A Molecular Epidemiology Case Control Study on Pleural Malignant Mesothelioma

Genomic instability in chronic obstructive pulmonary disease and lung cancer: A systematic review and meta-analysis of studies using the micronucleus assay

Respiratory tissues are highly susceptible to diseases due to the constant exposure to physical and chemical airborne pollutants. Chronic obstructive pulmonary disease (COPD) and lung cancer are among the most common causes of serious illness and death worldwide. The inflammatory environment associated with these respiratory diseases has long been accepted as the major player in the development of airway abnormalities. The presence and relevance of DNA damage and genomic instability makes the micronucleus assay a suitable candidate to quantitatively estimate these early pathogenetic events. A systematic review and meta-analysis were planned to determine underlying common mechanisms that can explain the relationships between COPD and lung cancer. A total of 17 studies from Jan 1999 to Dec 2019 comparing micronucleus frequency in patients affected by respiratory diseases vs healthy controls were analysed. Our results confirmed the presence of significant association between MN frequency and the diseases investigated, and suggested a circle of events linking inflammation induced oxidative stress to the risk of disease through genomic instability and hypoxia. Therefore, using non-invasive, robust and cost effective genomic instability assays such as the micronucleus assay, would allow us to capture unique phenotypic and biological changes that would allow the identification of subjects at high risk of developing lung diseases and improve early detection strategies.

Micronuclei and Their Association with Infertility, Pregnancy Complications, Developmental Defects, Anaemias, Inflammation, Diabetes, Chronic Kidney Disease, Obesity, Cardiovascular Disease, Neurodegenerative Diseases and Cancer

Micronuclei (MN) are a strong cytogenetic indicator of a catastrophic change in the genetic structure and stability of a cell because they originate from either chromosome breaks or whole chromosomes that have been lost from the main nucleus during cell division. The resulting genetic abnormalities can to lead to cellular malfunction, altered gene expression and impaired regenerative capacity. Furthermore, MN are increased as a consequence of genetic defects in DNA repair, deficiency in micronutrients required for DNA replication and repair and exposure to genotoxic chemicals and ultraviolet or ionising radiation. For all of these reasons, the measurement of MN has become one of the best-established methods to measure DNA damage in humans at the cytogenetic level. This chapter is a narrative review of the current evidence for the association of increased MN frequency with developmental and degenerative diseases. In addition, important knowledge gaps are identified, and recommendations for future studies required to consolidate the evidence are provided. The great majority of published studies show a significant association of increased MN in lymphocytes and/or buccal cells with infertility, pregnancy complications, developmental defects, anaemias, inflammation, diabetes, cardiovascular disease, kidney disease, neurodegenerative diseases and cancer. However, the strongest evidence is from prospective studies showing that MN frequency in lymphocytes predicts cancer risk and cardiovascular disease mortality.

Analyzing biological and molecular characteristics and genomic damage induced by exposure to asbestos

Asbestos is one of the most important occupational carcinogens. Currently, about 125 million people worldwide are exposed to asbestos in the workplace. According to global estimates, at least 107,000 people die each year from lung cancer, mesothelioma, and asbestosis as a result of occupational exposure to asbestos. The high pathogenicity of this material is currently known, being associated with the development of pulmonary diseases, of which lung cancer is the main cause of death due to exposure to this mineral. Pulmonary diseases related to asbestos are a common clinical problem and a major health concern worldwide. Extensive research has identified many important pathogenic mechanisms; however, the precise molecular mechanisms involved, and the generated genomic damage that lead to the development of these diseases, are not completely understood. The modes of action that underlie this type of disease seem to differ depending on the type of fiber, lung clearance, and genetics. This evidences the need to increase our knowledge about these effects on human health. This review focuses on the characteristics of asbestos and the cellular and genomic damage generated in humans via exposure.

Establishment and characterization of CRISPR/Cas9-mediated NF2-/- human mesothelial cell line: Molecular insight into fibroblast growth factor receptor 2 in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM), a highly refractory tumor, is currently incurable due to the lack of an early diagnosis method and medication, both of which are urgently needed to improve the survival and/or quality of life of patients. NF2 is a tumor suppressor gene and is frequently mutated in MPM. Using a CRISPR/Cas9 system, we generated an NF2‐knockout human mesothelial cell line, MeT‐5A (NF2‐KO). In NF2‐KO cell clones, cell growth, clonogenic activity, migration activity, and invasion activity significantly increased compared with those in NF2‐WT cell clones. Complementary DNA microarray analysis clearly revealed the differences in global gene expression profile between NF2‐WT and NF2‐KO cell clones. Quantitative PCR analysis and western blot analysis showed that the upregulation of fibroblast growth factor receptor 2 (FGFR2) was concomitant with the increases in phosphorylation levels of JNK, c‐Jun, and retinoblastoma (Rb) in NF2‐KO cell clones. These increases were all abrogated by the exogenous expression of NF2 in the NF2‐KO clone. In addition, the disruption of FGFR2 in the NF2‐KO cell clone suppressed cell proliferation as well as the phosphorylation levels of JNK, c‐Jun, and Rb. Notably, FGFR2 was found to be highly expressed in NF2‐negative human mesothelioma tissues (11/12 cases, 91.7%) but less expressed in NF2‐positive tissues. Collectively, these findings suggest that NF2 deficiency might play a role in the tumorigenesis of human mesothelium through mediating FGFR2 expression; FGFR2 would be a candidate molecule to develop therapeutic and diagnostic strategies for targeting MPM with NF2 loss.

New Perspectives on Diagnosis and Therapy of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare, but severe form of cancer, with an incidence that varies significantly within and among different countries around the world. It develops in about one to two persons per million of the general population, leading to thousands of deaths every year worldwide. To date, the MPM is mostly associated with occupational asbestos exposure. Asbestos represents the predominant etiological factor, with approximately 70% of cases of MPM with well-documented occupational exposure to asbestos, with the exposure time, on average greater than 40 years. Environmental exposure to asbestos is increasingly becoming recognized as a cause of mesothelioma, together with gene mutations. The possible roles of other cofactors, such as viral infection and radiation exposure, are still debated. MPM is a fatal tumor. This cancer arises during its early phase without clinical signs. Consequently, its diagnosis occurs at advanced stages. Standard clinical therapeutic approaches include surgery, chemo- and radiotherapies. Preclinical and clinical researches are making great strides in the field of this deadly disease, identifying new biomarkers and innovative therapeutic approaches. Among the newly identified markers and potential therapeutic targets, circulating microRNAs and the Notch pathway represent promising avenues that could result in the early detection of the tumor and novel therapeutic approaches.

The association between micronucleus, nucleoplasmic bridges, and nuclear buds frequency and the degree of uterine cervical lesions

BACKGROUND AND AIM

The loss of genomic stability plays an important role in carcinogenesis. Therefore, it is imperative to use certain biomarkers of DNA damage due to genomic instability in order to predict cancer risk. The aim of this study was the evaluation of genomic instability in patients with cervical lesions.

MATERIALS AND METHODS

We investigated the genetic damages in 80 subjects: 40 patients with high-grade squamous intraepithelial lesions (HSIL), 20 patients with invasive squamous cervical cancer (SCC) and 20 healthy women with a biomarker in two different tissues; the micronucleus (MN) test in peripheral blood lymphocytes (PBL), and in buccal exfoliated cells (BEC). This study also examined the frequency of other nuclear anomalies such as nucleoplasmic bridges (NPBs) and nuclear bunds (NBUDs) in PBL.

RESULTS

The frequency of MN in BEC, MN in PBL, NPB in PBL and NBUD in PBL were significantly higher (p < 0.001), in patients compared to controls. The DNA damages in BEC and PBL were correlated positively with histological grade of cervical lesions.

CONCLUSION

Although larger studies are needed, our data support the predictive value of MN, NPB and NBUD as biomarkers of genomic instability for evaluation of risk level of cancer diseases.

Genetic Instability in Peripheral Lymphocytes as Biological Marker for Non-Small Cell Lung Cancer Patients in the South Indian State of Andhra Pradesh

Objectives

This study aims, first, at evaluating the DNA and chromosomal damage in non-small cell lung cancer (NSCLC) patients from the South Indian state of Andhra Pradesh, and then at correlating these results with possible confounding factors that might potentially play a role in causing genetic damage.

Methods

The study included 246 NSCLC patients (177 men and 69 women) and 250 healthy controls (180 men and 70 women) for the analysis of DNA and chromosomal damage using the comet assay and micronucleus test.

Results

Both DNA and chromosomal damage were found to be increased in NSCLC patients compared to healthy controls, and the extent of the damage was higher in males than female patients. The smoking status had a profound effect on the extent of DNA and chromosomal damage in NSCLC patients. The degree of genetic damage correlated with the stage of the disease. However, the histological status had no effect on the extent of DNA and chromosomal damage among NSCLC patients.

Conclusions

We here report, for the first time, that the NSCLC patients selected form the Andhra Pradesh population had increased DNA damage and higher mean micronucleus frequencies in peripheral lymphocytes, indicating a strong background level of genetic instability.

Tumors that mimic asbestos-related mesothelioma: time to consider a genetics-based tumor registry?

The diagnosis of mesothelioma is not always straightforward, despite known immunohistochemical markers and other diagnostic techniques. One reason for the difficulty is that extrapleural tumors resembling mesothelioma may have several possible etiologies, especially in cases with no meaningful history of amphibole asbestos exposure. When the diagnosis of mesothelioma is based on histologic features alone, primary mesotheliomas may resemble various primary or metastatic cancers that have directly invaded the serosal membranes. Some of these metastatic malignancies, particularly carcinomas and sarcomas of the pleura, pericardium and peritoneum, may undergo desmoplastic reaction in the pleura, thereby mimicking mesothelioma, rather than the primary tumor. Encasement of the lung by direct spread or metastasis, termed pseudomesotheliomatous spread, occurs with several other primary cancer types, including certain late-stage tumors from genetic cancer syndromes exhibiting chromosomal instability. Although immunohistochemical staining patterns differentiate most carcinomas, lymphomas, and mestastatic sarcomas from mesotheliomas, specific genetic markers in tumor or somatic tissues have been recently identified that may also distinguish these tumor types from asbestos-related mesothelioma. A registry for genetic screening of mesothelioma cases would help lead to improvements in diagnostic criteria, prognostic accuracy and treatment efficacy, as well as improved estimates of primary mesothelioma incidence and of background rates of cancers unrelated to asbestos that might be otherwise mistaken for mesothelioma. This information would also help better define the dose-response relationships for mesothelioma and asbestos exposure, as well as other risk factors for mesothelioma and other mesenchymal or advanced metastatic tumors that may be indistinguishable by histology and staining characteristics.

Micronuclei levels in peripheral blood lymphocytes as a potential biomarker for pancreatic cancer risk

To find biomarkers for risk prediction of pancreatic cancer (PC), we evaluated the frequency of micronuclei (MN) in peripheral lymphocytes of 346 patients with PC and 449 healthy controls. The levels of baseline MN (mean ± standard error of micronucleated cells per 1000 binucleated cells) were significantly higher in patients (15.3 ± 0.3) than those in controls [9.7 ± 0.5; adjusted for body mass index (BMI), P < 0.001]. Using the median levels found in controls as the cut point, 78.9% of patients and 43.7% of controls had a higher frequency of MN. Logistic regression analysis with adjustment for known risk factors for PC showed that having a higher level of MN was significantly associated with increased risk of PC [odds ratio (OR): 8.32, 95% confidence interval (CI): 5.06-13.67, P < 0.001]; and the risk was much higher in men than in women [OR (95% CI): 14.19 (7.09-28.40) versus 4.19 (1.90-9.27)]. The level of MN was not associated with disease stage or resection status but was related to smoking status in men and to BMI in women among patients. The level of MN was higher in smokers (14.5 ± 0.6) than in nonsmokers (12.1 ± 0.6; P = 0.023) and in obese (25.3 ± 2.8) versus normal weight individuals (17.7 ± 0.8; P = 0.024). These data showed that elevated level of MN in peripheral lymphocytes was associated with increased risk of PC.

A₃ receptors are overexpressed in pleura from patients with mesothelioma and reduce cell growth via Akt/nuclear factor-κB pathway

RATIONALE

A strong link has been established between exposure to asbestos and increased risk for pleural malignant mesothelioma (MM). Adenosine plays a key role in inflammatory processes and cancer, where it is involved in the regulation of cell death and proliferation.

OBJECTIVES

The primary aim of this study was to investigate the presence of adenosine receptors (ARs) in human MM pleura (MMP) and healthy mesothelial pleura (HMP). To shed some light on the interaction between adenosine and MM, the presence and functionality of ARs were explored in human healthy mesothelial cells (HMC) and in malignant mesothelioma cells (MMC).

METHODS

ARs were analyzed by using reverse transcriptase-polymerase chain reaction, Western blotting, and saturation binding assays. HMC were treated with crocidolite asbestos, which is the principal risk factor for MM. The role of A₃ ARs on these cellular models, evaluating cAMP production, Akt phosphorylation, and nuclear factor (NF)-κB activation, was investigated. The dual effect of A₃AR stimulation on healthy and cancer cell growth was studied by means of proliferation, apoptosis, and cytotoxicity assays.

MEASUREMENTS AND MAIN RESULTS

A₃AR was up-regulated by 2.5-fold (P < 0.01) in MMP when compared with HMP. Stimulation of A₃ARs decreased proliferation and exerted a cytotoxic and proapoptotic effect on MMC and on HMC exposed to asbestos and tumor necrosis factor-α, but not on HMC with an involvement of the deregulation of Akt/NF-κB cell survival pathway.

CONCLUSIONS

These new findings suggest that A₃AR could represent a pharmacological target to prevent tumor development after asbestos exposure and to treat full-blown MM.

The CREST biorepository: a tool for molecular epidemiology and translational studies on malignant mesothelioma, lung cancer, and other respiratory tract diseases

OBJECTIVES

The Cancer of RESpiratory Tract (CREST) biorepository was established to investigate biological mechanisms and to develop tools and strategies for primary and secondary prevention of respiratory tract cancer. The CREST biorepository is focused on pleural malignant mesothelioma, a rare and severe cancer linked to asbestos exposure whose incidence is particularly high in the Ligurian region.

METHODS

The CREST biorepository includes biological specimens from (a) patients with pleural malignant mesothelioma and lung cancer, (b) patients with nonneoplastic respiratory conditions, and (c) control subjects. Whole blood, plasma, serum, lymphocytes, pleural fluid, saliva, and biopsies are collected, and a questionnaire is administered. Collection, transportation, and storage are done according to international standards.

RESULTS

As of January 31, 2008, the overall number of subjects recruited was 1,590 (446 lung cancer, 209 pleural malignant mesothelioma, and 935 controls). The biorepository includes a total of 10,055 aliquots (4,741 serum; 3,082 plasma; 1,599 whole blood; 633 pleural fluid; and 561 lymphocytes) and 107 biopsies. Demographic, clinical, and epidemiologic information is collected for each subject and processed in a dedicated database.

CONCLUSIONS

The CREST biorepository is a valuable tool for molecular epidemiology and translational studies. This structure relies on a network of contacts with local health districts that allows for an active search for patients. This is a particularly efficient approach, especially when the object of the study is a rare cancer type. The CREST experience suggests that the presence of limited resources can be overcome by the biorepository specialization, the high quality of the epidemiologic information, and the variety of samples.

Validation of micronuclei frequency in peripheral blood lymphocytes as early cancer risk biomarker in a nested case-control study

Aim of this work was to assess the predictive value of micronuclei (MN) frequency in peripheral blood lymphocytes (PBL) for the risk of cancer death in disease-free individuals. Blood samples from 1650 subjects selected from the general population of Pisa, Italy, were collected between June 1991 and November 1993. The follow-up until January 2005 recorded a total of 111 deaths (52 for cancer). MN frequency was assessed for 49 cancer cases and 101 matched controls. A significantly higher MN frequency was found in cancer cases (4.7+/-3.4 MN/1000 BN cells) versus controls (1.5+/-1.7; p<0.0001). Donors were stratified in two classes and multivariate logistic regression analysis confirmed that individuals with high MN frequency (>2.5 MN/1000 BN cells) had a significantly increased risk of cancer death (OR=10.7; 95% CI=4.6-24.9; p<0.0001) when compared to individuals with low MN frequency (<or=2.5 MN/1000 BN cells). Ageing was associated with a 6% increased risk per year (p=0.03). No influence of other potential confounders (gender, occupation, smoking and drinking habits) was observed. Finally, subjects with a higher MN frequency showed a higher MR for CVD (Logrank test, p=0.001). These findings provide strong evidence that MN frequency assessed in PBL of disease-free subjects is a good predictor of cancer death risk, evaluated by a nested case-control study performed 14 years after the original recruitment.

SV40 Multiple Tissue Infection and Asbestos Exposure in a Hyperendemic Area for Malignant Mesothelioma

To assess the presence of SV40 in malignant mesothelioma tissue, 19 formalin-fixed paraffin-embedded pleural cancer samples of patients from a hyperendemic area of northeastern Italy were analyzed retrospectively. A total of 48 other tissues from the malignant mesothelioma subjects were investigated. The SV40 load was determined by real-time quantitative PCR. Exposure to asbestos was evaluated through a careful review of the occupational history of patients, supplemented by histology and isolation of asbestos bodies. Three of 19 (15.8%) malignant mesothelioma tissues harbored SV40 genomic signals. Two patients with SV40-positive malignant mesothelioma had viral sequences in another tissue. Overall, 3 of 18 (16.7%) normal liver tissues tested positive for SV40, as did 1 of 8 (12.5%) kidney tissues. SV40 viral loads were higher in malignant mesothelioma than in normal cells (P = 0.045). This survey shows that SV40 sustains infections in multiple tissues in malignant mesothelioma patients from a geographic area affected with asbestos-related mesothelioma.

Polymorphisms of glutathione-S-transferase M1 and manganese superoxide dismutase are associated with the risk of malignant pleural mesothelioma

Individual response to oxidative stress, due to exposure to asbestos fibres plays a significant role in the malignant pleural mesothelioma (MPM) etiology. The differential impact on MPM risk of polymorphic alleles of glutathione-S-transferases (GSTs) and manganese superoxide dismutase (MnSOD/SOD2) genes involved in the defence against oxidative damage has been investigated. Ninety cases of MPM and 395 controls were genotyped using the arrayed-primer extension technique. Logistic regression analysis was applied to assess the predictive role of single nucleotide polymorphisms (SNPs) potentially involved in MPM carcinogenesis after adjustment for potential confounders. An increased risk of MPM was found in subjects bearing a GSTM1 null allele (OR = 1.69, 95% CI = 1.04-2.74; p = 0.034), and in those with the Ala/Ala genotypes at codon 16 within MnSOD (OR = 3.07, 95% CI = 1.55-6.05; p = 0.001). A stronger effect of MnSOD was observed among patients without a clear exposure to asbestos fibres. No effect was found for GSTA2, GSTA4, GSTM3, GSTP1 and GSTT1 genes. These findings, if replicated, contribute substantial evidence to the hypothesis that oxidative stress and cellular antireactive oxygen species systems are involved in the pathogenesis and in the natural history of MPM.

Polymorphisms in DNA repair genes as risk factors for asbestos-related malignant mesothelioma in a general population study

Differences in response to carcinogenic agents are due to the allelic variants of the genes that control it. Key genes are those involved in the repair of the DNA damage caused by such agents. This paper describes the results of a case-control epidemiological study designed to determine the genotypes of four of these genes in persons exposed to a single genotoxic factor, i.e. asbestos, who had or had not developed malignant mesothelioma (MM). Our working hypothesis was that an imperfect DNA repair, as revealed by subtle polymorphic variants, could reduce protection against the chronic DNA insult provoked by asbestos and eventually result in mutagenesis and cancer. Seven variants (i.e. XRCC1-R399Q-NCBI SNP, XRCC1-R194W, XRCC3-T241M, XRCC3-IVS6-14, XPD-K751Q, XPD-D312N, OGG1-S326C) were investigated in 81 patients and 110 age and sex-matched controls, all residents at Casale Monferrato, a Piedmontese town highly exposed to asbestos pollution. Unconditional multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). When considered as a categorical variable, XRCC1-399Q showed an increased OR both in heterozygotes (OR=2.08; 95% CI=1.00-4.33) and homozygotes (2.38; 95% CI=0.82-6.94), although individual ORs were not significant. When it was considered as a continuous variable OR was significant (OR=1.68; 95% CI: 1.02-2.75). When genotypes were divided into "non-risk" and "risk" genotypes, i.e. those thought to be associated with increased risk in the light of the functional significance of the variants, XRCC1-399Q (Q homozygotes+Q/R heterozygotes versus R homozygotes) had an OR=2.147 (95% CI: 1.08-4.28), whereas that of XRCC3-241T (T homozygotes+M/T heterozygotes versus M homozygotes) was 4.09 (95% CI: 1.26-13.21) and that of OGG1-326C was increased, though not significantly. None of the haplotypes showed a significantly different frequency between patients and controls. This is the first report of an association between polymorphisms in DNA repair genes and asbestos-associated MM. Our data indicate that genetic factors are involved in MM development.