Jerker M. Olsson

Electrochemical treatment of tumours

The electrochemical treatment (EChT) of tumours implies that tumour tissue is treated with a continuous direct current through two or more electrodes placed in or near the tumour. The treatment offers considerable promise of a safe, simple and relatively noninvasive anti-tumour therapy for treatment of localised malignant as well as benign tumours. Although more than 10,000 patients have been treated in China during the past 10 years, EChT has not yet been universally accepted. The reason for this is the lack of essential preclinical studies and controlled clinical trials. Uncertainties regarding the destruction mechanism of EChT also hinder the development of an optimised and reliable dose-planning methodology. This article reviews the collected Chinese and occidental experiences of the electrochemical treatment of tumours, alone and in combination with other therapies. The current knowledge of the destruction mechanism underlying EChT is presented along with different approaches towards a dose planning methodology. In addition, we discuss our view of different important parameters that have to be accounted for, if clinical trials are to be initiated outside of China.

Drug-resistant human lung cancer cells are more sensitive to selenium cytotoxicity. Effects on thioredoxin reductase and glutathione reductase.

The human U-1285 and GLC(4) cell lines, both derived from small cell carcinoma of the lung, are present in doxorubicin-sensitive (U-1285 and GLC(4)) and doxorubicin-resistant MRP-expressing (U-1285dox and GLC(4)/ADR) variants. These sublines were examined here with respect to their susceptibilities to the toxic effects of selenite and compared to the toxic effects of selenite on the promyelocytic leukemia cell line HL-60 and its doxorubicin-resistant P-glycoprotein expressing variant. The drug-resistant U-1285dox and GLC(4)/ADR sublines proved to be 3- and 4-fold, respectively, more sensitive to the cytotoxicity of selenite than the drug-sensitive U-1285 and GLC(4) sublines, whereas no difference was observed between the HL-60 sublines. The presence of doxorubicin at a concentration equal to the IC(10) did not significantly potentiate the toxic effects of selenite. The presence of selenite did not significantly affect the expression of the multi-drug resistant proteins (MRP1, LRP and topoisomerase IIalpha) in the drug-resistant cells. The activities of thioredoxin reductase (TrxR) were higher (50 and 25%, respectively) in the drug resistant cell sublines U-1285dox and GLC(4)/ADR compared to the drug-sensitive parental lines. The activity of glutathione reductase (GR) was essentially the same in the drug-sensitive and -resistant cell lines. Exposure to selenite resulted in a 4-fold increase in both TrxR and GR activities in U-1285 cells, an effect, which was less pronounced in the presence of doxorubicin. Under similar conditions the increase in the TrxR activity in the resistant U-1285dox cell line, was only 30% and the activity of GR was unaltered. Different responses in the activity of the key enzymes in selenium metabolism are one possible mechanism explaining the differential cytotoxicity of selenium in these cells.

Ubiquinone is reduced by lipoamide dehydrogenase and this reaction is potently stimulated by zinc

Ubiquinol is an endogenously synthesized lipid‐soluble antioxidant. Regeneration of ubiquinol from the oxidized form is essential to the maintenance of its antioxidant function. We demonstrated that lipoamide dehydrogenase can reduce ubiquinone to ubiquinol. Zinc increased the rate of the NADPH‐dependent reduction more than 10‐fold. The concentration ubiquinone resulting in the half‐maximal rate of reduction was approximately 5 μM in the presence and 4 μM in the absence of zinc. These data may explain how ubiquinone is reduced to the active antioxidant ubiquinol, which plays such an important role in protecting against oxidative stress and lipid peroxidation.

Electrochemical treatment (EChT) effects in rat mammary and liver tissue. In vivo optimizing of a dose-planning model for EChT of tumours

BACKGROUND A reinvented technique for tumour therapy, electrochemical treatment (EChT), is attracting increasing attention. This study compared results from treatment of liver and mammary tissue focusing on destruction and pH changes in the tissue close to the treatment electrodes. Subsequently, data were compared with a dose-planning model. METHODS Mammary or liver tissue in 50 adult female Sprague Dawley rats was given EChT with a constant, direct current. The electrodes used were Pt/Ir (9:1) with spherical tips. In situ pH measurements were taken with a micro-combination glass electrode. RESULTS Spherical lesions were produced in both liver and mammary tissue. No significant difference was detected when comparing the size of the lesions in the two kinds of tissue. Similar pH profiles were obtained in tissue surrounding the electrodes, with pH values changing rapidly from unphysiological to neutral status within the space of a few millimetres. The pH at the border of the macroscopic destruction zone, regardless of tissue type or coulomb dosage, correlated well with specific values (4.5-5.5 at the anode and between 9 and 10 at the cathode). CONCLUSION The analogous destruction patterns in mammary and liver tissue support the hypothesis that EChT has similar results in at least these two different types of tissue. This implies that the destructive pattern caused by the treatment may be the same also in tumours.

Dietary iron overload inhibits carbon tetrachloride-induced promotion in chemical hepatocarcinogenesis: effects on cell proliferation, apoptosis, and antioxidation

BACKGROUND/AIMS The aim of this study was to investigate if feeding with carbonyl iron would facilitate the development of preneoplastic lesions initiated by diethylnitrosamine (DEN) and promoted by CCl4-induced liver cirrhosis. METHODS Male Wistar rats were fed a diet with 1.25%-2.5% carbonyl iron for 23 weeks and received intragastric injections of CCl4 (1.0 or 2.0 ml/kg per week) for 13 weeks, followed by one i.p. injection of DEN (200 mg/kg), after which CCl4 was administered for 8 additional weeks. Animals were killed 48 h after the first CCl4 injection to evaluate liver necrosis, 8 weeks later to evaluate fibrosis, and 9 weeks after DEN to determine formation of glutathione S-transferase 7,7 (GST-7,7) positive foci. RESULTS Treatment with iron counteracted the increased serum alanine aminotransferase levels and liver necrosis following CCl4 administration. Hepatic levels of reduced Q9 and alpha-tocopherol were elevated in rats treated with CCl4 and decreased in rats treated with iron compared to the controls. Fibrogenesis was not altered by iron treatment. Nine weeks after DEN initiation, the number and volume density of GST-7,7-positive foci in rats treated with CCl4 were significantly increased as compared with controls, but co-treatment with iron inhibited this increase. Apoptotic index was increased in iron-loaded livers, and labelling index (the fraction of S-phase hepatocytes) was decreased by co-treatment with iron in livers exposed to CCl4. CONCLUSION Carbonyl iron depleted hepatic levels of antioxidants, it decreased CCl4-induced necrosis and cell proliferation, it enhanced apoptosis and did not facilitate fibrogenesis. These effects together may explain the suppression of CCl4-induced promotion after DEN initiation exerted by carbonyl iron in the present study.

Increased levels of cytosolic thioredoxin reductase activity and mRNA in rat liver nodules

BACKGROUND/AIMS Thioredoxin reductase, a redox active enzyme, is induced in several tumors. This study focuses on the presence of and subcellular localisation of thioredoxin reductase in a tumor model where neoplastic lesions are selected by their resistance to the toxic effects of the promotor. METHODS Liver nodules produced by intermittent feeding of 2-acetylaminofluorene to male Wistar rats were analyzed for thioredoxin reductase (TrxR) activity and mRNA. RESULTS This activity was increased 3.5-fold in the cytosol but decreased 60% in the mitochondrial fraction compared to the liver of age-matched untreated animals. Only traces of activity were observed in the microsomal, plasma membrane and nuclear fractions from normal liver or nodules. The level of TrxR mRNA was 3-fold higher in nodules than in normal rat liver. Furthermore, the total level of SH groups in homogenates was 2-fold higher in the case of the nodules. CONCLUSIONS These findings indicate that the thioredoxin system makes an important contribution to the resistant phenotype of the neoplastic liver cell, which conveys a growth advantage of significance for tumor progression.

Loss of nicotinic receptors induced by beta-amyloid peptides in PC12 cells: Possible mechanism involving lipid peroxidation

The mechanisms involved in the loss of nicotinic acetylcholine receptors (nAChRs), seen in brains of patients with Alzheimers disease (AD) and in cultured cells treated by β‐amyloid peptides (Aβs), remain elusive. We give results to show that lipid peroxidation induced directly by Aβ might be involved in the deficits of nAChRs. In the study, PC12 cells were treated by addition of 5 μM of Aβ25–35 and Aβ1–40, respectively, with or without a antioxidant, vitamin E. Besides significantly decreased MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5,diphenyltetrazolium bromide) reduction, an increased lipid peroxidation was detected in the cells, but no protein oxidation. Significant reductions in [3H]epibatidine and [125I]α‐bungarotoxin binding sites and in the protein levels of the α3 and α7 nAChR subunits were observed in the cells treated with Aβs. Furthermore, Aβ25–35 decreased the level of ubiquinone‐9 in PC12 cells, but did not change the amount of cholesterol, providing further evidence for lipid peroxidation. Interestingly, when PC12 cells were pretreated by antioxidant before the addition of Aβs, the lipid peroxidation and the decreased ubiquinone resulted from Aβs were prohibited. The decreases of nAChR binding sites and subunit proteins resulted from Aβs were mostly prevented by the pretreatment with antioxidant. These findings suggest that lipid peroxidation stimulated by Aβs might be a mechanism for the loss of nAChRs associated with the pathogenesis of AD.

Animal models for treatment of unresectable liver tumours: a histopathologic and ultra-structural study of cellular toxic changes after electrochemical treatment in rat and dog liver

INTRODUCTION Electrochemical treatment (EChT) has been taken under serious consideration as being one of several techniques for local treatment of malignancies. The advantage of EChT is the minimal invasive approach and the absence of serious side effects. Macroscopic, histopathological and ultra-structural findings in liver following a four-electrode configuration (dog) and a two-electrode EChT design (dog and rat) were studied. MATERIALS AND METHODS 30 female Sprague-Dawley rats and four female beagle dogs were studied with EChT using Platinum:Iridium electrodes and the delivered dose was 5, 10 or 90 C (As). After EChT, the animals were euthanized. RESULTS The distribution of the lesions was predictable, irrespective of dose and electrode configuration. Destruction volumes were found to fit into a logarithmic curve (dose-response). Histopathological examination confirmed a spherical (rat) and cylindrical/ellipsoidal (dog) lesion. The type of necrosis differed due to electrode polarity. Ultra-structural analysis showed distinct features of cell damage depending on the distance from the electrode. Histopathological and ultra-structural examination demonstrated that the liver tissue close to the border of the lesion displayed a normal morphology. CONCLUSIONS The in vivo dose-planning model is reliable, even in species with larger tissue mass such as dogs. A multi-electrode EChT-design could obtain predictable lesions. The cellular toxicity following EChT is clearly identified and varies with the distance from the electrode and polarity. The distinct border between the lesion and normal tissue suggests that EChT in a clinical setting for the treatment of liver tumours can give a reliable destruction margin.

Lovastatin stimulates up‐regulation of α7 nicotinic receptors in cultured neurons without cholesterol dependency, a mechanism involving production of the α‐form of secreted amyloid precursor protein

The cholesterol‐lowering drug lovastatin enhances the secretion of the α‐secretase cleavage product of amyloid precursor protein (APP). To investigate whether this effect is mediated via activation of α7 nicotinic acetylcholine receptors (nAChRs), we treated SH‐SY5Y cells and PC12 cells with lovastatin and measured the levels of α7 nAChRs, the α‐form of secreted APP (αAPPs), and lovastatin‐related lipids, including cholesterol and ubiquinone. The results showed that low concentrations of lovastatin significantly induced up‐regulation of α7 nAChRs. No effects of lovastatin were observed on α3‐containing nAChRs, muscarinic receptors, or N‐methyl‐D‐aspartate receptors. αAPPs levels increased in the culture medium of cells treated with lovastatin, whereas no change in whole APP was observed. The increase in αAPPs was inhibited by prior exposure of these cells to α‐bungarotoxin, an antagonist of α7 nAChRs. The concentrations of lovastatin used in the study did not change the cholesterol content, but high doses can decrease the levels of ubiquinone and cell viability. These results indicate that lovastatin may play a neuronal role that is cholesterol independent. We also show that the up‐regulation of α7 nAChRs stimulated by lovastatin is involved in a mechanism that enhances production of αAPPs during APP processing.

Overexpression of thioredoxin reductase 1 inhibits migration of HEK-293 cells.

Background information. TrxR (thioredoxin reductase), in addition to protecting against oxidative stress, plays a role in the redox regulation of intracellular signalling pathways controlling, among others, cell proliferation and apoptosis. The aim of the present study was to determine whether TrxR1 is involved in the regulation of cell migration.