Biomedical subjects

V L Kinnula

Publications and source records attributed to V L Kinnula.

At least 37 records · Page 2Linked to original sources

PubMed2001

Widespread expression of thioredoxin and thioredoxin reductase in non-small cell lung carcinoma.

We investigated the expression of thioredoxin (Trx) and thioredoxin reductase (TrxR) in 89 non-small cell lung carcinomas. Additionally, immortalized human bronchial epithelial cells (BEAS 2B) and four human lung carcinoma cells lines (A549, SK-MES-1, CALU-6, and A427) were studied by Western blot and reverse transcription-PCR for the synthesis of Trx and TrxR protein and mRNA expression in vitro. The histological samples were also studied for immunohistochemical p53 and proliferating cell nuclear antigen expression and apoptosis. In non-neoplastic lung, Trx and TrxR expression was seen in bronchial epithelial cells and alveolar macrophages, metaplastic alveolar epithelial cells, and chondrocytes of the bronchus. In non-small cell lung carcinomas, there was a widespread expression of Trx and TrxR with only three and eight cases negative, respectively. Trx and TrxR expression was located in both cytoplasmic and nuclear compartments of the cells. There was a statistical association between cytoplasmic and nuclear Trx or TrxR expression. Grade I-II tumors showed stronger cytoplasmic and nuclear Trx and TrxR immunoreactivity than grade III tumors. No association was found between p53 and proliferating cell nuclear antigen expression and Trx or TrxR immunoreactivity. However, apoptosis was inversely associated with nuclear Trx and TrxR positivity. In the cell lines studied, both non-neoplastic BEAS 2B cells and all of the carcinoma cell lines expressed Trx and TrxR proteins and mRNA. The results show that these redox-regulating proteins are highly expressed in lung carcinomas taking part in activation of transcriptional factors and regulation of apoptosis in non-small cell lung carcinoma. In high-grade tumors, Trx and TrxR expression is diminished, suggesting loss of redox regulation in tumors with low differentiation.

Apoptosis↗

PubMed2001

Interstitial lung disease induced by exogenous agents: factors governing susceptibility.

The purpose of this review is to describe the present state of knowledge regarding host susceptibility factors that may determine the occurrence, development and severity of interstitial lung disease (ILD) caused by exogenous agents. First, host susceptibility may pertain to differences in the delivery and/or persistence of the noxious agent in the lung. The deposition and clearance of inhaled particles or fibres may vary depending on innate anatomical or physiological characteristics, and on acquired changes, such as nasal disease or smoking-induced alterations. Genetically- or environmentally-induced interindividual differences in the expression of pulmonary biotransformation enzymes may form the basis for, or contribute to the risk of, drug-induced interstitial lung disease. Secondly, there are genetic and acquired variations in various enzymatic and nonenzymatic defence systems that protect cells and tissues against oxidative stress, which is often involved in the pathogenesis of interstitial lung disease caused by particles, fibres, metals, organic agents and drugs. Thirdly, the occurrence of immunological sensitization is dependent on both genetic and environmental factors. This has been demonstrated in chronic beryllium lung disease and in hypersensitivity pneumonitis. Fourthly, the propensity of individuals to develop particular types of inflammation, such as granulomas, is probably under genetic control. The regulation and resolution of inflammation and fibrogenesis caused by dust particles are also partly determined by genetic factors, involving cytokine networks and growth factors. In conclusion, although the issue of genetics pervades the entire discussion of host susceptibility, genes are not the only determinants of health and disease. Environmental factors may be equally important in shaping host susceptibility. Therefore, research must be focused on both the genetic bases and the environmental determinants of interstitial lung disease, in order to provide mechanism-based prevention strategies, early detection of, and improved therapy for these conditions.

Air Pollutants↗

PubMed2000

Modulation of cell and DNA damage by poly(ADP)ribose polymerase in lung cells exposed to H(2)O(2) or asbestos fibres.

Poly(ADP)ribose polymerase (PARP) may participate in cell survival, apoptosis and development of DNA damage. We investigated the role of PARP in transformed human pleural mesothelial (MeT-5A) and alveolar epithelial (A549) cells exposed from 0.05 to 5mM hydrogen peroxide (H(2)O(2)) or crocidolite asbestos fibres (1-10 microg/cm(2)) in the presence and absence of 3-aminobenzamide (ABA), a PARP inhibitor. The cells were investigated for the development of cell injury, DNA single strand breaks and depletion of the cellular high-energy nucleotides. Compared to H(2)O(2), fibres caused a minor decrease in cell viability and effect on the cellular high-energy nucleotide depletion, and a marginal effect on the development of DNA strand breaks when assessed by the single cell gel electrophoresis (the Comet assay). Inhibition of PARP transiently protected the cells against acute H(2)O(2) related irreversible cell injury when assessed by microculture tetrazolium dye (XTT) assay and potentiated oxidant related DNA damage when assessed by the Comet assay. However, PARP inhibition had no significant effect on fibre-induced cell or DNA toxicity with the exception of one fibre concentration (2 microg/cm(2)) in MeT-5A cells. Apoptosis is often associated with PARP cleavage and caspase activation. Fibres did not cause PARP cleavage or activation of caspase 3 further confirming previous results about relatively low apoptotic potential of asbestos fibres. In conclusion, maintenance of cellular high-energy nucleotide pool and high viability of asbestos exposed cells may contribute to the survival and malignant conversion of lung cells exposed to the fibres.

Asbestos↗

PubMed2000

Proliferation, apoptosis, and manganese superoxide dismutase in malignant mesothelioma.

Proliferation and apoptotic indices of tumour cells may have important prognostic significance. Manganese superoxide dismutase (MnSOD), an important anti-oxidant enzyme, has been shown to decrease proliferation of malignant cells transfected with the MnSOD gene. The aim of the present study was to investigate the indices of cell proliferation and apoptosis and their prognostic significance in human mesothelioma and to assess the effect of MnSOD on the proliferation and apoptosis of the mesothelioma cells expressing high constitutive MnSOD activity. Tissue sections from 35 subjects with malignant pleural mesothelioma were studied for cell proliferation by Ki-67 immunohistochemistry and for apoptosis by the TUNEL assay. In additional experiments, 2 mesothelioma cell lines expressing either low (M14K) or high (M38K) MnSOD levels were assessed for proliferative and apoptotic responses to epirubicin. The median proliferation and apoptotic indices of the mesothelioma tissue were 8.2% and 0.75%, respectively. Patients with a high proliferation (>8%) or apoptotic index (>0.75%) showed a worse prognosis (p < 0.001). MnSOD expression was inversely correlated with cell proliferation (p = 0.02). Our cell line experiments indicated that cells expressing high MnSOD levels were more resistant to apoptosis and showed lower proliferation when exposed to epirubicin in vitro. These findings show that high proliferation and apoptosis are associated with a poor prognosis of mesothelioma and that a high MnSOD level is associated with low proliferation of tumour cells. Furthermore, experiments with cultured mesothelioma cells suggest the importance of MnSOD in the proliferation and apoptosis caused by drug exposure.

Adult↗

PubMed2000

Manganese superoxide dismutase as a diagnostic marker for malignant pleural mesothelioma.

Although several immunohistochemical markers are available, differential diagnosis between mesothelioma and metastatic adenocarcinoma of the pleura is difficult. We have found that the immunoreactivity of manganese superoxide dismutase (MnSOD), an important antioxidant enzyme, is high in mesothelioma compared to healthy pleural mesothelium. The aim of the present study was to investigate whether MnSOD can be used in the differential diagnosis of malignant mesothelioma and metastatic adenocarcinoma of the pleura. MnSOD expression was assessed by using immunohistochemistry in biopsies of malignant mesothelioma (n = 35) and metastatic adenocarcinoma of the pleura (n = 21). MnSOD immunoreactivity was assessed semiquantitatively with and without microwave pretreatment. Fifteen of the 35 malignant mesotheliomas showed moderate or strong MnSOD expression without and 23 with microwave pretreatment, the corresponding figures for metastatic adenocarcinoma of the pleura being 1 and 2 out of 21 (P = 0.002 and P < 0.001, respectively by Fisher's exact test). Only mesothelioma biopsies showed strong MnSOD reactivity, and it was never negative in mesothelioma, whereas one-third of the adenocarcinomas showed no MnSOD reactivity. In conclusion, MnSOD immunoreactivity can, combined with other markers, aid the differential diagnosis between malignant mesothelioma and metastatic adenocarcinoma of the pleura.

Adenocarcinoma↗

PubMed2000

Expression of antioxidant enzymes in human inflammatory cells.

Because antioxidant enzymes may have an important role in the oxidant resistance of inflammatory cells, we investigated the mRNA levels and specific activities of manganese and copper-zinc superoxide dismutases (Mn SOD and Cu,Zn SOD), catalase (Cat), and glutathione peroxidase, as well as the concentrations of glutathione (GSH) in human neutrophils, monocytes, monocyte-derived macrophages, and alveolar macrophages. Levels of GSH and glutathione peroxidase activity in monocytes were three times higher than in neutrophils, whereas the mRNA of Cat was 50-fold and its specific activity 4-fold higher in neutrophils. Although Mn SOD mRNA levels were higher in neutrophils, enzyme activities, as well as those of Cu,Zn SOD, were similar in all phagocytic cells. Neutrophils lost their viability, assessed by adenine nucleotide depletion, within 24 h ex vivo and more rapidly if GSH was depleted. However, neutrophils were the most resistant cell type to exogenous H(2)O(2). In conclusion, high Cat activity of neutrophils appears to explain their high resistance against exogenous H(2)O(2), whereas low GSH content and GSH-related enzymes seem to account for the poor survival of human neutrophils.

Adenosine Diphosphate↗

PubMed2000

Antioxidant defense mechanisms of human mesothelioma and lung adenocarcinoma cells.

The development of drug resistance of tumors is multifactorial and still poorly understood. Some cytotoxic drugs generate free radicals, and, therefore, antioxidant enzymes may contribute to drug resistance. We investigated the levels of manganese superoxide dismutase (Mn SOD), its inducibility, and its protective role against tumor necrosis factor-alpha and cytotoxic drugs (cisplatin, epirubicin, methotrexate, and vindesin) in human pleural mesothelioma (M14K) and pulmonary adenocarcinoma (A549) cells. We also studied other major antioxidant mechanisms in relation to oxidant and drug resistance of these cells. A549 cells were more resistant than M14K cells toward both oxidants (hydrogen peroxide and menadione) and all the cytotoxic drugs tested. M14K cells contained higher basal Mn SOD activity than A549 cells (28.3 +/- 3.4 vs. 1.8 +/- 0.3 U/mg protein), and Mn SOD activity was significantly induced by tumor necrosis factor-alpha only in A549 cells (+524%), but the induction did not offer any protection during subsequent oxidant or drug exposure. Mn SOD was not induced significantly in either of these cell lines by any of the cytotoxic drugs (0.007-2 microM, 48 h) tested when assessed by Northern blotting, Western blotting, or specific activity. A549 cells contained higher catalase activity than M14K cells (7.6 +/- 1.3 vs. 3.6 +/- 0.5 nmol O(2). min(-1). mg protein(-1)). They also contained twofold higher levels of glutathione and higher immunoreactivity of the heavy subunit of gamma-glutamylcysteine synthetase than M14K cells. Experiments with inhibitors of gamma-glutamylcysteine synthetase and catalase supported our conclusion that mechanisms associated with glutathione contribute to the drug resistance of these cells.

Adenocarcinoma↗

PubMed2000

Manganese superoxide dismutase and catalase are coordinately expressed in the alveolar region in chronic interstitial pneumonias and granulomatous diseases of the lung.

Free radicals have been suggested to play an important role in the pathogenesis of interstitial lung diseases, the most important of which are chronic interstitial pneumonias such as usual interstitial pneumonia (UIP) and desquamative interstitial pneumonia (DIP) and granulomatous lung diseases such as sarcoidosis. Because manganese superoxide dismutase (MnSOD) and catalase are two important intracellular antioxidant enzymes that probably play a central role in lung defense, the localization and intensity of these two enzymes were assessed by immunohistochemistry in biopsies of UIP (n = 9), DIP (n = 11), pulmonary sarcoidosis (n = 14), and extrinsic allergic alveolitis (n = 6). The mRNA of these enzymes in selected samples of bronchoalveolar lavage was assessed by Northern blotting. Catalase, but not MnSOD, was constitutively expressed, especially in type II pneumocytes of the healthy lung of nonsmoking individuals. In contrast, manganese SOD immunoreactivity was markedly upregulated in all of the interstitial lung diseases investigated, whereas no increased expression of catalase could be detected in any case. Both enzymes were expressed, especially in type II pneumocytes and alveolar macrophages of DIP and UIP, in the well-preserved areas of the lung, in the acute fibromyxoid lesions of UIP, and in the granulomas of sarcoidosis and extrinsic allergic alveolitis. The simultaneous expression of MnSOD and catalase in the alveolar region suggests their protective role against the progression of lung disease.

Adult↗

PubMed2000

Tenascin expression and distribution in pleural inflammatory and fibrotic diseases.

We hypothesized that tenascin expression is increased in pleural inflammatory and fibrotic diseases and that its expression can be used as a marker of active pleural involvement. For this purpose we analyzed 71 histological samples of inflammatory and fibrotic pleura from patients with asbestos-induced pleural reaction (n = 6), postcardiac injury syndrome (n = 6), parapneumonic infection and/or empyema (n = 23), tuberculosis (n = 5, rheumatoid disease (n = 1), and fibrosis with inflammation of unknown etiology (n = 30). All 71 cases were studied by immunohistochemistry for tenascin. In 19 selected cases tenascin mRNA in situ hybridization was also performed. In every case, tenascin was increased by immunohistochemistry. Most prominent immunoreactivity was detected in areas of newly formed fibrosis. Increased tenascin mRNA expression by in situ hybridization was detected in the individual cells of the newly formed fibrosis underneath the fibrinous exudate. The tenascin mRNA-positive cells localized in areas in which by immunohistochemical studies the cells were positive for alpha-smooth muscle actin, desmin, and vimentin, suggesting a myofibroblast phenotype. Tenascin mRNA expression was also seen less frequently in areas in which some cells were positive for cytokeratin. These cells might represent mesothelial cells entrapped in the inflammatory lesion. Alternatively, they might represent fibroblast-type cells with aberrant cytokeratin expression. We conclude that in pleural inflammatory and fibrotic diseases tenascin immunoreactivity is increased and tenascin mRNA-positive cells localized mainly in the areas of myofibroblast- and, less often, mesothelial-type cells, suggesting that mainly myofibroblasts and, less commonly, also mesothelial cells might be responsible for tenascin expression in pleural inflammatory and fibrotic diseases. (J Histochem Cytochem 48:1257-1268, 2000)

Aged↗

PubMed1999

Carboxyterminal propeptide of type I procollagen in ELF: elevation in asbestosis, but not in pleural plaque disease.

Markers of collagen metabolism may possibly be used in the assessment of pulmonary involvement in asbestosis-related pulmonary diseases. In this study the levels of the carboxyterminal propeptide of type I procollagen (PICP) and the aminoterminal propeptide of type III procollagen (PIIINP) were evaluated in bronchoalveolar lavage fluid (BALF), epithelial lining fluid (ELF) and serum from patients with asbestos related pulmonary and pleural involvement. Forty-two consecutive patients with occupational exposure to asbestos fibres, who underwent bronchoscopy and bronchoalveolar lavage (BAL) at the time of the diagnosis were investigated. Five patients were diagnosed as having asbestosis, while 37 showed no parenchymal involvement. Of the latter group, 25 had pleural plaques, while 12 had no detectable changes in chest radiographs. The patients were followed-up for an average of 7 yrs. The PICP in BALF and ELF was detectable in all patients with asbestosis and in 8/37 subjects without parenchymal involvement. The levels of PICP in BALF and ELF were significantly higher in the asbestosis group compared to the patients without asbestosis (9.8+/-1.8 microg x L(-1) versus 0.6+/-1.3 microg x L(-1), p<0.001 and 488.9+/-208.8 microg x L(-1) versus 22.6+/-50.6 microg x L(-1), p<0.001, respectively). Only 1 patient with asbestosis and 3 patients without parenchymal involvement had detectable levels of PIIINP in BALF. The serum levels of PICP and PIIINP did not differ between the patients with asbestosis and those with exposure to asbestos fibres without asbestosis and were within the normal range. None of the 37 patients exposed to asbestos fibres without parenchymal involvement at the baseline developed asbestosis during the follow-up period of 7 yrs. In conclusion, the data show that the carboxyterminal propeptide of procollagen type I, but not the aminoterminal propeptide of type III procollagen is highly elevated in bronchoalveolar lavage fluid and epithelial lining fluid in patients with asbestosis, but not in those without parenchymal involvement. This suggests that the determination of carboxyterminal propeptide of procollagen type I in bronchoalveolar lavage fluid could be used as a marker of parenchymal involvement in patients exposed to asbestos fibres.

Asbestos↗

PubMed1999

Oxidant and antioxidant mechanisms of lung disease caused by asbestos fibres.

The pathogenesis of asbestos-related lung diseases is complicated and still poorly understood. Studies on animal models and cell cultures have indicated that asbestos fibres generate reactive oxygen and nitrogen species and cause oxidation and/or nitrosylation of proteins and deoxyribonucleic acid as a marker of cell injury. These effects are potentiated by the inflammation caused by the fibres. Recent studies have shown that individual variability in the antioxidant and/or detoxifying mechanisms probably has an important role in the development of asbestos-related lung diseases. Asbestos fibres cause both cell proliferation and apoptosis by multiple mechanisms, one of them being activation of signal transduction pathways by reactive oxygen and nitrogen species. Asbestos activates transcription factors such as nuclear factor kappa B, which has been shown to lead to the upregulation of antioxidant enzymes, most importantly manganese superoxide dismutase. This enzyme is also overexpressed in asbestos-related human malignant mesothelioma, whereas the induction of other antioxidant enzymes (copper-zinc superoxide dismutase, catalase, glutathione peroxidase) by asbestos fibres appears to be marginal. The significance of antioxidant enzymes in asbestos related diseases has, however, remained unclear. Furthermore, previous studies have not been able to offer successful therapies to the patients with asbestos-associated diseases. Only an improved understanding of the pathogenetic mechanisms in the human lung provides a basis for future therapies for asbestos-related diseases.

Animals↗

PubMed1999

Generation of reactive oxygen species by human mesothelioma cells.

Malignant mesothelioma cells contain elevated levels of manganese superoxide dismutase (MnSOD) and are highly resistant to oxidants compared to non-malignant mesothelial cells. Since the level of cellular free radicals may be important for cell survival, we hypothesized that the increase of MnSOD in the mitochondria of mesothelioma cells may alter the free radical levels of these organelles. First, MnSOD activity was compared to the activities of two constitutive mitochondrial enzymes; MnSOD activity was 20 times higher in the mesothelioma cells than in the mesothelial cells, whereas the activities of citrate synthase and cytochrome c oxidase did not differ significantly in the two cell lines. This indicates that the activity of MnSOD per mitochondrion was increased in the mesothelioma cells. Superoxide production was assayed in the isolated mitochondria of these cells using lucigenin chemiluminescence. Mitochondrial superoxide levels were significantly lower (72%) in the mesothelioma cells compared to the mesothelial cells. Oxidant production in intact cells, assayed by fluorimetry using 2',7'-dichlorodihydrofluorescein as a fluorescent probe, did not differ significantly between these cells. We conclude that mitochondrial superoxide levels are lower in mesothelioma cells compared to nonmalignant mesothelial cells, and that this difference may be explained by higher MnSOD activity in the mitochondria of these cells. Oxidant production was not different in these cells, which may be due to the previously observed increase in H2O2-scavenging mechanisms of mesothelioma cells.

Amitrole↗

PubMed1999

An epidemiological study of lung cancer: history and histological types in a general population in northern Finland.

A prospective epidemiological study was conducted to assess the incidence, diagnosis, histology and surgical treatment of lung cancer in northern Finland. The results were compared with those obtained in a similar survey 20 yrs earlier. Most of the patients with a suspected lung tumour were interviewed (72%) and the information was combined with that obtained from the national cancer registry. All pathological specimens were re-evaluated by a pathologist. A total of 602 new lung cancer cases (85% male, 15% female) were diagnosed during the years 1990-1992, the annual incidence per 100,000 being 63 for males and 9.5 for females. The number not reported to the Finnish Cancer Registry was low (<1%). Lung cancer was confirmed histologically in 381 cases (63%) and in addition cytologically in 135 cases (23%). Squamous cell carcinoma was the most common histological type (40%), the proportion of adenocarcinoma being 26%, small cell carcinoma 24% and large cell carcinoma 4%. The incidence of lung cancer had decreased significantly among males (from 87 to 63 per 100,000) compared with 20 yrs earlier but had increased among females (from 4.1 to 9.5), chiefly on account of adenocarcinoma. The findings of this prospective study show an increase in the incidence of lung adenocarcinoma among females, a histological type which is less closely related to smoking than the other cancers. This suggests that other risk factors may play an increasing role in the aetiology of lung cancer.

Aged↗

PubMed1999

DNA single strand breaks induced by asbestos fibers in human pleural mesothelial cells in vitro.

The mechanisms of the cellular effects and DNA damage caused by asbestos fibers in human mesothelial cells are not well understood. We exposed transformed human pleural mesothelial cells to 1-4 microg/cm2 crocidolite and to 10-100 ng/ml tumor necrosis factor alpha for up to 48 hr and studied the induction of DNA damage using the Comet assay. As a positive control, 100 microM H2O2 was used. The DNA single strand breaks were assessed as the mean tail moments and as distributions of the tail DNA in the cell. The Comet assay showed significant but reversible increases in the mean tail moments, but not in the distribution of Comet tails in the histograms in cells exposed to 1 microg/cm2 crocidolite for 6 hr. At higher concentrations of asbestos fibers all the indices in the Comet assay showed significant and irreversible change. All the doses of TNF-alpha caused marginal increase in the mean tail moments. The mean tail moments were highest in the cells with concurrent treatment to TNF-alpha and crocidolite. In the cells pretreated with inhibitors of antioxidant enzymes (aminotriazole for catalase and buthionine sulfoximine for gamma-glutamylcysteine synthetase) asbestos fibers slightly increased oxidant-related fluorescence of dichlorofluorescein (DCFH) but did not cause any further increases in the mean tail moments. This study shows that asbestos fibers cause DNA single strand breaks in human mesothelial cells. Since the inhibition of antioxidant enzymes did not have an effect on the DNA damage caused by the fibers, other mechanisms than free radicals seem to be involved in the induction of DNA damage by mineral fibers.

Asbestos, Crocidolite↗

PubMed1998

Similarities between TNF and exogenous oxidants on the cytotoxic response of c-Myc-expressing fibroblasts in vitro.

Normal fibroblasts are resistant to the cytotoxic activity of tumor necrosis factor-alpha, but are rendered TNF-sensitive upon oncogenic expression of c-Myc. Free radical generation has been implicated in non-cytotoxic TNF-signaling but also as a mediator of TNF-induced cell death. In this study we used Rat1 fibroblasts containing a conditionally active form of oncogenic c-Myc (MycER) to investigate single cell line TNF-induced free oxygen radical formation during the non-cytotoxic TNF-response (inactive c-Myc) and cytotoxic response (active c-Myc). The generation of reactive oxygen species (ROS) was assayed using a fluorescent probe, dichlorodihydrofluorescein (DCFH-DA), and the following cellular injury by measuring the high energy nucleotide (ATP, ADP and AMP) depletion. We found that TNF treatment of Rat1 cells containing c-Myc in an inactive form did not induce a detectable level of ROS generation. In contrast, TNF treatment of Rat1 cells containing activated c-Myc caused fluorescence reaction indicative of ROS generation within 80 min after DCFH-DA exposure of the cells. The nucleotide depletion likely reflected the action of ROS, since the nucleotide depletion caused by TNF or oxidants such as menadione or H2O2 in cells with active c-Myc was partly inhibited by the anti-oxidant N-acetylcysteine.

Adenine Nucleotides↗

PubMed1998

DNA single strand breaks and adenine nucleotide depletion as indices of oxidant effects on human lung cells.

The comet assay (single cell gel electrophoresis) is a novel method to assess DNA strand breaks in single cells. We studied the oxidant sensitivity of cultured primary and transformed (MeT-5A) human pleural mesothelial cells, as well as primary and transformed (BEAS 2B) human bronchial epithelial cells, and compared the results obtained with the Comet assay to other markers of oxidant effects on cells, such as depletion of intracellular high-energy nucleotides (ATP, ADP, AMP), accumulation of products of nucleotide catabolism (xanthine, hypoxanthine, uric acid), and release of lactate dehydrogenase (LDH). The cells were exposed for 5 min to 4 h to 50-500 microM H2O2 or to 5-50 microM menadione. Significant tail moment increase, which is a marker of DNA strand breaks in the Comet assay, and intracellular nucleotide depletion occurred simultaneously in MeT-5A and BEAS 2B cells during the first 30-60 min of exposure to H2O2 and menadione. In the Comet assay variation between the individual cells could be detected. LDH release, a marker of cell injury, showed that mesothelial cells were far more sensitive than epithelial cells to oxidant-induced lytic cell injury. MeT-5A and BEAS 2B cells contained similar intracellular antioxidant enzyme activities, which may explain their similar oxidant sensitivity in the Comet assay. A significant increase (164%) in the tail moment was detectable in MeT-5A cells exposed to 50 microM H2O2 for 30 min. This returned to control level during the 4 h of continuing exposure. A 30 min exposure of 25 microM menadione caused a 61% increase in the mean tail moment but, unlike with H2O2, the change was irreversible during the following 4 h incubation. We conclude that human pleural mesothelial cells and bronchial epithelial cells show similar oxidant sensitivity when assessed by the Comet assay, but various oxidants differ in their potency in causing DNA breaks in these cells.

Adenine Nucleotides↗

PubMed1998

Endogenous antioxidant enzymes and glutathione S-transferase in protection of mesothelioma cells against hydrogen peroxide and epirubicin toxicity.

We have previously shown that cultured malignant mesothelioma cells contain elevated manganese superoxide dismutase (MnSOD) mRNA levels and activities compared with non-malignant mesothelial cells. As many cytotoxic drugs generate both superoxide and hydrogen peroxide, we assessed the relative significance of catalase and the glutathione redox cycle, as well as glutathione S-transferase (GST), in protecting these cells against hydrogen peroxide and epirubicin toxicity. Mesothelioma cell lines containing high (M38K cells) and low (M14K cells) MnSOD, and non-malignant MeT-5A mesothelial cells were selected for the study. M38K cells were the most resistant of these three cell types to hydrogen peroxide (0.1-0.5 mM, 4 h) and epirubicin (0.1-0.5 microg ml(-1), 48 h) as judged by lactate dehydrogenase (LDH) release and by high-energy nucleotide (ATP, ADP, AMP) depletion. Total glutathione was higher in M38K cells (63.8 +/- 20.3 nnmol mg(-1) protein) than in M14K (25.2 +/- 8.2 nmol mg[-1]) or MeT-5A cells (23.5 +/- 4.5 nmol mg[-1]). Furthermore, GST specific activity was higher in M38K cells (111.3 +/- 15.8 U mg[-1]) than in M14K cells (77.4 +/- 6.6 U mg[-1]) or in MeT-5A cells (68.8 +/- 7.6 U mg[-1]). Western blotting indicated the presence of GST-pi in all these cells, the reactivity again being highest in M38K cells. Depletion of glutathione by buthionine sulphoximine and inhibition of catalase by aminotriazole enhanced hydrogen peroxide toxicity in all cell types, while only the depletion of glutathione increased epirubicin toxicity. We conclude that simultaneous induction of multiple antioxidant enzymes can occur in human mesothelioma cells. In addition to the high MnSOD activity, hydrogen peroxide scavenging antioxidant enzymes, glutathione and GST can partly explain the high hydrogen peroxide and epirubicin resistance of these cells in vitro.

Antibiotics, Antineoplastic↗

PubMed1998

Benign intrathoracic tumours. A population survey in northern Finland.

Benign intrathoracic tumours are uncommon, but their occurrence in unselected populations is poorly defined. We reviewed all cases of suspected intrathoracic tumour in a population (440,000) in northern Finland during 1990 through 1992. Diagnostic investigations included fiberoptic bronchoscopy and computed tomography in all cases. Of the 653 intrathoracic tumours, 36 were benign. The male/female ratio in these 36 cases was 1.25; the mean age was 54 years. Twenty-three of the lesions were symptomless, found at health check or examination for other disease. Bronchoscopy did not confirm the diagnosis of any benign tumour. Thoracotomy was considered necessary in most cases and histologic diagnosis was therefore available in 24 (67%). Hamartoma was the most common benign lung tumour. This prospective study in an unselected population confirms previous findings in surgical series concerning benign intrathoracic tumours and their histology.

Adult↗