Correlation Between Social Support and HPV Vaccination Behavior of Female Sex Workers in Entertainment Venues in a Region of Guangxi, China.

Objective: To understand the current situation for social support and HPV vaccination behavior of female sex workers (FSWs) in entertainment venues and to explore the association between the support and HPV vaccination behavior. Methods: 923 FSWs in entertainment venues in a region of Guangxi were selected as survey respondents by using intentional sampling and employing a self-developed basic information questionnaire. The social support rating and the HPV vaccination behavior scales were analyzed to determine the current status of support and HPV vaccination behavior of FSWs in entertainment venues. In addition, the correlations between these parameters were analyzed. Results: The total score of social support of FSWs in entertainment venues was 35.13±8.10, and the score for HPV vaccination behavior was 30.08±5.73. There were significant differences between these two parameters for FSWs of different ages, monthly incomes and working hours (P < 0.05). Objective, subjective and social support were positively correlated with all dimensions of HPV vaccination behavior (r = 0.212~0.236, 0.245~0.334 and 0.113~0.152, respectively; P < 0.01 in all cases). Typical correlation analysis yielded a correlation between these three dimensions of social support as well as with two dimensions of HPV vaccination behavior (self-decision-making and self-efficacy) (r = 0.373; P < 0.01). Conclusion: Social support and HPV vaccination behavior of FSWs in entertainment venues initially low. However, as social support for FSWs was increased, their behavior towards HPV vaccination was elevated. Both subjective and objective support helped FSWs in entertainment venues their behavior to HPV vaccination and to maintain their physical and mental health.

Aluminum causes irreversible damage to the development of hippocampal neurons by regulating m6A RNA methylation.

The underlying mechanism of the aluminum (Al) on neurotoxicity remains unclear. We explored whether the impairment of hippocampal neurons induced by developmental Al exposure was associated with the m6A RNA modification in mice. In this study, the pregnant female mice were administered 4 mg/mL aluminum-lactate from gestational day (GD) 6 to postnatal day (PND) 21. On PND 21, 10 offsprings per group were euthanized by exsanguination from the abdominal aorta after deep anesthetization. The other offsprings which treated with aluminum-lactate on maternal generation were divided into two groups and given 0 (PND60a) and 4 mg/mL (PND60b) aluminum-lactate in their drinking water until PND 60. Significant neuronal injuries of hippocampus as well as a reduction in the m6A RNA modification and the expression of methylase were observed at PND 21 and PND 60a mice. The results indicated that Al-induced developmental neurotoxicity could persist into adulthood despite no sustained Al accumulation. m6A RNA modification had a crucial role in developmental neurotoxicity induced by Al. In addition, Al exposure during the embryonic to adult stages can cause more severe nerve damage and decline of m6A RNA modification. Collectively, these results suggest that the mechanism underlying Al-induced neurotoxicity appears to involve m6A RNA modification.

METTL3-mediated m6A RNA methylation was involved in aluminum-induced neurotoxicity.

Aluminum (Al) exposure has been linked to the development of a variety of neurodegenerative diseases. However, whether m6A RNA methylation participated in Al-induced neurotoxicity remain to be defined. In this study, mice were administrated with aluminum-lactate at dose of 220 mg/kg. bw by gavage for 3 months. Meanwhile, the primary hippocampal neurons were isolated and treated with 0, 50, 100, 150 µM aluminum-lactate, respectively for 7 days. Al exposure caused neuronal shrinkage, decreased Nissl bodies, and increased apoptosis. In accordance, in vitro studies also showed that Al exposure led to neuronal apoptosis in a dose-dependent manner, together with the decline in m6A RNA methylation levels. Moreover, the mRNA expression of Mettl3, Mettl14, Fto, and Ythdf2 were decreased upon Al exposure. Notably, the protein expression of METTL3 was dramatically down-regulated by 42% and 35% in Al-treated mice and neurons, suggesting METTL3 might exert a crucial role in Al-induced neurotoxicity. We next established a mouse model with hippocampus-specific overexpressing of Mettl3 gene to confirm the regulatory role of RNA methylation and found that METTL3 overexpression relieved the neurological injury induced by Al. The integrated MeRIP-seq and RNA-seq analysis elucidated that 631 genes were differentially expressed at both m6A RNA methylation and mRNA expression. Notably, EGFR tyrosine kinase inhibitor resistance, Rap1 signaling pathway, protein digestion and absorption might be involved in Al-induced neurotoxicity. Moreover, VEGFA, Thbs1, and PDGFB might be the central molecules. Collectively, our findings provide the novel sight into the role of m6A RNA methylation in neurodegenerative disease induced by Al.

METTL3-mediated m6A mRNA modification was involved in cadmium-induced liver injury.

Cadmium is an environmental pollutant that has extensive deleterious effects. However, the mechanisms underlying the hepatotoxicity induced by long-term exposure to cadmium remained undefined. In the present study, we explored the role of m6A methylation in the development of cadmium-induced liver disease. We showed a dynamic change of RNA methylation in liver tissue from mice administrated with cadmium chloride (CdCl2) for 3, 6 and 9 months, respectively. Particularly, the METTL3 expression was declined in a time-dependent manner, associated with the degree of liver injury, indicating the involvement of METTL3 in hepatotoxicity induced by CdCl2. Moreover, we established a mouse model with liver-specific over-expression of Mettl3 and administrated these mice with CdCl2 for 6 months. Notably, METTL3 highly expressed in hepatocytes attenuated CdCl2-induced steatosis and liver fibrosis in mice. In vitro assay also showed METTL3 overexpression ameliorated the CdCl2-induced cytotoxicity and activation of primary hepatic stellate cells. Furthermore, transcriptome analysis identified 268 differentially expressed genes both in mice liver tissue treated with CdCl2 for 3 months and 9 months. Among them, 115 genes were predicted to be regulated by METTL3 determined by m6A2Target database. Further analysis revealed the perturbation of metabolic pathway, glycerophospholipid metabolism, ErbB signaling pathway, Hippo signaling pathway, and choline metabolism in cancer, and circadian rhythm, led to hepatotoxicity induced by CdCl2. Collectively, our findings reveal new insight into the crucial role of epigenetic modifications in hepatic diseases caused by long-term exposure to cadmium.

Morphological alterations in C57BL/6 mouse intestinal organoids as a tool for predicting chemical-induced toxicity.

Intestinal organoid may serve as an alternative model for toxicity testing. However, the linkage between specific morphological alterations in organoids and chemical-induced toxicity has yet to be defined. Here, we generated C57BL/6 mouse intestinal organoids and conducted a morphology-based analysis on chemical-induced toxicity. Alterations in morphology were characterized by large spheroids, hyperplastic organoids, small spheroids, and protrusion-loss organoids, which responded in a concentration-dependent manner to the treatment of four metal(loid)s including cadmium (Cd), lead (Pb), hexavalent chromium (Cr-VI), and inorganic trivalent arsenic (iAs-III). Notably, alterations in organoid morphology characterized by abnormal morphology rate were correlated with specific intestinal toxic effects, including reduction in cell viability and differentiation, induction of apoptosis, dysfunction of mucus production, and damage to epithelial barrier upon repeated administration. The benchmark dose (BMDL10) values of morphological alterations (0.007-0.195 µM) were lower than those of conventional bioassays (0.010-0.907 µM). We also established that the morphologic features of organoids upon Cd, Pb, Cr-VI, or iAs-III treatment were metal specific, and mediated by Wnt, bone morphogenetic protein, apoptosis induction, and Notch signaling pathways, respectively. Collectively, these findings provide novel insights into the relevance of morphological alterations in organoids to specific toxic endpoints and identify specific morphological alterations as potential indicators of enterotoxicity.

Protein phosphatase 2A regulates cytotoxicity and drug resistance by dephosphorylating AHR and MDR1.

Protein phosphatase 2A (PP2A) is a serine/threonine dephosphorylating enzyme complex that plays numerous roles in biological processes, including cell growth and metabolism. However, its specific actions in many of these critical pathways are unclear. To explore mechanisms underlying metabolic enzyme regulation in the liver, we investigated the key pathways involved in regulation of xenobiotic-metabolizing enzymes in a mouse model with hepatocyte-specific deletion of Ppp2r1a, encoding the Aα subunit of PP2A. We performed transcriptome and phosphoproteome analysis in mouse livers at the age of 3 months and identified 2695 differentially expressed genes and 549 upregulated phosphoproteins in homozygous knockout mouse livers compared with WT littermates. In particular, the expression of metabolic enzymes Cyp2e1, Cyp1a1, Cyp1a2, Mdr1a, and Abcg2 was dramatically altered in homozygous knockout mouse livers. We also demonstrated that activation of PP2A reversed the decline of metabolic enzyme expression in primary mouse hepatocytes. We found that specific PP2A holoenzymes were involved in metabolic enzyme induction through dephosphorylation of transcription factors, nuclear receptors, or the target enzymes themselves, leading to dysregulation of xenobiotic metabolism or drug-induced hepatotoxicity. Notably, we confirmed that a regulatory axis, PP2A B56α-aryl hydrocarbon receptor-Cyp1a1, was involved in benzo(a)pyrene-induced cytotoxicity through dephosphorylation of the metabolic nuclear receptor, aryl hydrocarbon receptor, at serine 36. In addition, we showed that PP2A B56δ complexes directly dephosphorylated the multidrug efflux pump MDR1 (encoded by multi-drug resistance gene 1), contributing to drug resistance against the chemotherapeutic 5-fluorouracil. Taken together, these novel findings demonstrate the involvement of PP2A in the regulation of liver metabolism.

Nonylphenol exposure-induced oocyte quality deterioration could be reversed by melatonin supplementation in mice.

Nonylphenol (NP) belongs to the metabolites of commercial detergents, which acts as an environmental endocrine disruptor. NP is reported to have multiple toxicity including reproductive toxicity. In present study, we reported the protective effects of melatonin on the NP-exposed oocyte quality. We set up a mouse in vivo model of NP exposure (500 µg/L), by daily drinking and continued feeding for 4 weeks; and we gave a daily dose of melatonin (30 mg/kg) to the NP-exposed mice. Melatonin supplementation restores the development ability of oocytes exposed to NP, and this was due to the reduction of ROS level and DNA damage by melatonin. Melatonin could rescue aberrant mitochondria distribution, mitochondria membrane potential, which also was reflected by ATP content and mtDNA copy number. Moreover, melatonin could restore the RPS3 expression to ensure the ribosome function for protein synthesis, and reduced GRP78 protein level to protect against ER stress and ER distribution defects. We also found that vesicle protein Rab11 from Golgi apparatus was protected by melatonin at the spindle periphery of oocytes of NP-exposed mice, which further moderated LAMP2 for lysosome function. Our results indicate that melatonin protects oocytes from NP exposure through its effects on the reduction of oxidative stress and DNA damage, which might be through its amelioration on the organelles in mice.

Identification of miRNAs involved in liver injury induced by chronic exposure to cadmium.

To elaborate the molecular mechanism underlying the hepatotoxicity induced by chronic exposure to cadmium (Cd), a mouse model with hepatocyte-specific deletion of Ppp2r1a (encoding protein phosphatase 2 A Aα subunit, PP2A Aα) gene was used to investigate the effect of cadmium exposure on liver injury. The wild type littermates (WT) and PP2A Aα-/- mice (KO) were treated with cadmium chloride (CdCl2) at concentrations of 0 mg/L, 10 mg/L, 100 mg/L in drinking water for 3, 6 and 9 months (KO mice only for 9 months), respectively. The pathological findings were characterized by progressive inflammation, steatosis, and liver fibrosis upon treatment of CdCl2 in a dose-response and time-dependent manner. Notably, PP2A Aα depletion leads to a more profound liver injury induced by CdCl2 treatment. The transcriptome analysis in livers of KO mice revealed 20 differentially expressed microRNAs (miRNAs) appeared in both 3- and 9-month. Particularly, the alterations of miR-34a-5p, miR-345-5p, and miR-30e-5p expressions were implicated in the development of liver disease and correlated with the degree of liver injury induced by cadmium treatment. Further analysis indicated that miR-34a-5p, miR-345-5p, and miR-30e-5p might be involved in CdCl2-induced liver injury, in part by dysregulation of lipid metabolism and inflammation. The in vitro studies showed that miR-34a-5p was involved in regulation of CdCl2-induced cytotoxicity through directly targeted adiponectin receptor 2 (AdipoR2) mRNA. Taken together, we identified that specific miRNAs were implicated in hepatotoxicity induced by chronic exposure to CdCl2. These findings also provide new insight into the role of PP2A in regulation of miRNAs-mediated liver injury.

MicroRNA-106b-5p inhibits growth and progression of lung adenocarcinoma cells by downregulating IGSF10.

In this study, we investigated the mechanistic role and prognostic significance of IGSF10 in lung adenocarcinoma. Oncomine database analysis showed that IGSF10 expression was significantly reduced in most cancer types, including lung adenocarcinoma (LUAD). In the TCGA-LUAD dataset, IGSF10 expression correlated positively with proportions of tumor-infiltrated B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages, and dendritic cells. Kaplan-Meier survival analysis showed that overall survival of patients with low IGSF10 expression was significantly shorter than those with high IGSF10 expression. MiRWalk2.0 database analysis and dual luciferase reporter assays confirmed that miR-106b-5p suppressed IGSF10 expression by binding to its 3'UTR. MiR-106b-5p levels inversely correlated with IGSF10 expression in the TCGA-LUAD dataset. Moreover, inhibition of miR-106b-5p significantly decreased in vitro proliferation, migration, and invasion by LUAD cells, whereas miR-106b-5p overexpression reversed those effects. These results demonstrate that IGSF10 is an independent prognostic factor for LUAD. Furthermore, miR-106b-5p suppressed IGSF10 expression in LUAD tissues by binding to its 3'UTR, which makes IGSF10 and miR-106b-5p potential prognostic biomarkers and therapeutic targets in LUAD patients.

Identification of prognostic markers of lung cancer through bioinformatics analysis and in vitro experiments.

Lung cancer is one of the most common types of cancer worldwide. Understanding the molecular mechanisms underlying the development and progression of lung cancer may improve early diagnosis, treatment and prognosis. The aim of the present study was to examine the pathogenesis of lung cancer and to identify potentially novel biomarkers. Gene expression datasets of patients with lung cancer were obtained from the Gene Expression Omnibus. Genes which were most closely associated with lung cancer (core genes) were screened by weighted gene co­expression network analysis. In vitro cell based experiments were further utilized to verify the effects of the core genes on the proliferation of lung cancer cells, adhesion between cells and the matrix, and the associated metabolic pathways. Based on WGCNA screening, two gene modules and five core genes closely associated with lung cancer, including immunoglobulin superfamily member 10 (IGSF10) from the turquoise module, and ribonucleotide reductase regulatory subunit M2, protein regulator of cytokinesis 1, kinesin family member (KIF)14 and KIF2C from the brown module were identified as relevant. Survival analysis and differential gene expression analysis showed that there were significant differences in IGSF10 expression levels between the healthy controls and patients with lung cancer. In patients with lung cancer, IGSF10 expression was decreased, and the overall survival time of patients with lung cancer was significantly shortened. An MTT and colony formation assay showed that IGSF10­knockout significantly increased proliferation of lung cancer cells, and Transwell assays and adhesion experiments further suggested that the adhesion between cells and the matrix was significantly increased in IGSF10­knockout cells. Gene Set Enrichment Analysis showed that the expression level of IGSF10 was significantly associated with the activation of the integrin­ß1/focal adhesion kinase (FAK) pathway. Western blotting revealed that knockout of IGSF10 resulted in the activation of the integrin­ß1/FAK pathway, as the protein expression levels of integrin­ß1, phosphorylated (p)­FAK and p­AKT were significantly upregulated. Activation of the integrin­ß1/FAK pathway, following knockout of IGSF10, affected the proliferation and adhesion of lung cancer cells. Therefore, IGSF10 my serve as a potential prognostic marker of lung cancer.

Effect of trichloroacetaldehyde on the activation of CD4+T cells in occupational medicamentosa-like dermatitis: An in vivo and in vitro study.

Occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) is a hypersensitivity disease with autoimmune liver injury, which has increasingly become a serious occupational health problem in China. However, the pathogenesis of OMLDT remained undefined. In this study, 30 TCE-induced OMLDT patients, 58 exposure controls, and 40 non-exposure controls were recruited. We showed that the ratio of activated CD4+ T cells (downregulation of CD62 L) was dramatically increased in OMLDT patients compared to exposure and non-exposure control, suggesting that CD4+ T cells activation was a key cellular event in the development of OMLDT. In parallel, the expression of cytokine including IL-2, IFN-γ, TNF-α and IL-17A were increased obviously and IL-4 decreased in CD4+ T cells from OMLDT patients. in vitro assay, we found that trichloroethylene metabolites trichloroacetaldehyde (TCAH), not trichloroacetic acid (TCA) or Trichloroethanol (TCOH) could activate the naïve CD4+ T cells characterized by a rise in intracellular calcium, down-regulated CD62 L and subsequently trigger the secretion of IL-2, IFN-γ and TNF-α. Notably, the phosphorylation status of NF-κB and p38MAPK were elevated in OMLDT patients. Moreover, TCAH also could activate the p38MAPK and NF-κB, suggesting the role of p38MAPK and NF-κB pathways in the activation of CD4+ T cells. In addition, we found that the inhibition of Schiff base formation decreased the ability of TCAH to induce the activation of naïve CD4+ T cells and p38MAPK and NF-κB pathway. In conclusion, we revealed that the CD4+ T activation and increased the cytokines including IL-2, IFN-γ and TNF-α but decreased IL-4 in CD4+ T cells were associated with OMLDT. TCAH could activate naïve CD4+ T cells through NF-κB and p38MAPK activation induced by Schiff base formation, which might contribute to the development of OMLDT. These findings provide a new insight into the pathogenesis of OMLDT.

1,2-Dichloroethane-induced hepatotoxicity and apoptosis by inhibition of ERK 1/2 pathways.

1,2-Dichloroethane (DCE) is a ubiquitous occupational environmental contaminant. Subacute exposure to DCE can cause severe toxic encephalopathy and has obvious toxic effects on the liver. However, the toxicity of DCE on the liver and its molecular mechanism remain elusive. In the present study, we established a DCE-exposed animal model by inhalation in SD rats and used HepG2 cells in in vitro tests. The DCE-exposed groups showed hepatic dysfunction relative to the control group. Moreover, apoptotic cells and decreased phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) were found in liver tissue of rats in 3 DCE-exposed groups. In vitro tests showed that short-term exposure to DCE induced apoptosis in HepG2 cells. Furthermore, the incubation of cells with DCE significantly decreased the phosphorylation of ERK1/2 in a concentration-dependent manner. Additionally, incubating HepG2 cells with epidermal growth factor, an ERK1/2 activator, significantly increased apoptosis in HepG2 cells. In conclusion, our results suggest that DCE induces apoptosis in HepG2 cells by inhibiting ERK1/2 pathways.

DNA repair gene deficiency does not predispose human bronchial epithelial cells to benzo(a)pyrene-induced cell transformation.

The development of cost and time-efficient in vitro assays to predict carcinogenicity of chemicals has become a very important direction for toxicological research. In this study, we generated a series of human bronchial epithelial (HBE) cells defect in DNA repair gene excision repair cross-completion 1 (ERCC1), excision repair cross-completion 2 (ERCC2), ataxia-telangiectasia mutated (ATM) and mutS homolog 2 (MSH2), respectively. The inhibition of gene expression was verified by detection of mRNA and protein levels of respective genes. The suppression of these DNA repair genes has no impact on cell proliferation or cell transformation. Although we found that the transgenic HBE cells were more sensitive in benzo(a)pyrene (BaP)-induced DNA damages measured by cytokinesis-block micronucleus (CBMN) assay and comet assay, we failed to observe enhanced effects on induction of cell transformation. HBE cells defect in DNA repair pathways did not exhibit malignantly transformed phenotype up to 20 weeks of BaP treatment, indicating that the deficiency of ERCC1, ERCC2, ATM, or MSH2 alone did not shorten the latency of cell transformation. In contrast, we found that HBE cells expressing H-Ras or c-Myc were transformed 8 or 12 weeks after BaP treatment. These findings demonstrate that silencing of a single DNA repair gene does not confer cells susceptible to chemical-induced cell transformation.

[Metabolic activation of benzo(a)pyrene enhanced transformation of human bronchial epithelium cell HBETR].

OBJECTIVE: To study the application of different metabolic activation systems in benzo(a)pyrene [B(a)P]-induced human bronchial epithelium cell HBETR transformation. METHODS: In vitro metabolic activations of B(a)P were compared with rat liver S9 fraction mix, overexpression of a key enzyme (P450 CYP1A1), and prior low dose B(a)P (1 micromol/L) induction. Using soft agar assay and tumorigenicity assay, the different metabolic activation systems were compared to the influence on transformation of human bronchial epithelium cell HBETR. RESULTS: Both immunoblotting and enzyme activity showed that cells overexpressing CYP1A1 (HBETR-1A1) and 48 h after low dose B(a)P induction (HBETR-IN) had high-level expression of CYP1A1. There were no obvious changes in the biology characteristic of these cells. The latencies of cell transformation in HBETR-1A1 and HBETR-IN cells were 11 weeks when cells were treated with B(a)P at concentration of 20 micromol/L, while it took 14 weeks to achieve cell transformation in their control cells. The latencies of malignant transformation in HBETR cells in presence or absence of S9-mix were 14 weeks and 20 weeks, respectively. The efficiencies of cell transformation were in consonance with the protein level of endogenous CYP1A1 enzyme and its enzyme activity. CONCLUSION: The three metabolic conditions of the addition of rat liver S9 fraction mix, overexpression of a key enzyme (CYP1A1), and low dose B(a) P induction could enhance the B(a)P metabolic activation and shorten the latency of malignant transformation. In terms of the feasibility, difficulty of manipulation, stability, and reliability, low dose B(a)P induction could seem to be a prospective system used in metabolic activation in comparison with rat liver S9 fraction mix addition.

[Establishment and application of oncogene over expressed human epithelial cell transformation model].

OBJECTIVE: To establish human bronchial epithelial cell lines over expressing oncogene and to investigate its application in detection of carcinogen-induced cell transformation. METHODS: Mediated by retrovirus infection, human telomerase catalytic subunit, hTERT was introduced into immortal human bronchial epithelial cells (16HBE) and followed by introduction of the oncogenic allele H-Ras(V12), or c-Myc or empty vector, creating cell lines 16HBETR, 16HBETM and 16HBETV, respectively. Biological characteristics of these cell lines including morphology, proliferation, and chromosomal aberration were examined to access whether they were transformed. Soft agar experiment and nude mice subcutaneous injection were performed using pre-transformed 16HBE cells induced by known carcinogens, nickel sulfate (NiSO4) and 7, 8, -dihydrodiol-9, 10-epoxide benzo[a] pyrene (BPDE). RESULTS: With detection of telomerase activity and Western blotting, the expression of target proteins was verified. Thus, the transgenic 16HBE cell lines were successfully established. Cells expressing oncogene H-Ras or c-Myc grew 30.3% or 10.4% faster than control cells. However, these cells failed to form colonies in soft agar or form tumor in nude mice. 16HBETR, 16HBETM cells obtained transformed phenotype at 5 wks, 11 wks, respectively after treatment with BPDE, which are 15 wks and 9 wks earlier than control cells 16HBETV (20 wks). Meanwhile, 16HBETR, 16HBETM cells obtained transformed phenotype at 11 wks, 14 wks, respectively after treatment with nickel sulfate, which are 21 wks and 18 wks earlier than control cells (32 wks). CONCLUSION: With the advantage of shorter latency, transgenic human cell transformation models could be used in potent carcinogen screening and applied to chemical-carcinogenesis mechanism study.

Development of human cell models for assessing the carcinogenic potential of chemicals.

To develop human cell models for assessing the carcinogenic potential of chemicals, we established transgenic human cell lines and tested the sensitivity of known carcinogens using a cell transformation assay. A retroviral vector encoding an oncogenic allele of H-Ras (HBER) or c-Myc (HBEM) was introduced into human bronchial epithelial cells (HBE) immortalized by SV40 large T (LT) antigen, leading to increased cell proliferation but failing to confer a transformed phenotype characterized by anchorage-independent cell growth and tumor formation of immunodeficient mice. When these pre-transformed cells were treated with nickel sulfate (NiSO4), we found that it shortened the latency of malignant transformation at least by 19 wk in HBER cells or 16 wk in HBEM cells compared to vector control cells. Similarly, the latency of cell transformation was shorter by 15 wk in HBER cells or 9 wk in HBEM cells when cells were treated with benzo(a)pyrenediol epoxide (BPDE). HBER cells appeared to be more sensitive to TPA, NiSO4 or BPDE-induced cell transformation compared to human embryonic kidney cells expressing H-Ras (HEKR), implying that cell-type specificity is one of important factors determining the effectiveness of the assay. Using AFB1 and BaP as the representative pro-carcinogens, we also compared the efficiency of three different metabolic conditions in mediating cell transformation. Low dose chemical induction seems to be a prospective system used for metabolic activation of pro-carcinogens. Our findings provided direct evidence that a genetically modified human cell transformation model can be applied to the assessment of potent carcinogens.

Epigenetic silencing of O6-methylguanine DNA methyltransferase gene in NiS-transformed cells.

Nickel (Ni) compounds are potent carcinogens and can induce malignant transformation of rodent and human cells. To uncover the molecular mechanisms of nickel sulfide (NiS)-induced cell transformation, we investigated epigenetic alterations in a set of DNA repair genes. The silencing of the O(6)-methylguanine DNA methyltransferase (MGMT) gene locus and upregulation of DNA methyltransferase 1 (DNMT1) expression was specifically detected in NiS-transformed human bronchial epithelial (16HBE) cells. In addition, we noted epigenetic alterations including DNA hypermethylation, reduced histone H4 acetylation and a decrease in the ratio of Lys-9 acetylated/methylated histone H3 at the MGMT CpG island in NiS-transformed 16HBE cells. Meanwhile, we identified concurrent binding of methyl-CpG-binding protein 2, methylated DNA-binding domain protein 2 and DNMT1 to the CpG island of the MGMT promoter, demonstrating that these components collaborate to maintain MGMT methylation in NiS-transformed cells. Moreover, depletion of DNMT1 by introduction of a small hairpin RNA construct into NiS-transformed cells resulted in a 30% inhibition of cell proliferation and led to increased MGMT gene expression by reversion of the epigenetic modifications at the MGMT promoter region. MGMT suppression and hypermethylation at the CpG island of the MGMT promoter occurred 6 days after NiS treatment, indicating that epigenetic modifications of MGMT might be an early event in tumorigenesis. Taken together, these observations demonstrate that epigenetic silencing of MGMT is associated with DNA hypermethylation, histone modifications and DNMT1 upregulation, which contribute to NiS-induced malignant transformation.

[Study on the inhibitory effects of juice of tomato on the growth of human prostate carcinoma PC-3 cells].

OBJECTIVE: To study on the inhibitory effects of juice of tomato on the growth of human prostate carcinoma PC-3 cells and its possible mechanism. METHODS: PC-3 cells were treated with the juice of tomato in different concentration (40, 80, 120 ul/ml) for 48h; the proliferation of PC-3 cells were measured by MTT assay, the comet assay was used to measure the DNA damage of PC-3 cells. RESULTS: Juice of tomato could inhibit the proliferation of PC-3 cells, the growth inhibitory rate of experimental groups were significantly higher than that of control group, with very statistical significance; and it could induce the breakage of DNA single strand of PC-3 cells and resulted in comet cells with tail, Rate of DNA tail and the tail length of DNA increased with the increasing of concentration of juice of tomato, showing the obvious dose effect relationship. CONCLUSION: Juice of tomato could lead to DNA damage of PC-3 cells, it was related to that could inhibit the proliferation of PC-3 cells.