Genetic susceptibility to malignant mesothelioma and exposure to asbestos: the influence of the familial factor

BACKGROUND: Asbestos is the principal etiological factor of malignant mesothelioma (MM), accounting for more than 80% of all tumor cases. However, other co-factors, including genetic susceptibility may play a role in the etiology of this disease, possibly modulating the effects of exposure to asbestos and other carcinogenic mineral fibers. The frequent report of familial clustering was the first indication supporting the involvement of genetic factors. Therefore, we performed an extensive literature search to evaluate existing studies reporting familial cases of MM. METHODS: Published reports addressing the issue of familial susceptibility to MM have been searched through PubMed using keywords and free text tools. Eighty-two citations were retrieved and 20 of them actually reported a familial cluster of MM. Three more articles were identified through the references. The probability that the observed familial clusters of mesothelioma could have randomly occurred in exposed families was evaluated with the Family History Score Zi (FHSi). RESULTS: The result of this analysis suggested that clustering of MM cases in families exposed to asbestos may be explained with the additional contribution of other familial factors. The FHSi allowed to reject the hypothesis of random occurrence of these clusters with a probability of a first type error ranging between 1 per cent and 1 per billion. CONCLUSIONS: The evaluation of the published materials supports the hypothesis that - although familial clustering of MM is largely attributable to shared asbestos exposure - the additional contribution of factors dealing with genetic susceptibility may play a role in the etiology of MM.     

Genetic susceptibility to malignant pleural mesothelioma and other asbestos-associated diseases

Exposure to asbestos fibers is a major risk factor for malignant pleural mesothelioma (MPM), lung cancer, and other non-neoplastic conditions, such as asbestosis and pleural plaques. However, in the last decade many studies have shown that polymorphism in the genes involved in xenobiotic and oxidative metabolism or in DNA repair processes may play an important role in the etiology and pathogenesis of these diseases. To evaluate the association between diseases linked to asbestos and genetic variability we performed a review of studies on this topic included in the PubMed database. One hundred fifty-nine citations were retrieved; 24 of them met the inclusion criteria and were evaluated in the review. The most commonly studied GSTM1 polymorphism showed for all asbestos-linked diseases an increased risk in association with the null genotype, possibly linked to its role in the conjugation of reactive oxygen species. Studies focused on GSTT1 null and SOD2 Ala16Val polymorphisms gave conflicting results, while promising results came from studies on alpha1-antitrypsin in asbestosis and MPO in lung cancer. Among genetic polymorphisms associated to the risk of MPM, the GSTM1 null genotype and two variant alleles of XRCC1 and XRCC3 showed increased risks in a subset of studies. Results for the NAT2 acetylator status, SOD2 polymorphism and EPHX activity were conflicting. Major limitations in the study design, including the small size of study groups, affected the reliability of these studies. Technical improvements such as the use of high-throughput techniques will help to identify molecular pathways regulated by candidate genes.     

Peritoneal mesothelioma mortality in Italy: Spatial analysis and search for asbestos exposure sources

BackgroundThis study is part of a national plan of epidemiological surveillance of malignant mesothelioma (MM) mortality in Italy. The paper shows the results of malignant peritoneal mesothelioma (MPeM) mortality study in Italian Regions and municipalities.MethodsNational Bureau of Statistics data for MPeM municipal mortality (ICD-10, Code C45.1) were analyzed in the time-window 2003–2014: mortality standardized rates (reference Italian population, census 2011), temporal trends of the annual national rates, Standardized Mortality Ratios and a municipal clustering analysis were performed.Results747 deaths for MPeM were recorded (0.10/100,000): 464 in men (0.14/100,000) and in 283 women (0.07/100,000). No significant MPeM mortality temporal trend was found.Seventeen municipalities showed excesses of mortality for MPeM in at least one gender and/or overall population.Four clusters in male population, and one in women were identified.ConclusionsThe study identifies some areas where remediation activities and/or health care actions may be warranted.     

Evidence for genetic heterogeneity of malignant hyperthermia susceptibility

A locus for malignant hyperthermia susceptibility (MHS) has been localized on chromosome 19q12-13.2, while at the same time the gene encoding the skeletal muscle ryanodine receptor (RYR1) also has been mapped to this region and has been found to be tightly linked to MHS. RYR1 was consequently postulated as the candidate for the molecular defect causing MHS, and a point mutation in the gene has now been identified and is thought to be the cause of MH in at least some MHS patients. Here we report the results of a linkage study done with 19q12-13.2 markers, including the RYR1 cDNA, in two Bavarian families with MHS. In one of the families, three unambiguous recombination events between MHS and the RYR1 locus were found. In the second family only one informative meiosis was seen with RYR1. However, segregation analysis with markers for D19S75, D19S28, D19S47, CYP2A, BCL3, and APOC2 shows that the crossovers in the first family involve the entire haplotype defined by these markers flanking RYR1 and, furthermore, reveals multiple crossovers between these haplotypes and MHS in the second family. In these families, pairwise and multipoint lod scores below -2 exclude MHS from an interval spanning more than 26 cM and comprising the RYR1 and the previously described MHS locus. Our findings thus strongly suggest genetic heterogeneity of the MHS trait and prompt the search for another MHS locus.     

Evidence for genetic heterogeneity in malignant hyperthermia susceptibility.

Malignant hyperthermia susceptibility (MHS) is a clinically heterogeneous pharmacogenetic disorder characterized by accelerated metabolism, hyperthermia, and frequently muscle rigidity. MHS is elicited by all commonly used potent inhalation anesthetics and depolarizing neuromuscular blockers and remains an important cause of death due to anesthesia. Recent linkage studies suggest a single genetic locus for this disorder on chromosome 19q13.1. The results of our linkage analyses exclude several loci on 19q13.1 as a site for the gene(s) that produces the MHS phenotype in three unrelated families and clearly establish genetic heterogeneity in this disorder. These results are consistent with the hypothesis that the genetic defect that alters thermoregulation may vary in MHS and that clinical variability in the expression of MHS may be explained by genetic heterogeneity.     

Annexin A4 is a possible biomarker for cisplatin susceptibility of malignant mesothelioma cells

Mesothelioma is a highly malignant tumor with a poor prognosis and limited treatment options. Although cisplatin (CDDP) is an effective anticancer drug, its response rate is only 20%. Therefore, discovery of biomarkers is desirable to distinguish the CDDP-susceptible versus resistant cases. To this end, differential proteome analysis was performed to distinguish between mesothelioma cells of different CDDP susceptibilities, and this revealed that expression of annexin A4 (ANXA4) protein was higher in CDDP-resistant cells than in CDDP-susceptible cells. Furthermore, ANXA4 expression levels were higher in human clinical malignant mesothelioma tissues than in benign mesothelioma and normal mesothelial tissues. Finally, increased susceptibility was observed following gene knockdown of ANXA4 in mesothelioma cells, whereas the opposite effect was observed following transfection of an ANXA4 plasmid. These results suggest that ANXA4 has a regulatory function related to the cisplatin susceptibility of mesothelioma cells and that it could be a biomarker for CDDP susceptibility in pathological diagnoses.     

Interleukin 6-producing malignant mesothelioma

Systemic amyloidosis of the amyloid A (AA) type, is occasionally associated with various neoplasms, but the cause is still unclear. We obtained interleukin 6 (IL-6)-producing cells designated YO from a primary culture of a malignant peritoneal mesothelioma of epithelial type obtained from a 62-year-old woman. Post mortem examination revealed that the patient had systemic amyloidosis of the AA type. The supernatant media of YO cells, as well as recombinant human IL-6, successfully induced nonneoplastic liver cells to produce serum AA (SAA). Our data suggest that IL-6 produced by the tumor cells may have played an important role in the paraneoplastic syndrome of AA amyloidosis in this patient.     

Cell-substrate adhesion and metastatic potential of cultured mesothelioma cells induced by asbestos

Cell-substrate adhesion was quantified for two cultured mesothelioma cell lines (epitheliomatus and sarcomatous) on glass, fibronectin and laminin substrates. Interference reflection microscopy (IRM) was used to image the adhesion patterns of cells and a grey level analysis was employed to quantify adhesion. Sarcomatous cells demonstrated marked adhesion to glass and fibronectin-coated substrates but not to laminin-coated substrate, with the greatest adhesion occurring on the fibronectin-coated surface. This adhesion was accompanied by cytoplasmic spreading. By contrast, epitheliomatous cells showed little tendency to adhere to any of the substrates and only showed significant spreading when in contact with the laminin substrate (P < 0.01). A bioassay was used to determine the metastatic potential of each of the cell lines. Via the intravenous route, the sarcomatous cells killed the host rats in 24.7 ± 1.5 (S.D.) days compared to 27.3 ± 0.9 (S.D.) days for the epitheliomatous cells (P < 0.01). After subcutaneous inoculation of tumour cells, the sarcomatous cells killed the host rats in 54.7 ± 0.7 (S.D.) days compared to 48.5 ± 0.5 (S.D.) days for the epitheliomatous cells (P < 0.01). We conclude that the results of the metastasis bioassays were consistent with the predicted behavior of these cell lines based on their ability to adhere to substrates in the in vitro adhesion assays.     

Unsuspected exposure to asbestos and bronchogenic carcinoma.

Two hundred and fifty men admitted to a thoracic surgical centre and matched controls were questioned in detail about their occupations after leaving school and their smoking habits. Of 201 men with confirmed bronchial carcinoma 58 gave a history of occupational exposure to asbestos, whereas only 29 out of 201 men matched for age and residential area who were admitted with other diseases gave such a history. This difference was statistically highly significant. The usual association of bronchial carcinoma with heavy smoking was observed, but asbestos exposure increased the risk of carcinoma whatever the level of smoking. These results are consistent with the hypothesis that asbestos exposure and the level of smoking act independently in causing bronchial carcinoma. The patients with carcinoma who had been exposed to asbestos presented on average three years earlier than those who had not been exposed. Asbestos regulations have eliminated the risk of exposure to workers in scheduled industries, so asbestos-induced diseases will probably be increasingly found among the many workers who have had incidental exposure to asbestos. It is therefore important to take a full occupational history.     

Neurotensin expression and outcome of malignant pleural mesothelioma

Malignant pleural mesothelioma is a frequently fatal disease and the impact of available treatments is globally poor. Identification of new prognostic factors would help in the understanding of disease progression and, possibly, patient management. Here, we evaluate the prognostic impact of the neurotensin (NTS) and its cognate receptor (NTSR1) known for mediating cellular proliferation, survival, invasiveness, and mobility. We studied a series of 52 consecutive patients with epithelioid malignant mesothelioma undergoing management with curative intent, by immunohistochemistry for the expression of NTS and NTSR1. Specimens were scored as 0, 1, or 2 for less than 10%, between 10 and 50%, or more than 50% of NTS positive staining in tumor cells, respectively. Immunohistochemistry revealed that NTS and NTSR1 expression was found in 71.1% and 90.4% of malignant mesotheliomas, respectively. Using univariate analysis, expression of NTS was significantly (p = 0.015) related with a poor prognosis, with median survivals of 11.0 months, 18.4 months, and 29.8 months in patients showing expression scored as 2, 1, and 0, respectively. Multivariate analysis showed that expression of NTS (p = 0.007) and non-surgical therapy (p = 0.004) were independent predictors of poor prognosis. In order to evaluate the role of NTS/NTSR1 complex in mesothelioma progression, in vitro cell invasion assays and wound healing were performed on the mesothelioma cell line, MSTO-211H, and showed that inhibition of the NTS system resulted in a significant reduction of both migration and collagen invasion of mesothelioma cells. The expression of NTS is identified as a prognostic marker in patients with malignant pleural mesothelioma (Patent EP 08305971.7).     

Biomarkers in risk assessment of asbestos exposure

Developments in the field of molecular epidemiology and toxicology have given valuable tools for early detection of impending disease or toxic condition. Morbidity due to respiratory distress, which may be due to environmental and occupational exposure, has drawn attention of researchers worldwide. Among the occupational exposure to respiratory distress factors, fibers and particles have been found to be main culprits in causing diseases like asbestosis, pleural plaques, mesotheliomas and bronchogenic carcinomas. An early detection of the magnitude of exposure or its’ effect using molecular end points is of growing importance. The early inflammatory responses like release of the inflammatory cells collected by non-invasive methods give an indication of the unwanted exposure and susceptibility to further complications. Since free radicals like O₂⁻, OH, OOH, NO, NOO, etc. are involved in the progression of asbestos-related diseases and lead to cytogenetic changes, an evaluation of antioxidant states reducing equivalents like GSH and ROS generation can be a good biomarker. The cytogenetic end points like chromosomal aberration, micronucleus formation and sister chromatid exchange give indication of genetic damage, hence they are used as effective biomarkers. New techniques like fluorimetric analysis of DNA unwinding, alkaline elution test, fluorescent in situ hybridization and comet assay are powerful tools for early detection of initiation of disease process and may help in planning strategies for minimizing morbidity related to asbestos fiber exposure. The present review article covers in detail possible biomarkers for risk assessment of morbidity due to fibers/particles in exposed population.     

Ozone exposure,vitamin C intake,and genetic susceptibility of asthmatic children in Mexico City: a cohort study

Background

We previously reported that asthmatic children with GSTM1 null genotype may be more susceptible to the acute effect of ozone on the small airways and might benefit from antioxidant supplementation. This study aims to assess the acute effect of ozone on lung function (FEF_25-75) in asthmatic children according to dietary intake of vitamin C and the number of putative risk alleles in three antioxidant genes: GSTM1, GSTP1 (rs1695), and NQO1 (rs1800566).

Methods

257 asthmatic children from two cohort studies conducted in Mexico City were included. Stratified linear mixed models with random intercepts and random slopes on ozone were used. Potential confounding by ethnicity was assessed. Analyses were conducted under single gene and genotype score approaches.

Results

The change in FEF_25-75 per interquartile range (60 ppb) of ozone in persistent asthmatic children with low vitamin C intake and GSTM1 null was −91.2 ml/s (p = 0.06). Persistent asthmatic children with 4 to 6 risk alleles and low vitamin C intake showed an average decrement in FEF_25-75 of 97.2 ml/s per 60 ppb of ozone (p = 0.03). In contrast in children with 1 to 3 risk alleles, acute effects of ozone on FEF_25-75 did not differ by vitamin C intake.

Conclusions

Our results provide further evidence that asthmatic children predicted to have compromised antioxidant defense by virtue of genetic susceptibility combined with deficient antioxidant intake may be at increased risk of adverse effects of ozone on pulmonary function.     

Asbestos,chromosomal deletions,and tumor suppressor gene alterations in human malignant mesothelioma

Exposure to the carcinogen asbestos is considered to be a major factor contributing to the development of most malignant mesotheliomas (MMs). We highlight the role of asbestos in MM and summarize cytogenetic and molecular genetic findings in this malignancy. The accumulation of numerous clonal chromosomal deletions in most MMs suggests a multistep process of tumorigenesis, characterized by the loss and/or inactivation of multiple tumor suppressor genes (TSGs). Cytogenetic and loss of heterozygosity (LOH) analyses of MMs have demonstrated frequent deletions of specific sites within chromosome arms 1p, 3p, 6q, 9p, 13q, 15q, and 22q. Furthermore, TSGs within two of these regions, i.e., p16/CDKN2A-p14^ARF at 9p21 and NF2 at 22q12, are frequently altered in MMs. Homozygous deletion appears to be the major mechanism affecting p16/CDKN2A-p14^ARF, whereas inactivating mutations coupled with allelic loss occur at the NF2 locus. Finally, recent studies have demonstrated the presence and expression of simian virus 40 (SV40) in many MMs. SV40 large T antigen has been shown to inactivate the TSG products Rb and p53, suggesting the possibility that asbestos and SV40 could act as cocarcinogens in MM. The frequent occurrence of homozygous deletions of p16/CDKN2A-p14^ARF and the ability of SV40 Tag to bind TSG products suggest that perturbations of both Rb- and p53-dependent growth-regulatory pathways are critically involved in the pathogenesis of MM. J. Cell. Physiol. 180:150–157, 1999. © 1999 Wiley-Liss, Inc.     

Establishment of a human malignant fibrous mesothelioma cell line and the biological characteristics compared with malignant epithelial mesothelioma cell line

Two human malignant mesothelioma cell lines, which we designated "epithelial mesothelioma cells" and "fibrous mesothelioma cells", were established from the pleural fluid containing malignant mesothelial cells of a 72-year-old Japanese man. These cell lines were separated by the colonial techniques from the initiation of the primary cultures and grew well without interruption for 12 years. They were characterized as producing hyaluronic acid. These cell lines displayed different biological characteristics, including morphology, heterotransplantability and genetics using with BAC array CGH. The epithelial mesothelioma cells were epithelial in shape and transplantable into the subcutis of nude mice, while the cells of the fibrous mesothelioma line were fibroblast-like and transplantable into the submucosa of Hamster's cheek pouches but not into the subcutis of nude mice. The mesotheliomas are classified into three types: epithelial mesothelioma, fibrous mesothelioma and mixed type. The gene copy number losses observed on 9p21.3, 9p21.2, 9p21.1, among others may be a major mechanism of malignant mesothelioma carcinogenesis. We considered and supported the combination theory for the histogenesis of malignant mesothelioma.     

Fine needle aspiration cytology of malignant mesothelioma

The results of fine needle aspiration (FNA) cytology in 19 cases of malignant mesothelioma are presented. Adequate material for a diagnosis of malignancy was obtained in 17 cases, and in 8 cases a specific diagnosis of mesothelioma could be made. In four other cases, the findings were either consistent with or suggestive of mesothelioma; in four, accurate distinction from other neoplasms was not possible, and in two cases, adenocarcinoma was suggested. The spectrum of cytologic findings ranged from neoplasms of purely epithelial appearance through more pleomorphic biphasic neoplasms to anaplastic tumors. A combination of epithelial-like cell clusters, pavement-like sheets of epithelial cells with well-defined cell borders and prominent cell separation, dispersed angular cells with dense cytoplasm and some spindle-cell forms was the most specific cytologic pattern for mesothelioma. In four neoplasms, ultrastructural examination of aspirated material provided the additional evidence for a definitive diagnosis. The identification of hyaluronic acid within intracytoplasmic vacuoles, either in smears or in cell blocks, confirmed the diagnosis in three tumors. Only in one case, with a strong clinical background suggesting mesothelioma, was the cytologic preparation sufficient for diagnosis without ancillary diagnostic methods. FNA is of particular value in the diagnosis of pleural mesothelioma in patients who do not present with a pleural effusion. Obtaining material for cell block preparations, cytochemistry or ultrastructural study is generally necessary for definitive tumor typing.