Jianlin Lou

DNA damage and oxidative stress in human B lymphoblastoid cells after combined exposure to hexavalent chromium and nickel compounds.

In the present study, human B lymphoblastoid cells were exposed to potassium dichromate and/or nickel chloride for 24h or 48h. The cell viability and DNA damage induced by these compounds was measured with the CCK-8 assay and Comet assay, respectively. In addition, the generation of reactive oxygen species (ROS) and the levels of malondialdehyde (MDA) were measured using commercially available kits. Our results indicated that potassium dichromate could decrease cell viability and induce DNA damage in human B lymphoblastoid cells in a time - and concentration - dependent manner, but the toxicity of nickel chloride was not so obvious at concentrations used in our study. The results of ROS showed that both two compounds could only induce weak elevation of ROS level, but MDA levels were significantly enhanced. Antagonistic effects of cytotoxicity were mainly found between Cr (VI) and Ni (II), and synergistic effects of DNA damage and oxidative stress were partially found between these two compounds. Moreover, there were good correlations between the results of comet assay and the results of oxidative stress assays. It is suggested that synergistic DNA damage induced by simultaneously exposure of hexavalent chromium and nickel compounds is possibly related to oxidative stress.

Role of DNA methylation in cell cycle arrest induced by Cr (VI) in two cell lines.

Hexavalent chromium [Cr(IV)], a well-known industrial waste product and an environmental pollutant, is recognized as a human carcinogen. But its mechanisms of carcinogenicity remain unclear, and recent studies suggest that DNA methylation may play an important role in the carcinogenesis of Cr(IV). The aim of our study was to investigate the effects of Cr(IV) on cell cycle progress, global DNA methylation, and DNA methylation of p16 gene. A human B lymphoblastoid cell line and a human lung cell line A549 were exposed to 5–15 µM potassium dichromate or 1.25–5 µg/cm2 lead chromate for 2–24 hours. Cell cycle was arrested at G1 phase by both compounds in 24 hours exposure group, but global hypomethylation occurred earlier than cell cycle arrest, and the hypomethylation status maintained for more than 20 hours. The mRNA expression of p16 was significantly up-regulated by Cr(IV), especially by potassium dichromate, and the mRNA expression of cyclin-dependent kinases (CDK4 and CDK6) was significantly down-regulated. But protein expression analysis showed very little change of p16 gene. Both qualitative and quantitative results showed that DNA methylation status of p16 remained unchanged. Collectively, our data suggested that global hypomethylation was possibly responsible for Cr(IV) - induced G1 phase arrest,but DNA methylation might not be related to up-regulation of p16 gene by Cr(IV).

Improving the Accuracy of Mesothelioma Diagnosis in China

Introduction In the Western world, malignant mesothelioma (MM) is most prevalent in the pleura of older males who have been professionally exposed to asbestos. Information about MM from rapidly industrializing countries such as China is minimal. There is concern that a proportion of MM diagnoses in China may be incorrect because most Chinese physicians do not have experience diagnosing this rare cancer. We recently reported an unusually high incidence of peritoneal MM among eastern Chinese female patients. Here, we review the accuracy of MM diagnoses in China and provide suggestions to improve the accuracy of diagnosis. Methods We reviewed 92 pathological diagnosis of MM in 2002–2015 from two reference centers in the province of Zhejiang in eastern China. We performed a large set of immunohistochemistry analyses to increase the reliability of the diagnosis. Results We confirmed the MM diagnosis in 12 of 34 of the pleural tumors (35.3%), in 38 of 56 of the peritoneal tumors (67.9%), and in two of two of the MMs of the tunica vaginalis (100%). MMs were characterized by tumor cells showing nuclear Wilms tumor 1 and calretinin staining and by strong membranous staining for cytokeratin CAM5.2. The results of staining for the epithelial markers carcinoembryonic antigen, thyroid transcription factor‐1, MOC31, BerEP4, p63, p40, paired box 8, ER and PR were negative. BRCA1 associated protein 1 nuclear staining was lost in percentages similar to what has been reported for samples from Western countries. Conclusions Our findings suggest that MM—especially in its pleural localization—is often misdiagnosed in eastern China. Identifying pitfalls and possible solutions in the pathological diagnosis of MM will affect both the standard of care and research in China.

Thyroid endocrine dysregulation and erythrocyte DNA damage associated with PBDE exposure in juvenile crucian carp collected from an e-waste dismantling site in Zhejiang Province, China

In the present study, 40 juvenile crucian carp (Carassius auratus) were caught from a river close to an electronic waste (e-waste) site (exposed group) and another located 80 km away from the e-waste site (control group) in Zhejiang, China. Results indicated that muscle levels of polybrominated diphenyl ethers (median PBDEs, 235.98 ng/g wet wt; range, 7.70-703.31 ng/g wet wt), serum levels of thyroid-stimulating hormone (median TSH, 2.32 µIU/ml; range, 2.05-2.72 µIU/ml) and erythrocyte DNA damage level (median Olive tail movement, 16.27 µm; range, 4.28-27.51 µm) were higher in the exposed group than those in the control group (0.56 ng/g wet wt, range, 0.34-1.24 ng/g wet wt, p < 0.01; 1.70 µIU/ml, range, 1.40-2.08 µIU/ ml, p < 0.01; 6.06 µm, range, 2.01-10.72 µm, p < 0.01, respectively). Thyroxine (T4) was significantly lower in the exposed group (8.97 µIU/ml) than in the control group (12.47 µIU/ml). In addition, thyroid endocrine disorder and erythrocyte DNA damage levels were significantly associated with polybrominated diphenyl ether exposure. Hence, PBDEs may affect wild fish populations in real ecosystems with thyroid endocrine disruption and DNA damage.

Serum HMGB1 as a Potential Biomarker for Patients with Asbestos-Related Diseases

High-mobility group box 1 (HMGB1) functions as a proinflammatory cytokine and is one of the most intriguing molecules in inflammatory disorders and cancers. Notably, HMGB1 is a potential therapeutic target and novel biomarker in related diseases. However, the diagnostic value of HMGB1 for benign and malignant asbestos-related diseases (ARDs) remains unclear. In this work, we detected preoperative serum HMGB1 levels in Chinese asbestos-exposed (AE) and ARDs populations and further evaluated the diagnostic value of HMGB1 in patients with certain types of ARDs, including those with pleural plaques, asbestosis, or malignant mesothelioma (MM). The experimental data presented that the serum level of HMGB1 was significantly elevated in AE and ARDs subjects. Our findings indicated that serum HMGB1 is a sensitive and specific biomarker for discriminating asbestosis- and MM-affected individuals from healthy or AE individuals. In addition, serum matrix metalloproteinases 2 and 9 are not correlated with HMGB1 in ARDs. Thus, our study provides supporting evidence for HMGB1 as a potential biomarker either for the clinical diagnosis of high-risk AE cohorts or for evaluating ARDs.

MWCNTs Induce ROS Generation, ERK Phosphorylation, and SOD-2 Expression in Human Mesothelial Cells:

Biological oxidative responses are involved in the toxicity of multiwall carbon nanotubes (MWCNTs), which may cause asbestos-like pathogenicity. Superoxide dismutase 2 (SOD-2) has been proposed as a biomarker of early responses to mesothelioma-inducing fibers. This study was conducted to investigate the alteration of SOD-2 expression in the human mesothelial cell lines Met-5A after exposure to nontoxic doses of MWCNTs and the potential signaling pathway. The parameters measured included the viability, morphological change, superoxide formation, extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, and messenger RNA (mRNA)/protein levels of SOD-2. Our results showed that MWCNTs upregulated SOD-2 expression at both mRNA and protein level. Coincidently, both superoxide formation and ERK1/2 phosphorylation were observed in Met-5A cells exposed to MWCNTs and were diminished by pretreatment with the reactive oxidative species (ROS) scavenger, N-acetyl-l-(+)-cysteine (NAC). To further investigate the role of ROS/ERK1/2 in MWCNTs-induced SOD-2 overexpression, prior to MWCNTs exposure, cells were pretreated with the Mitogen-activated protein kinase kinase 1/2 (MEK 1/2) inhibitor (U0126) or with NAC. Both pretreatments decreased the MWCNTs-induced overexpression of SOD-2. These results suggest that upregulation of SOD-2 in Met-5A cells exposed to MWCNTs is mediated by ROS formation and ERK1/2 activation.

PPAR Ligands Function as Suppressors That Target Biological Actions of HMGB1

High mobility group box 1 (HMGB1), which has become one of the most intriguing molecules in inflammatory disorders and cancers and with which ligand-activated peroxisome proliferator-activated receptors (PPARs) are highly associated, is considered as a therapeutic target. Of particular interest is the fact that certain PPAR ligands have demonstrated their potent anti-inflammatory activities and potential anticancer effects. In this review article we summarize recent experimental evidence that PPAR ligands function as suppressors that target biological actions of HMGB1, including intracellular expression, receptor signaling cascades, and extracellular secretion of HMGB1 in cell lines and/or animal models. We also propose the possible mechanisms underlying PPAR involvement in inflammatory disorders and discuss the future therapeutic value of PPAR ligands targeting HMGB1 molecule for cancer prevention and treatment.

Elevated tissue Cr levels, increased plasma oxidative markers, and global hypomethylation of blood DNA in male Sprague-Dawley rats exposed to potassium dichromate in drinking water.

Hexavalent chromium [Cr (VI)] is prevalent in ground water in some areas, but evidence on the toxic effects of Cr (VI) via ingestion through drinking water remains insufficient. The aims of our study were to investigate the toxic effects of Cr (VI) through oral water ingestion on oxidative stress and DNA methylation. Thirty‐two Sprague‐Dawley rats were randomly divided into four groups, and exposed to porassium dichromate (K2Cr2O7; 0, 30, 100, and 300 mg/L) in drinking water for 4 weeks. Mean body weight gain, mean water consumption, clinical chemistry determinations, and oxidative stress levels in plasma were measured. Global DNA methylation changes and DNA methylation status at the promoter of p16 gene were also detected. After 4 weeks, mild anemic effects and increased plasma malondialdehyde (MDA) levels occurred in rats exposed to 100 mg/L or 300 mg/L of Cr (VI). Plasma glutathione peroxidase (GSH‐Px) activity decreased in all exposed groups. Global DNA methylation levels were reduced in 100 mg/L and 300 mg/L exposure groups. However, DNA methylation status at the promoter of P16 gene remained unchanged in all K2Cr2O7‐treated groups. The correlation analysis indicated that increased MDA levels were closely correlated to global DNA hypomethylation. Our results indicated that oral ingestion of Cr (VI) through drinking water caused not only oxidative stress in plasma, but also global DNA hypomethylation in blood cells from male rats, and a good correlation was found between increased MDA levels and reduced global DNA methylation.

Proteome Changes of Human Bone Marrow Mesenchymal Stem Cells Induced by 1,4-Benzoquinone

Benzene is metabolized to hydroquinone in liver and subsequently transported to bone marrow for further oxidization to 1,4-benzoquinone (1,4-BQ), which may be related to the leukemia and other blood disorders. In the present study, we investigated the proteome profiles of human primary bone marrow mesenchymal stem cells (hBM-MSCs) treated by 1,4-BQ. We identified 32 proteins that were differentially expressed. Two of them, HSP27 and Vimentin, were verified at both mRNA and protein levels and their cellular localization was examined by immunofluorescence. We also found increased mRNA level of RAP1GDS1, a critical factor of metabolism that has been identified as a fusion partner in various hematopoietic malignancies. Therefore, these differentially expressed proteins can play important roles in benzene-mediated hematoxicity.

Application of the Benchmark Dose (BMD) Method to Identify Thresholds of Cadmium-Induced Renal Effects in Non-Polluted Areas in China.

The benchmark dose (BMD) method has been increasingly used to assess the health risks of cadmium (Cd) in epidemiological studies. The aim of our study was to estimate the threshold levels of urinary Cd (UCd) using the BMD method in a general population of Jiangshan City, Zhejiang Province of China. In our study, a total of 934 people (469 men, 465 women) were recruited and morning urine samples were collected from all the participants. Levels of Cd, creatinine, and renal dysfunction indicators such as retinol binding protein (RBP), β2-microglobulin (β2-MG), and N-acetyl-b-glucosaminidase (NAG) in urine were detected for analysis of BMD and BMD low (BMDL) of UCd. RBP, β2-MG, and NAG in urine all correlated significantly (P < 0.001) with UCd except of age (P = 0.767). When the benchmark response (BMR) was 5%, the BMD/BMDL of UCd for RBP, β2-MG, and NAG was 1.69/ 0.89, 1.24/0.62, 0.85/0.49 μg/g Cr in men and 1.70/0.76, 1.35/0.64, 1.36/0.65 μg/g Cr in women, respectively. If the BMR was set at 10%, the BMD/BMDL of UCd for RBP, β2-MG, and NAG was 2.44/1.59, 2.09/1.30, 1.80/1.04 μg/g Cr in men and 2.43/1.53, 2.10/1.34, 2.31/1.37 μg/g Cr in women, respectively. Our results provided evidence for Cd-induced tubular effects in cadmium non-polluted areas in China. Both β2-MG and NAG were more sensitive than RBP in response to Cd exposure. But β2-MG was the most sensitive indicator in women, and NAG was the most sensitive one in men.