Disruption of Smad-dependent signaling for growth of GST-P-positive lesions from the early stage in a rat two-stage hepatocarcinogenesis model

Chemical Profile of Cyperus laevigatus and Its Protective Effects against Thioacetamide-Induced Hepatorenal Toxicity in Rats

Cyperus species represent a group of cosmopolitan plants used in folk medicine to treat several diseases. In the current study, the phytochemical profile of Cyperus laevigatus ethanolic extract (CLEE) was assessed using UPLC-QTOF-MS/MS. The protective effect of CLEE at 50 and 100 mg /kg body weight (b.w.) was evaluated on hepatorenal injuries induced by thioacetamide (100 mg/kg) via investigation of the extract's effects on oxidative stress, inflammatory markers and histopathological changes in the liver and kidney. UPLC-QTOF-MS/MS analysis of CLEE resulted in the identification of 94 compounds, including organic and phenolic acids, flavones, aurones, and fatty acids. CLEE improved the antioxidant status in the liver and kidney, as manifested by enhancement of reduced glutathione (GSH) and coenzyme Q10 (CoQ10), in addition to the reduction in malondialdehyde (MDA), nitric oxide (NO), and 8-hydroxy-2'-deoxyguanosine (8OHdG). Moreover, CLEE positively affected oxidative stress parameters in plasma and thwarted the depletion of hepatorenal ATP content by thioacetamide (TAA). Furthermore, treatment of rats with CLEE alleviated the significant increase in plasma liver enzymes, kidney function parameters, and inflammatory markers. The protective effect of CLEE was confirmed by a histopathological study of the liver and kidney. Our results proposed that CLEE may reduce TAA-hepatorenal toxicity via its antioxidant and anti-inflammatory properties suppressing oxidative stress.

Toxic Effects of Thioacetamide-Induced Femoral Damage in New Zealand White Rabbits by Activating the p38/ERK Signaling Pathway

Thioacetamide (TAA) is widely used in the production of drugs, pesticides and dyeing auxiliaries. Moreover, it is a chemical that can cause liver damage and cancer. TAA has recently been identified to cause bone damage in animal models. However, the type of bone damage that TAA causes and its potential pathogenic mechanisms remain unclear. The toxic effects of TAA on the femurs of New Zealand white rabbits and the underlying toxicity mechanism were investigated in this study. Serum samples, the heart, liver, kidney and femurs were collected from rabbits after intraperitoneal injection of TAA for 5 months (100 and 200 mg/kg). The New Zealand white rabbits treated with TAA showed significant weight loss and femoral shortening. The activities of total bilirubin, total bile acid and gamma-glutamyl transpeptidase in the serum were increased following treatment with TAA. In addition, the cortical bone became thinner, and the trabecular thickness decreased significantly in TAA-treated rabbits, which was accompanied by significantly decreased mineral density of the cortical and trabecular bone. Moreover, there was a significant decrease in modulus of elasticity and maximum load on bone stress in TAA-treated rabbits. The western blotting results showed that the expression of phosphorylated (p)-p38 and p-ERK in femur tissues of rabbits were increased after TAA administration. Collectively, these results suggested that TAA may lead to femoral damage in rabbits by activating the p38/ERK signaling pathway.

Sulfated extract of Abelmoschus esculentus: A potential cancer chemopreventive agent

BACKGROUND

Abelmoschus esculentus (AE) (okra), is an edible plant used in many food applications.

OBJECTIVE

This study explored whether sulfated AE (SAE) has promising cancer chemopreventive activities that may recommend it as a functional food supplement ‎instead of (or in addition to) AE for the population at risk of cancer and in the health food industry.

METHODS

Cytochrome P450-1A (CYP1A)‎ was estimated by fluorescence enzymatic reaction, using β-naphthoflavone-treated cells (CYP1A inducer). Peroxyl and hydroxyl radical scavenging was assayed by an oxygen radical absorbance capacity assay. Flow cytometry was used to analyze apoptosis/necrosis in MCF-7 cells, cell cycle phases in MCF-7 cells, and macrophage binding to fluorescein isothiocyanate-lipopolysaccharide (FITC-LPS)‎. Nitric oxide was determined by Griess assay in LPS-stimulated macrophages, and cytotoxicity was determined by MTT assay. Diethylnitrosamine (DEN) was used to induce hepatic tumor initiation in rats. Placental glutathione-S-transferase (GSTP; an initiation marker) was stained in a fluorescence immunohistochemical analysis of liver sections, and histopathological changes were examined.

RESULTS

SAE exhibited strong antitumor initiation and antitumor promotion activities. It suppressed CYP1A, ‎scavenged peroxyl and hydroxyl radicals, induced macrophage proliferation, suppressed ‎macrophage binding to FITC-LPS, inhibited nitric oxide generation, showed specific cytotoxicity to ‎human breast MCF-7 adenocarcinoma cells, and disturbed the cell cycle phases (S and G2/M phases) ‎in association with an increased percentage of apoptotic/necrotic MCF-7 cells. Over a short time period, DEN stimulated liver cancer initiation, but SAE treatment reduced the DEN-induced histopathological alterations and ‎inhibited CYP1A and GSTP.

CONCLUSION

SAE extract has the potential for use as an alternative to AE in health foods to provide cancer chemoprevention in populations at risk for cancer.

Cancer Chemopreventive Properties of Sulfated Enterolobium cyclocarpum Extract

Enterolobium cyclocarpum (EC) is an edible plant and a gum source for food industries. Its sulfated polysaccharide extract (SEC) was examined for cancer chemopreventive properties to estimate its anti-tumor activity. The modulation of carcinogen metabolism and the antioxidant activity revealed that SEC is a potent tumor anti-initiator since it inhibited cytochrome P450-1A (CYP1A) and induced carcinogen detoxification enzyme glutathione-S-transferase. SEC is also a weak scavenger for hydroxyl and peroxyl radicals. SEC was found to modulate macrophage functions into an anti-inflammatory pattern, where it enhanced macrophage proliferation and phagocytosis of fluorescein isothiocyanate-lipopolysaccharide (FITC-LPS). In addition, SEC strongly inhibited the nitric oxide (NO) generation in LPS-stimulated macrophages and induced the binding affinity of FITC-LPS to macrophages. SEC exhibited specific cytotoxicity against human hepatocellular Hep G2 carcinoma cells. SEC disturbed the cell cycle phase, as indicated by the concomitant arrest in S- and G2/M-phases that was associated with necrosis induction. A short-term initiation model for liver cancer was prepared using diethylnitrosamine (DEN) in rats. SEC inhibited the DEN-histopathological findings and reduced both CYP1A and the tumor initiation marker placental glutathione S-transferase (GSTP). Taken together, SEC could be used as an alternative gum in health food industries to provide cancer prevention in high-risk populations.

Expression Characteristics of Genes Hypermethylated and Downregulated in Rat Liver Specific to Nongenotoxic Hepatocarcinogens

This study examined hypermethylated and downregulated genes specific to carbon tetrachloride (CCl₄) by Methyl-Seq analysis combined with expression microarray analysis in the liver of rats treated with CCl₄ or N-nitrosodiethylamine (DEN) for 28 days, by excluding those with DEN. Among 52 genes, Ldlrad4, Proc, Cdh17, and Nfia were confirmed to show promoter-region hypermethylation by methylation-specific quantitative PCR analysis on day 28. The transcript levels of these 4 genes decreased by real-time reverse transcription-PCR analysis in the livers of rats treated with nongenotoxic hepatocarcinogens for up to 90 days compared with untreated controls and genotoxic hepatocarcinogens. Immunohistochemically, LDLRAD4 and PROC showed decreased immunoreactivity, forming negative foci, in glutathione S-transferase placental form (GST-P)⁺ foci, and incidences of LDLRAD4⁻ and PROC⁻ foci in GST-P⁺ foci induced by treatment with nongenotoxic hepatocarcinogens for 84 or 90 days were increased compared with those with genotoxic hepatocarcinogens. In contrast, CDH17 and NFIA responded to hepatocarcinogens without any relation to the genotoxic potential of carcinogens. All 4 genes did not respond to renal carcinogens after treatment for 28 days. Considering that Ldlrad4 is a negative regulator of transforming growth factor-β signaling, Proc participating in p21^WAF1/CIP1 upregulation by activation, Cdh17 inducing cell cycle arrest by gene knockdown, and Nfia playing a role in a tumor-suppressor, all these genes may be potential in vivo epigenetic markers of nongenotoxic hepatocarcinogens from the early stages of treatment in terms of gene expression changes. LDLRAD4 and PROC may have a role in the development of preneoplastic lesions produced by nongenotoxic hepatocarcinogens.

Amelioration of thioacetamide-induced liver toxicity in Wistar rats by rutin

This study was designed to evaluate the effect of rutin on hepatotoxicity induced by thioacetamide (TAA) in rats. Four groups of male Wistar rats consisting of six rats each were used: Group I: control group; Group II: rats receiving single injection of 300 mg kg⁻¹ body weight of TAA intraperitoneally; Group III: rats administered rutin (10 mg kg⁻¹ body weight) dissolved in saline orally for 2 weeks; and Group IV: rats administered rutin (10 mg kg⁻¹ body weight) dissolved in saline orally for 2 weeks followed by TAA injection last day of second week. All groups were sacrificed after 24 h of treatment and hepatic toxicity was analyzed with respect to liver toxicity markers, liver DNA fragmentation, and histology of liver tissue. Administration of TAA in Wistar rats resulted in significant increase of hepatic markers, DNA fragmentation in the hepatocytes, and changes in histology. Pretreatment of rats with rutin before 2 weeks of TAA assault resulted in the complete reversal of TAA-mediated hepatic toxicity (P < 0.0001 to P < 0.01) with concomitant restoration of DNA fragmentation. This study suggests rutin as a protective agent for restoration of toxicity caused by TAA.

Immunohistochemical cellular distribution of proteins related to M phase regulation in early proliferative lesions induced by tumor promotion in rat two-stage carcinogenesis models

We have previously reported that 28-day treatment with hepatocarcinogens increases liver cells expressing p21(Cip1), a G1/S checkpoint protein, and M phase proteins, i.e., nuclear Cdc2, Aurora B, phosphorylated-Histone H3 (p-Histone H3) and heterochromatin protein 1α (HP1α), in rats. To examine the roles of these markers in the early stages of carcinogenesis, we investigated their cellular distribution in several carcinogenic target organs using rat two-stage carcinogenesis models. Promoting agents targeting the liver (piperonyl butoxide and methapyrilene hydrochloride), thyroid (sulfadimethoxine), urinary bladder (phenylethyl isothiocyanate), and forestomach and glandular stomach (catechol) were administered to rats after initiation treatment for the liver with N-diethylnitrosamine, thyroid with N-bis(2-hydroxypropyl)nitrosamine, urinary bladder with N-butyl-N-(4-hydroxybutyl)nitrosamine, and forestomach and glandular stomach with N-methyl-N'-nitro-N-nitrosoguanidine. Numbers of cells positive for nuclear Cdc2, Aurora B, p-Histone H3 and HP1α increased within preneoplastic lesions as determined by glutathione S-transferase placental form in the liver or phosphorylated p44/42 mitogen-activated protein kinase in the thyroid, and hyperplastic lesions having no known preneoplastic markers in the urinary bladder, forestomach and glandular stomach. Immunoreactive cells for p21(Cip1) were decreased within thyroid preneoplastic lesions; however, they were increased within liver preneoplastic lesions and hyperplastic lesions in other organs. These results suggest that M phase disruption commonly occur during the formation of preneoplastic lesions and hyperplastic lesions. Differences in the expression patterns of p21(Cip1) between thyroid preneoplastic and proliferative lesions in other organs may reflect differences in cell cycle regulation involving G1/S checkpoint function between proliferative lesions in each organ.

Integrative toxicopathological evaluation of aflatoxin B₁ exposure in F344 rats

In this study, male F344 rats were orally exposed to a single dose of aflatoxin B₁ (AFB₁) at 0, 50, 250, or 1,000 µg/kg body weight (BW) or repeated dose of 0, 5, 10, 25, or 75 µg/kg BW for up to 5 weeks. Biochemical and histological changes were assessed together with the formation of AFB1-lysine adduct (AFB-Lys) and liver foci positive for placental form glutathione S transferase (GST-P⁺). In single-dose protocol, serum aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP) showed dose-related elevation, with maximal changes observed (>100-fold) at day 3 after treatment. Animals that received 250 µg/kg AFB₁ showed concurrent bile duct proliferation, necrosis, and GST-P⁺ hepatocytes at 3 day, followed by liver GST-P⁺ foci appearance at 1 week. In repeated-dose protocol, bile duct proliferation and liver GST-P⁺ foci co-occurred after 3-week exposure to 75 µg/kg AFB₁, followed by proliferation foci formation after 4 week and dramatic ALT, AST, and CK elevations after 5 weeks. Liver GST-P⁺ foci were induced temporally and in a dose-related manner. Serum AFB-Lys increased temporally at low doses (5-25 µg/kg), and reached the maximum after 2-week exposure at 75 µg/kg. This integrative study demonstrated that liver GST-P⁺ cells and foci are sensitive biomarkers for AFB₁ toxic effect and correlated with bile duct proliferation and biochemical alterations in F344 rats.

Involvement of PTEN/Akt signaling and oxidative stress on indole-3-carbinol (I3C)-induced hepatocarcinogenesis in rats

We previously reported that indole-3-carbinol (I3C) had hepatocellular tumor-promoting activity in a short-term (8 weeks) two-stage liver carcinogenesis model in rats. It was suggested that this effect was related to the production of reactive oxygen species (ROS) caused by cytochrome P450 1A (CYP1A) induction. In the present study, 0.5% I3C was administered to DEN-initiated rats for 26 weeks to examine the effect of prolonged administration of I3C and to clarify the possible mechanisms of I3C-induced hepatocarcinogenesis. The number and area of GST-P positive foci, ROS production, TBARS level, 8-OHdG content and mRNA levels of Ahr and Nrf2 gene batteries significantly increased in the DEN-I3C group compared with the DEN-alone group. Furthermore, some GST-P positive preneoplastic foci progressed to hepatocellular adenomas with the prolongation of I3C administration. Lack of PTEN and phospho-Smad2/3 expression and translocations of PDPK1 and phospho-Akt substrates to underneath the cell membrane were observed in the majority of hepatocellular adenomas. In addition, the number of Ki-67 positive cells increased in adenomas compared with the preneoplastic foci. These results suggest that the administration of I3C for 26 weeks in DEN-initiated rats induces tumor progression from hepatocellular altered foci to hepatocellular adenomas by ROS-mediated Akt activation that inhibits the TGF-β/Smad signaling and results in the increased cell proliferation.