Does alpha-linolenic acid in combination with linoleic acid influence liver metastasis and hepatic lipid peroxidation in BOP-induced pancreatic cancer in Syrian hamsters?

The role of lipids in cancer progression and metastasis

Lipids have essential biological functions in the body (e.g., providing energy storage, acting as a signaling molecule, and being a structural component of membranes); however, an excess of lipids can promote tumorigenesis, colonization, and metastatic capacity of tumor cells. To metastasize, a tumor cell goes through different stages that require lipid-related metabolic and structural adaptations. These adaptations include altering the lipid membrane composition for invading other niches and overcoming cell death mechanisms and promoting lipid catabolism and anabolism for energy and oxidative stress protective purposes. Cancer cells also harness lipid metabolism to modulate the activity of stromal and immune cells to their advantage and to resist therapy and promote relapse. All this is especially worrying given the high fat intake in Western diets. Thus, metabolic interventions aiming to reduce lipid availability to cancer cells or to exacerbate their metabolic vulnerabilities provide promising therapeutic opportunities to prevent cancer progression and treat metastasis.

Ponicidin suppresses pancreatic cancer growth by inducing ferroptosis: Insight gained by mass spectrometry-based metabolomics

BACKGROUND

Pancreatic cancer is one of the most common malignant tumors of the digestive tract. Ponicidin, a tetracyclic diterpenoid active ingredient extracted from the traditional phytomedicine Rubescens, has high safety and great inhibitory effect on the proliferation of a variety of cancer cells, especially malignant tumor cells of the digestive tract. However, the inhibitory effect and mechanism of ponicidin on pancreatic cancer cells is still unclear. Our study aimed to use metabonomics technology to analyze and explore the suppressive effect of ponidicin against pancreatic cancer cells.

METHODS

MTT and flow cytometry were conducted to study the potential effect of ponicidin on SW1990 cells. Secondly, UPLC-MS/MS was used to analyze the small molecule metabolites and relevant differential metabolic pathways induced by ponicidin treatment. Furthermore, through the determination of glutathione peroxidase 4 (GPX4) activity and molecular docking simulation experiments, the effects of intracellular GPX4 activity and GSH/GSSG ratio after ponicidin were evaluated. Finally, the determination of the content of iron ions and malondialdehyde in cells, and the experiment of the effect of ferroptosis inhibitors on cell viability, the effect of ponicidin on the induction of ferroptosis in SW1990 cells was also detected.

RESULTS

The IC50 of ponicidin on SW1990 cells was 20 μM, which could significantly induce cell apoptosis and arrest the cells in G2/M phase. Metabolomics results showed that the contents of endogenous small molecules such as gamma-glutamylcysteine, 5-oxoproline, glutamic acid, reduced glutathione (GSH), oxidized glutathione (GSSG) and arachidonic acid have changed significantly. Main differential compounds were involved in the gamma-glutamyl cycle and polyunsaturated fatty acid metabolism of pancreatic cancer cell lines. Additionally, ponicidin could covalently bind to GSH in SW1990 cells to form a conjugate Pon-GSH, which further reduced the content of free GSH and GPX4 activity in cells. Notably, ponicidin dose-dependently increased levels of iron ions, malondialdehyde and reactive oxygen species in SW1990 cells, and the ferroptosis inhibitors could significantly block the effects of ponicidin on the proliferation of SW1990 cells.

CONCLUSION

Ponicidin could suppress the pancreatic cancer cell proliferation via inducing ferroptosis by inhibiting the gamma-glutamyl cycle and regulating the polyunsaturated fatty acid metabolism in SW1990 cells.

Detecting discordance enrichment among a series of two-sample genome-wide expression data sets

BACKGROUND

With the current microarray and RNA-seq technologies, two-sample genome-wide expression data have been widely collected in biological and medical studies. The related differential expression analysis and gene set enrichment analysis have been frequently conducted. Integrative analysis can be conducted when multiple data sets are available. In practice, discordant molecular behaviors among a series of data sets can be of biological and clinical interest.

METHODS

In this study, a statistical method is proposed for detecting discordance gene set enrichment. Our method is based on a two-level multivariate normal mixture model. It is statistically efficient with linearly increased parameter space when the number of data sets is increased. The model-based probability of discordance enrichment can be calculated for gene set detection.

RESULTS

We apply our method to a microarray expression data set collected from forty-five matched tumor/non-tumor pairs of tissues for studying pancreatic cancer. We divided the data set into a series of non-overlapping subsets according to the tumor/non-tumor paired expression ratio of gene PNLIP (pancreatic lipase, recently shown it association with pancreatic cancer). The log-ratio ranges from a negative value (e.g. more expressed in non-tumor tissue) to a positive value (e.g. more expressed in tumor tissue). Our purpose is to understand whether any gene sets are enriched in discordant behaviors among these subsets (when the log-ratio is increased from negative to positive). We focus on KEGG pathways. The detected pathways will be useful for our further understanding of the role of gene PNLIP in pancreatic cancer research. Among the top list of detected pathways, the neuroactive ligand receptor interaction and olfactory transduction pathways are the most significant two. Then, we consider gene TP53 that is well-known for its role as tumor suppressor in cancer research. The log-ratio also ranges from a negative value (e.g. more expressed in non-tumor tissue) to a positive value (e.g. more expressed in tumor tissue). We divided the microarray data set again according to the expression ratio of gene TP53. After the discordance enrichment analysis, we observed overall similar results and the above two pathways are still the most significant detections. More interestingly, only these two pathways have been identified for their association with pancreatic cancer in a pathway analysis of genome-wide association study (GWAS) data.

CONCLUSIONS

This study illustrates that some disease-related pathways can be enriched in discordant molecular behaviors when an important disease-related gene changes its expression. Our proposed statistical method is useful in the detection of these pathways. Furthermore, our method can also be applied to genome-wide expression data collected by the recent RNA-seq technology.

Impact of Octreotide and SOM-230 on liver metastasis and hepatic lipidperoxidation in ductal pancreatic adenocarcinoma in Syrian Hamster

Octreotide is a somatostatin analogue binding on two receptor subtypes. In previous trials Octreotide showed inhibitory effects on tumour growth and liver metastasis in experimental pancreatic cancer. Thus we evaluated whether the new somatostatin analogue SOM-230 binding on 4 receptor subtypes has superior effects on carcinogenesis in pancreatic carcinoma. About 120 Syrian hamsters were randomised into six groups (n = 20): Gr.1: Aqua/Aqua, Gr.2: BOP/Aqua, Gr.3: Aqua/Octreotide, Gr.4: BOP/Octreotide, Gr.5: Aqua/SOM-230, Gr.6: BOP/SOM-230. Tumour groups 2,4,6 subcutaneously received 10 mg/kg body weight N-nitrosobis-2-oxopropylamin (BOP) weekly for 10 weeks, healthy control Gr.1,3,5 were given aqua. In the 17th week therapy started with Octreotide and SOM-230 for 16 weeks, after 32 weeks animals were sacrificed. Pancreas and liver were histopathologically analysed. Hepatic lipidperoxidation was determined by activities of antioxidative enzymes gluthation-peroxidase (GSH-Px) and superoxiddismutase (SOD) as well as concentration of thiobarbituric-acid reactive substances (TBARS). Incidence of liver metastases was 88.2% in Gr.2 (BOP/Aqua), it was decreased in Gr.4 (BOP/Octreo: 40%) and Gr.6 (BOP/SOM-230: 50%) (P < 0.05). Mean number/animal and mean-2-dimensional size of liver metastases did not differ between tumour groups. Comparing GSH-Px-activity in intrametastatic and extrametastatic hepatic tissue revealed a significant increase extrametastatically in Gr.2 (BOP/Aqua) and Gr.6 (BOP/SOM-230). SOD-activity in liver metastases was decreased in Gr.2 (1,801) (P < 0.05) versus Gr.4 (8,304) and Gr.6 (7,038). Intrametastatic TBARS concentration was increased in Gr.2 compared to Gr.4 (BOP/Octreotid) and Gr.6 (BOP/SOM-230) (P < 0.05). Octreotide and SOM-230 equally reduced liver metastasis in ductal pancreatic adenocarcinoma probably by a reduction of lipidperoxidation.

Impact of polyunsaturated fatty acids on hepato-pancreatic prostaglandin and leukotriene concentration in ductal pancreatic cancer -- is there a correlation to tumour growth and liver metastasis?

Type and composition of polyunsaturated fatty acids (PUFAs) are suspected to play an important role in carcinogenesis. Thus we investigated the effects of n-3, n-6 and n-9 PUFAs on tumour growth, liver metastasis and concentration of prostaglandins (PG) and leukotrienes (LT) in experimental ductal pancreatic adenocarcinoma. Ninety male hamsters were randomised into six groups (Gr.) (n=15). While Gr. 1-3 were healthy control groups, Gr. 4-6 weekly received subcutaneous injections of 10mg N-nitrosobis-2-oxypropylamine (BOP)/kg body weight for 12 weeks in order to induce ductal pancreatic adenocarcinoma. Between week 1 and 16 all animals were fed with a standard diet with a raw fat content of 2.9%. In week 17 Gr. 1-6 were allocated to three types of diets: Gr. 1: standard high fat (=SHF diet, rich in n-6 PUFAs)/Gr. 2: FISH-OIL (rich in n-3 PUFAs)/Gr. 3: SMOF (=mixture of n-3, n-6 and n-9 PUFAs)/Gr. 4: BOP+SHF/Gr. 5: BOP+SMOF/Gr. 6: BOP+FISH-OIL. After 32 weeks all animals were sacrificed and pancreas as well as liver were analysed histologically. Furthermore pancreatic and hepatic concentrations of prostaglandins (PGF1alpha, PGE(2)) and LT were measured. FISH-OIL decreased number of macroscopically visible pancreatic tumours (Gr. 4-6: 54.5% vs. 45.5% vs. 9.1%, P<0.05) as well as incidence of liver metastasis (Gr. 4-6: 90.9% vs. 72.7% vs. 36.4%, P<0.05). Furthermore concentration of PGF(1)(alpha), PGE(2) and LT were significantly increased in pancreatic carcinoma compared to tumour-free tissue. Moreover levels of PGF(1)(alpha) and PGE(2) were higher in liver metastasis than in extrametastatic hepatic tissue. However, in Gr. 6 (FISH-OIL) intrametastatic concentration of LT was significantly lower than in non-metastatic hepatic tissue as well as in Gr. 4 and Gr. 5. FISH-OIL decreased number of visible pancreatic tumours and incidence of histological proven liver metastasis. This effect might be caused by a decrease of intrametastatic concentration of LT compared to extrametastatic hepatic tissue.

Does enteral nutrition of dietary polyunsaturated fatty acids promote oxidative stress and tumour growth in ductal pancreatic cancer? Experimental trial in Syrian Hamster

BACKGROUND

Type and composition of dietary fat intake is supposed to play an important role in carcinogenesis. Thus we investigated the effects of n-3, n-6 and n-9 polyunsaturated fatty acids (PUFA) on oxidative stress (lipidperoxidation) and tumour growth in ductal pancreatic cancer.

METHODS

Ninety male hamsters were randomized into 6 groups (gr.) (n=15) and allocated to 3 main dietary categories: gr. 1 and 2 received a standard high fat diet (SHF, rich in n-6 PUFA), while gr. 3 and 4 were fed with a diet containing a mixture of n-3, n-6 and n-9 PUFA (SMOF) and gr. 5 and 6 had free access to a diet rich in n-3 PUFA (FISH-OIL). Gr. 1, 3 and 5 received weekly subcutaneous (s.c.) injections of 10 mg N-nitrosobis-2-oxypropylamine (BOP)/kg body weight in order to induce ductal pancreatic adenocarcinoma. Healthy control gr. 2, 4 and 6 were treated with 0.5 ml 0.9% sodium chloride s.c. After 32 weeks all animals were sacrificed. Removed pancreata were weighed and analysed histologically and biochemically. Activities of glutathionperoxidase (GSH-Px), superoxiddismutase (SOD) and levels of lipidperoxidation were measured in samples of pancreatic carcinoma as well as in tumour-free pancreatic tissue.

RESULTS

While different diets did not significantly alter the overall incidence of histologically proven pancreatic adenocarcinoma, the number of macroscopically visible tumours was decreased in the FISH-OIL-gr.

CONCLUSION

Different diets did not significantly influence the incidence of histologically proven pancreatic adenocarcinoma. However, administration of a diet rich in n-3 PUFA (FISH-OIL) resulted in a decrease of macroscopically visible tumours, thus indicating its beneficial effects in respect to attenuation of tumour growth.

Influence of different dietary fat intake on liver metastasis and hepatic lipid peroxidation in BOP-induced pancreatic cancer in Syrian hamsters

OBJECTIVES

Effects of polyunsaturated fatty acids (PUFA) on carcinogenesis are discussed controversially. Thus, tumor growth seems to be influenced by type and composition of fat dietary; however, the pathomechanism is still unknown. Therefore, we investigated the impact of different PUFAs on liver metastasis and hepatic lipid peroxidation in a solid model of ductal pancreatic cancer in Syrian hamsters.

METHODS

90 male hamsters were randomized into 6 groups (n = 15). Accordingly groups 2, 4 and 6 received 10 mg N-nitrosobis-2-oxopropylamine (BOP)/kg body weight weekly by subcutaneous injection for 12 weeks in order to induce ductal pancreatic cancer, while groups 1, 3 and 5 were treated with 0.5 ml 0.9% sodium chloride. All hamsters received a standard fat diet (SFD) rich in n-6 PUFA for 16 weeks (2.9% fat). Afterwards, groups 1 and 2 had free access to SFD, while groups 3 and 4 were given a diet enriched with n-3, n-6 and n-9 PUFA (SMOF) and groups 5 and 6 were fed a diet high in n-3 PUFA (FISH-OIL). After 32 weeks all hamsters were sacrificed in order to determine incidence of pancreatic carcinoma and liver metastasis. Furthermore hepatic activities of glutathionperoxidase (GSH-Px) and superoxiddismutase (SOD) as well as levels of lipidperoxidation were analyzed intra- and extrametastatically.

RESULTS

The incidence of liver metastasis was decreased in the FISH-OIL tumor group compared to the SFD and SMOF groups. However, GSH-Px activity was not influenced by different diets. Extrametastatic hepatic SOD activity did not differ between all groups, while intrametastatic hepatic SOD activity in the SFD-BOP group was increased. In the FISH-OIL-BOP and the SMOF-BOP group intrametastatic SOD activity was lower than in non-metastatic hepatic tissue. Furthermore levels of hepatic lipid peroxidation were decreased in the tumor groups treated with fish oil and SMOF compared to the SFD group. Comparing intra- and extrametastatic TBARS concentration there was no difference in the SFD-BOP and the SMOF-BOP groups, while in the FISH-OIL-BOP group intrametastatic TBARS concentration was increased.

CONCLUSION

Conclusively, fish oil reduced the incidence of liver metastasis in experimental ductal pancreatic cancer. Maybe this effect is caused by an increase of intrametastatic hepatic lipid peroxidation.

Effects of selective COX-2 and 5-LOX inhibition on prostaglandin and leukotriene synthesis in ductal pancreatic cancer in Syrian hamster

Selective inhibition of eicosanoid synthesis seems to decrease carcinogenesis, however, the effect on liver metastasis in pancreatic cancer is still unknown. Ductal pancreatic adenocarcinoma was chemically induced by weekly injection of N-nitrosobis-2-oxopropylamine (BOP) in Syrian hamster. Animals received selective inhibition of cyclooxygenase-2 (Celebrex) and 5-lipoxygenase (Zyflo). In week 33, hamsters were sacrificed and incidence of pancreatic carcinomas as well as liver metastases were examined. Furthermore, size and number of liver metastases per animal were determined and concentration of PGF1alpha, PGE2 and leukotrienes was measured in hepatic and pancreatic tissue. Combined therapy (Celebrex+Zyflo) significantly decreased incidence, number and size of liver metastases. Furthermore extra- and intrametastatic concentration of PGE2 was reduced by this treatment in hepatic tissue. Single Cox-2-inhibition (Celebrex) decreased intrametastatic hepatic PGF1alpha and PGE2 concentration while PGF1alpha concentration was reduced in non-metastatic liver (nml). Moreover 5-LOX-inhibition (Zyflo) decreased intrametastatic PGE2 concentration as well as PGF1alpha and PGE2 in nml. In pancreatic carcinomas highest LT-concentration was found after combined treatment and this therapy group was the only one revealing a significantly higher amount of LTs in carcinomas compared to tumour-free tissue. Hepatic LT-concentration was significantly lower in the control groups than in nml of the tumour groups. Combination of Cox-2-inhibition and 5-Lox-inhibition might be a suitable adjuvant therapy to prevent liver metastasis in human ductal pancreatic adenocarcinoma.

Impact of taurolidin and octreotide on liver metastasis and lipid peroxidation after laparoscopy in chemical induced ductal pancreatic cancer

BACKGROUND

There is controversial discussion whether metastasis initiated by laparoscopy with carbon dioxide might be prevented by instillation of taurolidin or radical scavengers like the somatostatin analogue Octreotide. Therefore we evaluated the effects of laparoscopic lavage with taurolidin and Octreotide on liver metastasis after staging laparoscopy in ductal pancreatic cancer.

METHODS

In 60 Syrian hamsters pancreatic adenocarcinoma was induced by weekly subcutanous injection of 10 mg N-nitrosobis-2-oxopropylamin/kg body weight for 10 weeks. In the 16th week laparoscopic staging biopsy by use of carbon dioxide was performed. Finally animals underwent abdominal irrigation with saline (gr.1, n = 20), taurolidin (0.5%) (gr.2, n = 20) or Octreotide (gr.3, n = 20). In week 25 animals were sacrificed, pancreas and liver were analysed.

RESULTS

Size of pancreatic carcinomas was decreased in the taurolidin gr. compared to the other two groups. Furthermore the number of liver metastasis per animal was reduced after lavage with taurolidin (2 +/- 2) and Octreotide (2.5 +/- 2) compared to saline irrigation (4 +/- 4) (p < 0.05). Additionally the incidence of port site metastases was significantly reduced in the taurolidin group. Activity of antioxidative enzyme superoxide dismutase (SOD) was increased while concentration of products of lipidperoxidation was decreased in non-metastatic liver after taurolidin irrigation compared to saline or Octreotide irrigation.

CONCLUSIONS

Taurolidin irrigation during laparoscopy might be a new concept to reduce the number of liver metastasis and port site metastases in pancreatic cancer.

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 and conventional linoleic acid on tumor growth and lipid peroxidation in pancreatic adenocarcinoma in hamster

Conventional linoleic acid (LA) is regarded as a promotor of carcinogenesis. However, the effect of its conjugated derivative on cancer is still unknown. Therefore we investigated the influence of conventional and conjugated LA on tumor growth and lipid peroxidation in a solid model of pancreatic adenocarcinoma in Syrian hamsters. 60 male hamsters were randomized in 4 groups (Gr.) (n=15). Gr. 1 and 2 received 0.5 ml 0.9% sodium chloride subcutaneously (s.c.) once a week while Gr. 3 and 4 were injected 10 mg N-nitrosobis-2-oxopropylamine (BOP)/kg body weight weekly for 12 weeks to induce pancreatic cancer. Gr. 1 and 3 received a diet containing conventional LA, Gr. 2 and 4 were fed a diet of conjugated LA. After 29 weeks all animals were sacrificed, pancreas was weighed and examined macroscopically and histologically. The level of lipid peroxidation and activities of glutathion peroxidase and superoxide dismutase were determined in tumor-free as well as in pancreatic carcinoma tissue. Different diets did not influence the incidence of pancreatic carcinoma, however, pancreas weight was increased by conjugated LA compared to conventional LA. Furthermore both diets decreased the activity of glutathion peroxidase and increased the level of lipid peroxidation in pancreatic intratumoral tissue. The content of conjugated LA in dietary did not influence pancreatic tumor growth in a solid model of pancreatic adenocarcinoma in Syrian hamsters.

Effects of Celebrex and Zyflo on liver metastasis and lipidperoxidation in pancreatic cancer in Syrian hamsters

Selective inhibition of eicosanoid synthesis is thought to have effects on carcinogenesis in lung and colon cancer. However, it is still unknown whether pancreatic cancer might also be influenced. Therefore we evaluated the impact of selective cyclooxygenase-2 inhibitor Celebrex and selective 5-lipoxygenase inhibitor Zyflo on liver metastasis in a solid model of pancreatic adenocarcinoma in Syrian hamster. In week 33, the animals were sacrificed and incidence of pancreatic carcinomas and number and size of liver metastases were determined. Activities of antioxidative enzymes (GSHPX/SOD) and concentrations of products of lipidperoxidation were measured in liver metastases and non-metastatic hepatic tissue. The incidence (54.5 vs. 100%), number (3.17 +/- 0.98 vs. 6.75 +/- 0.71) and size (2.67 +/- 1.97 vs. 11.75 +/- 1.98 mm2) of liver metastases were decreased by combined therapy of Zyflo and Celebrex (P < 0.05). Furthermore, activities of GSHPX ([73.77 +/- 5.67]*10(5) vs. [15.49 +/- 4.02]*10(5) U/mg prot.; P < 0.05) and SOD (474.92 +/- 108.8 vs. 127.89 +/- 38.75 U/mg prot.; P < 0.05) were increased, while lipidperoxidation (0.31 +/- 0.08 nmol/mg prot. vs. 1.54 +/- 0.55 nmol/mg prot.; P < 0.05) was decreased by combination therapy, in non-metastatic hepatic tissue. Moreover, combined therapy increased lipidperoxidation in liver metastases (0.47 +/- 0.09 vs. 1.95 +/- 0.12 nmol/mg prot.; P < 0.05). Thus, a combination of Celebrex and Zyflo might be a new concept to decrease tumour growth in liver metastases in advanced pancreatic cancer.

Effects of Celebrex and Zyflo on BOP-induced pancreatic cancer in Syrian hamsters

BACKGROUND/AIMS

Selective inhibition of eicosanoid synthesis decreases inflammation, however, it is still unknown whether oxidative stress and carcinogenesis might be influenced in ductal pancreatic ductal cancer as well.

METHODS

120 male hamsters were randomized into 8 groups (n = 15). While control group 1-4 received 0.5 ml normal saline s.c. weekly for 16 weeks, groups 5-8 were injected 10 mg BOP/kg body weight to induce pancreatic cancer. After establishment of pancreatic cancer, groups 1 and 5 received no therapy, groups 2 and 6 were fed 7 mg Celebrex daily, groups 3 and 7 were given 28 mg Zyflo and groups 4 and 8 received Celebrex and Zyflo orally daily in weeks 17-32. In week 33, all animals were sacrificed, macroscopic size of pancreatic carcinomas was measured, incidence of pancreatic cancer was analyzed histopathologically and activities of antioxidative enzymes and concentration of products of lipid peroxidation in tumor-free and pancreatic intratumoral tissue were determined.

RESULTS

Incidence and size of macroscopic pancreatic carcinomas were decreased by single therapy with Zyflo as well as combined therapy (Zyflo + Celebrex). Activities of antioxidative enzymes were increased and the concentration of products of lipid peroxidation was decreased in tumor-free pancreas. On the other hand, lipid peroxidation was increased in pancreatic tumors.

CONCLUSION

Zyflo alone or in combination with Celebrex reduce tumor growth in pancreatic cancer and thus might be a new therapeutic option in advanced pancreatic cancer.

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

Persistent oxidative stress is thought to play an important role in carcinogenesis. Vitamins may influence oxygen radical metabolism and thus inhibit tumor growth. In the present trial the effects of Vitamins (Vit.) A, C and E on neoplastic growth and lipid peroxidation in pancreatic tissue were evaluated on chemically-induced pancreatic adenocarcinoma in the Syrian hamster. The incidence of pancreatic cancer was decreased by Vit. A (64.3%) and Vit. C (71.4%) as compared to the control group (100%, P<0.05). All vitamins increased the activity of superoxidedismutase (SOD) in pancreatic carcinomas. Accumulation of vitamins in tumor cells seems to be responsible for high levels of SOD and consecutive intracellular increase of hydrogen peroxide levels. Since this effect is selectively toxic for tumor cells it might be one of the mechanisms decreasing the incidence of pancreatic cancer in our trial.