Serum thioredoxin-1 as a diagnostic marker for malignant peritoneal mesothelioma.

BACKGROUND: Diffuse malignant peritoneal mesothelioma (DMPM) is an aggressive malignant tumor of mesothelial origin that shows a limited response to cytoreductive surgery along with intraperitoneal chemotherapy. Therefore, diagnosing DMPM early is very important. Reactive oxygen species play an important role in asbestos toxicity, which is associated with the pathogenesis of DMPM growth. Thioredoxin-1 (TRX) is a small redox-active protein that demonstrates antioxidative activity associated with tumor growth. Here, we investigated the serum levels of TRX in patients with DMPM and compared them with those of a population that had been exposed to asbestos but did not have DMPM. STUDY: The serum concentrations of TRX were measured in 15 DMPM patients and 34 individuals with benign asbestos-related diseases. RESULTS: We demonstrated that the patients with DMPM had significantly higher serum levels of TRX than the population that had been exposed to asbestos but did not have DMPM. CONCLUSIONS: Our data suggest that serum TRX concentration is a useful serum marker for DMPM.

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.

Frequent inactivation of the BAP1 gene in epithelioid-type malignant mesothelioma.

In the present study, we analyzed genomic alterations of BRCA1-associated protein 1 (BAP1) in 23 malignant mesotheliomas (MMs), 16 epithelioid and seven non-epithelioid, consisting of 18 clinical specimens and five established cell lines. In examining these samples for homozygous deletions and sequence-level mutations, we found biallelic BAP1 gene alterations in 14 of 23 MMs (61%). Seven of these 14 MMs had homozygous deletions of the partial or entire BAP1 gene, another five had sequence-level mutations, including small deletions, a nonsense mutation, and missense mutations with additional monoallelic deletions, and the remaining two had homozygous mutations without allelic loss. All but one of the 14 BAP1 gene mutations were found in the epithelioid-type MMs; BAP1 mutations were found in 13 of 16 epithelioid-type MMs, but in only one of seven non-epithelioid-type MMs (13/16 vs 1/7; P = 0.005). There was no BAP1 mRNA expression in MMs with biallelic deletion and repressed expression was confirmed in MM specimens with deletion/mutation as compared with Met5a, SV40-transformed normal mesothelial cells. Western blot showed that seven of eight epithelioid MMs analyzed were BAP1 negative. Immunostaining with anti-BAP1 antibody in normal lung tissues revealed clear nuclear staining of normal mesothelial cells. No nuclear staining was observed among BAP1 mutation-positive MM tumors, whereas nuclear staining was observed among BAP1 mutation-negative MM tumors. These results suggest that the lack of the tumor suppressor BAP1 may be more specifically involved in the pathogenesis of epithelioid MM rather than non-epithelioid MM, and would be useful for diagnosis of epithelioid-type MM.

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.

Frequent deletion of 3p21.1 region carrying semaphorin 3G and aberrant expression of the genes participating in semaphorin signaling in the epithelioid type of malignant mesothelioma cells.

Array-based comparative genomic hybridization analysis was performed on 21 malignant mesothelioma (MM) samples (16 primary cell cultures and 5 cell lines) and two reactive mesothelial hyperplasia (RM) primary cell cultures. The RM samples did not have any genomic losses or gains. In MM samples, deletions in 1p, 3p21, 4q, 9p21, 16p13 and 22q were detected frequently. We focused on 3p21 because this deletion was specific to the epithelioid type. Especially, a deletion in 3p21.1 region carrying seven genes including SEMA3G was found in 52% of MM samples (11 of 14 epithelioid samples). The allele loss of 3p21.1 might be a good marker for the epithelioid MM. A homozygous deletion in this region was detected in two MM primary cell cultures. A heterozygous deletion detected in nine samples contained the 3p21.1 region and 3p21.31 one carrying the candidate tumor suppressor genes such as semaphorin 3F (SEMA3F), SEMA3B and Ras association (RalGDS/AF-6) domain family member 1 (RASSF1A). SEMA3B, 3F and 3G are class 3 semaphorins and inhibit growth by competing with vascular endothelial growth factor (VEGF) through binding to neuropilin. All MM samples downregulated the expression of more than one gene for SEMA3B, 3F and 3G when compared with Met5a, a normal pleura-derived cell line. Moreover, in 12 of 14 epithelioid MM samples the expression level of SEMA3A was lower than that in Met5a and the two RM samples. An augmented expression of VEGFA was detected in half of the MM samples. The expression ratio of VEGFA/SEMA3A was significantly higher in the epithelioid MMs than in Met5a, RMs and the non-epithelioid MMs. Our data suggest that the downregulated expression of SEMA3A and several SEMA3s results in a loss of inhibitory activities in tumor angiogenesis and tumor growth of VEGFA; therefore, it may play an important role on the pathogenesis of the epithelioid type of MM.

Clinical significance of pleural effusion mesothelin in malignant pleural mesothelioma.

BACKGROUND: 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 early diagnosis of MPM is very important. This study investigated the pleural effusion mesothelin levels in patients with MPM and compared them to those of a population with a non-malignant pleuritis or lung cancer involving malignant pleural effusion. METHODS: The pleural effusion mesothelin concentrations were measured in 45 MPM patients and 53 non-MPM individuals (24 individuals with non-malignant pleural effusions and 29 individuals with lung cancer involving malignant pleural effusion). RESULTS: This study demonstrated that patients with MPM had significantly higher pleural effusion mesothelin levels than a population with non-malignant pleuritis or lung cancer involving malignant pleural effusion. The difference in overall survival between the groups with pleural effusion mesothelin levels lower and higher than the assumed cut-off of 10 nM was significant. CONCLUSIONS: The data suggest that the pleural effusion mesothelin concentration could be useful as an aid for the diagnosis of MPM.

Pleural effusion VEGF levels as a prognostic factor of malignant pleural mesothelioma.

BACKGROUND: 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 early diagnosis of MPM is very important. Vascular endothelial growth factor (VEGF), a potent mitogen for the vascular endothelium, is also known to be an autocrine growth factor for MPM. Here, we investigated the pleural effusion VEGF levels in patients with MPM and compared them to those of a population with a non-malignant pleuritis or lung cancer involving malignant pleural effusion. METHODS: The pleural effusion VEGF concentrations were measured in 46 MPM patients and 45 individuals with non-MPM individuals (25 individuals with non-malignant pleural effusions, and 20 individuals with lung cancer involving malignant pleural effusion). RESULTS: We demonstrated that patients with MPM had significantly higher pleural effusion VEGF levels than a population with non-malignant pleuritis or lung cancer involving malignant pleural effusion, and the patients with advanced stage MPM showed higher levels of VEGF than the early stage MPM patients. The difference in overall survival between the groups with pleural effusion VEGF levels lower and higher than the assumed cut-off of 2000pg/ml was significant. CONCLUSIONS: Our data suggest that the pleural effusion VEGF concentration could be useful as an aid for the diagnosis of MPM and as a prognostic factor.

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.