Adenosine deaminase, 5'-nucleotidase, xanthine oxidase, superoxide dismutase, and catalase activities in gastric juices from patients with gastric cancer, ulcer, and atrophic gastritis

Adenosine-Metabolizing Enzymes, Adenosine Kinase and Adenosine Deaminase, in Cancer

The immunosuppressive effect of adenosine in the microenvironment of a tumor is well established. Presently, researchers are developing approaches in immune therapy that target inhibition of adenosine or its signaling such as CD39 or CD73 inhibiting antibodies or adenosine A2A receptor antagonists. However, numerous enzymatic pathways that control ATP-adenosine balance, as well as understudied intracellular adenosine regulation, can prevent successful immunotherapy. This review contains the latest data on two adenosine-lowering enzymes: adenosine kinase (ADK) and adenosine deaminase (ADA). ADK deletes adenosine by its phosphorylation into 5′-adenosine monophosphate. Recent studies have revealed an association between a long nuclear ADK isoform and an increase in global DNA methylation, which explains epigenetic receptor-independent role of adenosine. ADA regulates the level of adenosine by converting it to inosine. The changes in the activity of ADA are detected in patients with various cancer types. The article focuses on the biological significance of these enzymes and their roles in the development of cancer. Perspectives of future studies on these enzymes in therapy for cancer are discussed.

Adenosine deaminase inhibition

Adenosine deaminase is a critical enzyme in purine metabolism that regulates intra and extracellular adenosine concentrations by converting it to inosine. Adenosine is an important purine that regulates numerous physiological functions by interacting with its receptors. Adenosine and consequently adenosine deaminase can have pro or anti-inflammatory effects on tissues depending on how much time has passed from the start of the injury. In addition, an increase in adenosine deaminase activity has been reported for various diseases and the significant effect of deaminase inhibition on the clinical course of different diseases has been reported. However, the use of inhibitors is limited to only a few medical indications. Data on the increase of adenosine deaminase activity in different diseases and the impact of its inhibition in various cases have been collected and are discussed in this review. Overall, the evidence shows that many studies have been done to introduce inhibitors, however, in vivo studies have been much less than in vitro, and often have not been expanded for clinical use.

Static magnetic field inhibits 5' nucleotidase activity in cancerous and non-cancerous human gastric tissues

The aim of the present study is to investigate possible effects of static magnetic field (SMF) on 5' nucleotidase (5'NT-CD73) and xanthine oxidase (XO) activities in cancerous and non-cancerous human gastric tissues in order to contribute to the elucidation of the anticancer activity of SMF. Cancerous and non-cancerous human gastric tissues removed from patients by surgical operations were used in the studies. SMF was created using two static magnets. Before and after treatment with SMF, 5'NT and XO activities in the tissue samples were measured. 5'NT activity was found to be lowered, but no significant change was observed in XO activity in the gastric tissues treated with the SMF. Our results suggest that SMF inhibits 5'NT enzyme in gastric tissues significantly. It is supposed that in addition to other proposed mechanisms, inhibition of purine catabolic activity due to inhibition of some key enzymes in the DNA turn-over like 5'NT might also play part in the anticancer activity of SMF.

A study of oxidative stress parameters in anti-helicobacter pylorus immunoglobulin g positive and negative gastric cancer patients

PURPOSE

Helicobacter pylorus (HP) is a Gram-negative spiral-shaped microaerophilic bacterium, which colonizes in the gastric mucosa of humans. The gastric human pathogen HP causes chronic gastritis and ulcers, and has a strong relationship with gastric cancer. The aim of this study was to determine advanced oxidation protein products (AOPP) levels, activities of myeloperoxidase (MPO) and catalase (CAT) in two groups.

MATERIALS AND METHODS

For this aim, one group included 30 patients with gastric cancer (Group 1) and the other included 30 subjects with non-gastric cancer and Anti-HP immunoglobulin (Ig) G antibody positive (group 2). Anti-HP IgG antibody test values were found as positive in fifty percent of group 1 and all of the group 2 patients.

RESULTS

Significantly increased AOOP levels were found in group 1 (p < 0.05) compared to group 2. There were no significant differences between the groups in regard to activities of MPO and CAT. In addition, AOPP level, MPO and CAT activities were similar among the Anti-HP IgG positive and negative subgroups of group 1 patients.

CONCLUSION

The result of this study indicated that gastric cancer patients were characterized by increased protein oxidation, whereas there was no significant difference in oxidative stress parameters and antioxidant enzyme activity between the Anti-HP IgG positive and negative gastric cancer patients.

Nitric oxide and antioxidant defense in patients with gastric cancer

In the present study, total nitrate and nitrite level (as end product of nitric oxide), superoxide dismutase activity, and glutathione peroxidase activity in leukocytes were determined in patients with gastric cancer, and the relationship between measured parameters and tumor grade were evaluated. Leukocyte nitrate and nitrite level was found to be increased and superoxide dismutase activity was found to be decreased in patients compared to controls. When the patient group was categorized, nitrate and nitrite level was found to be higher in patients with a high-grade tumor than in patients with a grade I tumor. We concluded that an increased level of leukocyte nitrate and nitrite is related to tumor grade in patients with gastric cancer; antioxidant activity is also impaired in these patients but it does not seem to be related to grade of tumor.

Association of adenosine deaminase, superoxide dismutase, and catalase activities with Helicobacter pylori

Our purpose was to investigate associations between adenosine deaminase (ADA), superoxide dismutase (SOD), and catalase (CAT) activities and H. pylori.Ninety-nine patients were studied. Eight antral mucosal biopsies were taken for biochemical assessment of ADA, CAT, AND SOD activity and histological assessment. H. pylori density wAS evaluated according to the updated Sydney system. Patients were divided into three groups according to Sydney classification. ADA activity was found to be higher in patients having H. pylori in the present study. Also, ADA activity was higher in patients with a severe density of H. pylori. SOD level was found to be significantly higher with increased H. pylori density in our study (P < 0.05). In addition, SOD activity was higher in it H. Pylori-positive than H. pylori-negative patients. We did not find CAT activity in some antral tissue specimens. The significantly high levels of ADA activity in patients with H. pylori infection may reflect the regulator role of ADA in acid secretion. The higher ADA level with increased H. pylori density and H. pylori positivity indicate the probable malign lymphoid process of the stomach. But these findings must be confirmed with larger studies that include different gastric lesions.

Role of antioxidant enzymes in brain tumours

Erythrocyte antioxidant enzymes were analysed in 100 patients with intracranial neoplasm and in 47 controls. There was a significant decrease in RBC glutathione reductase (GRx) and superoxide dismutase (SOD) activity in most types of brain tumor cases. Patients with acoustic neurinoma showed a significant reduction in selenium-dependent glutathione peroxidase (Se-GPx) activity. A decrease in catalase (CT) activity was seen in most of the brain tumor patients but remained statistically insignificant when compared to controls. A significant increase in plasma ceruloplasmin concentration was observed in patients with glioma. These enzymes were also studied in 27 post-treatment cases. GRx activity returned to normal levels in these patients. RBC SOD and plasma ceruloplasmin levels showed a tendency to return to normal. Hence, a marked decrease in the antioxidant enzymes may have a role in the genesis of considerable oxidative stress in patients with brain tumors.

Studies on purine enzymes in experimental colitis

Although the role of adenosine deaminase (ADA), adenylate deaminase (AMP-DA), purine nucleoside phosphorylase (PNP) is well documented in gastric and intestinal carcinoma, their role in inflammatory bowel diseases remains unknown. In the present study, we investigated the profile of these enzymes in blood and intestinal tissues during colitis. Colitis induced in Wistar rats by acetic acid was monitored by a marker enzyme myeloperoxidase (MPO). The tissue levels of MPO increased on 1, 2, 5 and 6 days post-administration (PA) of acetic acid and declined to the control levels by day 7 PA. In parallel the blood levels of ADA and AMP-DA decreased on days 1, 2 and 5 without any significant change on days 6 and 7 PA. Similar observations were recorded for these enzymes in the cytosolic extracts of colonic tissue specimens. In contrast, PNP remained unaltered in both blood and tissue samples. These findings suggest an inverse-relationship between inflammation and purine deaminases in both blood and tissues.

Adenosine deaminase, 5'-nucleotidase, guanase and cytidine deaminase activities in gastric tissues from patients with gastric cancer

The activities of some of the enzymes participating in nucleotide metabolism were measured in cancerous and noncancerous gastric tissues from patients with gastric cancer. The enzyme activities measured were found to be higher in the cancerous tissues than in the non-cancerous tissues. Adenosine deaminase (ADA), 5'-nucleotidase (5'-NT), guanase (GUA) and cytidine deaminase (CD) activities in the cancerous tissues were 56.0 +/- 24.0, 45.0 +/- 20.0, 0.34 +/- 0.16 and 4.65 +/- 2.04, respectively. The activities in non-cancerous tissues were 13.2 +/- 6.0, 19.8 +/- 8.3, 0.12 +/- 0.06 and 1.65 +/- 0.8, respectively. Cancerous tissues consisted of 7 gastric tissues with Grade I-II and 8 tissues with Grade III-IV adeno cancer. Non-cancerous adjacent tissues were obtained from the same patients with Grade I-II cancer. There were no meaningful differences between enzyme activities of the gastric tissues with Grade I-II and Grade III-IV cancer. Enzyme activity ratios indicates that ADA activity increased by the highest amount relative to other enzyme activities in the cancerous tissues. In the correlation analysis, we found positive correlations between some of the enzyme activities in the cancerous tissues. Results suggest that increased activities of these enzymes might play a part in the accelerated nucleotide metabolism in the cancerous gastric tissues.