Biomarkers for early detection of malignant mesothelioma: diagnostic and therapeutic application

Evaluation of soluble mesothelin-related peptides and MSLN genetic variability in asbestos-related diseases

Background

Asbestos exposure is associated with increased risk of several diseases, including malignant mesothelioma (MM). Cell surface glycoprotein mesothelin is overexpressed in MM and serum soluble mesothelin-related peptides (SMRP) were already proposed as a diagnostic or prognostic biomarker in MM. However, interindividual variability in serum SMRP levels limits the clinical usefulness. Our primary objective was to investigate the influence of MSLN rs1057147 on serum SMRP levels in asbestos-exposed subjects and patients with asbestos-related diseases as well as on survival in MM.

Subjects and methods

Among 782 asbestos-exposed subjects and patients with asbestos-related diseases, 154 had MM. Serum SMRP levels were determined using sandwich enzyme-linked immunosorbent assay. All subjects were genotyped for MSLN rs1057147 polymorphism using competitive allele-specific polymerase chain reaction. Nonparametric tests, logistic and Cox regression were used in statistical analysis to compare different subject groups.

Results

MM patients had significantly higher SMRP levels than all other subjects (p < 0.001). Compared to wild-type MSLN rs1057147 genotype, both heterozygotes and carriers of two polymorphic alleles had significantly higher SMRP levels among subjects without MM (p < 0.001), but not in MM patients (p = 0.424). If genotype information was included, specificity of SMRP increased from 88.5% to 92.7% for the optimal cutoff value. Overall survival was significantly shorter in MM patients carrying at least one polymorphic rs1057147 allele (HR = 1.72, 95% CI = 1.15-2.55, p = 0.008).

Conclusions

MSLN genetic variability affects serum SMRP levels and was associated with shorter survival of MM patients. Combination of genetic and serum factors could therefore serve as a better diagnostic or prognostic biomarker in MM patients.

NLRP3 and CARD8 polymorphisms influence risk for asbestos-related diseases

Background

This study aimed to investigate the association between NLRP3 rs35829419 and CARD8 rs2043211 polymorphisms and the risk of developing pleural plaques, asbestosis, and malignant mesothelioma (MM), and to study the influence of the interactions between polymorphisms and asbestos exposure on the risk of developing these diseases.

Methods

The case-control study included 416 subjects with pleural plaques, 160 patients with asbestosis, 154 subjects with MM and 149 subjects with no asbestos disease. The NLRP3 rs35829419 and CARD8 rs2043211 polymorphisms were determined using real-time PCR-based methods. In the statistical analysis, standard descriptive statistics was followed by univariate and multivariate logistic regression modelling.

Results

Asbestos exposure (medium and high vs low) was associated with the risk for each studied asbestos-related disease. An increased risk of pleural plaques was found for CARD8 rs2043211 at + TT genotypes (OR = 1.48, 95% CI 1.01-2.16, p = 0.042). When the analysis was performed for MM patients as cases, and pleural plaques patients as controls, a decreased MM risk was observed for carriers of CARD8 rs2043211 TT genotype (OR = 0.52, 95% CI 0.27-1.00, p = 0.049). The interactions between NLRP3 rs35829419 and CARD8 rs2043211 genotypes did not influence the risk of any asbestos-related disease. However, when testing interactions with asbestos exposure, a decreased risk of asbestosis was found for NLRP3 CA+AA genotypes (OR = 0.09, 95% CI 0.01-0.60, p = 0.014).

Conclusions

The results of our study suggest that NLRP3 and CARD8 polymorphisms could affect the risk of asbestos-related diseases.

Epigenetic Regulation of miRNA Expression in Malignant Mesothelioma: miRNAs as Biomarkers of Early Diagnosis and Therapy

Asbestos exposure leads to epigenetic and epigenomic modifications that, in association with ROS-induced DNA damage, contribute to cancer onset. Few miRNAs epigenetically regulated in MM have been described in literature; miR-126, however, is one of them, and its expression is regulated by epigenetic mechanisms. Asbestos exposure induces early changes in the miRNAs, which are reversibly expressed as protective species, and their inability to reverse reflects the inability of the cells to restore the physiological miRNA levels despite the cessation of carcinogen exposure. Changes in miRNA expression, which results from genetic/epigenetic changes during tumor formation and evolution, can be detected in fluids and used as cancer biomarkers. This article has reviewed the epigenetic mechanisms involved in miRNA expression in MM, focusing on their role as biomarkers of early diagnosis and therapeutic effects.

Four-miRNA Signature to Identify Asbestos-Related Lung Malignancies

BACKGROUND

Altered miRNA expression is an early event upon exposure to occupational/environmental carcinogens; thus, identification of a novel asbestos-related profile of miRNAs able to distinguish asbestos-induced cancer from cancer with different etiology can be useful for diagnosis. We therefore performed a study to identify miRNAs associated with asbestos-induced malignancies.

METHODS

Four groups of patients were included in the study, including patients with asbestos-related (NSCLC^Asb) and asbestos-unrelated non-small cell lung cancer (NSCLC) or with malignant pleural mesothelioma (MPM), and disease-free subjects (CTRL). The selected miRNAs were evaluated in asbestos-exposed population.

RESULTS

Four serum miRNAs, that is miR-126, miR-205, miR-222, and miR-520g, were found to be implicated in asbestos-related malignant diseases. Notably, increased expression of miR-126 and miR-222 were found in asbestos-exposed subjects, and both miRNAs are involved in major pathways linked to cancer development. Epigenetic changes and cancer-stroma cross-talk could induce repression of miR-126 to facilitate tumor formation, angiogenesis, and invasion.

CONCLUSIONS

This study indicates that miRNAs are potentially involved in asbestos-related malignancies, and their expression outlines mechanism(s) whereby miRNAs may be involved in an asbestos-induced pathogenesis.

IMPACT

The discovery of a miRNA panel for asbestos-related malignancies would impact on occupational compensation and may be utilized for screening asbestos-exposed populations.

Biomarkers for Predicting Malignant Pleural Mesothelioma in a Mexican Population

Background: Diagnosis of malignant pleural mesothelioma (MPM) remains a challenge, especially when resources in pathology are limited. The study aimed to evaluate cost-effective tumor markers to predict the probability of MPM in plasma samples in order to accelerate the diagnostic workup of the tissue of potential cases. Methods: We conducted a case-control study stratified by gender, which included 75 incident cases with MPM from three Mexican hospitals and 240 controls frequency-matched by age and year of blood drawing. Plasma samples were obtained to determine mesothelin, calretinin, and thrombomodulin using enzyme-linked immunosorbent assays (ELISAs). We estimated the performance of the markers based on the area under the curve (AUC) and predicted the probability of an MPM diagnosis of a potential case based on the marker concentrations. Results: Mesothelin and calretinin, but not thrombomodulin were significant predictors of a diagnosis of MPM with AUCs of 0.90 (95% CI: 0.85-0.95), 0.88 (95% CI: 0.82-0.94), and 0.51 (95% CI: 0.41-0.61) in males, respectively. For MPM diagnosis in men we estimated a true positive rate of 0.79 and a false positive rate of 0.11 for mesothelin. The corresponding figures for calretinin were 0.81 and 0.18, and for both markers combined 0.84 and 0.11, respectively. Conclusions: We developed prediction models based on plasma concentrations of mesothelin and calretinin to estimate the probability of an MPM diagnosis. Both markers showed a good performance and could be used to accelerate the diagnostic workup of tissue samples in Mexico.

CD44 and its ligand hyaluronan as potential biomarkers in malignant pleural mesothelioma: evidence and perspectives

Malignant pleural mesothelioma (MPM) is a rare and highly drug resistant tumor arising from the mesothelial surfaces of the lung pleura. The standard method to confirm MPM is the tedious, time-consuming cytological examination of cancer biopsy. Biomarkers that are detectable in pleural effusion or patient serum are reasonable options to provide a faster and noninvasive diagnostic approach. As yet, the current biomarkers for MPM lack specificity and sensitivity to discriminate this neoplasm from other lung tumors. CD44, a multifunctional surface receptor has been implicated in tumor progression in different cancers including MPM. The interaction of CD44 with its ligand, hyaluronan (HA) has demonstrated an important role in modulating cell proliferation and invasiveness in MPM. In particular, the high expression levels of these molecules have shown diagnostic relevance in MPM. This review will summarize the biology and diagnostic implication of CD44 and HA as well as the interaction of both molecules in MPM that will demonstrate their potential as biomarkers. Augmentation of the current markers in MPM may lead to an earlier diagnosis and management of this disease.

Secreted primary human malignant mesothelioma exosome signature reflects oncogenic cargo

Malignant mesothelioma (MM) is a highly-aggressive heterogeneous malignancy, typically diagnosed at advanced stage. An important area of mesothelioma biology and progression is understanding intercellular communication and the contribution of the secretome. Exosomes are secreted extracellular vesicles shown to shuttle cellular cargo and direct intercellular communication in the tumour microenvironment, facilitate immunoregulation and metastasis. In this study, quantitative proteomics was used to investigate MM-derived exosomes from distinct human models and identify select cargo protein networks associated with angiogenesis, metastasis, and immunoregulation. Utilising bioinformatics pathway/network analyses, and correlation with previous studies on tumour exosomes, we defined a select mesothelioma exosomal signature (mEXOS, 570 proteins) enriched in tumour antigens and various cancer-specific signalling (HPGD/ENO1/OSMR) and secreted modulators (FN1/ITLN1/MAMDC2/PDGFD/GBP1). Notably, such circulating cargo offers unique insights into mesothelioma progression and tumour microenvironment reprogramming. Functionally, we demonstrate that oncogenic exosomes facilitate the migratory capacity of fibroblast/endothelial cells, supporting the systematic model of MM progression associated with vascular remodelling and angiogenesis. We provide biophysical and proteomic characterisation of exosomes, define a unique oncogenic signature (mEXOS), and demonstrate the regulatory capacity of exosomes in cell migration/tube formation assays. These findings contribute to understanding tumour-stromal crosstalk in the context of MM, and potential new diagnostic and therapeutic extracellular targets.

Reactive oxygen species a double-edged sword for mesothelioma

It is well known that oxidative stress can lead to chronic inflammation which, in turn, could mediate most chronic diseases including cancer. Oxidants have been implicated in the activity of crocidolite and amosite, the most powerful types of asbestos associated to the occurrence of mesothelioma. Currently rates of mesothelioma are rising and estimates indicate that the incidence of mesothelioma will peak within the next 10-15 years in the western world, while in Japan the peak is predicted not to occur until 40 years from now. Although the use of asbestos has been banned in many countries around the world, production of and the potentially hazardous exposure to asbestos is still present with locally high incidences of mesothelioma. Today a new man-made material, carbon nanotubes, has arisen as a concern; carbon nanotubes may display 'asbestos-like' pathogenicity with mesothelioma induction potential. Carbon nanotubes resulted in the greatest reactive oxygen species generation. How oxidative stress activates inflammatory pathways leading to the transformation of a normal cell to a tumor cell, to tumor cell survival, proliferation, invasion, angiogenesis, chemoresistance, and radioresistance, is the aim of this review.

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.

Diagnostic accuracy of osteopontin for malignant pleural mesothelioma: a systematic review and meta-analysis

BACKGROUND

Osteopontin has been viewed as a promising biomarker for malignant pleural mesothelioma (MPM); however, the conclusions of various studies on diagnostic accuracy of osteopontin have not been consistent. The aim of this study was to conduct a systematic review and meta-analysis to evaluate the diagnostic accuracy of circulating osteopontin for MPM.

METHODS

Using appropriate key words, scientific literature that evaluated circulating levels of osteopontin for the diagnosis of MPM was retrieved from electronic databases. Only articles published in English till March 26, 2013 were included in this study. The quality of the studies was assessed using the revised Quality Assessment for Studies of Diagnostic Accuracy (QUADAS-2) tools. The random-effects models were applied for analysing the performance of pooled characteristics.

RESULTS

Six studies were included in the analysis. The overall diagnostic sensitivity and specificity were 0.65 (95% CI: 0.60-0.70) and 0.81 (95% CI: 0.78-0.85), respectively. The area under summary receiver operating characteristic (sROC) curves (AUC) was 0.83. The diagnostic accuracy of serum and plasma osteopontin was comparable.

CONCLUSIONS

Osteopontin is an effective marker for MPM diagnosis. However, more studies with a larger sample size and better design are needed to rigorously assess the diagnostic power of osteopontin.

Integrated high-resolution array CGH and SKY analysis of homozygous deletions and other genomic alterations present in malignant mesothelioma cell lines

High-resolution oligonucleotide array comparative genomic hybridization (aCGH) and spectral karyotyping (SKY) were applied to a panel of malignant mesothelioma (MMt) cell lines. SKY has not been applied to MMt before, and complete karyotypes are reported based on the integration of SKY and aCGH results. A whole genome search for homozygous deletions (HDs) produced the largest set of recurrent and non-recurrent HDs for MMt (52 recurrent HDs in 10 genomic regions; 36 non-recurrent HDs). For the first time, LINGO2, RBFOX1/A2BP1, RPL29, DUSP7, and CCSER1/FAM190A were found to be homozygously deleted in MMt, and some of these genes could be new tumor suppressor genes for MMt. Integration of SKY and aCGH data allowed reconstruction of chromosomal rearrangements that led to the formation of HDs. Our data imply that only with acquisition of structural and/or numerical karyotypic instability can MMt cells attain a complete loss of tumor suppressor genes located in 9p21.3, which is the most frequently homozygously deleted region. Tetraploidization is a late event in the karyotypic progression of MMt cells, after HDs in the 9p21.3 region have already been acquired.

Unusual presentation and location pleural malignant mesothelioma

Pleural malignant mesothelioma is an uncommon tumour of the thorax. We report two cases: a patient with atypically isolated location of the tumour at the right hilum and a young female patient. The histopathological and radiological features are reviewed with reference to relevant literature.

CCL2, galectin-3, and SMRP combination improves the diagnosis of mesothelioma in pleural effusions

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor with poor prognosis. One major challenge for this disease is the development of new, early, and highly reliable diagnostic markers. The aim of this study was to compare the diagnostic value of the chemokine chemokine (C-C motif) ligand 2 (CCL2), galectin-3, and the secretory leukocyte peptidase inhibitor (SLPI) with soluble mesothelin-related peptides (SMRP), and to evaluate the diagnostic performance of marker combinations.

METHODS

The levels of the different markers were measured by enzyme-linked immunosorbent assay in pleural fluids from patients with MPM (n = 61), adenocarcinomas (ADCA, n = 25), or with benign pleural effusions (BPE, n = 15).

RESULTS

SMRP, SLPI, and CCL2 concentrations were significantly higher in pleural effusions from mesothelioma patients. Conversely, galectin-3 levels seemed to be elevated in patients with pulmonary ADCA. Receiver operating characteristic curve analysis revealed that SMRP (area under the curve [AUC] = 0.9059), CCL2 (AUC = 0.7912), galectin-3 (AUC = 0.7584), and SLPI (AUC = 0.7219) were potentially interesting biomarkers for the differentiation of MPM patients from those with BPE or ADCA. Of interest, we showed that the combination of SMRP/CCL2/galectin-3 greatly improved MPM diagnosis (AUC = 0.9680), when compared with SMRP alone.

CONCLUSION

The combination of SMRP/CCL2/galectin-3 seems to represent a promising panel of biomarkers for the reliable diagnosis of MPM in pleural fluids.