NDEA-induced Hepatocarcinogenesis Research Articles

Biological and Phytochemical Screening of Fumaria indica extract on Chemically Induced Hepatocellular Carcinoma with Reference to Biochemical Parameters

Liver disease or liver cancer is the sixth most common cancer and the third leading cause of cancer mortality in the world. Hepatitis viral infection, food additives, alcohol, fungal toxins (aflatoxins), toxic industrial chemicals, air and water pollutants are the major risk factors of liver cancer. Moreover, due to high tolerance of liver, HCC is seldom detected at an early stage and once detected treatment faces a poor prognosis in most cases.Fumaria indica possesses hepatoprotective activity as evidenced by the significant and dose dependent restoring the activities of entire liver cancer marker enzymes, diminution in tumor incidence, decrease in lipid peroxidation (LPO) and increase in the level of antioxidant enzymes (GSH, CAT, SOD, GPx and GST) through scavenging of free radicals, or by enhancing the activity of antioxidant, which then detoxify free radicals. These factors protect cells from ROS damage in NDEA and CCl4-induced hepatocarcinogenesis. Histopathological observations of liver tissues too correlated with the biochemical observations. Thus, present investigation suggested that the Fumaria indica would exert a chemoprotective effect by reversing the oxidant-antioxidant imbalance during hepatocarcinogenesis induced by NDEA and CCl4. Besides Fumaria indicais very much effective in preventing NDEA-induced multistage hepatocarcinogenesis possibly through antioxidant and antigenotoxic nature, which was confirmed by various liver injury and biochemical tumour markers enzymes. The hepatoprotective activity of a Fumaria indicaof 50 % ethanolic extract was studied using rats. The animals received a single intraperitoneal injection of N-nitrosodiethylamine 200mg/kg body wt followed by subcutaneous injection of CCl4 in a dose of 3 ml/kg body wt. Fumaria indica extract dose dependently and significantly the increase in serum hepatic enzyme levels after NDEAand CCl4 treatment compared to the toxin control group. The results of this study confirmed the antioxidant and hepatoprotective activity of the Fumaria indicaextract against carbon tetrachlorideand N-nitrosodiethylamine induced hepatotoxicity in rats. In addition to this, studies on molecular aspect of hepatoprotective therapy will give mechanistic information in hepatoprotective therapy and also critical balance should be there between the animal model and clinical research. The hepatoprotective properties of Fumaria indicashould provide useful information in the possible application in hepatic liver disease.

Biological and Phytochemical Screening of Tephrosia purpurea extract on Chemically Induced Hepatocellular Carcinoma with Reference to Biochemical Parameters

Tephrosia purpurea possesses hepatoprotective activity as evidenced by the significant and dose dependent restoring the activities of entire liver cancer marker enzymes, diminution in tumor incidence, decrease in lipid peroxidation (LPO) and increase in the level of antioxidant enzymes (GSH, CAT, SOD, GPx and GST) through scavenging of free radicals, or by enhancing the activity of antioxidant, which then detoxify free radicals. These factors protect cells from ROS damage in NDEA and CCl4-induced hepatocarcinogenesis. Histopathological observations of liver tissues too correlated with the biochemical observations. Thus, present investigation suggested that the Tephrosia purpurea would exert a chemoprotective effect by reversing the oxidant-antioxidant imbalance during hepatocarcinogenesis induced by NDEA and CCl4. Besides Tephrosia purpurea is very much effective in preventing NDEA-induced multistage hepatocarcinogenesis possibly through antioxidant and antigenotoxic nature, which was confirmed by various liver injury and biochemical tumour markers enzymes. The hepatoprotective activity of aTephrosia purpurea of 50 % ethanolic extract was studied using rats. The animals received a single intraperitoneal injection of N-nitrosodiethylamine 200mg/kg body wt followed by subcutaneous injection of CCl4 in a dose of 3 ml/kg body wt.Tephrosia purpureaextract dose dependently and significantly the increase in serum hepatic enzyme levels after NDEAand CCl4 treatment compared to the toxin control group. The results of this study confirmed the antioxidant and hepatoprotective activity of the Tephrosia purpurea extract against carbon tetrachlorideand N-nitrosodiethylamine induced hepatotoxicity in rats.

Cytotoxic Effect of Fusarium Equiseti Fungus Metabolites Against N-Nitrosodiethylamine- and CCL4-Induced Hepatocarcinogenesis in Rats

Fusarium equiseti, an endophytic fungus isolated from the marine alga Padina pavonica, displayed in vitro potent cytotoxicity and selectivity against liver cancer (HEP-G2) cells. This endophyte was therefore submitted to large-scale liquid fermentation to isolate 11 bioactive constituents. The cytotoxic effect of the extract against in vivo hepatocellular carcinoma (HCC) was evaluated in rats with HCC induced by single intraperitoneal injection of N-nitrosodiethylamine (NDEA) followed by subcutaneous injections of CCl4. After the injection of carcinogen, the fungal extract was orally administered in 25, 50 and 100 mg/kg doses once a day for 10 weeks. The high levels of liver injury and liver cancer markers after NDEA administration were significantly decreased by this treatment with the total fungal metabolites. Histological observations of the liver tissues of rats treated with NDEA and fungal extract co-administered at 100 mg/kg are correlated with the biochemical observations. These findings confirm that F. equiseti total metabolites could restore the activity of hepatic marker enzymes of NDEA-induced hepatocarcinogenesis in rats.

Modulatory efficacy of dieckol on xenobiotic-metabolizing enzymes, cell proliferation, apoptosis, invasion and angiogenesis during NDEA-induced rat hepatocarcinogenesis

Dieckol (DEK) is a major polyphenol of marine brown seaweed Ecklonia cava which is a potential candidate for cancer therapy. However, the underlying mechanism of DEK as an anticancer drug remains to be elucidated. In this study, we evaluated the molecular mechanisms involved in the chemopreventive efficacy of DEK in N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis rats by analyzing markers of xenobiotic-metabolizing enzymes (XMEs), apoptosis, invasion, and angiogenesis. Rats administered NDEA developed hepatocarcinogenesis that displayed apoptosis avoidance coupled to upregulation of pro-inflammatory, invasion, and angiogenesis markers. Treatment of DEK effectively suppressed the NDEA-initiated hepatocarcinogenesis by modulation of XMEs, inducing of apoptosis via the mitochondrial pathway as revealed by modulating the Bcl-2 family proteins, cytochrome C, caspases, and inhibiting invasion, and angiogenesis as evidenced by changes in the activities of MMPs (MMP2/9) and the expression of VEGF. In addition, DEK exerts its anticancer effects via inhibition of pro-inflammatory transcription factor NF-κB (nuclear factor κB) and COX2 in NDEA-induced hepatocarcinogenesis. Taken together, this study demonstrates that DEK modulates the expression of key molecules that regulate apoptosis, inflammation, invasion, and angiogenesis. These results strongly indicate that DEK from E. cava is an attractive candidate for chemoprevention.

Protective effects of dieckol on N-nitrosodiethylamine induced hepatocarcinogenesis in rats.

Dieckol (DEK) is a naturally occuring phlorotannins found in marine brown algae Ecklonia cava which is attributed with various pharmacological properties. This study was aimed to investigate the protective role of DEK on N-Nitrosdiethylamine (NDEA) induced rat hepatocarcinogenesis. In this investigation 0.01% NDEA in drinking water for 15 weeks to induce hepatocellular carcinoma (HCC). DEK was administered orally (10, 20 and 40mg/kg body weight) for 15 weeks with 0.01% NDEA through drinking water. Hepatocarcinogesis was measured by the increased activities of serum liver marker enzymes namely aspartate trasaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), gamma glutamyl transferase (GGT), lactate dehydrogenase (LDH), α-fetoprotein (AFP) and total bilirubin along with increased elevation of cytochrome p450, lipid peroxidation markers, thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (HP), protein carbonyl content (PCC) and conjugated dienes (CD). The effect of NDEA was indicated by significant decreased activities of enzymatic antioxidants like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), glutathione reductase (GR) and non-enzymatic antioxidants like reduced glutathione, vitamin C and vitamin E. The oral administration of DEK at a dose of 40mg/kg body weight significantly reversed the activities of hepatic marker enzymes, dercreased lipid peroxidative markers, increased antioxidant cascade and decreased NDEA concentration in liver. DEK at a dose of 40mg/kg body weight was highly effective when compared to other two doses (10 and 20mg/kg body weight). All these changes were accompanied by histopathological observations in liver. The obtained results clearly demonstrated that DEK prevents lipid peroxidation, hepatic cell damage and promote the enzymatic and non-enzymatic antioxidant defense system in NDEA-induced hepatocarcinogenesis which might be due to activities like scavenging of oxy radicals by Dieckol.

Protective Effect of Morus alba Leaf Extract on N-Nitrosodiethylamine-induced Hepatocarcinogenesis in Rats.

The leaves of white mulberry (Morus alba L.) contain various polyphenolic compounds possessing strong antioxidant activity and anticancer potential. This study was designed to investigate the chemopreventive effect of aqueous extract of mulberry leaves against N-nitrosodiethylamine (NDEA)-induced liver carcinogenesis. Wistar rats were divided into four groups: control, mulberry extract-treated, NDEA-treated, and mulberry extract plus NDEA-treated. Mulberry extract was given in the diet (1,000 mg/kg b.w./day); NDEA was given in drinking water. Mulberry extract reduced the incidence of hepatocellular carcinoma, dysplastic nodules, lipid peroxidation, protein carbonyl formation, and DNA degradation. Treatment with mulberry leaf extract along with NDEA challenge did not affect the activity of antioxidant enzymes and glutathione content. Treatment with mulberry leaf extract partially protected the livers of rats from NDEA-induced hepatocarcinogenesis and a direct antioxidant mechanism appears to contribute to its anticarcinogenic activity.

Protective effect of yellow tea extract on N-nitrosodiethylamine-induced liver carcinogenesis

Context Yellow tea containing the same catechins as other types of tea but in different proportions has been suggested to possess potent anticancer activities.Objective This study investigates the chemopreventive effect of yellow tea aqueous extract against N-nitrosodiethylamine (NDEA)-induced liver carcinogenesis in rats by employing histological and biochemical methods.Materials and methods Wistar rats were divided randomly into four groups: control (I), yellow tea (II), NDEA (III), and yellow tea + NDEA (IV). Groups II and IV were exposed via a diet to yellow tea extract in a concentration of 10 g/kg feed; groups III and IV received 0.01% NDEA in drinking water. The experiment lasted for 13 weeks.Results Daily intake of yellow tea in an average dose of 800 mg/kg b.w. alleviated the carcinogenic effect of NDEA as evidenced by reversed histopathological changes towards normal hepatocellular architecture and decreased lipid peroxidation, protein carbonyl formation, and DNA degradation by 64%, 37% and 15%, respectively, as compared with values obtained in NDEA alone-treated rats. Treatment with yellow tea extract caused protection of superoxide dismutase (SOD) and catalase (CAT); their activity was recovered by 47% and 12%, respectively, as compared with the NDEA-treated rats. Moreover, the extract normalized the NDEA-induced activity of paraoxonase 1 (PON1) and glutathione peroxidase (GPx), while a further increase in the level of reduced glutathione (GSH) was noticed.Conclusions On the basis of these findings, it can be concluded that treatment with yellow tea partially protected the livers of rats from NDEA-induced hepatocarcinogenesis and that its antioxidant activity contributed to this effect.

Silibinin Inhibits the Hepatocellular Carcinoma in NDEA-Induced Rodent Carcinogenesis Model: An Evaluation through Biochemical and Bio-Structural Parameters

The present study was aimed to investigate the chemopreventive potential of Silibinin (SIB) against N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinoma (HCC) in wistar rats. Thirty experimental animals were subjected to partial hepatectomy (PH) and after 24 hours of stabilization period a single dose of NDEA (100 mg/kg b.w., i.p) was administered to each animal followed by CCl4 (1 ml/kg b.w., s.c.). The effect of SIB (25 and 50 mg/kg/day, i.p.) on NDEA-induced HCC was determined after 2 weeks of treatment (6th to 8th week after PH, in the promotional stage of tumor development). NDEA treatment to rats resulted in significant decrease in body weight and increase in liver weight along with levels of transaminases, γ-glutamyl transferase, lipoprotein, glycoproteins. Hepatic and serum malondialdehyde content, enzymatic and non-enzymatic antioxidant levels were also altered in HCC bearing animals without treatment. Bio-structural components (such as amide bands of proteins, symmetric phosphate stretching of nucleic acids, methylene chains in membrane lipids, methyl to methylene ratio of carbohydrates and proteins etc.) were marked in NDEA-treated groups of animals by analysing changes in the position and intensities of the peaks in Fourier transform infrared spectroscopy (FTIR). Immunohistochemical staining of Ki67 and histopathological analysis were also carried out in order to support the study. SIB treatment could attenuate NDEA-induced hepatocarcinogenesis by improving the biochemical and bio-structural changes of the hepatic tissue near normal levels in a dose dependent manner. Taken together, this study reveals that SIB may have potential as a multi-functional drug candidate for cancer therapy.

Garlic Oil Attenuated Nitrosodiethylamine-Induced Hepatocarcinogenesis by Modulating the Metabolic Activation and Detoxification Enzymes

Nitrosodiethylamine (NDEA) is a potent carcinogen widely existing in the environment. Our previous study has demonstrated that garlic oil (GO) could prevent NDEA-induced hepatocarcinogenesis in rats, but the underlying mechanisms are not fully understood. It has been well documented that the metabolic activation may play important roles in NDEA-induced hepatocarcinogenesis. Therefore, we designed the current study to explore the potential mechanisms by investigating the changes of hepatic phase Ⅰ enzymes (including cytochrome P450 enzyme (CYP) 2E1, CYP1A2 and CYP1A1) and phase Ⅱ enzymes (including glutathione S transferases (GSTs) and UDP- Glucuronosyltransferases (UGTs)) by using enzymatic methods, real-time PCR, and western blotting analysis. We found that NDEA treatment resulted in significant decreases of the activities of CYP2E1, CYP1A2, GST alpha, GST mu, UGTs and increases of the activities of CYP1A1 and GST pi. Furthermore, the mRNA and protein levels of CYP2E1, CYP1A2, GST alpha, GST mu and UGT1A6 in the liver of NDEA-treated rats were significantly decreased compared with those of the control group rats, while the mRNA and protein levels of CYP1A1 and GST pi were dramatically increased. Interestingly, all these adverse effects induced by NDEA were simultaneously and significantly suppressed by GO co-treatment. These data suggest that the protective effects of GO against NDEA-induced hepatocarcinogenesis might be, at least partially, attributed to the modulation of phase I and phase II enzymes.

Expression of Concern: Attenuation of NDEA‐induced hepatocarcinogenesis by naringenin in rats

Chemoprevention is one of the most promising and realistic approaches in the prevention of cancer. Several bioactive compounds present in fruits and vegetables have revealed their cancer curative potential on hepatocellular carcinoma. Naringenin is one such naturally occurring flavonoid widely found in citrus fruits. In this study, we examined the molecular mechanisms by which naringenin inhibited NDEA-induced hepatocellular carcinoma in rats by analysing the expression patterns of proliferating cell nuclear antigen, Bcl-2, NF-κB, VEGF and MMP-2/9. Enhanced cell proliferation and apoptotic evasion in NDEA-induced hepatocarcinogenesis was associated with imbalance in pro-apoptotic and anti-apoptotic proteins together with upregulation of proliferating cell nuclear antigen (PCNA) and downregulation of caspase-3. Administration of pretreatment and posttreatment of naringenin decreased the expression of PCNA and Bcl-2 and increased the expression of Bax and caspase-3, indicating antiproliferative and apoptotic effects, respectively. Administration of NDEA increased the tumour expression of NF-κB, COX-2, VEGF, MMP-2 and MMP-9 that was correlated with more aggressive lesions and tumour growth. Downregulation of NF-κB, VEGF and MMPs by naringenin seen in the present study were correlated with the inhibition of liver tumour induced by NDEA. Our results suggest that naringenin could act as a legitimate agent by inhibiting cancer processes.

Chemopreventive evaluation of Tephrosia purpurea against N-nitrosodiethylamine-induced hepatocarcinogenesis in Wistar rats

The chemopreventive potential of Tephrosia purpurea extract (TPE) on N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinoma (HCC) in Wistar rats was assessed. HCC was induced by a single intraperitoneal injection of NDEA (200 mg/kg) followed by subcutaneous injections of CCl(4) (3 ml/kg per week) for six weeks. After administration of the carcinogen, 200 and 400 mg/kg TPE were administered orally once a day throughout the study. The levels of liver cancer markers, including α-fetoprotein and carcinoembryonic antigen, were substantially increased by NDEA treatment. TPE treatment significantly reduced liver injury and restored the entire liver cancer markers. Additionally, TPE markedly normalized the activity of antioxidant enzymes, namely lipid peroxidation, reduced glutathione, catalase, superoxide dismutase, glutathione peroxidase and glutathione-S-transferase in the liver of NDEA-treated rats. Treatment with TPE significantly reduced the nodule incidence and multiplicity in the carcinogen-bearing rats. Histological observations of the liver tissues correlated with the biochemical observations. These findings powerfully support that T. purpurea prevented lipid peroxidation, suppressed the tumour burden, and promoted enzymatic and nonenzymatic antioxidant defence systems during NDEA-induced hepatocarcinogenesis. This might have been due to modulating the antioxidant defence status, which contributed to its anticarcinogenic potential.

Protective Effects of Garlic Oil on Hepatocarcinoma Induced by N-Nitrosodiethylamine in Rats

To investigate the protective effects and the possible mechanisms of garlic oil (GO) against N-nitrosodiethylamine (NDEA)-induced hepatocarcinoma in rats, Wistar rats were gavaged with GO (20 or 40 mg/kg) for 1 week, and then were gavaged with GO and NDEA (10 mg/kg) for the next 20 weeks. The changes of morphology, histology, the biochemical indices of serum, and DNA oxidative damage of liver were examined to assess the protective effects. Lipid peroxidation (LPO), antioxidant defense system, and apoptosis-related proteins were measured to investigate potential mechanisms. At the end of the study (21 weeks), GO administration significantly inhibited the increase of the nodule incidence and average nodule number per nodule-bearing liver induced by NDEA, improved hepatocellular architecture, and dramatically inhibited NDEA-induced elevation of serum biochemical indices (alanine aminotransferase , aspartate aminotransferase, alkaline phosphatase and gamma-glutamyl transpeptidase) and hepatic 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in a dose-dependent manner. The mechanistic studies demonstrated that GO counteracted NDEA-induced oxidative stress in rats illustrated by the restoration of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) levels, and the reduction of the malondialdehyde (MDA) levels in liver. Furthermore, the mRNA and protein levels of Bcl-2, Bcl-xl, andβ-arrestin-2 were significantly decreased whereas those of Bax and caspase-3 were significantly increased. These data suggest that GO exhibited significant protection against NDEA-induced hepatocarcinogenesis, which might be related with the enhancement of the antioxidant activity and the induction of apoptosis.

Potential chemoprevention of N-nitrosodiethylamine-induced hepatocarcinogenesis by polyphenolics from Acacia nilotica bark

Chemopreventive potential of Acacia nilotica bark extract (ANBE) against single intraperitoneal injection of N-nitrosodiethylamine (NDEA, 200 mg/kg) followed by weekly subcutaneous injections of carbon tetrachloride (CCl 4, 3 ml/kg) for 6 weeks induced hepatocellular carcinoma (HCC) in rats was studied. At 45 day after administration of NDEA, 100 and 200 mg/kg of ANBE were administered orally once daily for 10 weeks. The levels of liver injury and liver cancer markers such as alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), γ-glutamyl transferase (γ-GT), total bilirubin level (TBL), α-feto protein (AFP) and carcinoembryonic antigen (CEA) were substantially increased following NDEA treatment. However, ANBE treatment reduced liver injury and restored liver cancer markers. ANBE also significantly prevented hepatic malondialdehyde (MDA) formation and reduced glutathione (GSH) in NDEA-treated rats which was dose dependent. Additionally, ANBE also increased the activities of antioxidant enzymes viz., catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione- S-transferase (GST) in the liver of NDEA-administered rats. Eventually, ANBE also significantly improved body weight and prevented increase of relative liver weight due to NDEA treatment. Histological observations of liver tissues too correlated with the biochemical observations. HPLC analysis of ANBE showed the presence of gallic, protocatechuic, caffeic and ellagic acids, and also quercetin in ANBE. The results strongly support that A. nilotica bark prevents lipid peroxidation (LPO) and promote the enzymatic and non-enzymatic antioxidant defense system during NDEA-induced hepatocarcinogenesis which might be due to activities like scavenging of oxy radicals by the phytomolecules in ANBE.

Prevention of N-nitrosodiethylamine-induced hepatocarcinogenesis by S-allylcysteine

Chemopreventive effect of S-allylcysteine (constituent of garlic) on N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis was evaluated in Wistar rats. Significantly decreased lipid peroxidation products (thiobarbituric acid reactive substances-TBARS and lipid hydroperoxides) with increased level of reduced glutathione, increased activities of glutathione S-transferase, and glutathione peroxidase were observed in liver of NDEA-treated rats when compared with control rats. The activities of superoxide dismutase and catalase were significantly decreased in tumor tissue when compared with control. Administration of S-allylcysteine (SAC) showed the inhibition of tumor incidence, modulated the lipid peroxidation, and increased the reduced glutathione, glutathione-dependent enzymes, superoxide dismutase, and catalase in NDEA-induced carcinogenesis. From our results, we speculate that S-allylcysteine mediates its chemopreventive effects by modulating lipid peroxidation, GST stimulation, and by increasing the antioxidants. Hence SAC prevents cells from loss of oxidative capacity in NDEA-induced hepatocarcinogenesis.

Effect ofBauhinia racemosaStem Bark on N-nitrosodiethylamine-Induced Hepatocarcinogenesis in Rats

The aim of this study is to investigate the antioxidant defense system induced by the methanol extract of Bauhinia racemosa L.(MEBR) against N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis in Wister albino rats. The effects of MEBR on surface visible macroscopic (Morphometry) liver lesions (neoplastic nodules) and the levels of serum enzymes, lipid peroxidation and antioxidants were evaluated in NDEA-induced hepatocarcinogenesis in rats. In rats treated, with NDEA, significantly elevated levels of serum enzymes (SGOT, SGPT and ALP), bilirubin and decreased levels of protein and uric acid were observed. Significantly elevated amount of malondialdehyde (MDA), the end product of lipidperoxidation, indicated higher levels of lipid peroxidation, which was accompanied by significantly decreased levels of antioxidants like vitamin C, vitamin E, reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT). Administration of MEBR was able to suppress nodule development/hepatocellular lesion formation in rats. The extract treatment increases in antioxidant levels and dramatic decreases in lipid peroxidation levels. MEBR also produced a protective effect by decreasing the level of serum enzymes, bilirubin and increased the protein and uric acid levels. The results suggest that MEBR exert chemopreventive effects by suppressing nodule development and decreasing lipid peroxidation and enhancing the levels of antioxidants in NDEA carcinogenesis by reducing the formation of free radicals.

PREVENTIVE EFFECTS OF GARLIC EXTRACT ON LIPID PEROXIDATION AND ANTIOXIDANT DEFENCE SYSTEM IN N-NITROSODIETHYLAMINE INDUCED HEPATOCARCINOGENESIS IN RATS

ISHS III WOCMAP Congress on Medicinal and Aromatic Plants - Volume 6: Traditional Medicine and Nutraceuticals PREVENTIVE EFFECTS OF GARLIC EXTRACT ON LIPID PEROXIDATION AND ANTIOXIDANT DEFENCE SYSTEM IN N-NITROSODIETHYLAMINE INDUCED HEPATOCARCINOGENESIS IN RATS

Inhibition of nitrosodiethylamine-induced hepatocarcinogenesis by dietary turmeric in rats

Turmeric, widely used in food and medicine has been shown to prevent benzo(a)pyrene [B(a)P] or dimethylbenz(a)anthracene (DMBA)-induced forestomach, skin and mammary tumors in mice and/or rats. In this study we examine the modulatory effects of turmeric on nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis in rats. Female Wistar rats were administered NDEA (200 ppm) through drinking water (5 days per week) for 4 weeks. Control and/or NDEA-treated rats received 0, 0.2, 1.0 or 5.0% turmeric diet (w/w) either before (2 weeks), during (4 weeks) and after NDEA exposure (10 weeks) or starting from 24 h after NDEA exposure for 10 weeks. NDEA-treated rats receiving 1 or 5% turmeric before, during and after carcinogen exposure showed significant decrease in number of gamma glutamyl transpeptidase (GGT) positive foci measuring >500 or >1000 μm and decrease in the incidence of NDEA-induced focal dysplasia (FD) and hepatocellularcarcinomas. Decrease in the number of GGT positive foci measuring >1000 μm was also observed in NDEA-treated rats receiving 0.2% turmeric, although no decrease in tumor incidence was noted. On the other hand, similar levels of turmeric treatment (0.2, 1 and 5%) after exposure to NDEA did not show any protective effects. The underlying mechanism(s) of chemoprevention of NDEA-induced hepatocarcinogenesis need to be explored.

Differential expression of c-jun and c-myc in N-nitroso diethylamine-induced hepatic oncogenesis in AKR mice.

Expression of c-jun, c-myc, c-fos and c-Ha-ras was examined and correlated with the various stages of N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis in male AKR mice. The treated groups were given NDEA 100 ppm, in drinking water for 120 days. The histopathology along with the expression of oncogenes were studied at different durations of treatment such as after 1 day, 3 days, 6 days, 9 days, 15 days, 20 days 30 days, 60 days, 90 days and 120 days of treatment. The results of histological investigation indicate mild hyperplasia and anisonucleosis at 30 days of treatment and prominent pathological features from 60 days onwards until the appearance of hepatocarcinoma at 120 days even without the development of any preneoplastic or neoplastic nodule. The results of the Northern blot hybridization clearly indicate an increased expression of c-jun from 15 days onwards. This overexpression of c-jun at such an early stage indicates its association with the events earlier than the neoplastic changes. However, the persistent overexpression of c-jun at all durations of treatment indicates its association with the events during the later stage of hepatocarcinogenesis, whereas c-myc overexpression starts from 30 days of treatment and persists until the end of the experiment, i.e. 120 days of treatment. However, the results of densitometric quantification indicate that the extent of increase expression of c-myc is less than that of c-jun expression until 1 month of treatment, after which the induction of c-myc exceeds the expression of c-jun. Thus, the overexpression of c-myc from 2 months onwards might be playing a critical role in maintenance of the malignant phenotype. On the other hand, the expressions of c-fos and c-Ha-ras do not have any alteration during NDEA treatment. Thus, our data demonstrate the involvement of c-jun and c-myc in NDEA-induced hepatocarcinogenesis in AKR mice.