A(2a) adenosine receptor mediates HepG2 cell apoptosis by downregulating Bcl-X(L) expression and upregulating Bid expression.

Extracellular adenosine induced apoptosis in HepG2 cells, a human hepatoma cell line, by tuning apoptosis-mediator gene transcription. The present study aimed at identifying the responsible adenosine receptor and clarifying the signaling pathway underlying adenosine-induced HepG2 cell apoptosis. Adenosine and CGS21680, an A(2a) adenosine receptor agonist, induced HepG2 cell apoptosis, and the effect was inhibited by DMPX, an A(2a) adenosine receptor antagonist, or by knocking-down A(2a) adenosine receptors. Adenosine reduced expression of Bcl-X(L) mRNA and protein but otherwise increased expression of the Bid mRNA and protein in HepG2 cells, and those effects were also prevented by knocking-down A(2a) adenosine receptors. Adenosine caused disruption of mitochondrial membrane potentials and stimulated cytochrome c efflux from the mitochondria in HepG2 cells. Adenosine activated caspases-3 and -9 in HepG2 cells, which was significantly inhibited by knocking-down A(2a) adenosine receptors. The results of the present study indicate that extracellular adenosine downregulates Bcl-X(L) expression and upregulates Bid expression, thereby disrupting mitochondrial membrane potentials to allow cytochrome c efflux from the mitochondria, and then causing activation of caspase-9 and the effector caspase-3, as mediated via A(2a) adenosine receptors.

Heme oxygenase-1 promoter polymorphism is associated with risk of malignant mesothelioma.

BACKGROUND: Malignant mesothelioma is an aggressive tumor of serosal surfaces that is closely associated with asbestos exposure which induces oxidative stress. Heme oxygenase (HO)-1, a rate-limiting enzyme of heme degradation, plays a protective role against oxidative stress. The HO-1 gene promoter carries (GT)n repeats whose number is inversely related to transcriptional activity of the HO-1 gene. METHODS: To investigate the relationship between the length polymorphism of (GT)n repeats and mesothelioma susceptibility, we analyzed the HO-1 promoter in 44 asbestos-exposed subjects without mesothelioma and 78 asbestos-exposed subjects with mesothelioma using PCR-based genotyping. RESULTS: The number of repeats ranged from 16 to 38, with two peaks at 23 and 30 repeats. Polymorphisms of (GT)n repeats were grouped into two classes of alleles, short (S) (<24) and long (L) (≥24), and three genotypes: L/L, L/S, and S/S. The proportions of allele frequencies in class L as well as genotypic frequencies of L allele carriers (L/L and L/S) were significantly higher in the asbestos-exposed subjects with mesothelioma than in those without mesothelioma. CONCLUSION: The findings of this study suggest that long (GT)n repeats in the HO-1 gene promoter are associated with a higher risk of malignant mesothelioma in the Japanese population.

[Expression of mesothelin as a potential diagnostic marker in mesothelioma].

Histological discrimination of mesothelioma from adenocarcinoma is often difficult, therefore, many investigators have tried immunohistochemical, ultrastructual, and molecular methods. Economically, immunohistological studies are more excellent, compared with ultrastractual and molecular biological methods. Immunohistologically, many well known markers are divided into two category; adenocarcinoma-related markers, which expressed by adenocarcinoma, and mesothelioma-related makers, which are positive for mesothelioma. CEA, TTF-1, and Ber-Ep4 are well known adenocarcinoma-related markers, mesothelin, TM, HBME-1 and calretinin, have been used as mesothelioma-related markers. Most previous reports associated with discrimination of adenocarcinoma and mesothelioma mentioned that a diagnosis of epithelioid mesothelioma would be excluded by the presence of adenocarcinoma-related antibody. The positive ratio of mesothelioma-related antibodies is lower than that of adenocarcinoma-related antibodies. Only a single mesothelioma-related marker cannot lead to a diagnosis of epithelioid mesothelioma and a correct diagnosis can be made by combination of several makers, which contain both mesothelioma-related markers and adenocarcinoma-related markers. We immunohistologically examined 41 cases of mesothelioma and 16 cases of adenocarcinoma of the lung, and re-evaluated the use of immunohistochemical markers, compared with previous reports. Reactivity for mesothelin was obtained in 19 (73%) of the epithelioid mesotheliomas, but none (0%) of the lung adenocarcinomas. None of the sarcomatoid mesotheliomas exhibited positivity for this marker, nor was any reactivity seen in the spindle cell component of the biphasic mesotheliomas. These findings indicate that, in some instances, mesothelin immunostaining can assist in the diagnosis of mesothelioma.

[A case of primary lung cancer with cervical tuberculous lymphadenitis].

A 66-year-old woman was admitted due to right cervical lymphadenopathy and an abnormal chest radiograph. Acid-fast bacilli smear of fine needle aspiration from a right cervical lymph node was positive. Histopathological examination of the specimen obtained by percutaneous right cervical lymph node biopsy showed necrotizing epithelioid granulomas and no malignant cells. Therefore, right cervical tuberculous lymphadenitis was diagnosed. Partial lung resection of the right S4 was carried out by video-assisted thoracoscopic surgery and primary lung cancer was diagnosed. To our knowledge, there has been no previous report of both primary lung cancer and cervical tuberculous lymphadenitis being present at the time of the first examination. We report this very rare case.

Combined serum mesothelin and carcinoembryonic antigen measurement in the diagnosis of malignant mesothelioma.

Malignant mesothelioma (MM) is a highly aggressive tumor associated with asbestos exposure. The identification of a marker specific for MM may be of considerable value for the early detection of this tumor and may be used in particular to screen groups with a history of asbestos exposure. The aim of this study was to evaluate serum soluble mesothelin-related peptide (SMRP) levels as a diagnostic marker for MM and investigate whether its diagnostic value is enhanced by combination with other biomarkers. Serum SMRP levels were measured using a quantitative enzyme-linked immunosorbent assay in 96 patients with MM, 55 patients with lung cancer and 39 individuals with a history of asbestos exposure. Receiver operating characteristic curves were constructed for performance evaluation. Stepwise logistic regression analysis was used to select marker combinations (MCs). Serum SMRP levels in patients with MM were significantly higher compared to those in the other groups (P<0.001). The sensitivity of SMRP levels in diagnosing MM was 56% and its specificity for MM vs. lung cancer and individuals with asbestos exposure was 87 and 92%, respectively. The area under the curve (AUC) was 0.76 [95% confidence interval (CI): 0.68-0.83] for the differentiation between MM and lung cancer and 0.78 (95% CI: 0.71-0.86) for the differentiation between MM and individuals with asbestos exposure. For the MC of presence of effusion, SMRP and carcinoembryonic antigen (CEA) levels, the AUC for the differentiation between MM and lung cancer (0.92; 95% CI: 0.88-0.97) and the differentiation between MM and individuals with asbestos exposure (0.93; 95% CI: 0.87-1.0) was significantly higher compared to that for SMRP alone (P=0.0001 and 0.0058, respectively). While the specificity of this MC was comparable to SMRP alone, its sensitivity was ∼20% higher compared to that of SMRP alone. Therefore, combining SMRP and CEA improves the diagnostic performance of SMRP alone. A combination of serum biomarkers, including SMRP, may facilitate the non-invasive diagnosis of MM.

Methotrexate and gemcitabine combination chemotherapy for the treatment of malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an aggressive tumor of serosal surfaces with a poor prognosis. Methotrexate and gemcitabine have exhibited single-agent activity in MPM. We evaluated the feasibility of sequential administration of these agents in the treatment of MPM. A total of 21 patients with MPM received a 30-min infusion of 100 mg/m2 methotrexate and, 30 min later, a 30-min infusion of 800 mg/m2 gemcitabine. Twenty-four hours following the administration of methotrexate, leucovorin rescue therapy was initiated (10 mg/m2 leucovorin administered 4 times at 6-h intervals). These treatments were administered weekly, with 4 weekly administrations constituting a cycle of therapy. A total of 88 cycles were administered to the 21 patients, with each patient receiving 1-10 cycles (median, 4.2 cycles). Eight patients (38.1%) exhibited a partial response, 10 patients (47.6%) had stable disease and 3 patients (14.3%) had progressive disease. The median overall survival was 19.4 months (range, 02-41 months). One-year and 2-year survival rates were 61.9 and 38.1%, respectively. Hematological toxicity was considered acceptable, with grade 3-4 toxicities occurring in 3 (14.3%) patients. Non-hematologic toxicity was generally mild. There was no treatment-related mortality. Our results suggest that methotrexate and gemcitabine combination therapy is feasible and effective in the treatment of MPM. This regimen may offer an alternative to platinum-based chemotherapy and a prospective trial including a larger cohort of patients is recommended to confirm these results.

Clinical significance of serum vascular endothelial growth factor in malignant pleural mesothelioma.

INTRODUCTION: Malignant pleural mesothelioma (MPM) is an aggressive malignant tumor of mesothelial origin associated with asbestos exposure. MPM has a limited response to conventional chemotherapy and radiotherapy so diagnosing MPM early is very important. Vascular endothelial growth factor (VEGF) is an autocrine growth factor for MPM. Here, we investigated the serum levels of VEGF in patients with MPM in comparison with a population that had been exposed to asbestos without developing MPM. METHODS: Serum concentrations of VEGF were measured in 51 patients with MPM and 42 individuals with benign asbestos-related diseases (asbestosis or pleural plaques) or who were healthy despite asbestos exposure. RESULTS: We demonstrated that patients with MPM had significantly higher serum levels of VEGF than a population who had been exposed to asbestos but had not developed MPM, and the patients with advanced stage MPM showed higher levels of VEGF than the early stage patients with MPM. The difference in overall survival between the groups with VEGF serum levels lower and higher than the assumed cutoff of 460 pg/ml was significant. CONCLUSIONS: Our data suggest that the VEGF serum concentration could be a useful marker for screening MPM among asbestos-exposed individuals and as a prognostic factor.