Red cell pyrimidine 5'-nucleotidase and glutathione in myeloproliferative and lymphoproliferative disorders

Differences in Blood Glutathione Levels of Patients with Advanced or Localized Carcinoma

Aims and background

The increased level of blood glutathione (GSH) is an important biochemical feature in animal epithelial tumor. The aim of this study was to investigate the blood GSH concentrations in well characterized cancer patients and healthy volunteers.

Methods

Two different groups of carcinoma cases were used. The first group consisted of 15 blood samples drawn from disseminated gastric adenocarcinoma patients, and the second group comprised 15 samples obtained from localized or locally advanced skin carcinoma cases without lymph node metastasis. GSH and hemoglobin concentrations were measured by using the method of Beutler et al.

Results

The mean blood GSH in patients who had advanced malignant disease was 129.13 ± 7.49 mg/dl and in patients who had localized cancer was 96.24 ± 3.90 mg/dl. These results indicate that the blood GSH level is 31% higher in localized carcinoma cases and 78% higher in metastatic disease than those of controls. Blood GSH concentrations were expressed on the basis of blood volume and also on hemoglobin content. Similar results were calculated with either mode of expression.

Conclusion

By comparing the two groups of patients, we found that higher blood GSH concentration was correlated with metastatic growth.

Blood glutathione levels in head and neck malignancies

Blood glutathione was estimated in fifty patients of head and neck cancer in the age group of 18-76 years and the results were compared with a group of normal healthy controls. Mean blood glutathione level was found to be significantly lowered in patients than the controls. Irrespective of the site, TNM classification, histopathology, and character of lesion, fall in blood glutathione was nearly same in all the patients. The mean level was significantly increased after radiotherapy when compared with the levels before radiotherapy. The decreased levels of GSH in-patients with head and neck cancer, observed in the present study, may be due to its increased utilization by the cells. The results suggest that patients with head and neck cancer have increased oxidative stress.

Chronic non-spherocytic haemolytic anaemia due to congenital pyrimidine 5' nucleotidase deficiency: 25 years later

In 1972, Valentine et al described, under the name of 'non-spherocytic haemolytic anaemia, high red cell ATP and ribose phosphate pyrophosphokinase (RPK; EC 2.7.6.1) deficiency', an obscure congenital haemolytic anaemia with the characteristic feature of red blood cell basophilic stippling. The activity of Embden-Meyerhof pathway and hexose monophosphate shunt were normal, and the concentrations of reduced glutathione and of ATP were raised 2 SD above the normal mean. The low values of RPK also encountered were considered to be an epiphenomenon rather than a causative defect. One year later, further studies performed in two new kindreds with the same haemolytic disorder associated with persistent basophilic stippling were described under the name of 'haemolytic disorders associated with increased ATP'. In 1974, two new and important observations contributed to the final identification of the disease: the patients' red blood cells (RBCs) contained large amounts of nucleotides (pyrimidine nucleotides), and in all cases they were deficient in a hitherto unrecognized enzyme called pyrimidine 5' nucleotidase (P5N). In conclusion, all these cases were formerly referred to as 'high ATP syndromes' because of the erroneous assumption that the large number of nucleotides within deficient RBCs were adenine phosphate rather than pyrimidine phosphate. Twenty-five years after its description, P5N deficiency has been reported in about 35 unrelated families from different parts of the world, and it has become one commonly identified cause of hereditary non-spherocytic haemolytic anaemia due to RBC enzymopathy. Genetic transmission is via the autosomic recessive mode, and only homozygous or compound heterozygous are clinically affected. Family members who are biochemically heterozygous are haematologically normal and difficult to detect. Unfortunately, the precise gene mutation or mutations causing the disease remain unknown.

Effect of selenium compounds and thiols on human mammary tumor cells

The effect on cell viability and growth rate of sodium selenite, selenocystine, sodium selenate, and selenomethionine at selenium concentrations of 6.25 and 12.5 uM was studied in vitro on cells of the human mammary tumor cell line HTB123/DU4475. Selenite and selenocystine affected both cell viability and growth rate of the tumor cells at these selenium concentrations. Selenite and selenocystine decreased intracellular glutathione concentrations, but did not affect tumor cell glutathione peroxidase activity. After six days of exposure to either selenate or selenomethionine, the viability of tumor cells remained stable, but cell growth, as measured by numbers of cells, was retarded. Neither selenate nor selenomethionine produced changes in concentrations of intracellular glutathione. The toxic effect of selenite on tumor cells was enhanced by addition of 0.25 mM glutathione to the growth medium. Preincubation of the tumor cells with 62.5 uM buthionine sulfoximine decreased cellular glutathione to 15% of controls at 24 h and enhanced the toxicity of selenite toward the tumor cells. Glutathione, 2-mercaptoethanol, and L-cysteine were all toxic to the tumor cells in a dose-dependent manner.

Effect of dietary selenium and magnesium on human mammary tumor growth in athymic nude mice

The effect of dietary selenium (Se) supplementation and low dietary magnesium (Mg) on growth of cells of the human mammary tumor cell line (HTB123/DU4475) and the tissue glutathione (GSH) content in female athymic nude mice was studied. Sixty three- to four-week-old female athymic nude mice were randomly divided into six dietary groups of 10 animals. The mice were fed a modified AIN-76A diet with two levels of Mg (100 and 665 mg/kg) and three levels of Se (0.04, 0.2, and 4.0 mg/kg). At the fourth week of dietary treatment, mice were subcutaneously inoculated with 2.5 x 10(6) viable tumor cells on the dorsal lumbar region and then fed their respective diets for another four weeks. Dietary Se supplementation had no significant effect on tumor growth or tissue GSH content. Low dietary Mg limited both tumor growth and tissue GSH synthesis but raised Mg and GSH levels in tumor tissues. The growth of mice fed the diet containing 100 mg/kg Mg and 4.0 mg/kg Se was significantly retarded. This study demonstrated that neither Se deficiency nor Se supplementation had any effect on mammary tumor growth or tissue GSH content in athymic nude mice. Low dietary Mg did retard tumor growth and inhibited GSH synthesis. Low dietary Mg also resulted in an apparent increase in Se toxicity in these animals.

Erythrocyte-oxidized glutathione transport in pyrimidine 5'-nucleotidase deficiency

The oxidized form of glutathione transport was studied in human erythrocytes in pyrimidine 5'-nucleotidase (P5N) deficiency, a disorder in which the amounts of CTP and UTP in the erythrocytes are elevated. The inhibition of ATP-requiring oxidized glutathione (GSSG) transport by CTP and UTP is believed to play a role in elevating the levels of the reduced form of glutathione (GSH) in the erythrocytes of patients with P5N deficiency. The current investigation was undertaken to determine if GSSG transport actually decreases in the erythrocytes of such patients. Erythrocytes from a 17-year-old patient and a 13-year-old patient with P5N deficiency hemolytic anemia and from ten normal subjects were used as materials for the experiment. Erythrocytes, which had been previously incubated with [3H]glycine, were incubated at 37 degrees C, and the rate of [3H]GSSG transported by the cells was estimated. The velocity of GSSG transport out of the erythrocytes was quite low in the patients, 3.17-3.65 nmol GSSG/ml erythrocytes/hr at 37 degrees C in one case, and 3.30 nmol GSSG/ml erythrocytes/hr in the other case, vs that in the normal controls (6.00 +/- 0.80 nmol GSSG/ml erythrocytes/hr; mean +/- SD). The activity of gamma-glutamylcysteine synthetase and glutathione synthetase did not decrease in the patients. Decreased transport activity of GSSG in addition to a normal synthesis rate for GSH may explain the increased concentration of erythrocyte GSH in P5N deficiency.

Characteristics of red cell pyruvate kinase (PK) and pyrimidine 5'nucleotidase (P5N) abnormalities in acute leukaemia and chronic lymphoid diseases with leukaemic expression

Red cell pyruvate kinase (PK), pyrimidine 5'nucleotidase (P5N) and reduced glutathione content (GSH) were studied in 126 untreated patients with acute leukaemia (AL, 80 cases), chronic lymphocytic leukaemia (B-CLL, 38 cases) and B-cell lymphoma with leukaemic expression (LSCL, eight cases). Acute leukaemias were classified into lymphoblastic (ALL) and non-lymphoblastic (ANLL), the latter have been further sub-divided into four different variants according to FAB morphological criteria (1976). A significant decrease of PK activity was observed only in the ANLL group, leading to a clear-cut difference with the ALL group where a normal value was obtained. The decrease of P5N activity was similar in all the morphological variants of ANLL and no abnormalities in the low PEP assay system or after fructose 1,6-bisphosphate (Fru 1,6-P2) activation were observed. P5N activity was found to be significantly decreased in all groups of patients except in B-CLL, where it was normal. In regards to the different morphological groups of ANLL, a striking decrease of P5N activity was observed in the M3 variant. Although red cell GSH content was significantly increased in all groups of patients, no correlation was demonstrated between the raised GSH levels and the decreased P5N activities.

Superoxide dismutase, glutathione peroxidase and catalase in the red cells of patients with malignant lymphoma

Erythrocyte superoxide dismutase, glutathione peroxidase and catalase activities have been measured in patients with untreated malignant lymphomas. Marked deficiencies of superoxide dismutase (P less than 0.001) and glutathione peroxidase (P less than 0.001) were found, whereas catalase levels were normal. There was no apparent difference in enzyme activities between the different histological types of lymphoma.

Determination of erythrocyte pyrimidine 5'-nucleotidase activity by 31P nuclear magnetic resonance: comparison of normal controls and multiple sclerosis patients

A technique to assay erythrocyte pyrimidine 5'-nucleotidase activity in situ using 31P nuclear magnetic resonance spectroscopy is presented. The assay is chemically specific, simple and applicable to untreated lysates. A comparison of enzyme levels in normal controls and in multiple sclerosis patients employing the assay yielded no significant differences between both groups. Difficulties encountered in the quantitative analysis of the assay using 1H-NMR spectroscopy are briefly discussed.

Assay of human erythrocyte pyrimidine and deoxypyrimidine 5'-nucleotidase by isocratic reversed-phase high-performance liquid chromatography

We report a rapid and reproducible assay for activity of human erythrocyte pyrimidine 5'-nucleotidase and deoxypyrimidine 5'-nucleotidase. The nucleotides CMP, UMP, dUMP, dCMP or dTMP are individually incubated 30 min at 37 degrees C with erythrocyte hemolysate and 4 mM magnesium chloride in Tris, pH 7.5. Data are provided for standardization of the reaction with each substrate. Individual nucleoside products are assayed in less than 10 min by reversed-phase high-performance liquid chromatography at 280 nm with 0-14% methanol in 0.01 M potassium dihydrogen phosphate. This is the first report of a high-performance liquid chromatographic assay system which allows quantitation of the activity of pyrimidine 5'-nucleotidase isozymes using five individual pyrimidine and deoxypyrimidine nucleotides as the substrates.

Pyrimidine 5'nucleotidase and several other red cell enzyme activities in beta-thalassaemia trait

The activity of 18 red blood cell (RBC) enzymes and reduced glutathione (GSH) content were measured in 70 normal subjects, in 50 heterozygous beta-thalassaemia carriers and in 50 non-thalassaemic patients with haemolytic anaemia and high reticulocyte counts. In addition, pyrimidine 5'nucleotidase (P5N) activity was also determined in 34 patients with hypochromic, microcytic, iron deficiency anaemia. beta-Thalassaemia trait was associated with an increase in almost all of the enzyme activities, except for 2,3-bisphosphoglycerate synthetase (BPGS) and glutathione reductase (GR) which were normal and for acetylcholinesterase (AChE) and P5N which were slightly and markedly decreased respectively. The increases in enzyme activities were similar to those observed in patients with non-thalassaemic reticulocytosis except for glyceraldehydephosphate dehydrogenase (GAPD), phosphoglyceratekinase (PGK), pyruvate kinase (PK), glutathione peroxidase (GPX) and adenylate kinase (AK) which were higher than in non-thalassaemic group of patients with increased number of reticulocytes. No correlation was found between the severity of P5N deficiency and the intensity of basophilic stippling which was present in 46 of 50 thalassaemic carriers here studied. In addition, GSH content and UV absorption spectra of deproteinized thalassaemic RBC extracts were also found to be normal. The present findings provide further information on the metabolic status of RBC in beta-thalassaemia trait and suggest a possible molecular explanation for the frequently observed basophilic stippling in this disease.

Red cell nucleotide levels in patients with thalassaemia, iron deficiency, and renal failure

Red cell nucleotides, predominantly adenine nucleotides, were measured spectrophotometrically in normal individuals and in patients with iron deficiency, beta thalassaemia and renal failure following dialysis or transplantation. There was a significant correlation between the mean red cell haemoglobin (MCH) or the mean cell volume (MCV) and the nucleotide levels in red cells (P less than 0.001). Patients with beta thalassaemia did not have increased nucleotide levels compared to red cells having the same MCH or MCV. Patients with renal failure had significantly increased levels of nucleotides compared to normal individuals, and this level remained high after renal dialysis but returned to normal following renal transplantation.

Hereditary haemolytic anaemia due to red cell pyrimidine 5'-nucleotidase deficiency in two Irish families with a note on the benefit of splenectomy

Hereditary haemolytic anaemia with basophilic stippling caused by pyrimidine 5'-nucleotidase deficiency is described in three members of two unrelated Irish families. In one family, the disease was moderately severe and the patient's condition was improved by splenectomy. In the other family the haemolytic anaemia was well compensated. In neither family was there a marked elevation of reduced glutathione. The implications are that pyrimidine 5'-nucleotidase deficiency is a heterogeneous disorder, both clinically and biochemically. In more severe forms splenectomy may be beneficial.