Decreased stimulation by 12-O-tetradecanoylphorbol-13-acetate of superoxide radical production by polymorphonuclear leukocytes carrying the Mediterranean variant of glucose-6-phosphate dehydrogenase

Inverse Association between Glucose‒6‒Phosphate Dehydrogenase Deficiency and Hepatocellular Carcinoma

Background:

Studies in experimental models and humans suggest that glucose-6-phosphate dehydrogenase (G6PD) deficiency, an inherited condition, may be inversely related to hepatocellular carcinoma (HCC). We tested this hypothesis in a large cohort of Sardinian patients.

Methods:

A case-control study was performed using data from 11,143 records of patients who underwent upper endoscopy between 2002 and 2017. Gender, age, G6PD status and information regarding the presence of HCC, were recorded. Cases (HCC positive) and controls (HCC negative) were compared for the presence of G6PD deficiency adjusting for major HCC risk factors using logistic regression.

Results:

Overall, 114 HCC cases and 11,029 controls were identified. G6PD deficiency was detected in 11.5% of study participants, and was associated with a reduced risk of HCC [odds ratio (OR); 0.451; 95% confidence interval (CI), 0.207−0.982] after adjusting for all covariates. Factors significantly associated with HCC were cirrhosis (OR, 23.30; 95% CI, 11.48−47.25), diabetes (OR, 2.396; 95% CI, 1.449−3.963), among infection hepatitis HBV with an OR of 2.326, age ≥65 years (OR, 1.941; 95% CI, 1.234−2.581) and male gender (OR, 1.611; 95% CI, 1.006−3.081).

Conclusions:

Our study revealed a significant inverse association between G6PD deficiency and risk of HCC. These findings need to be confirmed in further studies.

Effect of age, period and birth-cohort on the frequency of glucose-6-phosphate dehydrogenase deficiency in Sardinian adults

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an inherited disorder common in Sardinia. In this study, the frequency variation of G6PD-deficiency across age groups and birth cohorts was investigated using Age-Period-Cohort analysis.

METHODS

Data were collected from the clinical records of 11,252 patients (6975 women, age range 17-94 years) who underwent endoscopy between 2000 and 2016 at a teaching hospital (University of Sassari), Italy. G6PD status was assessed by enzymatic assay based on G6PD/6GPD ratio. A Poisson log-linear regression model was used to identify age and time trend in G6PD deficiency.

RESULTS

Enzyme deficiency was detected in 11.4% of the entire cohort (men: 7.9%; women: 13.6%). Age-Period-Cohort analysis showed no inflection points across age groups, especially after age 80. The effects of time period and birth cohorts on G6PD deficiency were negligible (frequencies before and after 1950 were 11.0% and 11.8%, respectively).

CONCLUSIONS

These findings indicate that the frequency of G6PD deficiency does not vary significantly in oldest subjects. The lack of evidence for selection across the malaria eradication time may be explained by other factors, including somatic cell selection or misclassification of heterozygotes women as G6PD normal in the older birth cohorts. Additional molecular studies may help clarify these issues. Key message The frequency of glucose-6-phosphate dehydrogenase deficiency is stable across age groups and does not vary in generations born before or after malaria eradication.

Colorectal Cancer Mortality in Relation to Glucose - 6 - Phosphate Dehydrogenase Deficiency and Consanguinity in Sardinia: A Spatial Correlation Analysis

Background: Colorectal cancer (CRC) is one of the most diffuse malignancy in the world. In Southern Europe, the incidence and prevalence are lower than in most Western countries, although some hot spots of increased risk are emerging. In Sardinia, the cancer rate has risen steeply in the last years. Among risk factors for CRC, genomic homozygosity has been postulated. Glucose-6-phosphate dehydrogenase (G6PD) deficiency has been hypothesized to decrease CRC risk. In Sardinians, this disorder has a frequency of 12-24% due to selection by past malaria. In this study the relationship between mortality for CRC, homozygosity and G6PD deficiency was analysed using spatial analysis. Methods: The spatial association between CRC mortality and G6PD deficiency and homozygosity was assessed in the 377 municipalities of the island using ordinary least squares regression and geographically weighted regression. Results: A consanguinity index, available across all municipalities, was used as a proxy for homozygosity. A significant inverse correlation was found between CRC mortality and G6PD deficiency (ρ = ‒0.216; p = 0.002) whereas no association was found for consanguinity (ρ = ‒0.077; p = 0.498). The geographical map of CRC mortality showed a significant clustering in mountain areas compared to the population living in lowlands, whereas hot spot areas of G6PD deficiency were observed on the south-western side of Sardinia. Conclusions: These results indicate that G6PD deficiency might contribute to reduce colon carcinogenesis, and is in line with in vitro and in vivo studies.

Glucose-6-phosphate dehydrogenase deficiency decreases vascular superoxide and atherosclerotic lesions in apolipoprotein E(-/-) mice

OBJECTIVE

Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme in the pentose phosphate pathway that is a major source of cellular NADPH. The purpose of this study was to examine whether G6PD deficiency affects vascular oxidants and atherosclerosis in high-fat fed apolipoprotein (apo) E(-/-) mice.

METHODS AND RESULTS

G6PD-mutant mice whose G6PD activity was 20% of normal were crossbred with apoE(-/-) mice. Among male apoE(-/-) mice that were fed a western-type diet for 11 weeks, G6PD wild-type (E-WT), and G6PD hemizygous (E-Hemi) mice were compared. Basal blood pressure was significantly higher in E-Hemi. However, superoxide anion release, nitrotyrosine, vascular cell adhesion molecule (VCAM)-1, and inducible nitric oxide synthase immunohistochemical staining were less in E-Hemi compared with E-WT aorta. Serum cholesterol level was lower in E-Hemi, but aortic lesion area was decreased in E-Hemi even after adjusting for serum cholesterol.

CONCLUSIONS

Lower NADPH production in G6PD deficiency may result in lower NADPH oxidase-derived superoxide anion, and thus lower aortic lesion growth. The association of higher blood pressure with lower serum cholesterol levels in this mouse model is indicative of the complex effects that G6PD deficiency may have on vascular disease.

Glucose-6 Phosphate Dehydrogenase Deficiency Decreases the Vascular Response to Angiotensin II

Background— Glucose-6-phosphate dehydrogenase (G6PD) regulates production of the reduced form of NADPH through the pentose phosphate pathway. G6PD may therefore affect superoxide anion production via vascular NADPH oxidase, which is key in mediating the vascular response to angiotensin II (Ang II). We determined the hypertensive and vascular hypertrophic response to Ang II in G6PD-deficient mice.

Methods and Results— Ang II (0.7 mg/kg per day) was infused via subcutaneous osmotic pumps for 6 days in male hemizygote G6PD mutant (G6PD mut ) and wild-type (WT) C3H mice. (1) Compared with WT, G6PD mut mouse aorta had 10% to 20% of G6PD activity and 50% less NADPH. (2) Basal systolic blood pressure was not significantly different in G6PD mut mice (WT 88±4 mm Hg versus G6PD mut 95±4 mm Hg), but Ang II increased blood pressure to a lower level in G6PD mut mice (WT 139±4 mm Hg versus G6PD mut 123±5 mm Hg; P <0.05). (3) Ang II increased aortic medial thickness less in G6PD mut mice (WT 71±2 μm versus G6PD mut 62±1 μm; P <0.01). (4) 3- o -Nitrotyrosine staining and dihydroethidium oxidation in the aorta was increased by Ang II less in G6PD mut mice. (5) Smooth muscle cells isolated from G6PD mut mice showed less Ang II–induced phosphorylation of Akt and p42/44 ERK.

Conclusions— G6PD deficiency may reduce vascular superoxide anion production by limiting production of the substrate for NADPH oxidase, thereby inhibiting oxidant-mediated Ang II–induced signaling pathways that contribute to hypertension and smooth muscle hypertrophy.

Androstenediol stimulates myelopoiesis and enhances resistance to infection in gamma-irradiated mice

The ionizing radiation-induced hemopoietic syndrome is characterized by defects in immune function and increased mortality due to infections and hemorrhage. Since the steroid 5-androstene-3beta, 17beta-diol (5-androstenediol, AED) modulates cytokine expression and increases resistance to bacterial and viral infections in rodents, we tested its ability to promote survival after whole-body ionizing radiation in mice. In unirradiated female B6D2F1 mice, sc AED elevated numbers of circulating neutrophils and platelets and induced proliferation of neutrophil progenitors in bone marrow. In mice exposed to whole-body (60)Co gamma-radiation (3 Gy), AED injected 1 h later ameliorated radiation-induced decreases in circulating neutrophils and platelets and marrow granulocyte-macrophage colony-forming cells, but had no effect on total numbers of circulating lymphocytes or erythrocytes. In mice irradiated (0, 1 or 3 Gy) and inoculated four days later with Klebsiella pneumoniae, AED injected 2 h after irradiation enhanced 30-d survival. Injecting AED 24 h before irradiation or 2 h after irradiation increased survival to approximately the same extent. In K. pneumoniae-inoculated mice (irradiated at 3-7 Gy) and uninoculated mice (irradiated at 8-12 Gy), AED (160 mg/kg) injected 24 h before irradiation significantly promoted survival with dose reduction factors (DRFs) of 1.18 and 1.26, respectively. 5-Androstene-3beta-ol-17-one (dehydroepiandrosterone, DHEA) was markedly less efficacious than AED in augmenting survival, indicating specificity. These results demonstrate for the first time that a DHEA-related steroid stimulates myelopoiesis, and ameliorates neutropenia and thrombocytopenia and enhances resistance to infection after exposure of animals to ionizing radiation.

Impaired production of nitric oxide, superoxide, and hydrogen peroxide in glucose 6-phosphate-dehydrogenase-deficient granulocytes

Since the generation of superoxide and hydrogen peroxide by NADPH oxidase and nitric oxide (NO) by NO synthase (NOS) in granulocytes is NADPH-dependent, we investigated the production of NO, superoxide and H2O2 in glucose 6-phosphate dehydrogenase (G6PD)-deficient human granulocytes. Our results showed that upon stimulation with either 5 microg/ml of lipopolysaccharide (LPS) or 10 microM of phorbol 12-myristate 13-acetate (PMA), the production of nitrite in normal granulocytes was elevated, 252 +/- 135% and 239 +/- 72%, respectively, compared to the resting stage. In contrast, G6PD-deficient granulocytes did not produce more nitrite upon stimulation with either LPS or PMA compared to the resting stage. Western blot analysis indicated a normal expression pattern of inducible NOS in G6PD-deficient granulocytes. In addition, the production of H2O2 and superoxide was also significantly impaired in G6PD-deficient granulocytes compared to control cells. These data demonstrate that G6PD deficiency causes an impairment in the production of NO, superoxide and H2O2.

Mechanism of inhibition of growth of 3T3-L1 fibroblasts and their differentiation to adipocytes by dehydroepiandrosterone and related steroids: role of glucose-6-phosphate dehydrogenase

Dehydroepiandrosterone (DHEA) and certain structural analogues block the differentiation of 3T3-L1 mouse embryo fibroblasts to adipocytes. These steroids also are potent uncompetitive inhibitors of mammalian glucose-6-phosphate dehydrogenases (G6PDs). We provide direct evidence that treatment of the 3T3-L1 cells with DHEA and its analogues results in intracellular inhibition of G6PD, which is associated with the block of differentiation: (i) Levels of 6-phosphogluconate and other products of the pentose phosphate pathway are decreased; (ii) the magnitude of these decreases depends on the potency of steroids as inhibitors of G6PD and on concentration and duration of exposure, and it is accompanied by a proportionate block of differentiation; (iii) in cells exposed to 16 alpha-bromoepiandrosterone (a more potent inhibitor of G6PD than DHEA) at concentrations that block differentiation, introduction of exogenous 6-phosphogluconate in liposomes raises the levels of 6-phosphogluconate and other products of the pentose phosphate pathway and partially relieves the steroid block of cell growth and differentiation.

Antioxidants and multistage carcinogenesis in mouse skin

The two-step initiation-promotion protocol for the induction of skin tumors in mice is a convenient model to elucidate what molecular events are involved in the multistage process of carcinogenesis and how they can be modulated. The current theories concerning the mechanisms of skin tumor initiation, stages 1 and 2 of tumor promotion, and tumor progression are reviewed. Because chemical carcinogens and tumor promoters may, directly or indirectly, generate reactive oxygen species (ROS) and because various antioxidants inhibit effectively some of the biochemical and biological events linked to tumor initiation, promotion and/or progression, it is conceivable that different sequences and levels of free radical-induced macromolecule damage may contribute to the evolution of the epidermal target cells from the preneoplastic stage to the malignant stage.