Annona senegalensis extract demonstrates anticancer properties in N-diethylnitrosamine-induced hepatocellular carcinoma in male Wistar rats

Background: Hepatocellular carcinoma (HCC) is a common and leading cancer around the globe. This study investigated the anticancer properties of extract of Annona senegalensis in N-diethylnitrosamine (DEN) - induced hepatocellular carcinoma in male Wistar rats. Methods: Rats were simultaneously induced with a combination of 100 mg/kg b.wt of DEN and 0.5 mL/kg of carbon tetrachloride (CCl4) intraperitoneally once a week for three weeks in a row. Thereafter, animals were treated with 100 mg/kg and 200 mg/kg b.wt of A. senegalensis extract daily for 21days. Analysis using gas chromatography-mass spectrometry (GC–MS) was carried out to discover the phytoconstituents contained in the n-hexane extract of A. senegelensis. The levels of liver function parameters and antioxidant enzyme activities were determined via spectrophotometric analysis. Reverse transcriptase-polymerase chain reaction technique was used to assess the gene expression patterns of BCL-2, P53, P21, IL-6, FNTA, VEGF, HIF, AFP, XIAP, and EGFR mRNAs. Results: Treatment of DEN-induced hepatocellular carcinoma Wistar rats with the extract caused significant (p < 0.05) decrease in the activities of ALT and AST. It also resulted in a reduction of the concentration of MDA and a significant increase (p < 0.05) in SOD and GSH activities. IL-6, BCL-2, VEGF, EGFR, XIAP, FNTA, and P21 mRNAs expressions were significantly (p < 0.05) downregulated after treatment. Histopathological analysis revealed that the extract improved the liver architecture. Conclusion: A. senegelensis n-hexane extract demonstrates its anticancer properties by improving the liver architecture, increasing the antioxidant defense systems, downregulating the pro-inflammatory, anti-apoptotic, angiogenic, alpha-fetoprotein and farnesyl transferase mRNAs expression and hitherto up-regulate the expression of tumor suppressor (P21 and P53) mRNAs

Annona senegalensis extract demonstrates anticancer properties in N-diethylnitrosamine-induced hepatocellular carcinoma in male Wistar rats

investigated the anticancer properties of extract of Annona senegalensis in N-diethylnitrosamine (DEN) - induced hepatocellular carcinoma in male Wistar rats. Methods: Rats were simultaneously induced with a combination of 100 mg/kg b.wt of DEN and 0.5 mL/kg of carbon tetrachloride (CCl4) intraperitoneally once a week for three weeks in a row. Thereafter, animals were treated with 100 mg/kg and 200 mg/kg b.wt of A. senegalensis extract daily for 21days. Analysis using gas chromatography-mass spectrometry (GC–MS) was carried out to discover the phytoconstituents contained in the n-hexane extract of A. senegelensis. The levels of liver function parameters and antioxidant enzyme activities were determined via spectrophotometric analysis. Reverse transcriptase-polymerase chain reaction technique was used to assess the gene expression patterns of BCL-2, P53, P21, IL-6, FNTA, VEGF, HIF, AFP, XIAP, and EGFR mRNAs. Results: Treatment of DEN-induced hepatocellular carcinoma Wistar rats with the extract caused significant (p < 0.05) decrease in the activities of ALT and AST. It also resulted in a reduction of the concentration of MDA and a significant increase (p < 0.05) in SOD and GSH activities. IL-6, BCL-2, VEGF, EGFR, XIAP, FNTA, and P21 mRNAs expressions were significantly (p < 0.05) downregulated after treatment. Histopathological analysis revealed that the extract improved the liver architecture. Conclusion: A. senegelensis n-hexane extract demonstrates its anticancer properties by improving the liver architecture, increasing the antioxidant defense systems, downregulating the pro-inflammatory, anti-apoptotic, angiogenic, alpha-fetoprotein and farnesyl transferase mRNAs expression and hitherto up-regulate the expression of tumor suppressor (P21 and P53) mRNAs

Production of fumonisin B1 by Fusarium proliferatum in liquid culture medium, and toxicity and metabolism of fumonisin B1 in rats

Groups of eight six-week old female Sprague-Dawley rats were initiated with diethylnitrosamine (DEN, 30 mg/kg). Control and initiated groups were fed a semipurified diet, or diets supplemented with Fusarium proliferatum-contaminated corn to contain 20 or 50 mg/kg fumonisin B[subscript]1 (FB[subscript]1). Histochemical staining for gamma-glutamyltransferase (GGT) and immunochemical staining for placental glutathione S-transferase (PGST), markers of altered hepatic foci (AHF), were performed on serial frozen hepatic sections. Gamma-glutamyltransferase-(+) altered hepatic foci were not found in any group. Groups fed F. proliferatum-containing diets had a significantly increased number of PGST-(+) AHF compared with those fed no F. proliferatum (P \u3c 0.003). F. proliferatum treatment significantly increased the number of PGST-(+) AHF/liver and the volume percentage of liver occupied by PGST-(+) foci. In conclusion, the feeding of F. proliferatum containing only 20 mg/kg FB[subscript]1 promotes the development of DEN-initiated AHF in rats;Pregnant rats were dosed by oral intubation from days 9-13 of gestation with 30 or 60 mg purified fumonisin B[subscript]1 (FB[subscript]1)/kg body weight, or with a fat-soluble extract of F. proliferatum/corn culture derived from an amount of corn culture that would provide approximately 60 mg/kg FB[subscript]1. Control rats were dosed with water or corn oil. Relative litter weight was significantly suppressed by 60 mg/kg FB[subscript]1 (P \u3c 0.003). Ossification of the sternebrae and vertebral bodies was significantly impaired by FB[subscript]1 treatment. Litters from mothers treated with a fat-soluble extract of F. proliferatum/corn culture did not show suppression of litter weight or impairment of bone development. Therefore, fumonisin B[subscript]1 is fetotoxic to rats, suppressing growth and fetal bone development;A single dose of [superscript]14C-labelled fumonisin B[subscript]1 (0.1 [mu]Ci) given to rats by oral intubation was excreted mainly in the feces (96%) and urine (2.5%). Liver retained 0.7%, whereas kidneys retained 0.1% of the dose. There was no activity in the blood and only 4% of the counts were unaccounted for;Fumonisin B[subscript]1 was produced by F. proliferatum lyophilized cultures grown in basal salt medium that was supplemented with vitamins and 25 mg 1-methionine/100 mL medium. The cultures were incubated for 48 h at 22 ± 2°C while shaking at 50 rpm, in a pre-enrichment medium containing a malt extract as the main carbohydrate source. The amount of FB[subscript]1 produced was 340 [mu]g/mL after 24 days incubation at 22 ± 2°C and 50 rpm. Supplementing the basal salts medium with methionine increased the production of FB[subscript]1 by 10-fold

Anion Exchange Resins as Sources of Nitrosamines and Nitrosamine Precursors

Nitrosamines are a family of potent chemical carcinogens including, among others, N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA) and N-nitrosodi-n-butylamine (NDBA). NDMA and other nitrosamines have been identified as disinfection byproducts. They are regulated in the State of California and are candidates for Federal regulation. Anion exchange resins, used for the removal of anionic contaminants from drinking water, consist of polymer networks with positively charged amine groups. Resins are often synthesized using trimethylamine (TMA), triethylamine (TEA), tri-n-propylamine (TPA) or tri-n-butylamine (TBA) which can react with chloramines to form NDMA, NDEA, NDPA and NDBA, respectively. Drinking water treatment plants using anion exchange resins have been found to have higher levels of NDMA in finished waters. The objective of this research was to investigate the potential relationship between the use of anion exchange resins in drinking water treatment and the presence of nitrosamines and nitrosamine precursors in finished waters. A wide array of resins, representing those commonly used in practice, was investigated through bench-scale batch contact experiments, bench-scale continuous-flow column experiments, and measurements at water utilities using anion exchange for treatment. In the batch experiments, resins were found to release nitrosamines and their precursors after one hour of contact. Resins manufactured with TEA or TBA were found to release NDMA precursors in addition to NDEA or NDBA precursors. In column experiments, resins released high nitrosamines and precursors in the first 10 bed volumes of flow. Regeneration with NaCl resulted in a spike in precursor release, as did flow interruptions. The introduction of chlorine or preformed monochloramine resulted in increases in nitrosamines. Explanations for the presence of precursors and their increased release during regeneration and flow interruption are offered, and a mechanism for nitrosamine formation via reactions with free chlorine and monochloramine is proposed. A study of ten full-scale treatment plants using anion exchange resins found that three contained nitrosamines and five contained precursors in their anion exchange effluents. Experiments suggested that resins can be washed clean of any residual nitrosamines and precursors, and field observations confirmed that resins that have been in place for longer periods of time release lower levels of precursors.Doctor of Philosoph

Avaliação do efeito da cafeína na carcinogênese esofágica induzida pela dietilnitrosamina: estudo experimental em camundongos

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Mechanistic and quantitative aspects of liver tumour promotion in mice

A variety of xenobiotic compounds is known to induce characteristic changes in the livers of laboratory animals. These changes include enlargement of the liver, usually as a result of cell enlargement (hypertrophy) or Increased cell replication (hyperplasia), induction of drugmetabolizing enzymes and proliferation of the smooth endoplasmic reticulum (SER). Such changes are usually not accompanied by evidence of liver damage and thus are reversible upon withdrawal and elimination of the compound. Consequently, most authors regard this phenomenon as an adaptive response of the organ to increased functional demands.However, chronic exposure of various strains of mice to dieldrin, phenobarbitone, DDT and the α-, β- and γ-stereoisomers of hexachlorocyclohexane (HCH, also known as benzenehexachloride, MC) may lead to the development of liver tumours.The tumorigenic effects of microsomal enzyme Inducers In mice may result from (A) a weak carcinogenic action of the xenobiotics themselves or (h) an enhancing (promoting) action of xenobiotics on a pre-existing oncogenic factor in mouse liver. The first objective of this study was to discriminate between these two possible types.Druckrey and his associates have established both theoretically and experimentally the dose-response characteristics of chemical carcinogens:D.T n= constant (1)where D = daily dose, T = the median tumour Induction period and n = an exponent, always>1.Since the mechanisms by which enhancers or promotors of carcinogenesis operate is quite different from the one used by carcinogens, it is be conceivable that promotors also exhibit different dose-response characteristics.The dose-response characteristics of dieldrin-mediated enhancement of liver tumour formation in CF-1 mice were analysed, using existing tumour data from chronic feeding studies at six exposure levels of dieldrin (a model compound for microsomal enzyme induction). It was found that the dose- response relationship can be expressed as:(d o + δx).t = constant (2)where d o stands for the background dose equivalent required for the induction of spontaneous liver tumours, δx represents the actual dieldrin dose (ppm in the diet) and t the median tumour induction period in the respective treatment groups. It was also established that the doseresponse characteristics of limited dieldrin exposures and those of de layed exposure were consistent with equation (2), which is a Druckrey relation where n = 1.From these findings it is concluded that dieldrin interacts reversibly with its receptors, resulting in an acceleration of tumour formation (which is essentially Irreversible); dieldrin may thus be regarded as a tumour promotor. The validity of equation (2) for both chronic and limited dieldrin exposure Indicates that ( a ) the velocity of liver tumour development is proportional to the daily dose level (δx), ( b ) the total tumorigenic dose is constant across all doses, ( c ) the effects of dieldrin on the neoplastic process In mouse liver are essentially irreversible and cumulative, and ( d ) there is no evidence for a threshold level.Tumour formation Is a dose- and time-dependent process. The induction of liver enlargement, microsomal enzyme systems and proliferation of the smooth endoplasmic reticulum by dieldrin are only dose-dependent. In contrast, polyploldization Is dose- and time-dependent. To establish apossible link between microsomal enzyme induction, nuclear polyploidization and liver tumour formation, nuclear polyploidization in livers of CF-1 mice was studied at five different dieldrin dose levels from 1.85 months up to tumour development. Nuclear polyploidization, expressed in the proportion of octaploid (8c) nuclei, was found to be characterized by a linear increase with age in untreated control CF-1 mice. Dieldrin treatment induced a dose-dependent increase in the proportion of 8c-nuclei in the initial phases of treatment. In "steady-state" situations nuclear polyploidization (as expressed by the percentage of 8c-nuclei) was maintained on a dose-dependent, higher level, and the percentage was was observed to increase with age, the velocity of which was the same as in untreated controls. Tumour formation was found to be associated with a constant degree of nuclear polyploidization In all treatment groups Including controls. The observed quantitative link between nuclear polyploidization and tumour formation leads to the question whether or not a causal relationship between the two exists. Assuming that polyploidization reflects the ageing process, the data suggest that liver tumour formation Is Imminent at a constant biological age and that dieldrin could operate by advancing the biological age of CF-1 mouse liver.Further support for this hypothesis was obtained from the determination of cytoplasmic alanine amino transferase (AAT) isoenzymes. The expression of the isoenzyme decreases with age In untreated control CF-1 mice. Dieldrin treatment was found to enhance (accelerate) this process in a dose-dependent manner.Although the nature of the development of "spontaneous" liver tumours in CF-1 mice remains unknown, the decrease In the tetraplold(4c)-diplold (2c) ratio of liver nuclei, observed in the study of polyploidization, may be related to tumour formation. The decrease was observed in alltreatment groups, including controls, and its onset was dose-dependently advanced by dieldrin treatment, occurring approximately 4 months before the median liver tumour induction period in all cases. Two mechanisms are proposed that may explain the tumorigenic features of a decreasein the 4c-2c ratio.1. Tetraploid cells could be more sensitive to accumulative toxic stress. Thus, their turnover may be Increased. To replace one tetraploid cell a diploid cell has to divide twice; the loss of tetraploid cells would therefore result in a proliferative response of the diploidpopulation (resulting tumour formation).2. A reduction in the 4c-2c ratio could be induced by the occurrence of amitotic nuclear divisions in the tetraploid cells. Evidence for this possibility was obtained from experiments with 3H-thymidine-labelled nuclei. Amitotic nuclear divisions could give rise to chromosomalre-arrangements, resulting in the expression of the intrinsic neoplastic potential of CF-1 mouse liver.Both hypotheses imply that the diploid population is the source of livertumours. The determination of nuclear polyploidization in liver tumours confirmed that these tumours originate from the diploid liver cell population.</TT