Hepatocarcinogenesis In Rats Research Articles

Hepatoprotective effects of curcumin against diethyl nitrosamine induced hepatotoxicity in albino rats.

Curcumin is widely used as a traditional medicine. This work was aimed to investigate its possible protective effect against chemically induced hepatocellular carcinoma (HCC) in rats. Fifty male albino rats were divided into five groups (n=10, each). The control group received a single dose of normal saline, the diethylnitrosamine (DENA) group received a single intra-peritoneal dose at 200mg/kg body weight, and the 3rd, 4th and 5th groups were given DENA and daily administrated curcunine (CUR) via intra-gastric intubation in doses of 300,200 and 100 mg/kg b.wt. respectively for 20 weeks. Serum, and liver samples were used for determination of alpha feto-protein (AFP), interleukin-2 (IL-2), interleukine-6 (IL-6), serum liver enzymes (AST, ALT, ALP and GGT) levels as well the activities and gene expression of glutathione peroxidise (GPx), glutathione reductase (GR), catalase (CAT) and super oxide dismutase (SOD). Curcumin significantly lowered the serum levels of AFP, IL-2 and IL-6, ALT, ALT, and malondialdehyde (MDA) as well gene expression of IL-2 and IL-6. In contrast it increased the gene expression and activities of Gpx, GRD, CAT and SOD. The protective effect of CUR against DEN-induced hepatocarcinogenesis in albino rats was proven.

Interleukin-1β/Iinterleukin-1 receptor-associated kinase 1 inflammatory signaling contributes to persistent Gankyrin activation during hepatocarcinogenesis.

Hepatocellular carcinoma (HCC) is a prototype of inflammation-associated cancer. Oncoprotein Gankyrin, which mostly increases in HCC, plays a critical role in HCC development and metastasis. However, the exact mechanism of Gankyrin up-regulation in HCC remains unclear. A Gankyrin luciferase reporter was developed to screen a potential regulator for Gankyrin from a list of proinflammatory cytokines, and interleukin (IL)-1β was found as one of its activators. In clinical premalignant and malignant liver disease samples, enhanced IL-1β/interleukin-1 receptor-associated kinase 1 (IRAK-1) signaling accompanied by increased Gankyrin was observed. Lower expression of Gankyrin and phospho-IRAK-1 are favorable prognostic markers for HCC. A similar correlation was observed in the diethylnitrosamine (DEN) model of rat hepatocarcinogenesis. The results from Gankyrin reporter activity, real-time polymerase chain reaction, or immunoblotting further confirmed the up-regulation of Gankyrin by IL-1β/IRAK-1 inflammatory signaling. Moreover, a series of Gankyrin's truncated reporters were constructed, and electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) were performed to analyze the properties of Gankyrin promoter. Mechanistically, the core promoter of Gankyrin contains the binding site of nuclear factor Y (NF-Y) family members, which can recruit histone acetyltransferase coactivator E1A-binding protein p300 (p300) or CREB-binding protein (CBP) to promote Gankyrin transcription. Conversely, knockdown of NF-Y, p300, or CBP inhibits Gankyrin expression. IL-1β stimulation causes sequential phosphorylation of IRAK-1, c-Jun N-terminal kinase (JNK), and p300 and enhances recruitment of the p300/CBP/NF-Y complex to Gankyrin promoter. Inhibition of phospho-JNK impairs IL-1β/IRAK-1 signaling-mediated up-regulation of Gankyrin. The finding of IL-1β/IRAK-1 signaling promoting Gankyrin expression through JNK and NF-Y/p300/CBP complex provides a fresh view on inflammation-enhanced hepatocarcinogenesis.

Chemopreventive effects of korean red ginseng extract on rat hepatocarcinogenesis.

The objective of this study was to determine a chemopreventive activity of Korean red ginseng extract (KRG) in diethylnitrosamine (DEN) induced hepatocarcinogenesis in rats. After acclimatization for a week, Sprague-Dawley rats were randomized into five groups (n = 15) and fed either KRG (0.5, 1 or 2%) or control diets for 10 weeks. After two weeks of starting of experimental diets, the rats were initiated hepatocarcinogenesis by injection of DEN and were then subjected to two-thirds partial hepatectomy at five-week for developing the medium-term bioassay system. Both 0.5 and 1% KRG diets suppressed the area (55 and 60%; p= 0.0251 and 0.0144) and number (39 and 59%; p= 0.0433 and 0.0012) of glutathione S-transferase placental form (GST-P) positive foci when compared to the DEN-control group. The production of thiobarbituric acid reactive substances (TBARS) was significantly reduced in 0.5 and 1% KRG-treated rats. The supplementation of 1% KRG diet significantly elevated the levels of total glutathione (tGSH) and glutathione-related enzymes including cytosolic glutathione S-transferase (GST) and glutathione peroxidase (GPx) activities. It was also observed in cDNA microarray that the gene expressions (Cyp2c6, Cyp2e1, Cyp3a9, and Mgst1) involved in the xenobiotics metabolism via cytochrome P450 signaling pathway were down-regulated in the 1% KRG diet-treated group when compared to the DEN-control. The chemopreventive effects of KRG could be affected by 1) the decrease of lipid peroxidation, 2) the increase of tGSH content and GSH-dependent enzyme activities, and 3) the decrease of the gene expression profile involved in cytochrome P450 signaling pathway. These results suggest that KRG may prove to be a therapeutic agent against hepatocarcinogenesis.

Immunohistochemical study of p53, Ki-67, Bax and Bcl-2 in diethylnitrosamine induced hepatocarcinogenesis in rats treated withCassia fistulaleaf extract

Immunohistochemical study of p53, Ki-67, Bax and Bcl-2 in diethylnitrosamine induced hepatocarcinogenesis in rats treated with<i>Cassia fistula</i>leaf extract

Proteomic identification of differentially expressed proteins in rat hepatocarcinogenesis using iTRAQ technology

Proteomic identification of differentially expressed proteins in rat hepatocarcinogenesis using iTRAQ technology

Activation of oxidative stress and inflammatory factors could account for histopathological progression of aflatoxin-B1 induced hepatocarcinogenesis in rat.

Aflatoxin-B1 (AFB1) intoxication is known to develop hepatocellular carcinoma (HCC). However, pathogenesis and diagnosis of AFB1-induced HCC remain undefined. This article describes histopathological progression versus kinetics of the placental glutathione S-transferase (GST-pi) expression and profiles of the antioxidant enzymes, pro-inflammatory cytokines, and proliferative cell nuclear antigen (PCNA) in the liver from the rats administered with two doses of 1 mg AFB1/kg b.w. Histopathologically, hepatocytes necrosis could be observed after 4 weeks of the AFB1 treatment, which subsequently developed into the well-defined foci of altered hepatocytes (FAH) at 10 weeks post-treatment stage. This was consistent with an increasing trend of GST-pi immunostaining especially in the liver foci as a function of FAH progression and thus, suggesting that GST-pi over expression may serve as a marker for AFB1-induced hepatocarcinogenesis. The liver from AFB1-treated rats showed significantly enhanced level of reactive oxygen species coinciding with the declined immunostaining for superoxide dismutase-1, a committed enzyme of the antioxidant pathway, in the FAH regions and also with declined activity of the other antioxidant enzymes. Concordantly, the liver from the AFB1-treated rats showed over expression of pro-inflammatory cytokines; TNF-α & IL-1α and a cell proliferative marker PCNA. These findings present histological characterization of AFB1-induced HCC development and provide evidence for activation of oxidative stress-pro-inflammatory pathway during hepatocarcinogenesis induced by AFB1 toxicity.

Immunomodulatory effect of diethylcarbamazine citrate plus filarial excretory-secretory product on rat hepatocarcinogenesis.

Diethylcarbamazine citrate (DEC) had a significance in anti-filarial chemotherapy, while excretory-secretory product (ES) is released from adult filarial females. The target of the current study was to examine the immunomodulatory effect of DEC, Setaria equina ES or a combination of them on rat hepatocellular carcinoma (HCC) induced by diethylnitrosamine (DEN). In vitro effect of combined DEC and ES or ES alone on lipopolysaccharide (LPS)-stimulated rat peripheral blood mononuclear cells (PBMCs) was tested through IFN-γ assay in culture supernatants. In addition, single or repeated doses of DEC, ES or DEC+ES have been applied in white albino rats to test the effect on HCC. Levels of IFN-γ and anti-ES IgG antibodies in rat serum were assayed using ELISA. Hemolytic complement activity (CH50) was determined in serum while the concentration of nitric oxide (NO) was assayed in liver tissue. The infiltration of NK cells as well as the expression of MHC Iproliferating cell nuclear antigen (PCNA), inducible NO synthase (iNOS), Bcl2 and p53 were determined using immunohistochemistry. There was a dose-dependent increase in IFN-γ after in vitro exposure to DEC+ES. Repeated ES doses increased NO concentration (p<0.05) and expression of iNOS but reduced CH50 (p<0.001), while repeated DEC+ES doses could increase anti-ES IgG (p<0.01), IFN-γ level (p<0.05) and NK cell infiltration. The same treatments could also reduce the expression of MHC I expression, PCNA, Bcl2 and p53. This study has shown immunomodulatory and protective effects of DEC+ES repeated doses on rat HCC.

Camel milk inhibits murine hepatic carcinogenesis, initiated by diethylnitrosamine and promoted by phenobarbitone

This study was carried out in order to investigate the possible inhibitory effect of camel milk (CM) on induced hepatocarcinogenesis in rats. Twenty-eight male rats were assigned into 4 groups (7 rats per group). Group I served as control negative. Group II treated with camel milk. Group III was injected I/P with diethylnitrosamine (DENA) (200mg/kg) as a single dose and after one week received 500ppm phenobarbitone in drinking water. Group IV injected with DENA as group III and treated with camel milk. Estimation of AST, ALT, albumin, total protein and alpha fetoprotein (AFP) in the serum of euthanized rats was performed. Histopathological examination and immunohistochemical staining of AFP and placental glutathione s transferase of the liver were carried out. Biochemical result at 38th week revealed an increase in serum AFP and a decrease in serum albumin on group III although no significance was detected. Histopathologically, the size of altered hepatic foci was smaller in the milk treated group (group IV). The number of mitotic figures observed in group IV was lower than group III. Hepatocellular carcinoma developed only in group III but not group IV. Immunohistochemical staining of AFP demonstrated an intense positive staining in group III and a weak positive staining in group IV. Similarly, the area percent of preneoplastic P-GST positive foci in liver was higher in group III than group IV. In conclusion, camel milk halted the progression of hepatocellular carcinoma.

Valerian inhibits rat hepatocarcinogenesis by activating GABA(A) receptor-mediated signaling.

Valerian is widely used as a traditional medicine to improve the quality of sleep due to interaction of several active components with the γ-aminobutyric acid (GABA) A receptor (GABA(A)R) system. Recently, activation of GABA signaling in stem cells has been reported to suppress cell cycle progression in vivo. Furthermore, possible inhibitory effects of GABA(A)R agonists on hepatocarcinogenesis have been reported. The present study was performed to investigate modulating effects of Valerian on hepatocarcinogenesis using a medium-term rat liver bioassay. Male F344 rats were treated with one of the most powerful Valerian species (Valeriana sitchensis) at doses of 0, 50, 500 and 5000 ppm in their drinking water after initiation of hepatocarcinogenesis with diethylnitrosamine (DEN). Formation of glutathione S-transferase placental form positive (GST-P+) foci was significantly inhibited by Valerian at all applied doses compared with DEN initiation control rats. Generation of 8-hydroxy-2′-deoxyguanosine in the rat liver was significantly suppressed by all doses of Valerian, likely due to suppression of Nrf2, CYP7A1 and induction of catalase expression. Cell proliferation was significantly inhibited, while apoptosis was induced in areas of GST-P+ foci of Valerian groups associated with suppression of c-myc, Mafb, cyclin D1 and induction of p21Waf1/Cip1, p53 and Bax mRNA expression. Interestingly, expression of the GABA(A)R alpha 1 subunit was observed in GST-P+ foci of DEN control rats, with significant elevation associated with Valerian treatment. These results indicate that Valerian exhibits inhibitory effects on rat hepatocarcinogenesis by inhibiting oxidative DNA damage, suppressing cell proliferation and inducing apoptosis in GST-P+ foci by activating GABA(A)R-mediated signaling.

Glycolysis inhibitor 2-deoxy-D-glucose suppresses carcinogen-induced rat hepatocarcinogenesis by restricting cancer cell metabolism.

The abnormal metabolism of cancer cells is a crucial feature of tumors and provides promising therapeutic targets for cancer treatments. Aerobic glycolysis in cancer cells, termed the Warburg effect, is a highlighted characteristic of cancer‑specific metabolism. However, the effect of glycolysis inhibition on hepatocarcinogenesis remains to be elucidated. In the present study, the effects of the glycolysis inhibitor 2‑deoxy‑D‑glucose (2‑DG) on the N‑diethylnitrosamine (DEN)‑induced rat hepatocarcinoma model and its underlying mechanisms were investigated. It was observed that 2‑DG significantly delayed hepatocarcinogenesis and effectively prolonged survival time in the DEN‑treated rats. The glycolysis inhibitor, 2‑DG prominently decreased cell proliferation and increased cell apoptosis in the DEN‑induced rat hepatoma and had no evident impact on the pericarcinomatous liver tissues. Further investigation revealed that 2‑DG resulted in a reduction of glycolysis products, the compensatory increase of hexokinase 2 expression and a decrease in 6‑phosphofructo‑2‑kinase, pyruvate kinase M2 and lactate dehydrogenase A expression in the hepatoma tissues. The inhibition of glycolysis further suppressed the tricarboxylic acid cycle, fatty acid and cholesterol biosynthesis and ATP production, while it promoted autophagic activation. In addition, the in vitro study demonstrated that hypoxia, an important factor in the tumor microenvironment, may assist in increasing 2‑DG‑induced inhibition of cell viability, cell cycle retardation and the decrease of colony formation ability in hepatoma cells. Taken together, the present results suggested that 2‑DG may inhibit hepatocarcinogenesis in the DEN‑treated rats via restricting cancer cell metabolism. This finding provides a promising measure in the prevention and treatment of hepatoma.

Anti-proliferative activities of sinigrin on carcinogen-induced hepatotoxicity in rats.

Liver cancer is one of the leading causes of cancer death worldwide. A very high incidence of new liver cancer cases is diagnosed every year, and metastasis has been found to correlate to poor prognoses in humans. Better treatments for liver cancer are thus clearly needed. Sinigrin is one of the major ingredients present in Brassica nigra, which has been used in combination with other herbs for treatment of various diseases. The anti-proliferative activities of sinigrin were studied in a model of carcinogen-induced hepatotoxicity in rats. Rats were orally administered with sinigrin on a daily basis for three months before sacrifice. Sinigrin was found to significantly inhibit the proliferation of liver tumor cells; the number of surface tumors in the rat liver was dramatically reduced. Sinigrin induced apoptosis of liver cancer cells through up-regulation of p53 and down-regulation of Bcl-2 family members and caspases. Our findings indicated that the liver functions were gradually restored after treatment with sinigrin and that the agent did not cause liver toxicity. Cell cycle analysis indicated that sinigrin caused cell cycle arrest in G0/G1 phase. The results suggest that sinigrin exerts important anti-proliferative activities in carcinogen-induced hepatocarcinogenesis in rats, and highlight the potential of sinigrin as an anti-cancer agent for liver cancer.

Carvacrol modulates instability of xenobiotic metabolizing enzymes and downregulates the expressions of PCNA, MMP-2, and MMP-9 during diethylnitrosamine-induced hepatocarcinogenesis in rats.

Hepatocellular carcinoma is the fifth most common malignant tumor in the world, both in terms of incidence and mortality in Asian and Western countries. There are currently limited therapeutic regimens available for effective treatment of this cancer. Carvacrol is a predominant monoterpenoic phenol believed to impede cancer promotion and progression. The present study was conducted to decipher the role of carvacrol during diethylnitrosamine (DEN)-induced hepatocarcinogenesis in male wistar albino rats. Carvacrol (15mg/kg body weight) suppressed the elevation of serum tumor marker enzymes, carcinoembryonic antigen, and α-feto protein induced by DEN. The activities of phase I enzymes increased markedly during DEN induction, but was found to be significantly lowered upon carvacrol treatment. On the contrary, the phase II enzymes decreased in DEN-administered animals, which was improved normalcy upon carvacrol-treated animals. DEN-administered animals showed increased mast cell counts, argyrophilic nucleolar organizing regions, proliferating cell nuclear antigen, and matrix metalloproteinases (MMPs-2/9), whereas carvacrol supplementation considerably suppressed all the above abnormalities. The results suggest that the carvacrol exhibited the potential anticancer activity by inhibiting cell proliferation and preventing metastasis in DEN-induced hepatocellular carcinogenesis.

A possible antineoplastic potential of selective, irreversible proteasome inhibitor, carfilzomib on chemically induced hepatocarcinogenesis in rats.

The antineoplastic effect of carfilzomib (CFZ) against chemically induced hepatocarcinogenesis was studied. A total of 60 male Wistar albino rats were divided into six groups with 10 animals in each group. Rats in group 1 (control group) were given dimethylsulphoxide (DMSO) (0.4 mL/kg i.p) twice a week for 3weeks from week8 to week10. Animals in groups 2 and 3 were given CFZ (2 and 4 mg/kg i.p) twice a week from week8 to week10, respectively. Rats in group 4 were given diethylnitrosamine (DENA) at a dose of 0.01% in drinking water for 10 weeks and received a DMSO (0.4 mL/kg i.p) twice a week from week8 to week10. Animals in groups 5 and 6 were given DENA at a dose of 0.01% in drinking water for 10weeks and treated with CFZ (2 and 4 mg/kg i.p) twice a week from week8 to week10, respectively. CFZ succeeded in suppressing the elevated serum tumor marker α-fetoprotein and carcinoembryonic antigen. The antineoplastic effect of CFZ was also accompanied by normalization of elevated hepatic tissue growth factors, matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-1, and augmentation of hepatic endostatin and metallothionein. A histopathological examination of liver samples treated with CFZ after DENA intoxication correlated with the biochemical observation. Treatment with CFZ confers an antineoplastic activity against chemically induced hepatocarcinogenesis. These findings suggest that CFZ plays a pivotal role in the treatment of hepatocarcinogenesis.

Apoptotic effects of dipyrido [3,2-a:2',3'-c] phenazine (dppz) Au(III) complex against diethylnitrosamine/phenobarbital induced experimental hepatocarcinogenesis in rats.

We evaluated the effects of dipyrido [3,2-a:2',3'-c] phenazine (dppz) Au(III) complex ([Au(dppz)Cl2]Cl) on apoptosis during chemically induced hepatocellular carcinoma. 48 male Spraque-Dawley rats were divided into six groups; group I (control), group II [Dimethyl sulfoxide (DMSO)], group III ([Au(dppz)Cl2]Cl), group IV [diethylnitrosamine + Phenobabital (DEN + PB)], group V (DEN + PB + [Au(dppz)Cl2]Cl (2nd week)), and group VI (DEN + PB + [Au(dppz)Cl2]Cl (7th week). The rats in groups IV through VI were administrated with DEN in a single dose of intraperitoneal 175 mg/kg. After 2 weeks of DEN administration, these groups of rats were given daily PB in a dose of 500 ppm. In group V, after two weeks of DEN administration, [Au(dppz)Cl2]Cl complex (2 mg/kg) was given once a week by intraperitoneal injection. In the group VI, the rats were given a dose of 2 mg/kg [Au(dppz)Cl2]Cl complex once a week, 7 weeks after DEN administration. At the end of the study, blood and tissue samples were collected from the rats to determine levels of serum AST, ALT, and LDH, and caspase 3, p53, Bax, Bcl-2 and DNA fragmentation in liver. AST, ALT, LDH, and Bcl-2 levels were higher in group IV, compared to group I, but caspase 3 and p53 levels were lower. In group V, caspase 3, p53, Bax, and DNA fragmentation levels were higher than those of group IV. Caspase 3 and p53 levels increased in group VI compared with group IV. In conclusion, [Au(dppz)Cl2]Cl complex induced apoptosis by elevating levels of caspase 3, p53, Bax, and DNA fragmentation.

The protective role of ellagitannins flavonoids pretreatment against N-nitrosodiethylamine induced-hepatocellular carcinoma

Ellagitannins are esters of glucose with hexahydroxydiphenic acid; when hydrolyzed, they yield ellagic acid (EA), the dilactone of hexahydroxydiphenic acid. EA has been receiving the most attention, because it has potent antioxidant activity, radical scavenging capacity, chemopreventive and antiapoptotic properties. Hepatocellular carcinoma (HCC) is the most frequent primary malignancy of liver, and accounts for as many as one million deaths worldwide in a year. The aim of the present study was to evaluate the antioxidant and chemopreventive efficiency of ellagic acid against N-nitrosodiethylamine (NDEA) induced hepatocarcinogenesis in rats. Rats were classified into four groups as follows: normal control group, group injected i.p. with a single dose (200mg/kgb.wt.) of NDEA, third group daily administered orally EA with a dose of 50mg/kgb.wt. for 7days before and 14days after NDEA administration, and fourth group received a similar dose of EA for 21days after the dose of NDEA administration. The model of NDEA-injected hepatocellular carcinomic (HCC) rats elicited significant declines in liver antioxidant enzyme activities; glutathione peroxidase (GPX), gamma glutamyl transferase (γ-GT) and glutathione-S-transferase (GST), with a reduction in reduced glutathione (GSH) and serum total protein with concomitant significant elevations in tumor markers arginase and α-l-fucosidase, and liver enzymes; aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and glutathione-S-transferase (GST), glucose-6-phosphate dehydrogenase (G6PD), direct and total bilirubin. The oral administration of EA as a protective agent, produced significant increases in tested antioxidant enzyme activities and serum total protein concomitant with significant decreases in the levels of tumor markers arginase and α-l-fucosidase as well as liver enzymes, direct and total bilirubin. Similarly, the oral administration of EA, as a curative agent produced similar changes to those when EA was used as a protective agent, but to a lesser extent. In addition, it was noted that HCC rats exhibited a degree of DNA fragmentation; however, EA administration partially inhibited the DNA fragmentation. Therefore, EA has the ability to scavenge free radicals, prevent DNA fragmentation, reduce liver injury and protect against oxidative stress.

Cleistocalyx nervosum extract ameliorates chemical-induced oxidative stress in early stages of rat hepatocarcinogenesis.

To study the effect of Cleistocalyx nervosum extract (CE) on diethylnitrosamine (DEN) and phenobarbital (PB) induced oxidative stress in early stages of rat hepatocarcinogenesis. Male Wistar rats were divided into 4 groups, with Group 1 as a negative control and Group 2 was a positive control receiving DEN injections once a week and PB in drinking water for 6 weeks. Two weeks before DEN initiation and PB treatment, Groups 3 and 4, were fed with 500 and 1000 mg/kg of CEs, respectively, for 8 weeks. A number of GST-P-positive foci, preneoplastic lesions, in the liver were markedly increased in carcinogen administered rats, but was comparatively decreased in rats treated with 1000 mg/kg of CE. The CE reduced malondialdehyde in serum and in the livers of rats treated with DEN and PB. Moreover, CE significantly increased the activities of glutathione peroxidase and catalase in rat liver. CE appeared to exert its chemopreventive effects by modulating antioxidant status during DEN and PB induced early stages of hepatocarcinogenesis in rats.

Tumor suppression effects of bilberry extracts and enzymatically modified isoquercitrin in early preneoplastic liver cell lesions induced by piperonyl butoxide promotion in a two-stage rat hepatocarcinogenesis model

To investigate the protective effect of bilberry extracts (BBE) and enzymatically modified isoquercitrin (EMIQ) on the hepatocarcinogenic process involving oxidative stress responses, we used a two-stage hepatocarcinogenesis model in N-diethylnitrosamine-initiated and piperonyl butoxide (PBO)-promoted rats. We examined the modifying effect of co-administration with BBE or EMIQ on the liver tissue environment including oxidative stress responses, cell proliferation and apoptosis, and phosphatase and tensin homolog (PTEN)/Akt and transforming growth factor (TGF)-β/Smad signalings on the induction mechanism of preneoplastic lesions during early stages of hepatocellular tumor promotion. PBO increased the numbers and area of glutathione S-transferase placental form (GST-P)+ liver cell foci and the numbers of Ki-67+ proliferating cells within GST-P+ foci. Co-administration of BBE or EMIQ suppressed these effects with the reductions of GST-P+ foci (area) to 48.9–49.4% and Ki-67+ cells to 55.5–61.4% of the PBO-promoted cases. Neither BBE nor EMIQ decreased microsomal reactive oxygen species induced by PBO. However, only EMIQ suppressed the level of thiobarbituric acid-reactive substances to 78.4% of the PBO-promoted cases. PBO increased the incidences of phospho-PTEN– foci, phospho-Akt substrate+ foci, phospho-Smad3– foci and Smad4– foci in GST-P+ foci. Both BBE and EMIQ decreased the incidences of phospho-PTEN– foci in GST-P+ foci to 59.8–72.2% and Smad4– foci to 62.4–71.5% of the PBO-promoted cases, and BBE also suppressed the incidence of phospho-Akt substrate+ foci in GST-P+ foci to 75.2–75.7% of the PBO-promoted cases. These results suggest that PBO-induced tumor promotion involves facilitation of PTEN/Akt and disruptive TGF-β/Smad signalings without relation to oxidative stress responses, but this promotion was suppressed by co-treatment with BBE or EMIQ through suppression of cell proliferation activity of preneoplastic liver cells.

Orally Administered Lycopene Attenuates Diethylnitrosamine-Induced Hepatocarcinogenesis in Rats by Modulating Nrf-2/HO-1 and Akt/mTOR Pathways

Hepatocarcinogenesis is one of the most prevalent and lethal cancers. We studied the mechanisms underlying the inhibition of diethylnitrosamine (DEN)-induced hepatocarcinogenesis by lycopene in rats. Hepatocarcinogenesis was induced by an intraperitoneal injection of DEN followed by promotion with phenobarbital for 24 successive wk. The rats were given lycopene (20 mg/kg body weight) 3 times a week orally for 4 wk prior to initiation, and the treatment was continued for 24 consecutive wk. Lycopene reduced incidence, number, size, and volume of hepatic nodules. Serum alanine transaminase, aspartate aminotransferase, total bilirubin, and malondialdehyde (MDA) considerably increased and hepatic antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase) and glutathione decreased in DEN-treated rats when compared with the control group. Lycopene significantly reversed these biochemical changes and increased the expression of NF-E-2-related factor-2)/heme oxygenase-1, and it decreased NF-κB/cyclooxygenase-2, inhibiting the inflammatory cascade and activating antioxidant signaling (P < 0.05). Lycopene also decreased DEN-induced increases in phosphorylated mammalian target of rapamycin (p-mTOR), phosphorylated p70 ribosomal protein S6 kinase 1, phosphorylated 4E-binding protein 1, and protein kinase B (P < 0.05). Lycopene is an active chemopreventive agent that offers protection against DEN-induced hepatocarcinogenesis by inhibiting NF-κB and mTOR pathways.

Different roles of hepatic hypothermic ischemia and ischemic preconditioning in chemically induced hepatocarcinogenesis in rats

BackgroundHepatic ischemia–reperfusion (IR) injury, an unfavorable complication of hepatectomy, could be prevented by hypothermic ischemia and ischemic preconditioning (IPC). However, the effects of these two approaches on hepatocarcinogenesis have not been examined. The aim of the study was to investigate roles of hypothermic ischemia and IPC in a chemically induced rat liver tumor model. MethodsTwenty-four Sprague–Dawley rats were treated with diethylnitrosamine and phenobarbital to induce hepatocellular carcinoma. Rats underwent hepatic ischemic injury, hypothermic ischemia, and IPC. Twenty-eight-wk-old rats were sacrificed to evaluate the morbidity and growth of liver tumor. Cytokines were measured at the protein and messenger RNA level. ResultsIR injury significantly promoted liver tumor development. Intriguingly, hypothermic ischemia, but not IPC, delayed liver carcinogenesis, although both of them suppressed the hepatic IR injury. IPC-treated rats showed elevated interleukin (IL)-6 concentration in the serum and messenger RNA expression in liver. In addition, higher levels of IL-6 activated signal transducer and activator of transcription 3 in the liver of IPC-treated rats. The hepatic expression of target genes of signal transducer and activator of transcription 3 signaling, cyclin D1, c-myc, c-fos, and c-jun, all of which might participate in tumor progression, increased in IPC group, compared with that of IR group. ConclusionsThese data indicated hypothermic ischemia could ameliorate both IR injury and liver tumor development. However, IPC, another effective method to prevent hepatic IR injury, might exacerbate liver tumor growth. The elevated level of IL-6 was one of the reasons for the different effects of hypothermic ischemia and IPC on hepatocarcinogenesis in rats.

Preventive Effect of Hydrazinocurcumin on Carcinogenesis of Diethylnitrosamine-induced Hepatocarcinoma in Male SD Rats

The purpose of the present study was to evaluate the preventive effects of hydrazinocurcumin (HZC) on diethylnitrosamine (DEN)-induced hepatocarcinogenesis in a male Sprague Dawley (SD) rat model. One hundred and twenty male SD rats used in this study were divided into six groups. Those receiving DEN with curcumin (CUR) or HZC were studied compared with the DEN-alone group. The study demonstrated that DEN induced severe histological and immunohistochemical changes in liver tissues, significantly increasing the levels of liver marker enzymes (alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyltransferase (GGT) and total bilirubin level (TBL)). The hepatocarcinoma incidences were 100.0%, 36.7% and 20.0% in the DEN-alone, DEN-CUR and DEN-HZC groups, respectively. Although macroscopic and microscopic features suggested that both CUR and HZC were effective in inhibiting DEN- induced hepatocarcinogenesis, HZC was exerted a stronger influence. Immunohistochemical analysis with PCNA demonstrated significantly differences among the groups (all P < 0.05). Taken together, the results suggested application of CUR and HZC could prevent the occurrence of carcinogenesis and HZC may be a more potent compound for prevention of DEN-induced hepatocarcinogenesis in rats than CUR.