Inhibitory effect of CDA-II, a urinary preparation, on aflatoxin B(1)-induced oxidative stress and DNA damage in primary cultured rat hepatocytes

Epigenetic alterations caused by aflatoxin b1: a public health risk in the induction of hepatocellular carcinoma

Aflatoxin B1 (AFB1) is currently the most commonly studied mycotoxin due to its great toxicity, its distribution in a wide variety of foods such as grains and cereals and its involvement in the development of + (hepatocellular carcinoma; HCC). HCC is one of the main types of liver cancer, and has become a serious public health problem, due to its high incidence mainly in Southeast Asia and Africa. Studies show that AFB1 acts in synergy with other risk factors such as hepatitis B and C virus leading to the development of HCC through genetic and epigenetic modifications. The genetic modifications begin in the liver through the biomorphic AFB1, the AFB1-exo-8.9-Epoxy active, which interacts with DNA to form adducts of AFB1-DNA. These adducts induce mutation in codon 249, mediated by a transversion of G-T in the p53 tumor suppressor gene, causing HCC. Thus, this review provides an overview of the evidence for AFB1-induced epigenetic alterations and the potential mechanisms involved in the development of HCC, focusing on a critical analysis of the importance of severe legislation in the detection of aflatoxins.

Characterization of liver injury, oval cell proliferation and cholangiocarcinogenesis in glutathione S-transferase A3 knockout mice

We recently generated glutathione S-transferase (GST) A3 knockout (KO) mice as a novel model to study the risk factors for liver cancer. GSTA3 KO mice are sensitive to the acute cytotoxic and genotoxic effects of aflatoxin B1 (AFB1), confirming the crucial role of GSTA3 in resistance to AFB1. We now report histopathological changes, tumor formation, biochemical changes and gender response following AFB1 treatment as well as the contribution of oxidative stress. Using a protocol of weekly 0.5 mg AFB1/kg administration, we observed extensive oval (liver stem) cell (OC) proliferation within 1-3 weeks followed by microvesicular lipidosis, megahepatocytes, nuclear inclusions, cholangiomas and small nodules. Male and female GSTA3 KO mice treated with 12 and 24 weekly AFB1 injections followed by a rest period of 12 and 6 months, respectively, all had grossly distorted livers with macro- and microscopic cysts, hepatocellular nodules, cholangiomas and cholangiocarcinomas and OC proliferation. We postulate that the prolonged AFB1 treatment leads to inhibition of hepatocyte proliferation, which is compensated by OC proliferation and eventually formation of cholangiocarcinoma (CCA). At low-dose AFB1, male KO mice showed less extensive acute liver injury, OC proliferation and AFB1-DNA adducts than female KO mice. There were no significant compensatory changes in KO mice GST subunits, GST enzymatic activity, epoxide hydrolase, or CYP1A2 and CYP3A11 levels. Finally, there was a modest increase in F2-isoprostane and isofuran in KO mice that confirmed putative GSTA3 hydroperoxidase activity in vivo for the first time.

The aflatoxin B1 -fumonisin B1 toxicity in BRL-3A hepatocytes is associated to induction of cytochrome P450 activity and arachidonic acid metabolism

Human oral exposure to aflatoxin B₁ (AFB₁ ) and fumonisin B₁ (FB₁ ) is associated with increased hepatocellular carcinoma. Although evidence suggested interactive AFB₁ -FB₁ hepatotoxicity, the underlying mechanisms remain mostly unidentified. This work was aimed at evaluating the possible AFB₁ -FB₁ interplay to induce genetic and cell cycle toxicities in BRL-3A rat hepatocytes, reactive oxygen species (ROS) involvement, and the AFB₁ metabolizing pathways cytochrome P450 (CYP) and arachidonic acid (ArAc) metabolism as ROS contributors. Flow cytometry of stained BRL-3A hepatocytes was used to study the cell cycle (propidium iodide), ROS intracellular production (DCFH-DA, HE, DAF-2 DA), and phospholipase A activity (staining with bis-BODIPY FL C11-PC). The CYP1A activity was assessed by the 7-ethoxyresorufin-O-deethylase (EROD) assay. Despite a 48-h exposure to FB₁ (30 μM) not being genotoxic, the AFB₁ (20 μM)-induced micronucleus frequency was overcome by the AFB₁ -FB₁ mixture (MIX), presumably showing toxin interaction. The mycotoxins blocked G1/S-phase, but only MIX caused cell death. Overall, the oxidative stress led these alterations as the pretreatment with N-acetyl-l-cysteine reduced such toxic effects. While AFB₁ had a major input to the MIX pro-oxidant activity, with CYP and ArAc metabolism being ROS contributors, these pathways were not involved in the FB₁ -elicited weak oxidative stress. The MIX-induced micronucleus frequency in N-acetyl-l-cysteine pretreated cells was greater than that caused by AFB₁ without antioxidants, suggesting enhanced AFB₁ direct genotoxicity probably owing to the higher CYP activity and ArAc metabolism found in MIX. The metabolic pathways modulation by AFB₁ -FB₁ mixtures could raise its hepatocarcinogenic properties.

Antigenotoxic Effect of Piperine in Broiler Chickens Intoxicated with Aflatoxin B1

Piperine is an abundant amide extracted from black pepper seeds which has been shown to have protective effects against cytotoxic and genotoxic carcinogenesis induced by certain chemical carcinogens and aflatoxin B₁ (AFB₁) in vitro. The aim of this work was to study, in vivo, the antigenotoxic potential of feed-added piperine on broiler chickens experimentally intoxicated with AFB₁, using micronucleus and comet assays. The antigenotoxicity assessment of 9-day-old chicks was performed on a total of 60 chickens divided into four groups of 15 broilers each: (C) control, (P) 60 mg·piperine kg-1 feed, (A) 0.5 mg·AFB₁·kg-1 body weight, (daily by oral route), and (P + A) co-treatment with piperine and AFB₁. The experiment was conducted for 26 days. Chicks intoxicated with AFB₁ showed significant genotoxic effects in the first 24 h post intoxication, and the effects remained in the other periods analyzed (48, 72, and 96 h and 26 days of treatment). The DNA damage in peripheral blood cells, the number of erythrocytes with micronuclei, and polychromatic-to-normochromatic erythrocyte ratio were significantly reduced or absent in the piperine/AFB₁ group. No significant differences were observed between the group piperine/AFB₁ and the control and piperine-alone groups. The addition 60 mg·kg-1 of piperine to the diet of the broiler chicks was safe, promoting beneficial effects in poultry health with respect to the toxic effects 0.5 mg·AFB₁·kg-1 body weight.

Oxidative stress and Ca(2+) signals involved on cadmium-induced apoptosis in rat hepatocyte

Cadmium (Cd) is an important industrial and environmental pollutant. In animals, the liver is the major target organ of Cd toxicity. In this study, rat hepatocytes were treated with 2.5∼10 μM Cd for various durations. Studies on nuclear morphology, chromatin condensation, and apoptotic cells demonstrate that Cd concentrations ranging within 2.5∼10 μM induced apoptosis. The early-stage marker of apoptosis, i.e., decreased mitochondrial membrane potential, was observed as early as 1.5 h at 5 μM Cd. Significant (P < 0.01) reactive oxygen species (ROS) production at 5 μM Cd and 0.75 h occurred prior to the decrease of the mitochondrial membrane potential, suggesting the involvement of ROS in mitochondrial membrane damage. Glutathione (GSH) level significantly decreased after cell treatment with 5 and 10 μM Cd after 12 h (P < 0.01). Meanwhile, the intracellular free Ca(2+) concentration ([Ca(2+)] i ) of Cd-exposed cells significantly increased (P < 0.01) at 1.5 h, and pretreatment with the calcium chelator Bapta-AM partially blocked Cd-induced apoptosis. This finding indicated that the elevation of [Ca(2+)] i may play an important role in apoptosis. Overall, these results showed that oxidative stress and Ca(2+) signaling were critical mediators of the Cd-induced apoptosis of rat hepatocytes.

N-acetylcysteine protects against cadmium-induced oxidative stress in rat hepatocytes

Cadmium (Cd) is a well-known hepatotoxic environmental pollutant. We used rat hepatocytes as a model to study oxidative damage induced by Cd, effects on the antioxidant systems, and the role of N-acetylcysteine (NAC) in protecting cells against Cd toxicity. Hepatocytes were incubated for 12 and 24 h with Cd (2.5, 5, 10 µM). Results showed that Cd can induce cytotoxicity: 10 µM resulted in 36.2% mortality after 12 h and 47.8% after 24 h. Lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase activities increased. Additionally, reactive oxygen species (ROS) generation increased in Cd-treated hepatocytes along with malondialdehyde levels. Glutathione concentrations significantly decreased after treatment with Cd for 12 h but increased after 24 h of Cd exposure. In contrast, glutathione peroxidase activity significantly increased after treatment with Cd for 12 h but decreased after 24 h. superoxide dismutase and catalase activities increased at 12 h and 24 h. glutathione S-transferase and glutathione reductase activities decreased, but not significantly. Rat hepatocytes incubated with NAC and Cd simultaneously had significantly increased viability and decreased Cd-induced ROS generation. Our results suggested that Cd induces ROS generation that leads to oxidative stress. Moreover, NAC protects rat hepatocytes from cytotoxicity associated with Cd.

Antitumor activity of CDA-Ⅱ, a urinary preparation, on human multiple myeloma cell lines via the mitochondrial pathway

Cell differentiation agent II (CDA‑II) is a DNA methyltransferase inhibitor isolated from healthy human urine. In the present study, the antitumor activity of CDA‑II on human multiple myeloma (MM) cell lines via the mitochondrial pathway was first revealed. The human MM cell lines were exposed to CDA‑II. Cytotoxicity, caspase activation, apoptosis and the effects on the mitochondrial pathway were assessed. CDA‑Ⅱ was capable of decreasing the depolarized mitochondrial membranes and activating caspase‑3 and ‑9 and poly (ADP‑ribose) polymerase in MM cells treated with CDA‑II. CDA‑II induced caspase‑dependent cell death accompanied by a significant decrease in X-linked inhibitor of apoptosis protein (XIAP), survivin and Mcl‑1 levels. The caspase‑3 inhibitor, Z‑DEVD‑FMK, inhibited CDA‑II‑induced apoptosis. CDA‑II potently increased the Bax levels, decreased the Bcl‑2/Bax ratio and decreased the expression of the downstream targets of NF‑κB. In conclusion, the results of the present study demonstrated that CDA‑II treatment leads to the inhibition of p65 nuclear localization and potently induces caspase‑dependent apoptosis in MM cells mediated through the mitochondrial pathway at low nanomolar concentrations. These results indicate that CDA‑II is a novel inhibitor of NF‑κB activity, with notable antimyeloma efficacy. This study provides a rationale for the clinical investigation of CDA‑Ⅱ in human MM.

Meta-analytical study of productive and nutritional interactions of mycotoxins in growing pigs

A meta-analysis was carried out in order to study the association of mycotoxins with performance and organ weights in growing pigs. A total of 85 articles published between 1968 and 2010 were used, totaling 1012 treatments and 13 196 animals. The meta-analysis followed three sequential analyses: graphical, correlation and variance-covariance. The presence of mycotoxins in diets was seen to reduce the feed intake by 18% and the weight gain in 21% compared with the control group. Deoxynivalenol and aflatoxins were the mycotoxins with the greatest impact on the feed intake and growth of pigs, reducing by 26% and 16% in the feed intake and by 26% and 22% in the weight gain. The mycotoxin concentration in diets and the animal age at challenge were the variables that more improved the coefficient of determination in equations for estimating the effect of mycotoxins on weight gain. The mycotoxin effect on growth proved to be greater in younger animals. In addition, the residual analysis showed that the greater part of the variation in weight gain was explained by the variation in feed intake (87%). The protein and methionine levels in diets could influence the feed intake and the weight gain in challenged animals. The weight gain in challenged pigs showed a positive correlation with the methionine level in diets (0.68). The mycotoxin effect on growth was greater in males compared with the effect on females. The reduction in weight gain was of 15% in the female group and 19% in the male group. Mycotoxin presence in pig diets has interfered in the relative weight of the liver, the kidneys and the heart. Mycotoxins have an influence on performance and organ weight in pigs. However, the magnitude of the effects varies with the type and concentration of mycotoxin, sex and the animal age, as well as nutritional factors.

CDA-2, a urinary preparation, inhibits lung cancer development through the suppression of NF-kappaB activation in myeloid cell

CDA-2 (cell differentiation agent 2), a urinary preparation, has potent anti- proliferative and pro-apoptotic properties in cancer cells. However, the mechanisms of tumor inhibitory action of CDA-2 are far from clear, and especially there was no report on lung cancer. Here we demonstrate that CDA-2 and its main component phenylacetylglutamine (PG) reduce the metastatic lung tumor growth, and increases survival time after inoculation with Lewis lung carcinoma (LLC) cells in a dose-dependent manner in C57BL6 mice. Proliferative program analysis in cancer cells revealed a fundamental impact of CDA-2 and PG on proliferation and apoptosis, including Bcl-2, Bcl-XL, cIAP1, Survivin, PCNA, Ki-67 proteins and TUNEL assays. CDA-2 and PG significantly reduced NF-κB DNA-binding activity in lung cancer cells and in alveolar macrophages of tumor bearing mice and especially decreased the release of inflammatory factors including TNFα, IL-6, and KC. Furthermore, CDA-2 and PG decrease the expressions of TLR2, TLR6, and CD14, but not TLR1, TLR3, TLR4, and TLR9 in bone-marrow-derived macrophages (BMDM) of mice stimulated by LLC-conditioned medium (LLC-CM). Over-expressing TLR2 in BMDM prevented CDA-2 and PG from inhibiting NF-κB activation, as well as induction of TNFα and IL-6. TLR2:TLR6 complexes mediate the effect of NF-κB inactivation by CDA-2. In conclusion, CDA-2 potently inhibits lung tumor development by reduction of the inflammation in lung through suppression of NF-κB activation in myeloid cells, associating with modulation of TLR2 signaling.

Comparative proteomics and molecular mechanical analysis in CDA-II induced therapy of LCI-D20 hepatocellular carcinoma model

PURPOSE

To investigate the differential proteins and related molecular mechanism of CDA-II (cell differentiation agent-II) induced therapy on a human hepatocellular carcinoma model in nude mice with high metastatic potential (LCI-D20).

METHODS

After tumors were transplanted 11 days, mice were intraperitoneally injected with CDA-II (1,800 mg/kg) for 20 days continuously. The tumor growth-inhibitory efficiency in CDA-II treated groups was calculated. Proteins extracted from tumor tissue were separated by two-dimensional gel electrophoresis (2DE) and the differential proteins were identified by matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). Western blotting (WB) was performed to verify the expression of certain candidate proteins. Reverse transcription-polymerase chain reaction (RT-PCR) was engaged to study the molecular mechanism of the therapy.

RESULTS

CDA-II suppressed the growth and metastasis of tumor. The tumor growth-inhibitory efficiency was 41.8%. In total, 27 differentially expressed proteins were identified, including HSP27, UGDH, CK8, Hsp60, ENOA and AnxA5, with functions involved in oncogene expression and/or cell differentiation. In addition, apparent alternations of HSP60 and beta-actin expression levels and their different posttranslational modifications (PTMs) were investigated. RT-PCR analysis confirmed that the cancer related genes c-myc, N-ras and MMP-9 were significantly down-regulated.

CONCLUSION

Our results demonstrate that CDA-II presence can change the proteome profiling and favors of the tumor suppression in LCI-D20 cell differentiation. Our results also suggest that the dynamic PTM of HSP60 expression levels could be used to predict HCC and might be a promising and useful biomarker to prognosticate CDA-II therapeutic efficacy.

CDA-II, a urinary preparation, induces growth arrest and apoptosis of human leukemia cells through inactivation of nuclear factor-kappaB in a caspase-dependent manner

CDA-II (cell differentiation agent II) was a urinary preparation, isolated from healthy human urine. We determined the anticancer activity of CDA-II using human acute myeloid leukemia (AML) cell lines, K562, Kasumi-1 and KG-1. An in vitro cytotoxicity assay showed that CDA-II exhibited growth arrest in leukemic cells, while it did not induce cytotoxicity in normal peripheral blood mononuclear cells (PBMCs). In vivo studies using the Kasumi-1 xenografted SCID mouse model showed tumor inhibition rate were increased and the survival time were prolonged in a dose-dependent manner, without any significant toxicity on mice body. Depolarized mitochondrial membranes and the activation of caspase-3, 9 as well as PARP were found in leukemic cells treated with CDA-II for 6-24h. We further found NF-kappaB nuclear translocation were prevented by CDA-II treatment, which therefore inactivated NF-kappaB and down-regulated its target genes expression, including Bcl-2/Bax ratio, Mcl-1 and XIAP. The caspase-3 inhibitor Z-DEVD-FMK inhibited CDA-II-induced apoptosis and CDA-II combined with NF-kappaB inhibitor PDTC significantly increased the apoptotic rate of leukemic cells. We concluded that CDA-II potently induced caspase-dependent leukemia-specific apoptosis in leukemic cells mediated through inactivation of NF-kappaB, involving in Bcl-2 family and XIAP, which has no cytotoxicity on normal cells.

Human urine extract CDA-2 induces apoptosis of myelodysplastic syndrome-derived MUTZ-1 cells through the PI3K/Akt signaling pathway in a caspase-3-dependent manner

AIM

The aim of this study was to investigate the antitumoral activity of human urine extract against myelodysplastic syndrome (MDS)-derived MUTZ-1 cells in vitro and in vivo.

METHODS

The MDS-refractory anemia with excess of blasts (RAEB)-derived MUTZ-1 cell line was used to examine the effects of a human urine preparation, CDA-2, on the induction of growth arrest and apoptosis. Apoptotic proteins, including caspase family, Bcl-2 family, the inhibitor of apoptosis protein (IAP) family, and the FLICE-like inhibitory protein (FLIP), as well as cell cycle-associated proteins were studied. The phosphoinositide 3 kinase (PI3K)/Akt survival signaling pathway and the NF-kappaB pathway were also examined. The caspase-3 inhibitor Z-DEVD-fmk was used to examine the involvement of caspase-3 and poly (ADP-ribose) polymerase (PARP). PI3K inhibitor LY294002 was used to examine the involvement of the PI3K/Akt signaling pathway in this apoptosis-inducing effect. MUTZ-1 cell xenografted serious combined immunodeficiency disease mice were used for the in vivo study.

RESULTS

We found that CDA-2 could induce growth arrest and apoptosis of MUTZ-1 cells in vitro and in vivo. The main mechanisms were related to the inhibition of PI3Kp110alpha expression at the transcriptional level, which inactivated the phosphorylation of Akt involving the prevention NF-kappaB phosphorylation and nuclear translocation, the downregulation of the IAP family and FLIPL protein, and the dephosphorylation of the Bad protein, which then triggered the activation of the caspase cascades. This phenomenon could be inhibited by the PI3K inhibitor LY294002 and caspase-3 inhibitor Z-DEVD-fmk.

CONCLUSION

Our results demonstrate the presence of active components in the human urine extract that can induce the growth arrest and apoptosis of MDS-RAEB-derived MUTZ-1 cells and may involve the PI3K/Akt signaling pathway in a caspase-3-dependent manner. This may provide new insights for the treatment of high-risk MDS.