Diagnostic tumor marker of asbestos-related mesothelioma

Chemokine (C-C motif) ligand 3 detection in the serum of persons exposed to asbestos: A patient-based study

Exposure to asbestos results in serious risk of developing lung and mesothelial diseases. Currently, there are no biomarkers that can be used to diagnose asbestos exposure. The purpose of the present study was to determine whether the levels or detection rate of chemokine (C-C motif) ligand 3 (CCL3) in the serum are elevated in persons exposed to asbestos. The primary study group consisted of 76 healthy subjects not exposed to asbestos and 172 healthy subjects possibly exposed to asbestos. The secondary study group consisted of 535 subjects possibly exposed to asbestos and diagnosed with pleural plaque (412), benign hydrothorax (10), asbestosis (86), lung cancer (17), and malignant mesothelioma (10). All study subjects who were possibly exposed to asbestos had a certificate of asbestos exposure issued by the Japanese Ministry of Health, Labour and Welfare. For the primary study group, levels of serum CCL3 did not differ between the two groups. However, the detection rate of CCL3 in the serum of healthy subjects possibly exposed to asbestos (30.2%) was significantly higher (P < 0.001) than for the control group (6.6%). The pleural plaque, benign hydrothorax, asbestosis, and lung cancer groups had serum CCL3 levels and detection rates similar to that of healthy subjects possibly exposed to asbestos. The CCL3 chemokine was detected in the serum of 9 of the 10 patients diagnosed with malignant mesothelioma. Three of the patients with malignant mesothelioma had exceptionally high CCL3 levels. Malignant mesothelioma cells from four biopsy cases and an autopsy case were positive for CCL3, possibly identifying the source of the CCL3 in the three malignant mesothelioma patients with exceptionally high serum CCL3 levels. In conclusion, a significantly higher percentage of healthy persons possibly exposed to asbestos had detectable levels of serum CCL3 compared to healthy unexposed control subjects.

Malignant peritoneal mesothelioma with lymph node metastasis that originated in the transverse colon

Background

We report an extremely rare case of resection of localized biphasic malignant peritoneal mesothelioma of the transverse colon.

Case report

Computed tomography and magnetic resonance imaging in a 72-year-old man showed a tumor with enhanced borders consistent with the transverse colon. Colonoscopy showed ulcerative lesions in the transverse colon, but histological examination showed no malignancy. A gastrointestinal stromal tumor was strongly suspected, so an extended right hemicolectomy was performed. Histopathological examination showed that the tumor was a localized malignant peritoneal mesothelioma of the transverse colon. The patient did not receive postoperative chemotherapy and died 18 months after surgery.

Conclusions

The number of patients with malignant mesotheliomas is predicted to increase in the future both in Japan and in western countries. We report this case due to its probable usefulness in future studies pertaining to the diagnosis and treatment of malignant mesotheliomas.

ERC/mesothelin is expressed in human gastric cancer tissues and cell lines

ERC/mesothelin is expressed in mesothelioma and other malignancies. The ERC/mesothelin gene (MSLN) encodes a 71-kDa precursor protein, which is cleaved to yield 31-kDa N-terminal (N-ERC/mesothelin) and 40-kDa C-terminal (C-ERC/mesothelin) proteins. N-ERC/mesothelin is a soluble protein and has been reported to be a diagnostic serum marker of mesothelioma and ovarian cancer. Gastric cancer tissue also expresses C-ERC/mesothelin, but the significance of serum N-ERC levels for diagnosing gastric cancer has not yet been studied. We examined the latter issue in the present study as well as C-ERC/mesothelin expression in human gastric cancer tissues and cell lines. We immunohistochemically examined C-ERC/mesothelin expression in tissue samples from 50 cases of gastric cancer, and we also assessed the C-ERC/mesothelin expression in 6 gastric cancer cell lines (MKN-1, MKN-7, MKN-74, NUGC-3, NUGC-4 and TMK-1) using reverse transcription-polymerase chain reaction, flow cytometry, immunohistochemistry and immunoblotting. We also examined the N-ERC/mesothelin concentrations in the supernatants of cultured cells and in the sera of gastric cancer patients using an enzyme-linked immunosorbent assay (ELISA). N-ERC/mesothelin was detected in the supernatants of 3 gastric cancer cell lines (MKN-1, NUGC-4 and TMK-1) by ELISA, but its concentration in the sera of gastric cancer patients was almost same as that observed in the sera of the normal controls. In the gastric cancer tissues, C-ERC/mesothelin expression was associated with lymphatic invasion. N-ERC/mesothelin was secreted into the supernatants of gastric cancer cell lines, but does not appear to be a useful serum marker of gastric cancer.

[Regarding the special feature of "the frontline of nanoparticle research": progress of the Study Group on Fibrous and Particulate Substances (SGFPS)]

Among the symposia organized by various study groups in the Japanese Society of Hygiene (JSH), the Study Group on Fibrous and Particulate Substances (SGFPS) presented a symposium entitled "The frontline of nanoparticle research" chaired by Professor Takemi Otsuki (Kawasaki Medical School, Japan) and Dr. Seishiro Hirano (National Institute for Environmental Studies, Japan) on 26 March, 2012, as a part of the program of the 82nd Annual Meeting of JSH in Kyoto, Japan. Special features consist of three presentations given at the above-mentioned symposium. In this article, we introduce the progress of the Study Group on Fibrous and Particulate Substances (SGFPS) from the initial symposium entitled "Asbestos: Science and Society" held at the 76th Annual Meeting of JSH at Ube, Japan to the last above-mentioned symposium in Kyoto. The health-related issues caused by exposure to fibrous materials such as asbestos and also particulated substances such as nanoparticles will be lasting in the future and researchers including our study group have to make their best efforts to resolve these problems and to reduce health impairments due to exposure to environmental fibrous and particulated substances.

Aberrant DNA methylation profile in pleural fluid for differential diagnosis of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) usually develops pleural fluid. We investigated the value of DNA methylation in the pleural fluid for differentiating MPM from lung cancer (LC). Pleural fluid was collected from 39 patients with MPM, 46 with LC, 25 with benign asbestos pleurisy (BAP) and 30 with other causes. The methylation of O(6)-methylguanine-DNA methyltransferase (MGMT), p16(INK4a) , ras association domain family 1A (RASSF1A), death-associated protein kinase (DAPK), and retinoic acid receptor β (RARβ) was examined using quantitative real-time PCR. DNA methylation of RASSF1A, p16(INK4a), RARβ, MGMT and DAPK was detected in 12 (30.8%), 3 (7.7%), 11 (28.2%), 0 (0.0%) and five patients (12.8%) with MPM, and in 22 (47.8%), 14 (30.4%), 24 (52.2%), 1 (2.2%) and six patients (13.0%) with LC, respectively. The mean methylation ratios of RASSF1A, p16(INK4a) and RARβ were 0.37 (range 0.0-2.84), 0.11 (0.0-2.67) and 0.44 (0.0-3.32) in MPM, and 0.87 (0.0-3.14), 1.16 (0.0-5.35) and 1.69 (0.0-6.49) in LC, respectively. The methylation ratios for the three genes were significantly higher in LC than in MPM (RASSF1A, P = 0.039; p16(INK4a), P = 0.005; and RARβ, P = 0.002). Patients with methylation in at least one gene were 3.51 (95% confidence interval, 1.09-11.34) times more likely to have LC. Hypermethylation seemed no greater with MPM than with BAP. Extended exposure to asbestos (≧30 years) was correlated with an increased methylation frequency (P = 0.020). Hypermethylation of tumor suppressor genes in pleural fluid DNA has the potential to be a valuable marker for differentiating MPM from LC.

[Archives of "comprehensive approach on asbestos-related diseases" supported by the "special coordination funds for promoting science and technology (H18-1-3-3-1)"-- overview of group research project, care and specimen registration, cellular characteristics of mesothelioma and immunological effects of asbestos]

The research project entitled "Comprehensive approach on asbestos-related diseases" supported by the "Special Coordination Funds for Promoting Science and Technology (H18-1-3-3-1)" began in 2006 and was completed at the end of the Japanese fiscal year of 2010. This project included four parts; (1) malignant mesothelioma (MM) cases and specimen registration, (2) development of procedures for the early diagnosis of MM, (3) commencement of clinical investigations including multimodal approaches, and (4) basic research comprising three components; (i) cellular and molecular characterization of mesothelioma cells, (ii) immunological effects of asbestos, and (iii) elucidation of asbestos-induced carcinogenesis using animal models. In this special issue of the Japanese Journal of Hygiene, we briefly introduce the achievements of our project. The second and third parts and the third component of the fourth part are described in other manuscripts written by Professors Fukuoka, Hasegawa, and Toyokuni. In this manuscript, we introduce a brief summary of the first part "MM cases and specimen registration", the first component of the fourth part "Cellular and molecular characterization of mesothelioma cells" and the second component of the fourth part "Immunological effects of asbestos". In addition, a previous special issue presented by the Study Group of Fibrous and Particulate Substances (SGFPS) (chaired by Professor Otsuki, Kawasaki Medical School, Japan) for the Japanese Society of Hygiene and published in Environmental Health and Preventive Medicine Volume 13, 2008, included reviews of the aforementioned first component of the fourth part of the project. Taken together, our project led medical investigations regarding asbestos and MM progress and contributed towards the care and examination of patients with asbestos-related diseases during these five years. Further investigations are required to facilitate the development of preventive measures and the cure of asbestos-related diseases, particularly in Japan, where asbestos-related diseases are predicted to increase in the next 10 to 20 years.

Deficiency of the Erc/mesothelin gene ameliorates renal carcinogenesis in Tsc2 knockout mice

Genetic crossing experiments were performed between tuberous sclerosis-2 (Tsc2) KO and expressed in renal carcinoma (Erc) KO mice to analyze the function of the Erc/mesothelin gene in renal carcinogenesis. We found the number and size of renal tumors were significantly less in Tsc2+/-;Erc-/- mice than in Tsc2+/-;Erc+/+ and Tsc2+/-;Erc+/- mice. Tumors from Tsc2+/-;Erc-/- mice exhibited reduced cell proliferation and increased apoptosis, as determined by proliferating cell nuclear antigen (Ki67) and TUNEL analysis, respectively. Adhesion to collagen-coated plates in vitro was enhanced in Erc-restored cells and decreased in Erc-suppressed cells with siRNA. Tumor formation by Tsc2-deficient cells in nude mice was remarkably suppressed by stable knockdown of Erc with shRNA. Western blot analysis showed that the phosphorylation of focal adhesion kinase, Akt and signal transducer and activator of transcription protein 3 were weaker in Erc-deficient/suppressed cells compared with Erc-expressed cells. These results indicate that deficiency of the Erc/mesothelin gene ameliorates renal carcinogenesis in Tsc2 KO mice and inhibits the phosphorylation of several kinases of cell adhesion mechanism. This suggests that Erc/mesothelin may have an important role in the promotion and/or maintenance of carcinogenesis by influencing cell-substrate adhesion via the integrin-related signal pathway.

[Immunological effects of silica/asbestos]

Silica and asbestos cause pneumoconioses known as silicosis and asbestosis, respectively, that are each characterized by progressive pulmonary fibrosis. On the other hand, silicosis patients often suffer from a type of immunological dysregulation that gives rise to autoimmunity. These epidemiological findings suggest that silica may affect the immune system in humans. In addition, as asbestos itself is a mineral silicate, it may possess generalized immunotoxicological effects similar to those associated with silica particles. Because asbestos-exposed patients are well-known to often develop malignant diseases such as lung cancer and mesothelioma, one silica-like dysregulatory outcome that needs to be considered (apart from autoimmunity) is an alteration in host tumor immunity. In this review, the immunotoxicological effects of both silica and asbestos are presented and discussed in terms of immune system dysregulation as manifested by the onset of autoimmunity or alterations in host tumor immunity.