Assessment of no-observed-effect-levels for DNA adducts formation by genotoxic carcinogens in fetal turkey livers.

For genotoxic carcinogens, covalent binding to DNA is a critical initiating event in tumorigenesis. The present research investigated dose-effect relationships of three genotoxic carcinogens representing different structural classes, 2-acetylaminofluorene (2-AAF), benzo[a]pyrene (B[a]P) and quinoline (QUI), to assess the existence of no-observed-effect-levels (NOELs) for the formation of DNA adducts. Carcinogens were administered into the air sac of fertilized turkey eggs over wide dose ranges in three daily injections on days 22 to 24 of incubation. DNA adducts were measured in the fetal turkey livers by the 32P-nucleotide postlabeling (NPL) assay. B[a]P and QUI produced DNA adducts in a dosage-related manner and exhibited NOELs at 0.65 and 0.35 mg/kg bw/day, respectively. In contrast, 2-AAF formed DNA adducts at all tested dosages down to 0.005 mg/kg bw/day. Benchmark dose (BMD) analysis identified the potencies of 2-AAF and QUI to be similar, while B[a]P was the least potent compound. Overall, findings in fetal turkey livers demonstrated that exposure levels to genotoxic compounds that do not result in DNA adducts can exist but are not evident with all carcinogens of this type. The use of mechanistic dose-effect studies for genotoxic endpoints can provide critical information for prioritization of concerns for risk assessment.

The anticarcinogenic effect of eugenol on lung cancer induced by diethylnitrosamine/2-acetylaminofluorene in Wistar rats: insight on the mechanisms of action.

This study was designed to assess the ameliorative effects of eugenol and to propose the possible mechanisms of action of eugenol in diethylnitrosamine (DENA)/acetylaminofluorene (AAF)-caused lung cancer in Wistar rats. To induce lung cancer, DENA at a dose of 150 mg/kg body weight (b.wt) for 2 weeks were intraperitoneally injected once each week and AAF was administered orally at a dose of 20 mg/kg b.wt. four times each week for the next 3 weeks. DENA/AAF-administered rats were orally supplemented with eugenol at a dose of 20 mg/kg b.wt administered once a day until 17 weeks starting from the 1st week of DENA administration. Lung histological lesions, including sheets of tumor cells, micropapillary adenocarcinoma, and apoptotic cells, resulting from the DENA/AAF dosage, were ameliorated by eugenol treatment. However, a significant drop in the levels of LPO in the lungs and a remarkable rise in GSH content and GPx and SOD activities were observed in DENA/AAF-administered rats treated with eugenol compared with those in DENA/AAF-administered controls. Moreover, in DENA/AAF-administered rats, eugenol supplementation significantly reduced TNF-α and IL-1ß levels and mRNA expression levels of NF-κB, NF-κB p65, and MCP-1 but significantly elevated the level of Nrf2. Furthermore, the DENA/AAF-administered rats treated with eugenol exhibited a significant downregulation of Bcl-2 expression levels in addition to a significant upregulation in P53 and Bax expression levels. Otherwise, the administration of DENA/AAF elevated the protein expression level of Ki-67, and this elevation was reversed by eugenol treatment. In conclusion, eugenol has effective antioxidant, anti-inflammatory, proapoptotic, and antiproliferative properties against lung cancer.

Chronic Administration of Diethylnitrosamine and 2-Acetylaminofluorene Induces Hepatocellular Carcinoma in Wistar Rats.

This study aimed to analyze the biochemical, histological, and gene expression alterations produced in a hepatocarcinogenesis model induced by the chronic administration of diethylnitrosamine (DEN) and 2-acetylaminofluorene (2-AAF) in Wistar rats. Thirteen rats weighing 180 to 200 g were divided into two groups: control and treated. Rats in the treated group were administered an intraperitoneal (i.p.) injection of DEN (50 mg/kg/week) and an intragastric (i.g.) dose of 2-AAF (25 mg/kg/week) for 18 weeks. The treated group had significant increases in their total cholesterol, HDL-C, AST, ALT, ALKP, and GGT levels. Furthermore, a histological analysis showed the loss of normal liver architecture with nuclear pleomorphism in the hepatocytes, atypical mitosis, and fibrous septa that were distributed between the portal triads and collagen fibers through the hepatic sinusoids. The gene expressions of 24 genes related to fibrosis, inflammation, apoptosis, cell growth, angiogenesis, lipid metabolism, and alpha-fetoprotein (AFP) were analyzed; only TGFß, COL1α1, CYP2E1, CAT, SOD, IL6, TNF-α, and ALB showed significant differences when both groups were compared. Additionally, lung histopathological alterations were found in the treated group, suggesting metastasis. In this model, the chronic administration of DEN+2-AAF induces characteristic alterations of hepatocellular carcinoma in Wistar rats without AFP gene expression changes, highlighting different signatures in hepatocellular carcinoma heterogeneity.

[Alteration of Wnt3a overexpression and its early monitoring value during hepatocellular carcinogenesis].

Objective: To investigate the dynamic expression pattern of carcinoembryonic Wnt3a and its early monitoring value using a hepatocellular carcinoma model. Methods: Forty-eight Sprague Dawley (SD) rats were fed with pellet feed containing 2-acetylaminofluorene (2-AAF, 0.05%) to induce hepatocarcinogenesis, and control rats were fed a pellet diet. Liver tissue and blood samples were collected every two weeks. Liver tissues were pathologically examined using HE staining and grouped. The gene and Wnt3a mRNA expression were analyzed by genome-wide microarray. The expression and distribution of Wnt3a in liver tissue were analyzed by immunohistochemistry. Wnt3a concentration in liver tissue and serum was quantified by enzyme-linked immunosorbent assay. Statistical methods such as χ2 test, Mann-Whitney test and analysis of variance were used to analyze the differences between groups. Results: According to the pathological examination results, the rat livers were divided into four groups: control, hepatocyte degeneration, precancerous lesions and hepatocellular carcinoma. Genome-wide expression profiling analysis and comparison with the control group revealed that 268 and 312 genes were up-regulated and 57 and 201 genes were down-regulated in the precancerous and cancerous group when signal logarithm ratio (SLR) was >8 log2cy5/cy3, and these significantly altered genes mainly involved in cell proliferation, signal transduction, tumor metastasis, and apoptosis. The expression of Wnt3a at mRNA level was significantly increased in all stages of cancer induction, including degeneration group (1.15±0.24, q=8.227), precancerous group (1.85±0.18, q=12.361) and cancerous group (2.59±0.55, q=18.082). Compared with the control group (0.25±0.11, F=121.103, P<0.001), the degeneration group, the precancerous group and the liver cancer group were up-regulated by 4.6, 7.4 and 10.4-folds, respectively. Immunohistochemistry showed that compared with the control group, the positive rate of Wnt3a in the degeneration group was 66.7% (12/18, χ2=10.701, P=0.001), and both the precancerous and liver cancer groups were positive (9/9, χ2=17.115, P<0.001). Wnt3a expression was gradually increased in liver and blood samples during the process of carcinogenesis, and the difference between two groups was statistically significant (F=176.711, P<0.001). Wnt3a overexpression was secreted into blood stream via cancerous liver tissue, and there was a linear correlation between Wnt3a levels in blood and liver samples (r=0.732, P<0.001). Conclusions: Wnt3a overexpression is closely related with hepatocellular carcinogenesis, and thus may become a new monitoring marker.

The Protective Role of Etoricoxib Against Diethylnitrosamine/2-acetylaminofluorene- Induced Hepatocarcinogenesis in Wistar Rats: The Impact of NF-κB/COX-2/PGE2 Signaling.

BACKGROUND: Liver cancer ranks as the 7th and 5th leading cause of cancer morbidity worldwide in men and women, respectively. Hepatocellular Carcinoma (HCC) is the most common type of liver cancer and is associated with an increasing global burden of Nonalcoholic Fatty Liver Disease (NAFLD) and Nonalcoholic Steatohepatitis (NASH). OBJECTIVE: The present study aimed to investigate the possible chemopreventive effect of etoricoxib on diethylnitrosamine (DENA) and 2-acetylaminofluorene (2AAF)-induced HCC in male Wistar rats. METHODS: HCC was induced by DENA (150 mg/kg/week; i.p) for 2 weeks, then 2AAF (20 mg/kg; p.o) every other day for three successive weeks. Etoricoxib (0.6 mg/kg, p.o.) was given to DENA/ 2AAF-administered rats for 20 weeks. RESULTS: Etoricoxib significantly suppressed alpha-fetoprotein (AFP) and carbohydrate antigen 19-9 (CA19.9) as liver tumor biomarkers. It also decreased serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin levels while increased serum albumin levels. Besides, it alleviated DENA/2AAF-induced histopathological abrasions and inflammatory cell infiltration. Furthermore, etoricoxib showed a potent antioxidant effect, supported by a significant lipid peroxide reduction and elevation in superoxide dismutase activity and GSH content. In addition, Etoricoxib significantly down-regulated the protein expression of interleukin 1 beta (IL-1ß), tumor necrosis factor α (TNFα), nuclear Factor-kappa B (NF-κB), phosphorylated nuclear Factor-kappa B (p-NF-κB), cyclooxygenase-2 (COX-2), and prostaglandin E2 (PGE2). CONCLUSION: In conclusion, the current results proved that etoricoxib possesses an anticarcinogenic effect via its antioxidant, anti-inflammatory, and modulation of NF-κB/COX-2/PGE2 signaling.

Quercetin and naringenin abate diethylnitrosamine/acetylaminofluorene-induced hepatocarcinogenesis in Wistar rats: the roles of oxidative stress, inflammation and cell apoptosis.

This study was designed to assess the preventive effects and to suggest the probable mechanisms of action of quercetin and naringein in diethylnitrosamine (DEN)/2-acetylaminofluorene (2AAF)-induced hepatocarcinogenesis in Wistar male rats. The chemical-induction of hepatocarcinogenesis was performed by injection of DEN intraperitoneally at 150 mg/kg body weight (b.w.) twice/week for two weeks, followed by oral administration of 2AAF at 20 mg/kg body weight (b.w.) 4 times/week for 3 weeks. The DEN/2AAF-administered rats were co-treated with quercetin and naringenin at dose level of 10 mg/kg b. w. by oral gavage for 20 weeks. The treatment of DEN/2AAF-administered rats with quercetin and naringenin significantly prevented the elevations in serum levels of liver function indicators (ALT, AST, ALP, γ-GT, total bilirubin and albumin) and liver tumor biomarkers including AFP, CEA and CA19.9. The cancerous histological lesions and inflammatory cells infiltration in liver of DEN/2AAF-administered rats were remarkably suppressed by treatments with quercetin and naringenin. The hepatic oxidative stress markers including NO level and lipid peroxidation significantly decreased while the SOD, GPx and CAT activities and GSH content significantly increased in DEN/2AAF-administered rats treated with quercetin and naringenin when compared to DEN/2AFF-administered control rats. Furthermore, the lowered mRNA expression of liver IL-4, P53 and Bcl-2 in of DEN/2AAF-administered rats were significantly counteracted by treatment with quercetin and naringenin. Taken together, our results demonstrate that quercetin and naringenin may abate hepatocarcinogenesis via enhancement of anti-inflammatory, anti-oxidant and apoptotic actions.

Yiguanjian decoction inhibits macrophage M1 polarization and attenuates hepatic fibrosis induced by CCl4/2-AAF.

CONTEXT: Our previous studies indicated that Yiguanjian decoction (YGJ) has an anti-hepatic-fibrosis effect and could regulate macrophage status. OBJECTIVE: To elucidate the mechanism of YGJ in regulating macrophages. MATERIALS AND METHODS: Liver cirrhosis was induced by CCl4 for 12 weeks combined with 2-acetylaminofluorene (2-AAF) for the last 4 weeks in male Wistar rats. YGJ (3.56 mg/kg) orally administered in the last 4 weeks, and SORA (1 mg/kg) as control. In vitro, RAW264.7 cells were treated with lipopolysaccharides (LPSs) to induce macrophage polarization to the M1 phenotype, and they were co-cultured with WB-F344 cells and allocated to M group, YGJ group (2 µg/mL) and WIF-1 group (1 µg/mL) with untreated cells as control. The differentiation direction of WB-F344 cell line was observed in the presence or absence of YGJ. Pathology, fibrosis-related cytokines, macrophage polarization-related components, and Wnt signalling pathway components were detected. RESULTS: In vivo, the expression levels of α-SMA, Col (1), OV6, SOX9, EpCAM and M1 macrophage-related components (STAT1, IRF3, IRF5, IRF8, SOCS3) significantly decreased in the YGJ group compared with those in the 2-AAF/CCl4 group (p < 0.01 or 0.05). In vitro, the expression levels of M1 macrophage-related components, including STAT1, NF-κB, IRF3, IRF5, and SOCS3, in RAW264.7 cells decreased significantly in the YGJ group compared with those in the M group (p < 0.05 or p < 0.01). The expression levels of Wnt3A, FZD5, LRP-5/-6, and ß-catenin significantly increased in the YGJ group compared with those in the M group (p < 0.05 or p < 0.01). In addition, the expression levels of Wnt-4/-5A/-5B, and FZD2 significantly decreased in the YGJ group compared with those in the M group (p < 0.05 or p < 0.01). CONCLUSION: This study suggests that the anti-cirrhosis effect of YGJ is associated with its ability to inhibit macrophage M1-polarization, which provides a scientific basis for the clinical application of YGJ.

Enrichment of progenitor cells by 2-acetylaminofluorene accelerates liver carcinogenesis induced by diethylnitrosamine in vivo.

The potential role of hepatocytes versus hepatic progenitor cells (HPC) on the onset and pathogenesis of hepatocellular carcinoma (HCC) has not been fully clarified. Because the administration of 2-acetylaminofluorene (2AAF) followed by a partial hepatectomy, selectively induces the HPC proliferation, we investigated the effects of chronic 2AAF administration on the HCC development caused by the chronic administration of the carcinogen diethylnitrosamine (DEN) for 16 weeks in the rat. DEN + 2AAF protocol impeded weight gain of animals but promoted prominent hepatomegaly and exacerbated liver alterations compared to DEN protocol alone. The tumor areas detected by γ-glutamyl transferase, prostaglandin reductase-1, and glutathione S-transferase Pi-1 liver cancer markers increased up to 80% as early as 12 weeks of treatment, meaning 6 weeks earlier than DEN alone. This protocol also increased the number of Ki67-positive cells and those of CD90 and CK19, two well-known progenitor cell markers. Interestingly, microarray analysis revealed that DEN + 2AAF protocol differentially modified the global gene expression signature and induced the differential expression of 30 genes identified as HPC markers as early as 6 weeks of treatment. In conclusion, 2AAF induces the early appearance of HPC markers and as a result, accelerates the hepatocarcinogenesis induced by DEN in the rat. Thus, since 2AAF simultaneously administrated with DEN enriches HPC during hepatocarcinogenesis, we propose that DEN + 2AAF protocol might be a useful tool to investigate the cellular origin of HCC with progenitor features.

Effect of 2-acetylaminofluorene and its genotoxic metabolites on DNA adduct formation and DNA damage in 3D reconstructed human skin tissue models.

In vitro genotoxicity assays utilising human skin models are becoming important tools for the safety assessment of chemicals whose primary exposure is via the dermal route. In order to explore metabolic competency and inducibility of CYP450 activating enzymes, 3D reconstructed human skin tissues were topically treated with 2-acetylaminofluorene (2-AAF) and its genotoxic metabolites, N-hydroxy-2-acetylaminofluorene (N-OH-2-AAF) and N-hydroxy-2-aminofluorene (N-OH-2-AF), which primarily cause DNA damage by forming DNA adducts. 2-AAF did not increase DNA damage measured in the reconstructed skin micronucleus (RSMN) assay when administered in multiple applications at 24 h intervals but was detected in the skin comet assay in the presence of the DNA polymerase inhibitor aphidicolin (APC). Similarly, no increase was found with N-OH-2-AAF in the RSMN assay after multiple treatments whereas a single 3 h exposure to N-OH-2-AAF caused a large dose-related increase in the skin comet assay. A significant increase in the RSMN assay was only obtained with the highly reactive N-OH-2-AF metabolite after multiple treatments over 72 h, whereas N-OH-2-AF caused a strong increase after a single 3 h exposure in the skin comet assay. In support of these results, DNA adduct formation, measured by the 32P-postlabelling assay, was examined. Adduct levels after 2-AAF treatment for 3 h were minimal but increased >10-fold after multiple exposures over 48 h, suggesting that enzyme(s) that metabolise 2-AAF are induced in the skin models. As expected, a single 3 h exposure to N-OH-2-AAF and N-OH-2-AF resulted in adduct levels that were at least 10-fold greater than those after multiple exposures to 2-AAF despite ~100-fold lower tested concentrations. Our results demonstrate that DNA damage caused by 2-AAF metabolites is more efficiently detected in the skin comet assay than the RSMN assay and after multiple exposures and enzyme induction, 2-AAF-induced DNA damage can be detected in the APC-modified comet assay.

Investigation of the Effects of Octreotide Agent on Oxidative Stress, 8-Hydroxy Deoxyguanosine in Experimental Hepatic Carcinogenesis Rat Model.

INTRODUCTION: 2-AAF and DEN are well-known liver toxicants commonly used to stimulate tumors in laboratory animals. AIM: The aim of this study was to investigate the effect of octreotide on DEN-induced and 2-AAF-supplemented hepatocarcinogenesis in Wistar albino rats. MATERIALS AND METHODS: In this study, 64 Wistar albino rats were divided into 8 groups. DEN (175 mg/kg) initiated and 2-AAF (20 mg/kg) promoted liver carcinogenesis in rats. The tumor growth inhibitor octreotide (300 µg/kg) was used. Rats were sacrificed at the end of experiment and their liver tissues were taken for the study. SOD, GSH-Px, CAT activities, NO and MDA levels were measured spectrophotometrically. Also, Hsp70 and 8-OHdG was measured by the ELISA method. RESULTS: In group 7, MDA, 8-OHdG, and Hsp70 levels were significantly increased. In addition, SOD, GSH-Px activity was significantly reduced in this group. MDA, 8-OHdG and Hsp70 levels were significantly reduced in Group 8, which received octreotide for treatment. CONCLUSION: DEN and 2-AAF cause very serious liver damage. Octreotide protects the liver from carcinogenesis, increases the activity of cellular antioxidant enzymes and helps reduce DNA damage. Therefore, octreotide may be an inhibitor in tumor cells and may reduce oxidative stress.

Quinazolinone derivative BNUA-3 ameliorated [NDEA+2-AAF]-induced liver carcinogenesis in SD rats by modulating AhR-CYP1B1-Nrf2-Keap1 pathway.

Cytochrome P450 1B1, considered as one of the novel chemotherapeutic targets involved in cancer prevention and therapy is also associated with the conversion of procarcinogens into their active metabolites. The aryl hydrocarbon receptor (AhR) is responsible for mediating different biological responses to a wide variety of environmental pollutants and also causes transcriptional activation of cytochrome P450 enzymes including CYP1B1 and thus plays a pivotal role for initiating cancer and its progression. On the other hand, active carcinogenic metabolites and reactive oxygen species-mediated stress alter different molecular signalling pathways and gene expressions. Quinazoline derivatives are recognized for their diversified biological activities including anticancer properties. The current study was designed for evaluation of chemotherapeutic efficacy of a synthetic quinazolinone derivative BNUA-3 against hepatocellular cancer in Sprague-Dawley (SD) rats. A detailed in vivo analysis was performed by administrating BNUA-3 (15, 30 mg/kg b.w. for 28 days, i.p.) in N-Nitrosodiethylamine + 2-Acetylaminofluorene induced partially hepatectomized liver cancer in SD rats. This was followed by morphological evaluations, biochemical estimations and analysis of different mRNA and protein expressions. The results demonstrated the potency of BNUA-3 in efficient restoration of the altered morphology of liver, its protective effect against lipid peroxidation, enzymic and non-enzymic antioxidants levels in liver tissue which was disrupted after cancer induction. The study also demonstrated downregulation of AhR, CYP1B1 and Keap1 expressions with subsequent augmentation of protective Nrf2, HO-1, NQO1 and GSTA1 expressions thus, revealing the chemotherapeutic potency of BNUA-3 in inhibiting liver carcinogenesis through AhR/CYP1B1/Nrf2/Keap1 pathway.

Diwu Yanggan Modulates the Wnt/ß-catenin Pathway and Inhibits Liver Carcinogenesis Signaling in 2-AAF/PH Model Rats.

The activation of the Wnt/ß-catenin signaling pathway in oval cells after liver injury is implicated in hepatocarcinogenesis. Diwu Yanggan capsule is a Chinese herbal medicine that has been used for treating liver disorder. The present study aimed to examine the mechanism by which Diwu Yanggan inhibits liver carcinogenesis, and the involvement of the Wnt/ß-catenin signaling pathway. Diwu Yanggan capsule was administered to 2-acetaminofluorene/partial hepatectomy (2-AAF/PH) rats, a murine model of liver injury. The biomarkers of oval cells and key proteins in the Wnt/ß-catenin signaling pathway were assessed on postoperative day 8, 10, 14, 17, 19 and 22. The results showed that treatment with Diwu Yanggan was associated with reduced expression of oval cell and stem cell biomarkers in the 2-AAF/PH animals. The expression pattern of key proteins in the Wnt/ß-catenin pathway was altered in Diwu Yanggan-treated animals, indicating that the Diwu Yanggan treatment accelerated the activation of the Wnt/ß-catenin pathway in the initial stage and contributed to its deactivation in the later stage. Histological findings indicated that hepatocyte proliferation was suppressed in Diwu Yanggan-treated animals, compared with untreated 2-AAF/PH animals. Taken together, Diwu Yanggan capsule may reduce the risk of hepatocarcinogenesis by modulating the Wnt/ß-catenin signaling pathway.

Development of Asialoglycoprotein Receptor-Targeted Nanoparticles for Selective Delivery of Gemcitabine to Hepatocellular Carcinoma.

Selective targeting of anticancer drugs to the tumor site is beneficial in the pharmacotherapy of hepatocellular carcinoma (HCC). This study evaluated the prospective of galactosylated chitosan nanoparticles as a liver-specific carrier to improve the therapeutic efficacy of gemcitabine in HCC by targeting asialoglycoprotein receptors expressed on hepatocytes. Nanoparticles were formulated (G1-G5) by an ionic gelation method and evaluated for various physicochemical characteristics. Targeting efficacy of formulation G4 was evaluated in rats. Physicochemical characteristics exhibited by nanoparticles were optimal for administering and targeting gemcitabine effectively to the liver. The biphasic release behavior observed with G4 can provide higher drug concentration and extend the pharmacotherapy in the liver target site. Rapid plasma clearance of gemcitabine (70% in 30 min) from G4 was noticed in rats with HCC as compared to pure drug (p < 0.05). Higher uptake of gemcitabine predominantly by HCC (64% of administered dose; p < 0.0001) demonstrated excellent liver targeting by G4, while mitigating systemic toxicity. Morphological, biochemical, and histopathological examination as well as blood levels of the tumor marker, alpha-fetoprotein, in rats confirmed the curative effect of G4. In conclusion, this study demonstrated site-specific delivery and enhanced in vivo anti-HCC efficacy of gemcitabine by G4, which could function as promising carrier in hepatoma.

Hepatocyte transplantation.

We have read with great interest the study by Vera MC et al. on the intrasplenic transplantation of hepatocytes from donors receiving the carcinogenic drugs diethylnitrosamine (DEN) and 2-actylaminofluorene (2-AAF). The most important conclusion of the study is that there were no signs of tumor progression in the recipient liver at seven and 60 days after hepatocellular transplantation and no differences were found in the animals with healthy hepatocyte transplants.

Pantoprazole attenuates tumorigenesis via inhibition of exosomal secretion in a rat model of hepatic precancerous lesion induced by diethylnitrosamine and 2-acetamidofluorene.

The present study aimed to evaluate the potential therapeutic effect of pantoprazole, a proton-pump inhibitor, on precancerous lesion (PCL) in rats. diethylnitrosamine and 2-acetylaminofluorene were used to induce PCL in rats, in vivo. The rats were treated with three doses of pantoprazole (100, 50, and 25  mg/kg; three times weekly) during the last 4 weeks of the total 10 weeks of the experiment. Blood and liver tissue samples were collected for measurement of the exosomal abundance and exosomal competing endogenous RNA markers. Results revealed that pantoprazole administration had an ameliorating effect on liver function tests and microscopic features of the liver; and decreased exosome abundance in the liver tissue samples and sera of the rats. Meanwhile, the treatment also resulted in a dose-dependent decrease in exosomal RAB11A mRNA and long noncoding RNA RP11-513I15.6, which is an important participant in th exosomal secretion process with an increase in exosomal miRNA-1262. Based on these results, we postulated that pantoprazole has the potential to attenuate liver tumorigenesis in this rat model.

Immunohistochemistry of γ-H2AX as a method of early detection of urinary bladder carcinogenicity in mice.

Phosphorylated histone H2AX (γ-H2AX) has been demonstrated as a DNA damage marker both in vitro and in vivo. We previously reported the effects of genotoxic carcinogens in the urinary bladder of rats by immunohistochemical analysis of γ-H2AX using samples from 28-day repeated-dose tests. To evaluate the application of γ-H2AX as a biomarker of carcinogenicity in the bladder, we examined species differences in γ-H2AX formation in the urinary bladder of mice. Six-week-old male B6C3F1 mice were treated orally with 12 chemicals for 4 weeks. Immunohistochemical analysis demonstrated that N-butyl-N-(4-hydroxybutyl)nitrosamine, p-cresidine and 2-acetylaminofluorene (2-AAF), classified as genotoxic bladder carcinogens, induced significant increases in γ-H2AX levels in the bladder urothelium. In contrast, genotoxic (2-nitroanisole, glycidol, N-nitrosodiethylamine and acrylamide) and non-genotoxic (dimethylarsinic acid and melamine) non-bladder carcinogens did not upregulate γ-H2AX. Importantly, 2-nitroanisole, a potent genotoxic bladder carcinogen in rats, significantly increased the proportion of γ-H2AX-positive cells in rats only, reflecting differences in carcinogenicity in the urinary bladder between rats and mice. Significant upregulation of γ-H2AX was also induced by uracil, a non-genotoxic bladder carcinogen that may be associated with cell proliferation, as demonstrated by increased Ki67 expression. 2-AAF caused γ-H2AX formation mainly in the superficial layer, together with reduced and disorganized expression of uroplakin III, unlike in rats, suggesting the mouse-specific cytotoxicity of 2-AAF in umbrella cells. These results suggest γ-H2AX is a useful biomarker reflecting species differences in carcinogenicity in the urinary bladder.

A general dose-response relationship for chronic chemical and other health stressors and mixtures based on an emergent illness severity model.

Current efforts to assess human health response to chemicals based on high-throughput in vitro assay data on intra-cellular changes have been hindered for some illnesses by lack of information on higher-level extracellular, inter-organ, and organism-level interactions. However, a dose-response function (DRF), informed by various levels of information including apical health response, can represent a template for convergent top-down, bottom-up analysis. In this paper, a general DRF for chronic chemical and other health stressors and mixtures is derived based on a general first-order model previously derived and demonstrated for illness progression. The derivation accounts for essential autocorrelation among initiating event magnitudes along a toxicological mode of action, typical of complex processes in general, and reveals the inverse relationship between the minimum illness-inducing dose, and the illness severity per unit dose (both variable across a population). The resulting emergent DRF is theoretically scale-inclusive and amenable to low-dose extrapolation. The two-parameter single-toxicant version can be monotonic or sigmoidal, and is demonstrated preferable to traditional models (multistage, lognormal, generalized linear) for the published cancer and non-cancer datasets analyzed: chloroform (induced liver necrosis in female mice); bromate (induced dysplastic focia in male inbred rats); and 2-acetylaminofluorene (induced liver neoplasms and bladder carcinomas in 20,328 female mice). Common- and dissimilar-mode mixture models are demonstrated versus orthogonal data on toluene/benzene mixtures (mortality in Japanese medaka, Oryzias latipes, following embryonic exposure). Findings support previous empirical demonstration, and also reveal how a chemical with a typical monotonically-increasing DRF can display a J-shaped DRF when a second, antagonistic common-mode chemical is present. Overall, the general DRF derived here based on an autocorrelated first-order model appears to provide both a strong theoretical/biological basis for, as well as an accurate statistical description of, a diverse, albeit small, sample of observed dose-response data. The further generalizability of this conclusion can be tested in future analyses comparing with traditional modeling approaches across a broader range of datasets.

Troxerutin subdues hepatic tumorigenesis via disrupting the MDM2-p53 interaction.

Hepatocellular carcinoma (HCC) is the leading cause of cancer death worldwide that lacks proper medical prognosis and treatment. In the present study, the anti-tumoral potential of troxerutin (TX), an ethnomedicine, was examined in relation to its effects on the promoter 2-acetylaminofluorene (2-AAF) in N-nitrosodiethylamine (NDEA) initiated HCC, as compared to its effects on HCC induced by NDEA alone. Liver samples from each experimental group were collected and evaluated for histological, biochemical and cellular characterization. The protein expressions of apoptotic and cell proliferation markers were determined via immunohistochemistry and western blotting. Molecular docking was also performed to delineate the inhibitory mechanism of TX on HCC. The results show that only higher doses of TX showed a significant reduction in the incidence of hepatic nodule formation, and they also counteracted NDEA plus 2-AAF induced alterations in the enzymic status. The frequencies of glutathione-S-transferase and proliferating cell nuclear antigen, markers of S phase progression, were markedly reduced during TX treatment. TX also modulated the imbalance in the MDM2-p53 interaction. The molecular docking results confirmed the interaction of TX with the upstream kinases that regulate apoptosis. This study provides evidence that a copious dose of TX is required to counteract the differential mitoinhibitory effect of 2-AAF in NDEA initiated hepatomas, and TX exhibits an anti-tumoral effect via suppressing oxidative stress, regulating liver function enzymes, inhibiting inflammatory responses and modulating MDM2-p53 interactions, thus inducing apoptosis, and thereby suggesting that TX may provide promising therapeutic effects for the chemoprevention of HCC.

Abnormal expression of HMGB-3 is significantly associated with malignant transformation of hepatocytes.

AIM: To explore the relationship between dynamic expression of high mobility group box-3 (HMGB3) and malignant transformation of hepatocytes. METHODS: Expression of HMGB family proteins were observed in rat hepatocarcinogenesis models induced with 2-acetylaminofluorene. Alterations of HMGB3 were analyzed at the mRNA level by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and at the protein level by immunohistochemistry or Western blotting. HMGB3 in human liver cancer tissues were evaluated using bioinformatics databases from GEO, TCGA, and Oncomine. A specific HMGB3-shRNA was used to knock down HMGB3 expression in order to investigate its effects on proliferation and cell cycle in vitro and in vivo. RESULTS: Elevated HMGB3 levels were first reported in hepatocarcinogenesis, with increasing expression from normal liver to cancer. Bioinformatic databases showed that HMGB3 expression in hepatocellular carcinoma tissues was significantly higher than that in normal liver tissues. Higher HMGB3 expression was discovered in liver cancer cells compared with LO2 cells in vitro. According to gene set enrichment analysis, HMGB3 mRNA levels were correlated with cell cycle and DNA replication pathways. Knocking down HMGB3 by specific shRNA significantly inhibited proliferation of HepG2 cells by cell cycle arrest and downregulating DNA replication related genes (cyclin B1, FEN1, and PCNA) at the mRNA and protein level. Furthermore, silencing HMGB3 significantly inhibited xenograft tumor growth (measured by Ki67) in vivo. CONCLUSION: HMGB3 is involved in malignant transformation of hepatocytes and could be a useful biomarker for diagnosis and a potential target for therapy of liver cancer.