Increased expression of mitochondrial glycerophosphate dehydrogenase and antioxidant enzymes in prostate cancer cell lines/cancer

The involvement of mitochondrial glycerophosphate dehydrogenase (mGPDH) has previously been established in the production of ROS in prostate cancer cell lines (LNCaP, DU145, PC3 and CL1). The current study demonstrates that the mRNA level of mGPDH in prostate cancer cells is 3.3–8.9-fold higher compared to the normal prostate epithelial cell line, PNT1A. This is consistent with the enzymatic activity and protein level of mGPDH. However, cytochrome c oxidase (COX) activity is 2.9–3.2-fold down-regulated in androgen-independent prostate cancer cell lines. The level of antioxidant enzymes, catalase, MnSOD and CuZnSOD are up-regulated in prostate cancer cell lines. Furthermore, it was observed that the activity of mGPDH is significantly higher in liver tissues from all mice with cancer compared to liver tissues from control mice. These data suggest that the up-regulation of mGPDH, due to a highly glycolytic environment, contributes to the overall increase in ROS generation and may result in the progression of the cancer.     

Increased expression of mitochondrial glycerophosphate dehydrogenase and antioxidant enzymes in prostate cancer cell lines/cancer

The involvement of mitochondrial glycerophosphate dehydrogenase (mGPDH) has previously been established in the production of ROS in prostate cancer cell lines (LNCaP, DU145, PC3 and CL1). The current study demonstrates that the mRNA level of mGPDH in prostate cancer cells is 3.3-8.9-fold higher compared to the normal prostate epithelial cell line, PNT1A. This is consistent with the enzymatic activity and protein level of mGPDH. However, cytochrome c oxidase (COX) activity is 2.9-3.2-fold down-regulated in androgen-independent prostate cancer cell lines. The level of antioxidant enzymes, catalase, MnSOD and CuZnSOD are up-regulated in prostate cancer cell lines. Furthermore, it was observed that the activity of mGPDH is significantly higher in liver tissues from all mice with cancer compared to liver tissues from control mice. These data suggest that the up-regulation of mGPDH, due to a highly glycolytic environment, contributes to the overall increase in ROS generation and may result in the progression of the cancer.     

Action of antioxidant enzymes and cytochrome P-450 monooxygenases in the cabbage looper in response to plant phototoxins

Effects of two biosynthetically distinct plant phototoxins—xanthototoxin, a furanocoumarin, and harmine, a β-carboline alkaloid, which are known to produce toxic oxygen species—on the food utilization efficiencies and enzymatic detoxification systems of the polyphagous cabbage looper. Trichoplusia ni (Lepidoptera: Noctuidae), were studied. Newly molted fifth-instar larvae were allowed 36 h to ingest diets containing these two phototoxins at 0.15% wet weight in the presence of near ultraviolet (UVA). The growth and development of the larvae, as well as the corresponding activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPOX), and glutathione reductase (GR) and the detoxification enzyme cytochrome P-450, were measured. Xanthotoxin reduced rates of relative growth and consumption and efficiencies of conversion of ingested and digested food to biomass. Harmine reduced rates of growth and consumption without affecting efficiencies of conversion. Specific activities of SOD, CAT, GPOX, and GR of whole-body homogenates in the absence of compounds were 0.88 units, 153μmol H₂O₂ decomposed·mg protein^?1·min—¹, 38.3 nmol NADPH oxidized·mg protein^?1·min^?1, and 0.56 nmol NADPH oxidized·mg protein^?1·min^?1, respectively. SOD activity was induced 2.9-fold and 3.8-fold by dietary xanthotoxin and harmine, respectively. CAT and GPOX activities were induced 1.2-fold by harmine only, and GR activity was not changed by either chemical. The P-450 activity toward xanthotoxin in the microsomal fraction of midguts was low (0.15 nmol xanthotoxin metabolized·mg protein^?1·min^?1) and was not induced by xanthotoxin ingestion. These studies indicate that P-450 and antioxidant enzyme systems may be independent but consequential, the induction of antioxidant enzymes by phototoxins occurring when low P-450 activity toward the phototoxin permits the accumulation of oxidative stress from unmetabolized phototoxin, which in turn induces antioxidant enzymes.     

Studies on hepatic oxidative stress and antioxidant defence systems during arteether treatment of Plasmodium yoelii nigeriensis infected mice

Reactive Oxygen species play an important role in pathology during malaria infection. The status of hepatic oxidative stress and antioxidant defence indices was studied during Plasmodium yoelii nigeriensis (P. y. nigeriensis) infection in mice and arteether treatment of P. y. nigeriensis infected mice. P. y. nigeriensis infection caused a significant increase in hepatic xanthine oxidase, rate of lipid peroxidation, reduced glutathione (GSH) and glutathione reductase with progressive rise in parasitemia. This was accompanied by a significant decrease in hepatic superoxide dismutase (SOD) and catalase with increase in parasitemia. Arteether treatment (10 mg/kg body weight of mice) of infected mice from day 2 of post infection resulted in complete clearance of parasitemia on day 4 of post infection which was accompanied by restoration of all the oxidative stress and antioxidant defence indices to normal levels.     

Studies on hepatic oxidative stress and antioxidant defence system during chloroquine/poly ICLC treatment of Plasmodium yoelii nigeriensis infected mice

Reactive oxygen species are important mediators of tissue injury during malaria infection. The status of hepatic oxidative stress and antioxidant defence indices were studied during Plasmodium yoelii nigeriensis (P. y. nigeriensis) infection and chloroquine/polyinosinic-polycytidylic acid stabilized with polylysine and carboxymethylcellulose (poly ICLC) treatment of infected mice. P. y. nigeriensis infection resulted in a significant increase in oxidative stress indices viz., xanthine oxidase and rate of lipid peroxidation (LPO). This was accompanied by a highly significant increase in antioxidant defence indices viz., reduced glutathione (GSH) and glutathione reductase while superoxide dismutase (SOD) and catalase showed a highly significant decrease with respect to normal mice. Chloroquine treatment of infected mice caused a decrease in parasitaemia which was associated with restoration of indices altered during infection towards normalization. Poly ICLC treatment of infected mice caused no change in blood parasitaemia but resulted in a significant increase in GSH, glutathione reductase, SOD and catalase with respect to infected mice. Combination therapy of chloroquine and poly ICLC resulted in clearance of parasitaemia and restoration of all oxidative stress and antioxidant defence indices to normal levels.     

Role of antioxidant enzymes in cell immortalization and transformation

Summary The role of antioxidant enzymes, particularly superoxide dismutase (SOD), in immortalization and malignant transformation is discussed. SOD (generally MnSOD) has been found to be lowered in a wide variety of tumor types when compared to an appropriate normal cell control. Levels of immunoreactive MnSOD protein and mRNA for MnSOD also appear to be lowered in tumor cells. Tumor cells have the capacity to produce superoxide radical, the substrate for SOD. This suggests that superoxide production coupled with diminished amounts of MnSOD may be a general characteristic of tumor cells. The levels of MnSOD in certain cells correlates with their degree of differentiation; non-differentiating cells, whether normal or malignant, appear to have lost the ability to undergo MnSOD induction. These observations are used to elucidate a two-step model of cancer. This model involves not only the antioxidant enzymes, but also organelle (particularly mitochondria and peroxisomes) function as a dominant theme in carcinogenesis.     

Antioxidant enzymes of the black swallowtail butterfly,Papilio polyxenes,and their response to the prooxidant allelochemical,quercetin

The black swallowtail butterfly larvae, Papilio polyxenes, are specialist feeders that have adapted to feeding on plants containing high levels of prooxidant allelochemicals. Third, fourth, and fifth instar larvae were tested for their antioxidant enzyme activities, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GPOX), using 850-g supernatants from whole-body homogenates. The overall antioxidant enzyme profile for P. polyxenes was high compared to other insects, with activities ranging as follows: SOD, 1.1–7.5; CAT, 124–343; GR, 1.0–7.5; and GPOX, 0 units. To determine whether these antioxidant enzymes were inducible, P. poly xenes larvae were given a prooxidant challenge by dipping parsley leaves (their diet in the initial studies) in solutions of quercetin, such that the leaves became coated with this prooxidant flavonoid. Mid-fifth instar larvae fed on quercetin-coated leaves were assayed for antioxidant enzyme activities as was previously done with the larvae fed the standard diet. Food consumption and quercetin intake were monitored. SOD activity was increased almost twofold at the highest quercetin concentration tested. CAT and GR activity, on the other hand, were inhibited by increased quercetin consumption, with GR activity completely inhibited at the highest quercetin concentration after 12 h of feeding. GPOX activity, not present in control insects, was also not inducible by a quercetin challenge. These studies point out the key role that the antioxidant enzymes play in insect defenses against plant prooxidants.     

Enhancing 5-aminolevulinic acid tolerance and production by engineering the antioxidant defense system of Escherichia coli

5-Aminolevulinic acid (ALA) is a value-added compound with potential applications in the fields of agriculture and medicine. Although massive efforts have recently been devoted to building microbial producers of ALA through metabolic engineering, few studies focused on the cellular response and tolerance to ALA. In this study, we demonstrated that ALA caused severe cell damage and morphology change of Escherichia coli via generating reactive oxygen species (ROS), which were further determined to be mainly hydrogen peroxide and superoxide anion radical. ALA treatment activated the native antioxidant defense system by upregulating catalase (CAT) and superoxide dismutase (SOD) expression to combat ROS. Further overexpressing CAT (encoded by katG and katE) and SOD (encoded by sodA, sodB, and sodC) not only improved ALA tolerance but also its production level. Notably, coexpression of katE and sodB in an ALA synthase expressing strain enhanced the biomass and final ALA titer by 81% and 117% (11.5 g/L) in a 5 L bioreactor, respectively. This study demonstrates the importance of tolerance engineering in strain development. Reinforcing the antioxidant defense system holds promise to improve the bioproduction of chemicals that cause oxidative stress.     

Cytokinin-induced activity of antioxidant enzymes in transgenic Pssu-ipt tobacco during plant ontogeny

Cytokinin (CK) content and activities of several antioxidant enzymes were examined during plant ontogeny with the aim to elucidate their role in delayed senescence of transgenic Pssu-ipt tobacco. Control Nicotiana tabacum L. (cv. Petit Havana SR1) and transgenic tobacco with the ipt gene under the control of the promoter of small subunit of Rubisco (Pssu-ipt) were both grown either as grafts on control rootstocks or as rooted plants. Both control plant types showed a decline in total content of CKs with proceeding plant senescence. Contrary to this both transgenic plant types exhibited at least ten times higher content of CKs than controls and a significant increase of CK contents throughout the ontogeny with maximal values in the later stages of plant development. Significantly higher portion of O-glucosides was found in both transgenic plant types compared to control ones. In transgenic plants, zeatin and zeatin riboside were predominant type of CKs. Generally, Pssu-ipt tobacco exhibited elevated activities of antioxidant enzymes compared to control tobacco particularly in the later stages of plant development. While in control tobacco activity of glutathione reductase (GR) and superoxide dismutase (SOD) showed increasing activity up to the onset of flowering and then gradually decreased, in both transgenic types GR increased and SOD activity showed only small change throughout the plant ontogeny. Ascorbate peroxidase (APOD) was stimulated in both transgenic types. The manifold enhancement of syringaldazine and guaiacol peroxidase activities was observed in transgenic grafts throughout plant ontogeny in contrast to control and transgenic rooted plants, where the increase was found only in the late stages. Electron microscopic examination showed higher number of crystallic cores in peroxisomes and abnormal interactions among organelles in transgenic tobacco in comparison with control plant. The overproduction of cytokinins resulted in the stimulation of activities of AOE throughout the plant ontogeny of transgenic Pssu-ipt tobacco.     

Subcellular distribution and activities of superoxide dismutase,catalase, glutathione peroxidase,and glutathione reductase in the southern armyworm,Spodoptera eridania

In mid-fifth-instar larvae of the southern armyworm, Spodoptera eridania, the subcellular distribution of four antioxidant enzymes—superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPOX), and glutathione reductase (GR)—were examined. Two-thirds (4.26 units ·mg protein^?1) of the SOD activity was found in the cytosol, and one-thirds (2.13 units ·mg protein^?1) in the mitochondria. CAT activity was unusually high and not restricted to the microsomal fraction where peroxisomes are usually isolated. The activity was distributed as follows: cytosol (163 units) mitochondria (125 units) and microsomes (119 units). Similar to CAT, the subcellular compartmentalization of both GPOX and GR was unusual. No activity was detected in the cytosol, but in mitochondria and microsomes, GR levels were 5.49 and 3.09 units. Although GPOX activity exhibited 14–16-fold enrichment in mitochondria and microsomes, respectively, over the 850g crude homogenate, the level was negligible (mitochondria = 1.4 × 10^?3 units; microsomes = 1.6 × 10^?3 units), indicating that this enzyme is absent. The unusual distribution of CAT has apparently evolved as an evolutionary answer to the absence of GR from the cytosol, and the lack of GPOX activity.     

Effects of post-injury hypothermia and nerve growth factor infusion on antioxidant enzyme activity in the rat: implications for clinical therapies

The pathological sequelae of traumatic brain injury (TBI) include increased oxidative stress due to the production of reactive oxygen species (ROS). Regulation of ROS levels following TBI is determined primarily by antioxidant enzyme activity that in turn can be influenced by nerve growth factor (NGF). Hypothermia is one of the current therapies designed to combat the deleterious effects of TBI. However, it has been shown to suppress post-trauma increases in NGF levels in rat brain. The present study sought to determine whether post-injury hypothermia also impairs the antioxidant response to injury, and if such an effect could be reversed by infusion of exogenous NGF. We employed a lateral controlled cortical impact injury model in rat, followed by moderate hypothermia treatment with supplemental intracerebroventricular infusion of NGF or vehicle. The time course of changes in post-injury/intervention levels of NGF and activity of three major enzymes responsible for ROS scavenging, catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), was determined in the hippocampus. Relative to levels in injured, normothermic animals, hypothermia treatment not only suppressed NGF levels, but also attenuated CAT and GPx activity, and increased SOD activity. Infusion of NGF in injured, hypothermia-treated animals was ineffective in restoring hippocampal antioxidant enzymes activity to levels produced after injury under normothermic conditions, although it was able to increase septal cholinergic (choline acetyltransferase) enzyme activity. These results have implications for clinical treatment of TBI, demonstrating that moderate hypothermia suppresses NGF and the antioxidant response after TBI; the latter cannot be countered by exogenous NGF administration.     

Antioxidant enzymes as biochemical defenses against phototoxin-induced oxidative stress in three species of herbivorous lepidoptera

Many secondary plant compounds are capable of photoactivation resulting in the production of toxic species of oxygen. One mechanism of defense for insects feeding on phototoxic plants may be the presence of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPOX), and glutathione reductase (GR). The activities of these enzymes were examined in larvae of three lepidoptera: Ostrinia nubilalis, Manduca sexta, and Anaitis plagiata. Highest levels of antioxidant enzyme activity were found in A. plagiata, a specialist feeder on Hypericum perforatum, which contains high levels of the phototoxin hypericin. Larvae of A. plagiata fed leaf discs treated with hypericin exhibited a short-term, concentration-dependent decline in enzyme activity. Longer term studies with A. palgiata fed either the photoxic H. perforatum, or the closely related but non-phototoxic H. calycinum, resulted in increased CAT and GR activity in larvae fed the phototoxic plant whereas SOD activity was not significantly different. These results suggest that CAT and GR may be inducible defenses against phototoxins.     

Activities of enzymes that detoxify superoxide anion and related toxic oxyradicals in Trichoplusia ni

In third-, fourth-, and fifth-instar larvae of the cabbage looper moth, Trichoplusia ni, the activities of the antioxidant enzymes, superoxide dismutase (SOD*), catalase (CAT), glutathione peroxidase (GPOX), and glutathione reductase (GR) were examined using 850 g supernatants of whole-body homogenates. The enzyme activities, expressed as units mg⁻¹ protein min⁻¹ at 25°C ranged as follows: SOD, 0.67-2.13 units; CAT, 180.5-307.5 units; GPOX, none detectable; and GR, 0.40-1.19 units. There was a similar pattern of changes for SOD and CAT activities with larval ontogeny, but not for GR. The cabbage looper apparently uses SOD and CAT to form a “defensive team” effective against endogenously produced superoxide anion (O₂⪸). Glutathione may serve as an antioxidant for the destruction of any organic/lipid peroxides formed, and GSH oxidized to glutathione disulfide would be recycled by GR. Bioassays against pro-oxidant compounds exogenous sources of (O₂⪸) show high sensitivity of mid-fifth instars to the linear furanocoumarin, 8-methoxypsoralen (xanthotoxin) primarily from photoactivation (320-380 nm), and auto-oxidation of the flavonoid, quercetin. The LC₅₀s are 0.0004 and 0.0045% (w/w) concentration of xanthotoxin and quercetin, respectively. Both pro-oxidants have multiple target sites for lethal action and, in this context, the role of antioxidant enzymes is discussed.     

Retinol supplementation induces oxidative stress and modulates antioxidant enzyme activities in rat Sertoli cells

Recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer. Recently the causal mechanism has begun to be clarified. We report here that retinol caused cellular oxidative stress and modulated superoxide dismutase, catalase and glutathione peroxidase activities. Retinol (7 μM) significantly increased TBARS, conjugated dienes, and hydroperoxide-initiated chemiluminescence in cultured Sertoli cells. In response to retinol treatment superoxide dismutase, catalase and glutathione peroxidase activities increased. TBARS content and catalase activities were decreased by a free radical scavenger. These findings suggest that retinol may induce oxidative stress and modulate antioxidant enzyme activities in Sertoli cells.     

Influence of indole acetic acid on antioxidant levels and enzyme activities of glucose metabolism in rat liver

Indole acetic acid (IAA) is an auxin and can be synthesized in animals. This compound is metabolized in vitro by peroxidase, producing reactive oxygen species. The toxic effect of indole acetic acid in leukocytes is associated with peroxidase activities and these processes have been implicated in activation of glucose and glutamine metabolism. However, studies in vitro have shown that IAA, in absence of peroxidase, is an antioxidant almost as high in potency as those of other indolic compounds. The purpose of this study was to investigate the possible involvement of a toxic effect of indole acetic acid in the liver, as evidenced by oxidative stress and enzyme activities of the glucose pathway. The animals received IAA by subcutaneous or gavage administration in a phosphate buffered saline (the control group received only the phosphate buffered saline). The other groups received IAA at concentrations of 1 mg, 18 mg and 40 mg per kg of body mass per day. Treatments with 18 mg and 40 mg IAA decreased the activity of catalase by both subcutaneous (30% and 26%) or gavage administration (19% and 28%), respectively. A similar effect was observed on the activity of glutathione peroxidase of animals exposed to 18 mg and 40 mg IAA: A decrease of 34% and 29%, respectively, for subcutaneous administration and a decrease of 29% and 25%, respectively, for gavage administration. However, in neither source of administration did the acid alter superoxide dismutase, glutathione reductase and myeloperoxidase activities. Another alteration was observed in respect of reduced glutathione content in this organ. The lipid peroxidation level showed a significant decrease with subcutaneous (30%, 29% and 24%) and gavage administration (25%, 26% and 24%) using 1 mg, 18 mg and 40 mg of IAA, respectively compared with the control. The reduced glutathione content and catalase activity in the plasma were not altered by either of the two methods of administration. In addition to these findings, after subcutaneous or gavage administration of IAA, the activities of hepatic enzymes of glucose metabolism were not affected (glucokinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase and citrate synthase). Evidence is presented herein that IAA did not have a pro-oxidant effect in the liver as deduced from a reduction of catalase and glutathione peroxidase activities, a decrease of lipid peroxidation content and no alteration of the pool of reduced glutathione. The effects of IAA were independent of the way of administration.     

Lipid peroxidation and activity of antioxidant enzymes in diabetic rats

We hypothesized that oxygen free radicals (OFRs) may be involved in pathogenesis of diabetic complications. We therefore investigated the levels of lipid peroxidation by measuring thiobarbituric acid reactive substances (TBARS) and activity of antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)] in tissues and blood of streptozotocin (STZ)-induced diabetic rats. The animals were divided into two groups: control and diabetic. After 10 weeks (wks) of diabetes the animals were sacrificed and liver, heart, pancreas, kidney and blood were collected for measurement of various biochemical parameters. Diabetes was associated with a significant increase in TBARS in pancreas, heart and blood. The activity of CAT increased in liver, heart and blood but decreased in kidney. GSH-Px activity increased in pancreas and kidney while SOD activity increased in liver, heart and pancreas. Our findings suggest that oxidative stress occurs in diabetic state and that oxidative damage to tissues may be a contributory factor in complications associated with diabetes.     

The changes in the antioxidant status of heart during experimental hypomagnesemia in balb/c mice

The present experiment was performed to assess if hypomagnesemia can influence antioxidant status in mice heart. The results could explain possibly a free radical theory of heart damage in magnesium deficiency. We used a rodent model of hypomagnesemia. The magnesium sufficient group received a standard diet whereas a magnesium deficient group received the diet containing a trace amount of magnesium. The activities of the most important antioxidant enzymes – catalase, glutathione peroxidase and superoxide dismutase were assessed in mice heart and liver in a time dependent manner, on the 10th and the 20th day of experiment. The level of magnesium in plasma of animals receiving the magnesium deficient diet dropped twice after the 8th day and four times after the 13th day and then reached a plateau value. The activity of catalase in heart in the magnesium deficient group increased gradually and was significantly (P<0.05) elevated by 27% on the 20th day of experiment whereas the superoxide dismutase activity was significantly decreased by 17% on the 20th day. Glutathione peroxidase activity was insignificantly elevated. The alterations of antioxidant enzyme activities in the heart indicate cardiomyocytes's exposure to oxidative stress, which can be responsible for the cardiac lesions observed during hypomagnesemia.     

Effect of intravenous nitroglycerin therapy on erythrocyte antioxidant enzymes

Intravenous nitroglycerin (GTN) has been used as an anti-ischemic agent for the therapy of unstable and post-infarction angina. Nitric oxide (^?NO) and S-nitrosothiols constitute the biologically active species formed via nitroglycerin bioactivation. Increased levels of reactive oxygen species can diminish the therapeutic action of organic nitrates by scavenging donated ^?NO and oxidizing tissue thiols important in nitrate biotransformation. Studies reported here show that the red cell activity of antioxidant enzymes, catalase and glutathione peroxidase, are significantly decreased after intravenous nitroglycerin treatment. Catalase activity decreased to and after 1 and 24?hr GTN infusion, respectively. Similarly, glutathione peroxidase activity decreased to and after 1 and 24?hr GTN infusion, respectively. The reported decrease in antioxidant enzyme activities can lead to an oxidant milieu and contribute to the generation of nitrate tolerance.     

Trace element concentrations and superoxide dismutase and catalase activities in benign and malignant larynx tumors

The plasma and erythrocyte levels of zinc, copper, and magnesium and the activities of red-cell copper-zinc superoxide dismutase (Cu/Zn-SOD) and catalase (CAT) were determined in patients with benign and malignant tumors of the larynx. Blood samples from patients and healthy controls were drawn using heparinized tubes. The erythrocyte Cu/Zn-SOD and CAT activities were determined spectrophotometrically and the zinc, copper, and magnesium concentrations were determined in erythrocyte and plasma by atomic absorption spectrometry. Variance analysis was employed in the statistical evaluation of the findings. There was a significant increase in red-cell Cu/Zn-SOD activity in the subjects with malignant and benign tumors compared to controls (p<0.001). The CAT activity increased only in the benign tumor group (p<0.01). The plasma zinc concentrations were significantly lower in the malignant tumor group (p<0.05) and significantly higher in the benign tumor group (p<0.01). The erythrocyte copper concentrations were significantly lower in both benign and malignant tumor groups (p<0.001). The plasma copper and magnesium and the erythrocyte magnesium concentrations did not show significant differences relative to controls (p>0.05). The increases in the activities of SOD and CAT activities and the changes in trace elements concentrations can indicate the presence of increased reactive oxygen species that might play a part in the pathogenesis larynx tumors. Presented at the IX Asian-Pacific Congress of Clinical Biochemistry, March 9–14, 2002, New Delhi, India.     

Gene expression evaluation of antioxidant enzymes in patients with hepatocellular carcinoma: RT-qPCR and bioinformatic analyses

Any condition leading to chronic liver disease is a potential oncogenic agent for hepatocellular carcinoma (HCC). Alterations in the expression of antioxidant enzymes could alter the redox balance. Our aim was to evaluate the expression of the genes GPX1, GPX4, SEP15, SELENOP, SOD1, SOD2, GSR, CAT, and NFE2L2 in patients with HCC. Differential gene expression analysis was performed using RNA-Seq data from the TCGA and GTEx databases, and RT-qPCR data from HCC patient samples. Bioinformatic analysis revealed significant differential expression in most genes. GPX4 expression was significantly increased (p=0.02), while SOD2 expression was significantly decreased (p=0.04) in experimental data. In TCGA samples, alpha-fetoprotein levels (mg/dL) were negatively correlated with the expression of SEP15 (p<0.001), SELENOP (p<0.001), SOD1 (p<0.001), SOD2 (p<0.001), CAT (p<0.001), and NFE2L2 (p=0.004). Alpha-fetoprotein levels were positively correlated with the expression of GPX4 (p=0.02) and SELENOP (p=0.01) in the experimental data. Low expression of GPX1 (p=0.006), GPX4 (p=0.01), SELENOP (p=0.006), SOD1 (p=0.007), CAT (p<0.001), and NFE2L2 (p<0.001), and higher levels of GSR, were associated with low overall survival at 12 months. These results suggest a significant role for these antioxidant enzymes in HCC pathogenesis and severity.