Influence of antioxidative vitamins A, C and E on lipid peroxidation in BOP-induced pancreatic cancer in Syrian hamsters

Vitamin E in the management of pancreatic cancer: A scoping review

Pancreatic cancer is the leading cause of cancer mortality worldwide. Research investigating effective management strategies for pancreatic cancer is ongoing. Vitamin E, consisting of both tocopherol and tocotrienol, has demonstrated debatable effects on pancreatic cancer cells. Therefore, this scoping review aims to summarize the effects of vitamin E on pancreatic cancer. In October 2022, a literature search was conducted using PubMed and Scopus since their inception. Original studies on the effects of vitamin E on pancreatic cancer, including cell cultures, animal models and human clinical trials, were considered for this review. The literature search found 75 articles on this topic, but only 24 articles met the inclusion criteria. The available evidence showed that vitamin E modulated proliferation, cell death, angiogenesis, metastasis and inflammation in pancreatic cancer cells. However, the safety and bioavailability concerns remain to be answered with more extensive preclinical and clinical studies. More in-depth analysis is necessary to investigate further the role of vitamin E in the management of pancreatic cancers.

Vitamin intake and pancreatic cancer risk reduction: A meta-analysis of observational studies

BACKGROUND

The relationship between vitamin intake and pancreatic cancer (PC) risk is disputed. We aimed to investigate the association between vitamin intake and the risk of PC via meta-analysis.

METHODS

We conducted a meta-analysis of studies concerning vitamin intake and the risk of PC from EMBASE, MEDLINE, and Cochrane Library. The search yielded 25 correlative studies including 1,214,995 individuals. The relative risks (RR) were examined by a random-effect model or fixed-effect model. Subgroup analysis, dose-response analysis, sensitivity analysis, meta-regression, and publication bias analysis were used to analyze studies.

RESULTS

The RR of PC in the highest vitamin intake group was 0.90 (95% confidence interval, 0.83-0.98) compared with that in the lowest vitamin intake in the prospective studies. Different increments of vitamin intake and the risk of PC were examined with dose-response analysis, and a decrease in the risk of PC was observed with vitamin D (25%) and vitamin B12 (27%).

CONCLUSIONS

This meta-analysis found that vitamin intake can decrease the risk of PC, particularly vitamin D and vitamin B12.

Targeting reactive oxygen species in development and progression of pancreatic cancer

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDA) is characterized by expression of oncogenic KRas which drives all aspects of tumorigenesis. Oncogenic KRas induces the formation of reactive oxygen species (ROS) which have been implicated in initiation and progression of PDA. To facilitate tumor promoting levels and to avoid oncogene-induced senescence or cytotoxicity, ROS homeostasis in PDA cells is balanced by additional up-regulation of antioxidant systems. Areas covered: We examine the sources of ROS in PDA, the mechanisms by which ROS homeostasis is maintained, and the biological consequences of ROS in PDA. Additionally, we discuss the potential mechanisms for targeting ROS homoeostasis as a point of therapeutic intervention. An extensive review of the relevant literature as it relates to the topic was conducted using PubMed. Expert commentary: Even though oncogenic mutations in the KRAS gene have been detected in over 95% of human pancreatic adenocarcinoma, targeting its gene product, KRas, has been difficult. The dependency of PDA cells on balancing ROS homeostasis could be an angle for new prevention or treatment strategies. These include use of antioxidants to prevent formation or progression of precancerous lesions, or methods to increase ROS in tumor cells to toxic levels.

Improvement of capecitabine antitumoral activity by melatonin in pancreatic cancer

OBJECTIVE

The purpose of our study was to evaluate the effects of the addition of melatonin and capecitabine on experimental pancreatic cancer.

METHODS

Fifty Syrian hamsters were randomized in 5 groups: group 1: no tumor induction (control group); group 2: tumor induction with BOP [N-nitrosobis(2-oxopropyl) amine]; group 3: tumor induction with BOP and melatonin administration; group 4: tumor induction with BOP and capecitabine administration; and group 5: tumor induction with BOP and administration of combined capecitabine and melatonin therapy. The evaluation of pathological tumor evolution and oxidative stress markers in pancreatic tissue was carried out.

RESULTS

All animals under BOP exposure presented poorly or moderately differentiated pancreatic adenocarcinoma associated with increased lipoperoxide levels and decreased antioxidant activity in pancreatic tissue. Pancreatic cancer was shown in only 66% of the capecitabine-treated group and 33% of melatonin-treated group (P < 0.05), most of them moderately differentiated adenocarcinoma. When capecitabine and melatonin were combined, a well-differentiated pancreatic adenocarcinoma was observed in 10% of animals. The beneficial effect was associated with a decrease in lipoperoxide levels and increased antioxidant activity in pancreatic tissue.

CONCLUSIONS

The combined administration of capecitabine and melatonin provided an improvement in antioxidant status as well as a synergistic antitumoral effect in experimental pancreatic cancer.

Experimental animal models of pancreatic carcinogenesis for prevention studies and their relevance to human disease

Pancreatic cancer is difficult to cure, so its prevention is very important. For this purpose, animal model studies are necessary to develop effective methods. Injection of N-nitrosobis(2-oxopropyl)amine (BOP) into Syrian golden hamsters is known to induce pancreatic ductal adenocarcinomas, the histology of which is similar to human tumors. Moreover, K-ras activation by point mutations and p16 inactivation by aberrant methylation of 5' CpG islands or by homozygous deletions have been frequently observed in common in both the hamster and humans. Thus, this chemical carcinogenesis model has an advantage of histopathological and genetic similarity to human pancreatic cancer, and it is useful to study promotive and suppressive factors. Syrian golden hamsters are in a hyperlipidemic state even under normal dietary conditions, and a ligand of peroxizome proliferator-activated receptor gamma was found to improve the hyperlipidemia and suppress pancreatic carcinogenesis. Chronic inflammation is a known important risk factor, and selective inhibitors of inducible nitric oxide synthase and cyclooxygenase-2 also have protective effects against pancreatic cancer development. Anti-inflammatory and anti-hyperlipidemic agents can thus be considered candidate chemopreventive agents deserving more attention.

Effects of capecitabine and celecoxib in experimental pancreatic cancer

INTRODUCTION

Pancreatic cancer is a major health problem because of its aggressiveness and the lack of effective systemic therapies. The aim of the study was the identification of beneficial properties of combined celecoxib and capecitabine treatment during an experimental pancreatic cancer model.

METHODS

N-nitrosobis (2-oxopropyl)amine (BOP) was used as a tumoral agent for 12 weeks. Celecoxib and capecitabine were administered either as monotherapy or combined 12 weeks after cancer induction for a period of 24 weeks. The presence of well-developed or moderate adenocarcinoma was evaluated in the pancreas. Several markers of stress, such as lipoperoxides, reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GHS-Px) were determined.

RESULTS

BOP induced the presence of pancreatic tumors associated with a rise in lipoperoxides and the reduction of the antioxidant status in the pancreas. The administration of celecoxib and capecitabine reduced the number of animals with tumors (33 and 66%, respectively). This antitumoral effect was associated with a recovery of GSH, SOD and CAT activity in the pancreas of BOP-treated animals. The combined treatment exerted a synergic antitumoral effect and reduced pancreatic oxidative stress.

CONCLUSION

The combined administration of celecoxib and capecitabine exerted a synergistic antitumoral effect and increased the antioxidant status restoration in pancreatic cancer.

Melatonin and celecoxib improve the outcomes in hamsters with experimental pancreatic cancer

Pancreatic cancer is a major health problem because of the aggressiveness of the disease and the lack of effective systemic therapies. Melatonin (MEL) has antioxidant activity and prevents experimental genotoxicity. The specific inhibitor of cyclooxygenase-2 (COX-2), celecoxib (CEL), increases the efficacy of chemoradiotherapy in advanced pancreatic cancer. The objective of the study was the comparison and synergic effect of MEL and CEL during either the induction or progression phases of the tumor process, measuring parameters of oxidative stress, number of tumor nodules and survival of animals with pancreatic cancer. Pancreatic cancer was induced by N-nitrosobis (2-oxopropyl)amine) (BOP) in Syrian hamsters. Melatonin and/or CEL were administered during the induction, postinduction as well as during both phases. The presence of tumor nodules were observed macroscopically in pancreatic and splenic areas, and the levels of lipoperoxides (LPO), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in pancreatic tissue were measured. The increases in tumor nodules and LPO as well as the reductions in GSH and enzymatic antioxidants in the pancreas induced by BOP were related to a lower survival rate of animals. The administration of MEL exerted a more potent beneficial effect than CEL treatment on the reduction in tumor nodules, oxidative stress and death of experimental BOP-treated animals. The combined treatment only exerted a synergistic beneficial effect when administered during the induction phase. Melatonin by itself had significant beneficial actions in improving the survival of hamsters.

Vitamin E intake, alpha-tocopherol status, and pancreatic cancer in a cohort of male smokers

BACKGROUND

Evidence indicates that vitamin E has anticarcinogenic properties for gastrointestinal cancers; however, few studies have examined this with respect to exocrine pancreatic cancer.

OBJECTIVE

The objective was to examine whether vitamin E intake and serum alpha-tocopherol concentrations were prospectively associated with exocrine pancreatic cancer.

DESIGN

We conducted a cohort analysis of prediagnostic vitamin E intake (4 tocopherols, 4 tocotrienols), serum alpha-tocopherol concentrations, and pancreatic cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study of male Finnish smokers aged 50-69 y at baseline. During follow-up from 1985 to 2004 (maximum: 19.4 y; median: 16 y), 318 incident cases were diagnosed among cohort participants with complete serum samples (n = 29,092); 306 cases had complete dietary data (n = 27,111). Cox proportional hazards models adjusted for age, smoking history, history of diabetes mellitus, and/or serum cholesterol were used to calculate hazard ratios (HRs) and 95% CIs.

RESULTS

Higher alpha-tocopherol concentrations were associated with lower pancreatic cancer risk (highest compared with lowest quintile, HR: 0.52; 95% CI: 0.34, 0.80; P for trend = 0.03; continuous HR: 0.91; 95% CI: 0.84, 0.99). Polyunsaturated fat, a putative prooxidant nutrient, modified the association such that the inverse alpha-tocopherol association was most pronounced in subjects with a high polyunsaturated fat intake (ie, >9.9 g/d; highest compared with lowest quintile, HR: 0.38; 95% CI: 0.20, 0.70; P for trend = 0.03; continuous HR: 0.86; 95% CI: 0.75, 0.97; P for interaction = 0.05 and 0.02, respectively). No associations were observed for dietary tocopherols and tocotrienols.

CONCLUSION

Our results support the hypothesis that higher alpha-tocopherol concentrations may play a protective role in pancreatic carcinogenesis in male smokers.

Beneficial properties of melatonin in an experimental model of pancreatic cancer

Pancreatic cancer is a major health problem because of the aggressiveness of the disease and the lack of effective systemic therapies. Melatonin has antioxidant activity and prevents experimental genotoxicity. However, the effect of melatonin in pancreatic cancer has not been tested. Pancreatic carcinogenesis was induced by N-nitrosobis (2-oxopropyl)amine (BOP) in Syrian hamsters. Melatonin was administered during the BOP-induction phase (12 wk) and/or following the postinduction phase (12 wk). Different parameters of oxidative stress including lipid peroxides (LPO) and antioxidants (superoxide dismutase, catalase, reduced glutathione and glutathione peroxidase) were determined in pancreatic tissue. Also, the presence of atypical hyperplasia (AH), well and moderately differentiated adenomacarcinoma (ADC-WD and ADC-MD, respectively) were studied. The administration of BOP induced an intense oxidative stress and ADC induction in the pancreas. The administration of melatonin during the induction or postinduction phase reduced LPO and improved the antioxidant status, as well as drastically reducing the presence of ADC but some AH remained. In conclusion, treatment with melatonin reduced oxidative damage and cancer nodules induced by BOP in the pancreas.

Paradoxical dose- and time-dependent regulation of superoxide dismutase and antioxidant capacity by vitamin E in rat

BACKGROUND

Previous data about the regulation of SOD activity as the key part of the endogenous antioxidant system by vitamin E is conflicting.

METHODS

We investigated the effect of different nontoxic doses of vitamin E on erythrocyte SOD activity and plasma total antioxidant capacity in rats, receiving 0 (control group), 100, 300 and 600 mg vitamin E/kilogram of body weight intramuscularly twice a week over 6-weeks.

RESULTS

We observed a linear increase in SOD activity in the first dosing group, which was significant (p<0.05) after 6th week compared to the control level. There was an increase in SOD activity at the end of 2nd and significant increase after 4th weeks, which was followed by a significant decrease at the end of 6th week in the second dosing group. In the third dosing group, there was a significant increase at the end of 2nd week and a significant decrease at the end of 4th and 6th weeks in the SOD activity. The changes in plasma antioxidant capacity were parallel to that of SOD activity with a significant and strong degree of correlation in the 4th and 6th weeks (r=0.7 and r=0.8, respectively). Serum levels of Vitamin E also increased in a time- and dose-dependent manner; the highest level was achieved in the 600 mg/kg dosing group after 6 weeks.

CONCLUSIONS

Non-toxic doses of vitamin E at some levels can up-regulate SOD activity, but cumulative effect of the same doses can lead to attenuation of SOD activity and hence antioxidant defense.

Role of inflammation in pancreatic carcinogenesis and the implications for future therapy

BACKGROUND

The link between inflammation and pancreatic cancer has been observed for a number of gastrointestinal neoplasms. This review examines the role of inflammation in pancreatic carcinogenesis and how it can be utilised to develop new therapies against pancreatic cancer.

METHODS

A literature review of Pubmed, Medline and Web of Science databases was undertaken using the key words, pancreatic cancer, inflammation, inducible nitric oxide, interleukins, pro-inflammatory cytokines, cyclooxygenase-2, NF-kappa B, reactive oxygen species, DNA adducts, lipoxygenases, chemoprevention.

RESULTS

Epidemiological evidence and molecular studies both in vitro and in vivo all support the hypothesis that inflammation plays an important in the initiation and progression of pancreatic tumours.

CONCLUSION

Sustained damage caused by chronic inflammation may precede the onset of frank malignancy by a significant interval. As such, suppression of inflammatory changes and oxidative damage, may help delay or even prevent the inception of pancreatic neoplasia.

Effects of the antioxidative vitamins A, C and E on liver metastasis and intrametastatic lipid peroxidation in BOP-induced pancreatic cancer in Syrian hamsters

BACKGROUND/AIMS

Antioxidative vitamins are known to inhibit metastasis. Therefore we evaluated the impact of vitamins A (retinol), C (ascorbic acid) and E (alpha-tocopherol) on liver metastasis in a model of ductal pancreatic adenocarcinoma in hamster.

METHODS

One hundred and twenty male Syrian hamsters were randomized into 8 groups (Gr.) (n = 15). Gr. 1-4 were given 0.5 ml normal saline subcutaneously (s.c.) weekly, whereas Gr. 5-8 received 10 mg N-nitrosobis(2-oxopropyl)amine (BOP)/kg body weight s.c. for 3 months for tumor induction. In the 13th week Gr. 2 and 6 were administered retinol, Gr. 3 and 7 received ascorbic acid and Gr. 4 and 8 were given alpha-tocopherol orally. No treatment was performed in Gr. 1 and 5. After 24 weeks animals were sacrificed, pancreas and liver were histologically determined. Activities of glutathione-peroxidase (GSH-Px), superoxide dismutase (SOD) and concentration of thiobarbituric-acid-reactive substances (TBARS) were analyzed in hepatic tissue.

RESULTS

Retinol and alpha-tocopherol decreased the incidence of liver metastases (44.4 vs. 86.7%, p < 0.05). The number and size of liver metastases were significantly reduced by retinol. Activities of GSH-Px and SOD were increased and concentration of TBARS was decreased in NML and LiMe by all vitamins.

CONCLUSION

Obviously, antioxidative vitamins prevent oxidative stress in hepatocytes. This may be one mechanism decreasing liver metastasis in pancreatic cancer in the present trial.

Nutritional links to plausible mechanisms underlying pancreatic cancer: a conference report

Adenocarcinoma of the pancreas is one of most catastrophic and least understood of cancers. Evidence from clinical studies indicates that the development of pancreas cancer progresses over many years before symptoms appear. Most people with pancreatic cancer die within six months of diagnosis. The lack of early disease markers, the paucity of direct subject/patient interview data and limited availability of high quality biological samples have slowed progress toward identifying environmental and genetic disease risk factors. Much remains to be learned about the development of pancreatic cancer and about potential interventions for disease prevention. Epidemiological and mechanistic studies examining risk factors for pancreatic cancer supply little consistent or strong evidence to provide a cohesive prevention strategy for this cancer, but offer clues for future research concerning the prevention and early detection of this devastating disease. This Executive Summary provides background discussion on pancreatic cancer and summaries of each of the topics discussed at the workshop, including 1) Molecular aspects, 2) Dietary and other risk factors for pancreatic cancer, 3) The metabolic hypothesis for pancreatic cancer, 4) Preclinical studies on pancreatic cancer, 5) Methylation, 6) Oxidative stress and 7) Biomarker Profiling. This document also contains a compilation of recommendations for future research, concluding remarks, a list of speakers and participants attending the workshop, and a selection of key references to aid future research into nutritional links to mechanisms underlying pancreas cancer. The recommendations section suggests gaps in current knowledge and articulates future directions for this area of investigation.

Effects of taurolidine and octreotide on tumor growth and lipid peroxidation after staging-laparoscopy in ductal pancreatic cancer

Irrigation with taurolidine after laparoscopy decreases tumor growth in colon carcinoma. In pancreatic cancer subcutaneous therapy with octreotide decreases oxidative stress and carcinogenesis as well. However, it is still unclear, whether irrigation with taurolidine or octreotide after laparoscopic pancreatic biopsy reduces tumor growth in pancreatic cancer as well. In 60 Syrian hamsters ductal pancreatic adenocarcinoma was induced by weekly injection of 10mg/kg body weight N-nitrosobis-2-oxopropylamine s.c. for 10 weeks. In week 16 laparoscopic pancreatic biopsy by use of carbon dioxide was performed (gr. 1, n = 20) with subsequent laparoscopic irrigation with taurolidine (gr. 2, n = 20) or octreotide (gr. 3, n = 20). In week 25 hamsters were sacrificed. Our results show that macroscopic visible primary tumors were found in only one animal of the taurolidine group (5.9%), compared to 42.1% in the saline and 62.5% in the octreotide group (P<0.05). Carcinomas were smaller after saline (6+/-23 mm(2)) than after octreotide irrigation (70+/-120 mm(2), P<0.05). In conclusion this study showed that laparoscopic irrigation with taurolidine after pancreatic biopsy inhibited tumor growth in ductal pancreatic adenocarcinoma.

Influence of conjugated vs. conventional linoleic acid on liver metastasis and hepatic lipidperoxidation in BOP-induced pancreatic cancer in Syrian hamster

While conjugated linoleic acid (CLA) is regarded as an essential fatty acid with anticarcinogenic effects, conventional linoleic acid (LA) is reported to promote tumour growth in various experimental studies probably caused by high sensitivity to non-enzymatic lipid peroxidation. In order to evaluate the impact of dietary LA and CLA on liver metastasis and lipidperoxidation (LPO), 60 Syrian hamsters were injected with 10 mg N -nitrosobis-2-oxopropylamine (BOP)/kg body weight s.c. for 12 weeks. Animals were fed a special diet containing LA or CLA. The experiment was terminated after 24 weeks. Incidence, number and size of liver metastases were histologically determined. Furthermore, the activities of antioxidative enzymes and concentration of hepatic lipidperoxidation were measured intra- and extrametastatically. Incidence, number and size of liver metastases did not differ between the tumour groups. Otherwise, antioxidative enzyme activity of GSH-Px was higher in non-metastatic liver, while SOD activity and lipidperoxidation were increased in liver metastases. Conclusively there was no difference between the groups fed with LA and CLA according to the impact on liver metastasis in ductal pancreatic cancer.

A new automated method for the determination of the Total Antioxidant Capacity (TAC) of human plasma, based on the crocin bleaching assay

BACKGROUND: Antioxidant molecules, which scavenge free radical species to prevent or delay oxidative damage of important macromolecules, membrane lipids and lipoproteins, are prevalent in plasma and other biological fluids. Among them, bilirubin, uric acid and protein thiols are the major endogenous antioxidants, while vitamins C and E, as well as a number of food-derived (poly)aromatic substances, belonging to stilbens, flavonoids and phenolic acids, are the main classes of nutritional antioxidants. Assays for total antioxidant capacity in plasma differ in their type of oxidation source, target and measurement used to detect the oxidized product. METHODS: In the present work we present an automated assay for the estimation of blood total antioxidant capacity (TAC assay), based on the crocin bleaching (oxidation) method. This method was adapted on a modern autoanalyzer, was linear over a wide range of values (0-3 mmol/L), and performed using an end point measurement. RESULTS: The TAC method presented a linear correlation with another automated commercial Total Antioxidant Status (TAS) test. Detection of the interference of different metabolites revealed a significant participation of TAC from uric acid, bilirubin, albumin, a minor interference from ascorbic acid, and no interference from hemoglobin. TAC was not modified by two freeze/thawing cycles, and was stable in samples stored at room temperature for 4 hours. K-EDTA and heparin were the best anticoagulants, while citrate decreased TAC by 20%. Reference values derived from samples of normal blood donors was 1.175 PlusMinus; 0.007 mmol/L (mean PlusMinus; SEM), while a diet rich in antioxidants more than doubled this value. CONCLUSIONS: The proposed TAC assay, is fully automated, stable and reliable, and could be of value in the estimation of the AC of plasma. It is further proposed to calculate the antioxidant capacity of plasma after a subtraction of all interference deriving from endogenous and/or exogenous metabolites. The antioxidant capacity of plasma thus calculated can be used as a useful indicator of the antioxidant value of foods and beverages in the daily diet.