin resistance and T2DM development. This led us to hypothesize that changes in this ratio value could be used as a biomarker for the management of the inflammatory response in insulin resistance and diabetes.

The relationship between three heat shock protein 70 gene polymorphisms and susceptibility to lung cancer

BACKGROUND

Heat shock protein 70 (Hsp70) has been shown to act as a chaperone and be associated with a variety of tumors. We investigated HSP70-1 G+190C, HSP70-2 A+1267G, and HSP70-hom T+2437C polymorphisms to assess whether genetic variation in HSP70 plays a role in the occurrence and development of lung cancer.

METHODS

A case-control study was conducted using 159 patients with lung cancer and 202 control subjects. Genomic DNA was typed for HSP70 polymorphisms using polymerase chain reactions with restriction fragment length polymorphism (PCR-RFLP). Unconditional logistic regression was used to estimate the relative risks of lung cancer.

RESULTS

There were significant differences in genotype and allele distributions between patients and controls for the HSP70-1 G+190C polymorphisms with and without adjustment for age, gender, smoking history, drinking history and family history of cancer (p<0.05). No significant differences were found in the polymorphisms of HSP70-2 A+1267G and HSP70-hom T+2437C. The haplotype analysis showed that the G/A/C and C/G/T haplotypes were associated with a significantly increased risk of lung cancer compared to the G/G/T haplotype. After adjustments for other risk factors, such as age, gender, drinking history and family history of cancer, the interactions between the HSP70-1 and HSP70-hom genotypes and smoking were confirmed [I(AB), 2.56 and 5.12, respectively].

CONCLUSIONS

HSP70-1 G+190C may be a functional polymorphism and affect susceptibility to lung cancer, and homozygous C/C genotype may enhance the risk of lung cancer. In addition, smoking along with HSP70-1 G+190C and HSP70-hom T+2437C, may increase the risk of lung cancer.

Functional FEN1 polymorphisms are associated with DNA damage levels and lung cancer risk

Flap endonuclease 1 (FEN1) is a key enzyme in maintaining genomic stability and protecting against carcinogenesis. This study investigated whether functional variations in FEN1 gene are associated with DNA damage and lung cancer risk. Thirty DNA samples were sequenced to identify variants and function of the variants was examined by a set of biochemical assays. DNA damage levels were detected by comet assays in a cohort of 303 coke-oven workers and 297 controls. The association with lung cancer risk was examined in two independent case-control panels consisted of a total 1,840 lung cancer patients and 1,958 controls. We identified two single nucleotide polymorphisms (SNPs) located in the FEN1 promoter c.-69G>A (rs174538:G>A) and 3'-untranslational region c.4150G>T (rs4246215:G>T) that were associated with reduced FEN1 expression. Among coke-oven workers, DNA damage levels were significantly higher in the -69GG or GA carriers compared with the -69AA carriers. The -69GG or 4150GG carriers had a significantly increased risk for developing lung cancer compared with the -69AA or 4150TT carriers. These results highlight FEN1 as an important gene in human carcinogenesis and genetic polymorphisms in FEN1 confer susceptibility to lung cancer.

Application of semipermeable membrane device (SPMD) to assess air genotoxicity in an occupational environment

Semipermeable membrane device (SPMD) is a passive sampler that sequesters lipophilic contaminants, mimicking the bioconcentration in the fatty tissue of organisms. This study was designed to assess the use of SPMD and biological tests (Comet assay and Ames test) for air monitoring. For this purpose an occupational environment with expected polycyclic aromatic hydrocarbons (PAHs) contamination (coke plant) was selected for a case study. The SPMDs were deployed in five occupational contaminated sites and in a control site. The SPMD dialysates were chemically analysed and examined for in vitro DNA-damaging activity in human cells (Jurkat) by Comet assay and for mutagenicity with the Ames test (TA98 strain, w/o S9). Total suspended particulates were also collected and analysed (GC-MS). No biological effect of SPMD extract was revealed in the control site. On the other hand, air samples collected with SPMDs within the coke plant showed variable degrees of genotoxic and mutagenic activity. The highest effects were associated with the highest PAH level recovered in the SPMDs extracts and in particulate samples. Results obtained support the sensitivity of biological tests associated to SPMD sampling for evaluating the health risk of potentially contaminated work environments highlighting the usefulness of SPMDs for environmental air quality monitoring.