Serum and pleural fluid biomarkers for mesothelioma:

Selection of microRNAs in extracellular vesicles for diagnosis of malignant pleural mesothelioma by in vitro analysis

Malignant pleural mesothelioma (MPM) is a malignant tumor which is a challenge for diagnosis and is associated with a poor patient prognosis. Thus, early diagnostic interventions will improve the quality of life and life expectancy of these patients. Recently, cellular microRNAs (miRNAs) have been found to be involved in maintaining homeostasis, and abnormal miRNA expression has often been observed in various diseases including cancer. Extracellular vesicles (EVs) released by many cells contain proteins and nucleic acids. miRNAs are secreted from all cells via EVs and circulate throughout the body. In this study, culture media were passed sequentially through membrane filters 220–50 nm in size, and EVs with diameters of 50 to 220 nm (EVcap50/220) were collected. miRNAs (EV50-miRNAs) in EVcap50/220 were purified, and microarray analysis was performed. EV50-miRNA expression profiles were compared between MPM cells and a normal pleural mesothelial cell line, and six EV50-miRNAs were selected for further investigation. Of these, hsa-miR-193a-5p and hsa-miR-551b-5p demonstrated higher expression in MPM-derived EVcap50/220. These miRNAs reduced the expression of several genes involved in cell-cell interactions and cell-matrix interactions in normal pleural mesothelial cells. Our data suggest that hsa-miR-193a-5p and hsa-miR-551b-5p in EVcap50/220 could be diagnostic markers for MPM.

Fibulin-3 as biomarker of malignant mesothelioma

Many malignant diseases are associated with past asbestos exposure; the most lethal and strictly related to previous fiber exposure being malignant mesothelioma (MM). Effective preventive protocols may include sensitive and specific biomarkers. The role of Fb-3 has been recently investigated for MM early detection, but its role is still under debate. After an independent search for scientific literature, nine studies were included for a systematic review. Human Fb-3 levels seem to be able to separate healthy people with previous exposure to asbestiform fibers from MM patients. Fb-3 blood levels can distinguish MM effusions from other malignant and benign effusions. Furthers investigations on more significant groups of patients are desirable to validate and assess the validity of combining Fb-3 with other biomarkers.

Biomarkers for malignant pleural mesothelioma: a meta-analysis

Malignant pleural mesothelioma (MPM) is a rare but aggressive cancer, and early detection is associated with better survival. Mesothelin, fibulin-3 and osteopontin have been suggested as screening biomarkers. The study conducted a meta-analysis of the mean differences of mesothelin, osteopontin and fibulin-3 in blood and pleural samples. PubMed searches were conducted for studies that measured levels of mesothelin, osteopontin and fibulin-3 in participants with MPM compared with malignancy, benign lung disease or healthy participants. Thirty-two studies with mesothelin levels, 12 studies with osteopontin levels and 9 studies with fibulin-3 levels were included in the meta-analysis. Statistically significant mean differences were seen between MPM patients and all other comparison groups for mesothelin blood and pleural levels. Statistically significant differences in blood osteopontin levels were seen between participants with benign lung disease and healthy participants compared with participants with MPM, but not when comparing participants with cancer with MPM participants. There were not enough studies that reported osteopontin levels in pleural fluid to complete a meta-analysis. Statistically significant differences were seen in both blood and pleural levels of fibulin-3 in MPM patients compared with all other groups. On the basis of these results, mesothelin and fibulin-3 levels appear to be significantly lower in all control groups compared with those with MPM, making them good candidates for screening biomarkers. Osteopontin may be a useful biomarker for screening healthy individuals or those with benign lung disease but would not be useful for screening patients with malignancies.

Biomarkers for Early Diagnosis and Prognosis of Malignant Pleural Mesothelioma: The Quest Goes on

Malignant pleural mesothelioma (MM) is a highly aggressive tumor characterized by a poor prognosis. Although its carcinogenesis mechanism has not been strictly understood, about 80% of MM can be attributed to occupational and/or environmental exposure to asbestos fibers. The identification of non-invasive molecular markers for an early diagnosis of MM has been the subject of several studies aimed at diagnosing the disease at an early stage. The most studied biomarker is mesothelin, characterized by a good specificity, but it has low sensitivity, especially for non-epithelioid MM. Other protein markers are Fibulin-3 and osteopontin which have not, however, showed a superior diagnostic performance. Recently, interesting results have been reported for the HMGB1 protein in a small but limited series. An increase in channel proteins involved in water transport, aquaporins, have been identified as positive prognostic factors in MM, high levels of expression of aquaporins in tumor cells predict an increase in survival. MicroRNAs and protein panels are among the new indicators of interest. None of the markers available today are sufficiently reliable to be used in the surveillance of subjects exposed to asbestos or in the early detection of MM. Our aim is to give a detailed account of biomarkers available for MM.

Targeting microRNA to improve diagnostic and therapeutic approaches for malignant mesothelioma

Malignant mesothelioma is an aggressive and often fatal cancer associated with asbestos exposure. The disease originates in the mesothelial lining of the serosal cavities, most commonly affecting the pleura. Survival rates are low as diagnosis often occurs at an advanced stage and current treatments are limited. Identifying new diagnostic and therapeutic targets for mesothelioma remains a priority, particularly for the new wave of victims exposed to asbestos through do-it-yourself renovations and in countries where asbestos is still mined and used. Recent advances have demonstrated a biological role for the small but powerful gene regulators microRNA (miRNA) in mesothelioma. A number of potential therapeutic targets have been identified. MiRNA have also become popular as potential biomarkers for mesothelioma due to their stable expression in bodily fluid and tissues. In this review, we highlight the current challenges associated with the diagnosis and treatment of mesothelioma and discuss how targeting miRNA may improve diagnostic, prognostic and therapeutic approaches.

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.

CD157 enhances malignant pleural mesothelioma aggressiveness and predicts poor clinical outcome

Malignant mesothelioma is a deadly tumor whose diagnosis and treatment remain very challenging. There is an urgent need to advance our understanding of mesothelioma biology and to identify new molecular markers for improving management of patients. CD157 is a membrane glycoprotein linked to ovarian cancer progression and mesenchymal differentiation. The common embryonic origin of ovarian epithelial cells and mesothelial cells and the evident similarities between ovarian and mesothelial cancer prompted us to investigate the biological role and clinical significance of CD157 in malignant pleural mesothelioma (MPM). CD157 mRNA and protein were detected in four of nine MPM cell lines of diverse histotype and in 85.2% of MPM surgical tissue samples (32/37 epithelioid; 37/44 biphasic). CD157 expression correlated with clinical aggressiveness in biphasic MPM. Indeed, high CD157 was a negative prognostic factor and an independent predictor of poor survival for patients with biphasic MPM by multivariate survival analysis (HR = 2.433, 95% CI 1.120-5.284; p = 0.025). In mesothelioma cell lines, CD157 gain (in CD157-negative cells) or knockdown (in CD157-positive cells) affected cell growth, migration, invasion and tumorigenicity, most notably in biphasic MPM cell lines. In these cells, CD157 expression was associated with increased activation of the mTOR signaling pathway, resulting in decreased platinum sensitivity. Moreover, a trend towards reduced survival was observed in patients with biphasic MPM receiving postoperative platinum-based chemotherapy. These findings indicate that CD157 is implicated in multiple aspects of MPM progression and suggest that CD157 expression could be used to stratify patients into different prognostic groups or to select patients that might benefit from particular chemotherapeutic approach.

Fibulin-3 as a diagnostic biomarker in patients with malignant mesothelioma

BACKGROUND

New tumour biomarkers are being intensely investigated for malignant mesothelioma (MM). Fibulin-3 is produced in MM but its role remains uncertain. The aim of this study was to evaluate the validity of measuring serum fibulin-3 in the diagnosis and prognosis of MM.

MATERIALS AND METHODS

This prospective study was performed on 43 patients and 40 healthy controls who were admitted to our hospital between January 2012 and January 2014. Data from MM patients, including demographic and clinical features, routine laboratory data, levels of serum fibulin-3, and treatment outcomes were defined as potential prognostic factors. The receiver operating characteristic (ROC) curve for fibulin-3 was used to detect the cut-off value with highest sensitivity and specificity. Univariate survival analysis was performed using the Kaplan-Meier method in patients with MM. Afterwards, the possible factors identified with univariate analyses were entered into the cox regression analysis.

RESULTS

Our results revealed that patients with MM had significantly higher serum levels of fibulin-3 than controls. The results showed that the best cut-off point was 36.6 ng/ml with an AUC (area under the curve)=0.976, sensitivity=93.0% and specificity=90.0. In our study, the initial significant poor prognostic factors were advanced stage, high white blood cell count, high platelet count, high C-reactive protein (p<0.05 for each variable). Later, according to multivariate analysis the results showed only advanced stage as significant parameter (p=0.040).

CONCLUSIONS

We determined that real use for serum fibulin-3 was not for prognosis but for diagnosis in MM. Also advanced stage was associated with poor MM prognosis.

Preoperative serum levels of mesothelin in patients with colon cancer

Background. Screening for biochemical markers is important for diagnosing colon cancer. In this study, the reliability of serum mesothelin levels as a potential diagnostic and screening instrument was evaluated concerning colon cancer. Methods. Ninety-five patients who had undergone colonoscopic examination and who were diagnosed with colon cancer were included in the study. The serum mesothelin levels were measured with the ELISA kits and were evaluated in terms of significant difference when compared between colon cancer and control group. Results. Patients with colon cancer had significantly higher mesothelin serum levels (P < 0.001) than the control groups. We found significant associations between serum levels and tumor grade, perineural invasion, and vascular invasion (resp., P < 0.001). Conclusion. Evaluating the serum levels of mesothelin has a potential to detect and screen the colon cancer in affected patients. Our data suggest that mesothelin exhibits effects towards colon cancer and serves as a biomarker for this deadly disease.

Significance of serum mesothelin in an asbestos-exposed population in the Czech Republic

AIMS

Pleural mesothelioma is a highly aggressive and difficult-to-treat form of cancer induced by asbestos in 80-90% of cases. The population group most at risk of the condition are asbestos-exposed workers. Mesothelin or soluble mesothelin-related protein (SMRP) is studied as a potential marker of mesothelioma in the at-risk population.

METHODS

The study comprised 239 subjects with a mean duration of occupational exposure to asbestos of 19.9 years. In all of them, a complete medical history was taken, focused on exposure duration and a physical examination, a chest X-ray or other imaging investigations and a lung function test were performed. Their serum SMRP levels were measured and biopsy samples were taken to diagnose pleural disease. Based on the above examinations, the subjects were classified into subgroups and serum SMRP concentrations were statistically analyzed with respect to individual parameters.

RESULTS

In asbestos-exposed individuals, mesothelin levels were significantly higher in those with pathological X-ray findings than in those with normal X-ray results (0.78 ± 0.63 vs. 0.50 ± 0.35, P<0.0001). The group of patients with benign disease had statistically significantly higher mesothelin levels than those with normal X-ray findings (0.755 ± 0.543 vs. 0.50 ± 0.35, P<0.001). In the group with present malignant processes, mesothelin levels were higher than in individuals with benign disease (1.19 ± 0.89 vs. 0.76 ± 0.54, P=0.015). Only a weak correlation was found between mesothelin levels and asbestos exposure duration. There were relatively high sensitivity and high specificity (75% and 90.6%, respectively) of serum mesothelin for pleural mesothelioma. However, given the small number of mesothelioma cases in the group, the results cannot be considered as statistically significant.

CONCLUSIONS

In persons followed up for asbestos exposure, increased mesothelin levels signalize pathological processes in the chest and correlate with severity of the disease. The study suggests that mesothelin cannot be considered a reliable marker for the early stage of malignant degeneration of pleural disease but only an additional criterion for examination of the followed-up individuals.

CA 125 concentration in portal blood as a predictor of resectability in pancreatic tumor

AIM OF THE STUDY

Pancreatic cancer is one of the most frequent cancers in the world. Only 20% of patients seem to have disease confined to the pancreas, but in only every second case the tumor turns out to be resectable during surgery. Tumor markers may be a useful tool in differentiating benign from malignant pancreatic tumors and in clinical staging. The purpose of the study is to assess CA 125 utility as a predictor of resectability in pancreatic tumor.

MATERIAL AND METHODS

66 patients were operated on for pancreatic tumor between October 2010 and July 2012. CA 125 concentration was measured in peripheral and portal blood. 57 patients were diagnosed with malignant and 9 with inflammatory tumor. Seven patients had metastases to the liver. Radical surgery was performed in 34 patients.

RESULTS

Significantly higher CA 125 concentration in portal blood was found in the pancreatic cancer than in the inflammatory tumor group (36.5 ±99.6 vs. 16.4 ±26.5; p < 0.05). CA 125 concentration in peripheral blood and in portal blood as well of patients with malignant pancreatic tumors and with metastases to the liver was significantly higher than in the group without metastases (146.15 ±256.1 vs. 18.5 ±17.5; p < 0.01 and 147.5 ±261.2 vs. 19.7 ±24.3; p < 0.05, respectively). CA 125 values in the group without metastases to the liver and in the case of radical surgery were significantly higher in portal than in peripheral blood (19.7 ±24.3 vs. 18.5 ±17.5; p < 0.001 and 13.2 ±15.0 vs. 13.0 ±15.2; p < 0.001, respectively).

CONCLUSIONS

Determination of CA 125 concentration in peripheral blood and in portal blood as well might be a useful tool in differentiating between malignant and inflammatory pancreatic tumors and when decisions on surgery extensiveness are being made.

Identification of novel autoantibodies for detection of malignant mesothelioma

Background

The malignant mesothelioma (MM) survival rate has been hampered by the lack of efficient and accurate early detection methods. The immune system may detect the early changes of tumor progression by responding with tumor-associated autoantibody production. Hence, in this study, we translated the humoral immune response to cancer proteins into a potential blood test for MM.

Methodology/Principal Findings

A T7 phage MM cDNA library was constructed using MM tumor tissues and biopanned for tumor-associated antigens (TAAs) using pooled MM patient and normal serum samples. About 1008 individual phage TAA clones from the biopanned library were subjected to protein microarray construction and tested with 53 MM and 52 control serum samples as a training group. Nine candidate autoantibody markers were selected from the training group using Tclass system and logistic regression statistical analysis, which achieved 94.3% sensitivity and 90.4% specificity with an AUC value of 0.89 in receiver operating characteristic analysis. The classifier was further evaluated with 50 patient and 50 normal serum samples as an independent blind validation, and the sensitivity of 86.0% and the specificity of 86.0% were obtained with an AUC of 0.82. Sequencing and BLASTN analysis of the classifier revealed that five of these nine candidate markers were found to have strong homology to cancer related proteins (PDIA6, MEG3, SDCCAG3, IGHG3, IGHG1).

Conclusions/Significance

Our results indicated that using a panel of 9 autoantibody markers presented a promising accuracy for MM detection. Although the results need further validation in high-risk groups, they provided the potentials in developing a serum-based assay for MM diagnosis.

Comparison of the diagnostic accuracy of the MSLN gene products, mesothelin and megakaryocyte potentiating factor, as biomarkers for mesothelioma in pleural effusions and serum

The MSLN gene products, soluble mesothelin and megakaryocyte potentiating factor (MPF), are being investigated as biomarkers for the asbestos-related cancer malignant mesothelioma (MM). Pleural fluid biomarkers of MM can be elevated when serum levels remain normal. The aim of this study was to determine if this was true for MPF and to compare levels of mesothelin. Biomarker concentrations were compared in 66 MM patients, 39 patients with other malignancies, 37 with benign disease, 18 asbestos-exposed healthy individuals, and 53 patients with chronic kidney disease. In pleural effusions, MPF and soluble mesothelin concentrations were both significantly elevated in MM patients relative to controls. No significant difference between the area under the receiver operator curve (AUC) for MPF (0.945 ± 0.02) and mesothelin (0.928 ± 0.03) when distinguishing MM from all other causes of effusion was observed. MPF and mesothelin serum concentrations were highly correlated and of equivalent diagnostic accuracy with AUCs of 0.813 ± 0.04 and 0.829 ± 0.03, respectively. Serum levels of both markers increased with decreasing kidney function. In conclusion, MPF is elevated in the pleural effusions of MM patients similar to that of mesothelin. Mesothelin and MPF convey equivalent diagnostic information for distinguishing MM from other diseases in pleural effusions as well as serum.

The classic pneumoconioses: new epidemiological and laboratory observations

The purpose of this article is to provide an update on selected issues of current interest and recent developments related to 3 types of inorganic mineral dust exposures causing classic forms of pneumoconiosis: coal mine dust, crystalline silica, and asbestos. Common themes include new imaging modalities, emerging exposures, and evolving appreciation of additional adverse health effects associated with exposure to these inorganic mineral dusts.

Development of a biosensor for detection of pleural mesothelioma cancer biomarker using surface imprinting

Hyaluronan-linked protein 1 (HAPLN1) which has been shown to be highly expressed in malignant pleural mesotheliomas (MPM), was detected in serum using an electrochemical surface-imprinting method. First, the detection method was optimized using Bovine serum albumin (BSA) as a model protein to mimic the optimal conditions required to imprint the similar molecular weight protein HAPLN1. BSA was imprinted on the gold electrode with hydroxyl terminated alkane thiols, which formed a self-assembled monolayer (SAM) around BSA. The analyte (BSA) was then washed away and its imprint (empty cavity with shape-memory) was used for detection of BSA in a solution, using electrochemical open-circuit potential method, namely potentiometry. Factors considered to optimize the conditions include incubation time, protein concentration, limit of detection and size of electrode. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used to confirm selectivity of imprints. With the obtained imprinting control parameters, HAPLN1 was imprinted in duplicate and the detection of spiked HAPLN1 was successfully conducted in serum.

Changes of mesothelin and osteopontin levels over time in formerly asbestos-exposed power industry workers

PURPOSE

In patients developing malignant pleural mesothelioma (MPM) or lung cancer, using effective tumour markers is the quickest way to ensure early diagnosis and improve survival time. The aim of our study was to assess the influence of age and asbestos exposure on the blood levels of the proposed tumour markers, mesothelin and osteopontin, and to determine the change of these markers over time.

METHODS

We analysed 3,329 blood samples of 2,262 participants including 1,894 formerly asbestos-exposed power industry workers, a mixed group of 266 participants with an unknown history of asbestos exposure and a group of 102 non-asbestos-exposed controls. Marker concentrations were determined using commercial ELISA kits.

RESULTS

While age had a strong influence on marker levels, there was no association between exposure duration or benign asbestos-related disease and marker levels. In order to assess the maximum increase that can be expected to occur in asbestos-exposed workers those with an at least 10 % increase were selected (n = 290 for mesothelin and n = 81 for osteopontin). The 95th percentile of the annual change was 0.402 nmol/l for mesothelin and 334 ng/ml for osteopontin. In two patients with MPM and five with lung cancer, we could obtain more than one marker result before the diagnosis was made. Both MPM patients showed a steep increase of mesothelin levels.

CONCLUSIONS

Fixed cut-off values for deciding between intensive clinical work-up and continued surveillance appeared inadequate for the evaluated markers. While general conclusions cannot be drawn, we can say that the results of the two patients would be consistent with a mesothelin increase between 6 and 18 months before clinical symptoms developed.

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.

Early detection of malignant pleural mesothelioma in asbestos-exposed individuals with a noninvasive proteomics-based surveillance tool

BACKGROUND

Malignant pleural mesothelioma (MM) is an aggressive, asbestos-related pulmonary cancer that is increasing in incidence. Because diagnosis is difficult and the disease is relatively rare, most patients present at a clinically advanced stage where possibility of cure is minimal. To improve surveillance and detection of MM in the high-risk population, we completed a series of clinical studies to develop a noninvasive test for early detection.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted multi-center case-control studies in serum from 117 MM cases and 142 asbestos-exposed control individuals. Biomarker discovery, verification, and validation were performed using SOMAmer proteomic technology, which simultaneously measures over 1000 proteins in unfractionated biologic samples. Using univariate and multivariate approaches we discovered 64 candidate protein biomarkers and derived a 13-marker random forest classifier with an AUC of 0.99±0.01 in training, 0.98±0.04 in independent blinded verification and 0.95±0.04 in blinded validation studies. Sensitivity and specificity at our pre-specified decision threshold were 97%/92% in training and 90%/95% in blinded verification. This classifier accuracy was maintained in a second blinded validation set with a sensitivity/specificity of 90%/89% and combined accuracy of 92%. Sensitivity correlated with pathologic stage; 77% of Stage I, 93% of Stage II, 96% of Stage III and 96% of Stage IV cases were detected. An alternative decision threshold in the validation study yielding 98% specificity would still detect 60% of MM cases. In a paired sample set the classifier AUC of 0.99 and 91%/94% sensitivity/specificity was superior to that of mesothelin with an AUC of 0.82 and 66%/88% sensitivity/specificity. The candidate biomarker panel consists of both inflammatory and proliferative proteins, processes strongly associated with asbestos-induced malignancy.

SIGNIFICANCE

The SOMAmer biomarker panel discovered and validated in these studies provides a solid foundation for surveillance and diagnosis of MM in those at highest risk for this disease.

Two novel polymorphisms in 5' flanking region of the mesothelin gene are associated with soluble mesothelin-related peptide (SMRP) levels

BACKGROUND AND AIMS

Increased concentrations of soluble mesothelin-related peptides (SMRP) have been found in sera of patients with malignant pleural mesothelioma (MPM) even if a relatively high rate of false positives has hampered their clinical use as a tumor marker. Individual SMRP levels could be affected by polymorphic elements. The aim of this study was to investigate the association between single nucleotide polymorphisms within the promoter-5'UTR regions and SMRP levels in healthy asbestos-exposed individuals and patients suffering from MPM.?

METHODS

The promoter-5'UTR regions of the mesothelin gene were genotyped in 59 healthy asbestos-exposed subjects and 27 MPM patients. SMRP levels were measured using a commercially available ELISA kit.?

RESULTS

Two novel polymorphisms, an A>C variant (called New1) and a C>T variant (called New2), were identified. In healthy subjects, high SMRP levels were associated with the C-variant of New1, with an average 1.62-fold increase compared with AA homozygotes (p<0.0001). Most of the C-allele carriers had SMRP levels above the threshold of 1.00 nM. We set two different SMRP cutoffs on the basis of the combined New1+New2 genotypes.?

CONCLUSIONS

New1-New2 genotypes could be employed as markers for setting individualized and appropriate thresholds of "normality" when SMRP is used in surveillance programs of asbestos-exposed people.

Early stages of mesothelioma, screening and biomarkers

The early diagnosis of mesothelioma is notoriously difficult, both from a clinical and pathological perspective. Patients often undergo several medical investigations without definitive diagnosis. The discovery of biomarkers that can be assessed in pleural effusions, histological samples, and serum may assist with the difficult early diagnosis of mesothelioma. In this chapter we focus on those markers that have been examined in the setting of either early diagnosis of mesothelioma in symptomatic individuals or that have been proposed as suitable for screening of asbestos-exposed individuals, with an emphasis on cytology and histology.

Diagnostic molecular biomarkers for malignant pleural effusions

Malignant pleural effusions (MPEs) are a common and important cause of cancer-related mortality and morbidity. Prompt diagnosis using minimally invasive tests is important because the median survival after diagnosis is only 4–9 months. Pleural fluid cytology is pivotal to current MPE diagnostic algorithms but has limited sensitivity (30–60%). Consequently, many patients need to undergo invasive diagnostic tests such as thoracoscopic pleural biopsy. Recent genomic, transcriptomic, methylation and proteomic studies on cells within pleural effusions have identified novel molecular diagnostic biomarkers that demonstrate potential in complementing cytology in the diagnosis of MPEs. Several challenges will need to be addressed prior to the incorporation of these molecular tests into routine clinical diagnosis, including validation of molecular diagnostic markers in well-designed prospective, comparative and cost–effectiveness studies. Ultimately, minimally invasive diagnostic tests that can be performed quickly will enable clinicians to provide the most effective therapies for patients with MPEs in a timely fashion.

Markers for the non-invasive diagnosis of mesothelioma: a systematic review

Background:

Numerous markers have been evaluated to facilitate the non-invasive diagnostic work-up of mesothelioma. The purpose of this study was to conduct a structured review of the diagnostic performance of non-invasive marker tests for the detection of mesothelioma in patients with suspected mesothelioma.

Methods:

Studies on the diagnostic accuracy of serum and cytological markers published till 31 December 2009, available in either PUBMED or Embase, to detect or exclude the presence of mesothelioma were extracted. Study quality was assessed with use of the Quadas criteria.

Results:

In total, 82 articles were included in this systemic review. Overall, quality of the incorporated studies to address our objective was poor. The most frequently studied immunohistochemical markers for cytological analysis were EMA, Ber-Ep4, CEA, and calretinin. The most frequently investigated serum marker was soluble mesothelin-related protein (SMRP). The markers CEA, Ber-EP4, and calretinin were most valuable in discriminating mesothelioma from other malignant diseases. Markers EMA and SMRP were most valuable in discriminating mesothelioma from non-malignant diseases. No marker performed well in discriminating between mesothelioma and all other diseases.

Conclusion:

Currently, there is only limited evidence to properly assess the value of non-invasive marker tests in the diagnosis of mesothelioma. Studies were of limited value to address our objective and results showed considerable unexplained study heterogeneity.

Plasma versus serum levels of osteopontin and mesothelin in patients with malignant mesothelioma--which is best?

BACKGROUND

Blood-based markers for malignant mesothelioma (MM), particularly soluble mesothelin and osteopontin, are currently of great clinical interest. As there is some concern about the sensitivity of osteopontin in serum versus plasma, we compared them in the same patient population to mesothelin.

METHODS

Soluble mesothelin and osteopontin concentrations were determined by commercial assays in blood samples from 66 patients with pleural MM, 47 patients with non-malignant asbestos-related lung or pleural disease, 42 patients with other benign pleural and lung diseases and 21 patients with lung cancer.

RESULTS

Soluble mesothelin and osteopontin in serum and plasma were significantly elevated in MM patients compared to patients with benign lung and pleural disease. At a level of specificity of 95% relative to patients with benign disease, the sensitivity of mesothelin in serum and plasma at presentation with symptoms was 67%, and for osteopontin in the plasma was 40% and in the serum was 20% for MM patients. Combining the serum mesothelin and plasma osteopontin markers using a logistic regression model did not significantly increase the area under the receiver operator curve.

CONCLUSION

Plasma osteopontin has a superior diagnostic accuracy to serum. As the choice of blood sample type has limit effect on soluble mesothelin sensitivity, plasma should be collected for biomarker evaluation in patients suspected of having mesothelioma.

Mesothelin and kidney function--analysis of relationship and implications for mesothelioma screening

PURPOSE

Malignant mesothelioma (MM) carries a poor prognosis and remains a major public health issue in many countries. Outcomes may be improved with earlier detection and this justifies screening the at-risk asbestos-exposed population. Soluble mesothelin is a potential biomarker for MM, but it has been observed to be elevated in patients with reduced kidney function. Defining the relationship between mesothelin concentrations and kidney function will allow more accurate interpretation of this assay.

MATERIALS AND METHODS

A cross-sectional study consisting of 144 patients with chronic kidney disease (CKD) was conducted at Sir Charles Gairdner Hospital and Royal Perth Hospital in Western Australia. Only patients with CKD stages II-V were recruited while those with a history of renal transplant, dialysis, or malignancy were excluded. Serum and urine mesothelin and creatinine concentrations were determined.

RESULTS

There were 33, 49, 31 and 31 patients in CKD stages II, III, IV and V, respectively recruited. Serum mesothelin increased significantly with increasing serum creatinine (p<0.0001), and worsening stage of CKD (p<0.0001). A significant correlation between urine mesothelin to creatinine ratio and serum mesothelin concentration was detected (p=0.002). No significant difference was found in urine mesothelin to creatinine ratios across the four CKD stage groups.

CONCLUSION

Serum mesothelin concentration is elevated in individuals with renal impairment. Renal function should therefore be taken into account during interpretation of this assay.

Osteopontin levels are elevated in patients with eosinophilic pneumonia

BACKGROUND AND OBJECTIVE

Osteopontin is a key cytokine involved in pro-inflammatory T helper type 1 (Th1)-associated immune responses, which has recently been implicated in allergic diseases. We investigated the pathogenic role of osteopontin in eosinophilic pneumonia.

METHODS

The concentrations of osteopontin and Th1- or Th2-associated cytokines were measured in BAL fluid (BALF) from 41 patients with eosinophilic pneumonia, including those with acute (AEP, n = 12), chronic (CEP, n = 16), or drug-induced eosinophilic pneumonia (DEP, n = 13). The results were compared with those from patients with other interstitial lung diseases. Immunocytochemistry and double immunofluorescence labelling were performed to determine the cellular source of osteopontin.

RESULTS

Osteopontin was significantly elevated in BALF from patients with eosinophilic pneumonia as compared with BALF from patients with drug-induced interstitial pneumonia, hypersensitivity pneumonitis, idiopathic interstitial pneumonia, or sarcoidosis, and also compared with BALF from healthy volunteers. Osteopontin concentrations elevated at the time of exacerbation decreased during clinical improvement, either spontaneously or as a result of corticosteroid therapy. Elevated concentrations of CXCL10, CCL17 and IL-10 were also detected in BALF from patients with eosinophilic pneumonia. Osteopontin concentrations in BALF of AEP patients were correlated with IL-5, as well as IL-10, CCL11, CCL17 and CXCL10 concentrations. In AEP and DEP patients, serum osteopontin concentrations were also elevated. Double immunofluorescence labelling showed that in patients with eosinophilic pneumonia, osteopontin was expressed in lung eosinophils.

CONCLUSIONS

Osteopontin is likely to contribute to the development of inflammation in patients with eosinophilic pneumonia.

Management of malignant pleural mesothelioma

Malignant pleural mesothelioma is a rare neoplasm arising from the surface serosal cells of the pleural cavity. More than 80% of cases of malignant pleural mesothelioma have been attributed to asbestos exposure. In its natural course median survival is 4 to 12 months. If untreated most of patients die due to local complications of the disease. Surgery improves local control but is not sufficient as a single treatment modality. The recommended treatment strategy for a select group of patients is multimodal therapy that includes surgery, radiotherapy and chemotherapy.

Development of an enzyme-linked immunosorbent assay for the detection of human calretinin in plasma and serum of mesothelioma patients

Background

Calretinin is one of the well-established immunohistochemical markers in the diagnostics of malignant mesothelioma (MM). Its utility as a diagnostic tool in human blood, however, is scarcely investigated. The aim of this study was to develop an enzyme-linked immunosorbent assay (ELISA) for human calretinin in blood and to assess its usefulness as a potential minimally invasive diagnostic marker for MM.

Methods

Initially, attempts were made to establish an assay using commercially available antibodies and to optimize it by including a biotin-streptavidin complex into the assay protocol. Subsequently, a novel ELISA based on polyclonal antibodies raised in rabbit immunized with human recombinant calretinin was developed. The assay performance in human serum and plasma (EDTA/heparin) and the influence of calcium concentrations on antibody recognition were studied. Stability of spiked-in calretinin in EDTA plasma under different storage conditions was also examined. In preliminary studies serum and plasma samples from 97 healthy volunteers, 35 asbestos-exposed workers, and 42 MM patients were analyzed.

Results

The mean detection range of the new ELISA was 0.12 to 8.97 ng/ml calretinin. The assay demonstrated markedly lower background and significantly higher sensitivity compared to the initially contrived assay that used commercial antibodies. Recovery rate experiments confirmed dependence of calretinin antibody recognition on calcium concentration. Calcium adjustment is necessary for calretinin measurement in EDTA plasma. Spiked-in calretinin revealed high stability in EDTA plasma when stored at room temperature, 4°C, or after repeated freeze/thaw cycles. Median calretinin values in healthy volunteers, asbestos workers, and MM patients were 0.20, 0.33, and 0.84 ng/ml, respectively (p < 0.0001 for healthy vs. MM, p = 0.0036 for healthy vs. asbestos-exposed, p < 0.0001 for asbestos-exposed vs. MM). Median values in patients with epithelioid and biphasic MM were similar. No influence of age, gender, smoking status, or type of medium (plasma/serum) on calretinin values was found.

Conclusions

The novel assay is highly sensitive and applicable to human serum and plasma. Calretinin appears to be a promising marker for the blood-based detection of MM and might complement other markers. However, further studies are required to prove its usefulness in the diagnosis of MM patients.

Ovarian tumor marker HE4 is differently expressed during the phases of the menstrual cycle in healthy young women

The objective of the present study was to investigate in healthy young women the fluctuations in serum concentration of human epididymal secretory protein human epididymis-specific protein 4 (HE4) and CA125 during the phases of the menstrual cycle and the correlation between HE4 and CA125 values and age. Forty women with regular menstrual cycles were included in the study. Pelvic and transvaginal ultrasound were performed in order to exclude ovarian pathologies. Blood samples were collected at follicular (FP), ovulatory (OP), and luteal (LP) phases of the hormonal cycle. The values of HE4 (expressed as picomoles per liter) observed were (mean ± SEM) 39.1 ± 1.1 (FP), 45.3 ± 1.19 (OP), and 42.0 ± 1.3 (LP). The difference between FP and OP was statistically significant (p = 0.0002). By contrast, serum CA125 levels (expressed as units per milliliter) were 14.35 ± 0.66 (FP), 13.15 ± 0.54 (OP), and 13.70 ± 0.54 (LP), respectively. The levels of HE4 observed in serum samples of women below 35 years were 37.5 ± 1.28 in the FP, 46.6 ± 1.4 in the OP, and 42.8 ± 1.49 in the LP. In this group, a statistically significant difference was observed in the FP compared with the OP (p < 0.0001), whereas no statistically significant difference was observed during the different hormonal phases in the group of women over 35. In conclusion, the correct interpretation of laboratory data is essential to define a threshold of normality, and for what concerns HE4 levels, the menstrual cycle phase-dependent variability appears indicated in the interpretation of the results.

Classification of genes and putative biomarker identification using distribution metrics on expression profiles

Background

Identification of genes with switch-like properties will facilitate discovery of regulatory mechanisms that underlie these properties, and will provide knowledge for the appropriate application of Boolean networks in gene regulatory models. As switch-like behavior is likely associated with tissue-specific expression, these gene products are expected to be plausible candidates as tissue-specific biomarkers.

Methodology/Principal Findings

In a systematic classification of genes and search for biomarkers, gene expression profiles (GEPs) of more than 16,000 genes from 2,145 mouse array samples were analyzed. Four distribution metrics (mean, standard deviation, kurtosis and skewness) were used to classify GEPs into four categories: predominantly-off, predominantly-on, graded (rheostatic), and switch-like genes. The arrays under study were also grouped and examined by tissue type. For example, arrays were categorized as ‘brain group’ and ‘non-brain group’; the Kolmogorov-Smirnov distance and Pearson correlation coefficient were then used to compare GEPs between brain and non-brain for each gene. We were thus able to identify tissue-specific biomarker candidate genes.

Conclusions/Significance

The methodology employed here may be used to facilitate disease-specific biomarker discovery.