Sensitive and specific new enzyme-linked immunosorbent assay for N-ERC/mesothelin increases its potential as a useful serum tumor marker for mesothelioma

Pleural Mesothelioma: Current Practice and Approach

Pleural mesotheliomas represent one of the most common diagnostic challenges in thoracic pathology. The diagnosis of pleural mesothelioma weighs heavily on clinical and radiologic information. In addition, in the past, before the era of immunohistochemistry, the diagnosis was aided with the use of special histochemical stains-PAS, D-PAS, and mucicarmine, which now very much have been replaced by immunohistochemical stains. In the era of immunohistochemistry, a combination of carcinomatous epitopes and positive mesothelioma markers has become paramount in the diagnosis of mesothelioma, and more recently the use of molecular techniques has become another ancillary tool in supporting such a diagnosis. At the same time, the treatment and clinical outcome of these patients may in some measure be determined by the histopathological features of the tumor and one that also over the years has changed from a palliative type to surgery, chemotherapy, radiotherapy, or a combination of these types. The histopathological growth patterns of mesothelioma are also wide, and in some cases may mimic other tumors that may be primary or metastatic to the pleura. Therefore, the assessment of the diagnosis of mesothelioma is one that requires a global view of the different factors including clinical, radiologic, pathologic-including immunohistochemistry and molecular diagnosis.

Serum Levels of N- and C-ERC/Mesothelin and Clinicopathological Factors in Mesothelioma Patients and Those without Mesothelioma

Objectives

ERC/mesothelin is a glycosylphosphatidylinositol (GPI)-anchor protein expressed in mesothelioma. A precursor protein is cleaved by proteases and an N-terminal fragment (N-ERC) is extracellularly secreted. A remaining C-terminal fragment (C-ERC) is tethered on cellular membranes by the GPI-anchor, but C-ERC is also released after cleavage by proteases. We and other groups reported that serum N-/C-ERC levels are associated with stages of mesothelioma and suggested the possibility of their usefulness as diagnostic markers. However, the N-ERC level is also influenced by renal functions that are not directly associated with conditions of mesothelioma. It is not known whether other clinical factors influence serum N-/C-ERC values. Furthermore, their relationship to the amount of ERC/Mesothelin in mesothelioma is not yet validated. The objective of this study is to clarify the relationship of serum N-/C-ERC levels and the status of mesothelioma and several clinical factors.

Materials and Methods

We analyzed relations of serum N-/C-ERC levels and ages, gender and other clinical factors in 522 patients without mesothelioma and examined their relation to the amount of ERC/Mesothelin in mesothelioma tissues in 13 mesothelioma cases.

Results

Serum N-ERC levels were influenced by renal functions. On the contrary, those of C-ERC were not influenced by any clinical factors examined in this study and were significantly correlated with the amount of ERC/Mesothelin in mesothelioma.

Conclusion

Although both markers are good indicators of treatment-responses in individual patients with mesothelioma, only C-ERC reflected the amount of ERC/Mesothelin in mesothelioma among multiple patients, possibly because N-ERC was influenced by renal functions.

Mesothelin Gene Variants Affect Soluble Mesothelin-Related Protein Levels in the Plasma of Asbestos-Exposed Males and Mesothelioma Patients from Germany

Malignant mesothelioma (MM) is a severe disease mostly caused by asbestos exposure. Today, one of the best available biomarkers is the soluble mesothelin-related protein (SMRP), also known as mesothelin. Recent studies have shown that mesothelin levels are influenced by individual genetic variability. This study aimed to investigate the influence of three mesothelin (MSLN) gene variants (SNPs) in the 5′-untranslated promoter region (5′-UTR), MSLN rs2235503 C > A, rs3764246 A > G, rs3764247 A > C, and one (rs1057147 G > A) in the 3′-untranslated region (3′-UTR) of the MSLN gene on plasma concentrations of mesothelin in 410 asbestos-exposed males without cancer and 43 males with prediagnostic MM (i.e., with MM diagnosed later on) from the prospective MoMar study, as well as 59 males with manifest MM from Germany. The mesothelin concentration differed significantly between the different groups (p < 0.0001), but not between the prediagnostic and manifest MM groups (p = 0.502). Five to eight mutations of the four SNP variants studied were associated with increased mesothelin concentrations (p = 0.001). The highest mesothelin concentrations were observed for homozygous variants of the three promotor SNPs in the 5′-UTR (p < 0.001), and the highest odds ratio for an elevated mesothelin concentration was observed for MSLN rs2235503 C > A. The four studied SNPs had a clear influence on the mesothelin concentration in plasma. Hence, the analysis of these SNPs may help to elucidate the diagnostic background of patients displaying increased mesothelin levels and might help to reduce false-positive results when using mesothelin for MM screening in high-risk groups.

Plasmonic Metasurfaces for Medical Diagnosis Applications: A Review

Plasmonic metasurfaces have been widely used in biosensing to improve the interaction between light and biomolecules through the effects of near-field confinement. When paired with biofunctionalization, plasmonic metasurface sensing is considered as a viable strategy for improving biomarker detection technologies. In this review, we enumerate the fundamental mechanism of plasmonic metasurfaces sensing and present their detection in human tumors and COVID-19. The advantages of rapid sampling, streamlined processes, high sensitivity, and easy accessibility are highlighted compared with traditional detection techniques. This review is looking forward to assisting scientists in advancing research and developing a new generation of multifunctional biosensors.

Colorimetric immunosensor based on glassy carbon microspheres test strips for the detection of prostate-specific antigen

Micro-sized glassy carbon microspheres (GCMs, typically 3 μm in diameter) instead of nano-sized gold nanoparticles (AuNPs, typically 20 nm in diameter) were for the first time used as signal markers for the quantitative detection of antigen such as prostate-specific antigen (PSA). After being treated with concentrated HNO₃, GCMs bear carboxyl groups at their surfaces, which enables antibodies to be conjugated with GCMs to yield new type of micro-sized material-based colorimetric probes used for immunochromatographic test strips (ICTSs). The captured black GCMs (with strong and wide-band light absorption) on the T-line of ICTS were used both for qualitative and quantitative determination of PSA. In the case of quantitative determination, a lab-assembled optical strip reader system was used to measure the reflected LED light intensity at 550 nm. The sensing performances of the developed GCM-based ICTSs, such as sensitivity, selectivity, reproducibility, stability, and applicability, were investigated in detail. The developed GCM-based ICTSs can have much higher (3 times) detection sensitivity than AuNP-based ICTSs, showing promising applications in sensitive immunoassay.

Mesothelin, Calretinin, and Megakaryocyte Potentiating Factor as Biomarkers of Malignant Pleural Mesothelioma

PURPOSE

Malignant pleural mesothelioma (MPM) is a highly lethal cancer caused by exposure to asbestos. Currently, the diagnosis is a challenge, carried out by means of invasive methods of limited sensitivity. This is a case-control study to evaluate the individual and combined performance of minimally invasive biomarkers for the diagnosis of MPM.

METHOD

A study of 166 incident cases of MPM and 378 population controls of Mestizo-Mexican ethnicity was conducted. Mesothelin, calretinin, and megakaryocyte potentiating factor (MPF) were quantified in plasma by ELISA. The samples were collected from 2011 to 2016.

RESULTS

Based on ROC analysis and a preset specificity of 95%, the combination of the three biomarkers reached an AUC of 0.944 and a sensitivity of 82% in men. In women, an AUC of 0.937 and a sensitivity of 87% were reached. In nonconditional logistic regression models, the adjusted ORs in men were 7.92 (95% CI 3.02-20.78) for mesothelin, 20.44 (95% CI 8.90-46.94) for calretinin, and 4.37 (95% CI 1.60-11.94) for MPF. The ORs for women were 28.89 (95% CI 7.32-113.99), 17.89 (95% CI 3.93-81.49), and 2.77 (95% CI 0.47-16.21), respectively.

CONCLUSIONS

To our knowledge, this is the first study evaluating a combination of mesothelin, calretinin, and MPF, and demonstrating a sex effect for calretinin. The biomarker panel showed a good performance in a Mestizo-Mexican population, with high sensitivity and specificity for the diagnosis of MPM.

In commemoration of the 2018 Mataro Nagayo Prize: A road to early diagnosis and monitoring of asbestos-related mesothelioma

Primarily caused by exposure to asbestos, mesothelioma is a typical occupational disease. The latency of mesothelioma is as long as 20-40 years, and the cancer initially progresses mainly along the surfaces of pleura or peritoneum without forming masses. As symptoms do not develop until late stages, it has been challenging to diagnose this disease in its early stages and to carry out complete surgical removal. In responding to Japan's asbestos crisis in the mid-2000s, we have developed and improved ERC/MSLN-based serum and radiological markers and pioneered the use of an N-ERC ELISA kit for screening populations at risk for asbestos exposure. In the present article, we review our research toward early diagnosis of asbestos-related mesothelioma before symptoms develop and share our clinical experience of screening, diagnosing and monitoring of this disease. This paper is dedicated to the author (Dr Okio Hino) to commemorate the honor bestowed upon him as the recipient of the Mataro Nagayo Prize in 2018.

Biomarkers in the prevention and follow-up of workers exposed to asbestos

Although in most developed countries the use of asbestos is banned, there is still a consistent portion of the world where asbestos extraction, trading and manufacturing of asbestos-made products is largely diffuse. Worldwide, hundreds of millions of people are at risk of developing an asbestos caused disease because of occupational, environmental or domestic exposure. The WHO estimates that asbestos is responsible for more than 100,000 deaths yearly. This scenario has prompted the research on biomarkers potentially useful for early diagnosis, prognosis and preventive programs on exposed population as well. Here we reviewed the up-to-date literature on this field of research highlighting that along with mesothelin and osteopontin (OPN), some more recently investigated molecules, such as high mobility group box 1 (HMGB1) protein, fibulin-3 and some miRNAs showed very promising. Most of the carried-out studies showed an interesting diagnostic and prognostic performance of some biomarkers, but since they usually lack adequate either specificity or sensitivity, their use in screening or in preventive programs is still not recommended on a routine basis. However, this review suggests the need for more reliable experimental design involving larger population and preferring longitudinal screening of asbestos exposed individuals rather than a single baseline assessment investigation. In addition, given their better diagnostic accuracy, the use of panels including several biomarkers is highly recommended.

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.

Indolent peritoneal mesothelioma: PI3K-mTOR inhibitors as a novel therapeutic strategy

Peritoneal mesothelioma (MPeM) is a scarce abdominal-pelvic malignancy that presents with non-specific features and exhibits a wide clinical spectrum from indolent to aggressive disease. Due to it being a rare entity, there is a lack of understanding of its molecular drivers. Most treatment data are from limited small studies or extrapolated from pleural mesothelioma. Standard treatment includes curative surgery or pemetrexed-platinum palliative chemotherapy. To date, the use of novel targeted agents has been disappointing. Described is the management of two young women with papillary peritoneal mesothelioma with widespread recurrence having received platinum-pemetrexed chemotherapy. Both patients obtained symptomatic and disease benefit with apitolisib, a dual phosphoinositide 3-kinase-mammalian target of rapamycin (PI3K-mTOR) inhibitor for subsequent relapses, with one patient having a partial response for almost 3 years. Both are alive and well 10-13 years from diagnosis.

CONCLUSION

These case presentations highlight a subgroup of rare MPeM that behave indolently that is compatible with long-term survival. This series identifies the use of targeted therapies with PI3K-mTOR-based inhibitors as a novel approach, warranting further clinical assessment. Development of prognostic biomarkers is essential to aid identify tumour aggressiveness, help stratify patients and facilitate treatment decisions.

A recombinant polypeptide of the megakaryocyte potentiating factor is a potential biomarker in plasma for the detection of mesothelioma

Malignant mesothelioma (MM) is a fatal disease mostly associated with asbestos exposure and difficult to detect by non-invasive methods. This study aimed to use recombinant fragments of the megakaryocyte potentiating factor (MPF) for the development of cost-effective MPF ELISAs. Three polypeptides spanning the MPF region (MPF_1-148, MPF _34-288, MPF/MSLN_254-400) were produced in E.coli as maltose-binding protein hybrids. After isolation, Factor Xa digest, and purification, the polypeptides were used for the generation of rabbit antibodies and development of ELISAs. Forty-one MM patients with known histological subtype before tumor-specific treatment and 70 asbestos-exposed individuals free of any cancer were matched according to age, gender, and smoking. Plasma of all subjects was tested with the three newly developed polyclonal antibody-based ELISAs and a commercial mesothelin assay (MESOMARK™). The latter differentiated patients (median concentration 1.95 nM) from controls (median 1.07 nM, p < 0.0001) and showed an area under curve (AUC) of 0.77 in receiver operating characteristics (ROC) analysis. Of the MPF variants, exclusively the ELISA based on antibodies against the MPF_34-288 fragment displayed significantly (p = 0.0002) higher values in patients than in controls (median 1.61 nM versus 0.88 nM; AUC = 0.72). The combination of the MPF_34-288 and mesothelin displayed an improved ROC performance (AUC = 0.80). The MPF_34-288 ELISA could be a cost-effective and minimal-invasive contribution to support a diagnosis of mesothelioma, especially in regions with a limited medical care.

Environmental carcinogenesis - 100th anniversary of creating cancer

Asbestos is an environmental carcinogen, and asbestos‐related diseases represent a global‐scale environmental issue. Mesothelioma is an aggressive, malignant tumor that initially progresses along the surfaces of the pleura and peritoneum that is chiefly attributed to asbestos exposure. X‐rays are commonly used for tumor screening in populations at risk for developing this cancer. We previously reported that the N‐terminal of mesothelin may be a useful blood marker for early diagnosis method for mesothelioma and since then developed an N‐terminal of mesothelin ELISA kit in collaboration with IBL Co., Ltd. and confirmed its utility as a diagnostic system for mesothelioma. Recently, we performed a large‐scale research screening for mesothelioma and showed that it is a good model for early diagnosis in at‐risk populations. The year 2015 is the 100th anniversary of Yamagiwa's great work on coaltar‐induced carcinogenesis by formative stimulation in 1915 and the 10th year since 2005, “Kubota shock”, people recognized that asbestos induces mesothelioma. We dedicate this review to this memorial year for environmental carcinogenesis.

In this year, 2015, is the 100th anniversary of Yamagiwa's great work in induced carcinogenesis and the 10th years from ‘Kubota shock’. We dedicate for this review to this memorial year for environmental carcinogenesis.

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.

Clinical significance of soluble CD26 in malignant pleural mesothelioma

There is no established single diagnostic marker for malignant pleural mesothelioma (MPM). CD26 is a 110 kDa, multifunctional, membrane-bound glycoprotein that has dipeptidyl peptidase IV (DPPIV) enzyme activity. The aim of this study was to evaluate the clinical significance of soluble CD26 (sCD26) in patients with MPM. The study included 80 MPM patients, 79 subjects with past asbestos exposure (SPE), and 134 patients with other benign pleural diseases (OPD) that were included as a control group. sCD26 levels and DPPIV activity in serum and/or pleural fluid were determined using an ELISA kit. Serum sCD26 levels and DPPIV enzyme activity in patients with MPM were significantly decreased compared with those in the SPE group (P = 0.000). The level of serum sCD26 was significantly decreased in patients with advanced stages of MPM compared with those with earlier stages (P = 0.047). The median OS of patients with MPM who had higher DPPIV enzyme activity was significantly longer than that of those with lower DPPIV enzyme activity (P = 0.032). The sCD26 levels in the pleural fluid of MPM patients with an epithelioid subtype were significantly increased compared with the OPD cohort (P = 0.012). Moreover, DPPIV enzyme activity in the pleural fluid of patients with MPM with an epithelioid subtype were significantly increased compared with those in the OPD cohort (P = 0.009). Patients with MPM who had lower specific DPPIV activity, determined as DPPIV/sCD26, showed significantly prolonged survival compared with those with higher specific DPPIV activity (P = 0.028). Serum sCD26 and DPPIV enzyme activity appear to be useful biomarkers for differentiating patients with MPM from SPE. The sCD26 levels or DPPIV enzyme activity in pleural fluid appear to be biomarkers in patients with an epithelioid subtype of MPM. DPPIV activity in serum or pleural fluid appears to be predictive for the prognosis of patients with MPM.

Rat N-ERC/mesothelin as a marker for in vivo screening of drugs against pancreas cancer

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal disease, which is usually diagnosed in an advanced stage. We have established transgenic rats carrying a mutated K-ras gene controlled by Cre/loxP activation. The animals develop PDA which is histopathologically similar to that in humans. Previously, we reported that serum levels of N-ERC/mesothelin were significantly higher in rats bearing PDA than in controls. In the present study, to determine whether serum levels of N-ERC/mesothelin correlated with tumor size, we measured N-ERC/mesothelin levels in rats bearing PDA. Increased serum levels of N-ERC/mesothelin correlated with increased tumor size. This result indicates an interrelationship between the serum level of N-ERC/mesothelin and tumor size. We next investigated the effect of chemotherapy on serum N-ERC/mesothelin levels. Rat pancreatic cancer cells were implanted subcutaneously into the flank of NOD-SCID mice. In the mice treated with 200 mg/kg gemcitabine, tumor weight and the serum level of N-ERC/mesothelin were significantly decreased compared to controls. These results suggest that serum N-ERC/mesothelin measurements might be useful for monitoring response to therapy.

Newly established ELISA for N-ERC/mesothelin improves diagnostic accuracy in patients with suspected pleural mesothelioma

Pleural mesothelioma is an aggressive tumor, commonly caused by exposure to asbestos. The prognosis of mesothelioma remains disappointing despite multimodal treatment. We reported previously that N-ERC/mesothelin could be a useful biomarker for the early diagnosis of pleural mesothelioma and developed an enzyme-linked immunosorbent assay (ELISA) system for its detection. However, the reproducibility of our previous 7–16 ELISA system has been revealed to be unsatisfactory. To measure N-ERC/mesothelin more precisely, we developed a new 7–20 ELISA system. The subjects of this study were patients who were referred to our department with suspected pleural mesothelioma. The current study demonstrated that the newly established 7–20 ELISA system improved the sensitivity and specificity for diagnosing pleural mesothelioma compared with the previous system. Moreover, the 7–20 ELISA system showed better reproducibility and displayed the tendency of both higher sensitivity and higher specificity in plasma than in serum. Particularly for the epithelioid type, the area under the curve (AUC) and the diagnostic accuracy of N-ERC/mesothelin were excellent; the AUC was 0.91, the sensitivity was 0.95, and the specificity was 0.76 in plasma. In conclusion, assessment of N-ERC/mesothelin with our newly established 7–20 ELISA system is clinically useful for the precise diagnosis of pleural mesothelioma.

Diagnostic values of soluble mesothelin-related peptides for malignant pleural mesothelioma: updated meta-analysis

OBJECTIVE

Although the values of soluble mesothelin-related peptides (SMRPs), including mesothelin and megakaryocyte potentiating factor, in serum and/or pleural fluid for diagnosing malignant pleural mesothelioma (MPM) have been extensively studied, the exact diagnostic accuracy of these SMRPs remains controversial. The purpose of the present meta-analysis is to update the overall diagnostic accuracy of SMRPs in serum and, furthermore, to establish diagnostic accuracy of SMRPs in pleural fluid for MPM.

DESIGN

Systematic review and meta-analysis.

METHODS

A total of 30 articles of diagnostic studies were included in the current meta-analysis. Sensitivity, specificity and other measures of accuracy of SMRPs in serum and pleural fluid for the diagnosis of MPM were pooled using random effects models. Summary receiver operating characteristic curves were used to summarise overall test performance.

RESULTS

The summary estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic OR were 0.61, 0.87, 5.71, 0.43 and 14.43, respectively, for serum and 0.79, 0.85, 4.78, 0.30 and 19.50, respectively, for pleural fluid. It was also found that megakaryocyte potentiating factor in serum had a superior diagnostic accuracy compared with mesothelin for MPM.

CONCLUSIONS

SMRPs in both serum and pleural fluid are helpful markers for diagnosing MPM with similar diagnostic accuracy. The negative results of SMRP determinations are not sufficient to exclude non-MPM, and the positive test results indicate that further invasive diagnostic steps might be necessary for the diagnosis of MPM.

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

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

Retrospective analysis of large-scale research screening of construction workers for the early diagnosis of mesothelioma

The early diagnosis of mesothelioma, an aggressive malignant tumor, is considered to be important for prognosis. X-ray is commonly used for the assessment of a mass in a population exhibiting a risk factor. However, there are currently no available studies indicating that such an assessment may be used to achieve early diagnosis and improve the patient's outcome. We previously reported that N-ERC/mesothelin may be a useful blood tumor marker for mesothelioma. In order to investigate whether this tumor marker is useful for early diagnosis in a mass examination, in 2007 we initiated a 5-year large-scale screening of construction workers with a risk of asbestos exposure in Japan. Blood samples were collected annually and N-ERC/mesothelin levels were determined. Based on the results of those findings, along with medical history and related data, we screened the participants to identify a high-risk population. As a result, 62 subjects were identified among ~40,000 participants as the high-risk population. Two of these 62 participants subsequently developed mesothelioma, although the remaining participants have not yet developed mesothelioma. In conclusion, N-ERC/mesothelin may be useful as a blood tumor marker in the early diagnosis of mesothelioma in a mass examination. A future prospective study to confirm the findings of this research screening is currently under planning.

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 challenge of prognostic markers in pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a very aggressive tumor, highly resistant to chemo- and radio-therapy. Treatment of MPM patients is often disappointing, regardless of the modality used. Inter-individual variability of response to multimodal treatment remains a challenge and generally the MPM prognosis continues to be poor. Knowledge of predicting factors of outcome is currently insufficient; therefore, it would be highly desirable to find specific prognostic markers for MPM. Translational research projects are to be implemented.

The N-ERC index is a novel monitoring and prognostic marker for advanced malignant pleural mesothelioma

BACKGROUND

Although N-ERC/mesothelin (N-ERC) is an attractive diagnostic and treatment monitoring biomarker for malignant pleural mesothelioma (MPM), its clinical utility for predicting the prognosis has not yet been clarified. The aim of this study is to investigate whether the serum N-ERC level can accurately predict the outcome in patients with MPM.

METHODS

Twenty-six patients with MPM were enrolled. Serum N-ERC level was measured before and after chemotherapy. The N-ERC index was determined by the logarithm of the division of the N-ERC level after two courses of chemotherapy by the prior level.

RESULTS

The median N-ERC index in the partial response (PR) group was significantly lower than that in patients with the stable disease (SD) plus the progressive disease (PD) group. The overall survival in the group whose median N-ERC index was lower than its median value was significantly longer than the group whose median N-ERC index was higher than its median value.

CONCLUSIONS

The N-ERC index is therefore considered to be a useful biomarker for predicting not only the chemotherapeutic response, but also the prognosis in patients with advanced MPM.

Hyaluronic acid in the pleural fluid of patients with malignant pleural mesothelioma

BACKGROUND

We retrospectively analyzed hyaluronic acid (HA) concentrations in pleural fluid and evaluated its utility for the differential diagnosis of malignant pleural mesothelioma (MPM).

METHODS

Pleural fluid HA concentrations were measured in 334 patients, including 50, 48, 85, 18, 86, 6, and 41 patients with MPM, benign asbestos pleurisy (BAP), lung cancer (LC), other malignant conditions (OMCs), infectious pleuritis (IP), collagen disease (CD), and other conditions, respectively.

RESULTS

The median (range) HA concentrations in pleural fluid were 78,700 (7920-2,630,000)ng/ml in the MPM group, 35,950 (900-152,000)ng/ml in the BAP group, 19,500 (2270-120,000)ng/ml in the LC group, 14,200 (900-101,000)ng/ml in the OMC group, 23,000 (900-230,000)ng/ml in the IP group, 24,600 (9550-80,800)ng/ml in the CD group, and 8140 (900-67,800)ng/ml in the other diseases group. HA levels were significantly higher in the MPM group than in the other groups. Receiver operating characteristic (ROC) analysis revealed an area under the ROC curve value of 0.832 (95% confidence interval, 0.765-0.898) for the differential diagnosis of MPM. With a cutoff value of 100,000ng/ml, the sensitivity and specificity were 44.0 and 96.5%, respectively. In the MPM group, HA values were significantly higher for the epithelioid subtype than for the sarcomatous subtype (p=0.007), and higher in earlier stages (I and II) than in advanced stages (III and IV) (p=0.007).

CONCLUSIONS

A diagnosis of MPM should be strongly considered in patients with pleural fluid HA concentrations exceeding 100,000ng/ml.

The utility of serum N-ERC/mesothelin as a biomarker of ovarian carcinoma

Ovarian carcinoma has been difficult to diagnose at an early stage. Recently, it has been recognized that the measurement of blood N-ERC/mesothelin levels aids early detection in and postoperative therapeutic monitoring of patients with mesothelioma, who have been exposed to asbestos. ERC/mesothelin has also been reported to be expressed in ovarian carcinoma. We determined serum N-ERC/mesothelin levels in patients with ovarian carcinoma using an enzyme-linked immunosorbent assay (ELISA). In addition, we immunohistochemically evaluated surgically resected specimens for C-ERC/mesothelin expression. As a result, of the 32 patients with ovarian tumors (18 carcinoma, 2 borderline tumors), one patient with serous adenocarcinoma showed increased N-ERC/ mesothelin levels. Immunohistochemically, of the 20 ovarian tumor (carcinoma and borderline tumor) specimens evaluated for serum N-ERC/mesothelin, 9 (45.0%) were positive for C-ERC/mesothelin. The C-ERC/mesothelin-positive specimens were found to be serous and clear cell adenocarcinomas. If serum N-ERC/mesothelin, which is considered useful for early detection in and therapeutic monitoring of patients with mesothelioma, may also be used for ovarian carcinoma monitoring, it may be a valuable serum tumor marker for the early detection of ovarian carcinoma.

Soluble mesothelin, megakaryocyte potentiating factor, and osteopontin as markers of patient response and outcome in mesothelioma

INTRODUCTION

Soluble mesothelin (SM), megakaryocyte potentiating factor (MPF), and osteopontin (OPN) are blood biomarkers of mesothelioma. This study evaluates their use as markers of response to therapy and outcome.

METHODS

Sixty-two patients with malignant pleural mesothelioma were included in an observational multicenter study. Blood samples and matched computed tomography scans were collected at diagnosis and, when possible, during and after therapy. For each patient, the best overall radiological response was compared with the changes in serum SM, MPF, and plasma OPN levels across corresponding time points.

RESULTS

In five patients, blood sampling was done shortly before and after extrapleural pneumonectomy. SM and MPF levels markedly decreased after surgery, whereas OPN levels showed a median increase. Fifty-seven patients were surveilled during (and after) chemotherapy, of whom 27 (47%) had stable disease, 14 (25%) partial response, and 16 (28%) progressive disease. In patients with stable disease, SM and MPF levels did not change significantly across the corresponding time points, whereas OPN levels significantly decreased. In those with partial response, SM and MPF levels significantly decreased, whereas OPN levels showed no significant change. In patients with progressive disease, all three biomarker levels significantly increased. Patient responses correlated with a 15% change in all three biomarkers, although SM and MPF appeared more accurate than OPN. Low baseline OPN levels were independently associated with favorable progression-free survival and overall survival. Neither SM nor MPF showed prognostic value.

CONCLUSIONS

SM and MPF levels were more closely associated with disease course than OPN and might prove useful in monitoring patient response in mesothelioma. Baseline OPN levels were an independent negative predictor of survival. These promising results require further validation.

Diffuse malignant peritoneal mesothelioma--an update on treatment

Mesotheliomas are aggressive and lethal neoplasms arising from mesothelial cells lining the pleura, peritoneum, tunica vaginalis testis and pericardium. Malignant peritoneal mesothelioma accounts for about 30% of all mesotheliomas. Asbestos is the main known cause of the disease. Presenting symptoms in these patients include: ascites, abdominal pain, asthenia, weight loss, anorexia, abdominal mass, fever, diarrhea and vomiting. Electron microscopy, immunohistochemistry, computed tomography scan, echotomography, magnetic resonance imaging, positron emission tomography and laparoscopy are used in diagnosis and follow-up. Chemotherapy alone is considered as a palliative treatment for these patients who are not eligible for radical surgery. The most promising non-surgical approach today in the management of peritoneal mesothelioma is the use of the combination chemotherapy regime of an antifolate (pemetrexed and raltitrexed) and a platinum based (cisplatin) agent with a median survival of about 12-14 months. Due to peritoneal confinement of malignant mesothelioma and low occurrence of metastasis, a locoregional approach consisting of cytoreductive surgery and perioperative intraperitoneal chemotherapy has been introduced as a curative treatment option over the last decade with an overall 5-year survival rate of 29-63%. In this locoregional approach, surgery can separate the adhesions and remove the bulky tumor, leaving microscopic residual tumors much more susceptible to the killing effect of chemotherapeutic drugs. Here in St. George hospital, cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (using cisplatin and doxorubicin) resulted in significant survival advantage. This article describes how the prognosis of the disease has changed over the last decade.

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.

Soluble markers for diagnosis of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly aggressive and invasive tumor, whose incidence is expected to peak, in many countries, at the end of the present decade, 20–40 years after the peak of asbestos use (asbestos being the most important etiological factor). MPM has a poor prognosis, in part, owing to a difficult and often late diagnosis hindered by a lack of available tests able to diagnose or predict this cancer in its early stages. Recently, there has been increased interest in noninvasive, economic and well-accepted diagnostic tests for screening of asbestos-exposed subjects, as well as for monitoring response of MPM patients to treatment. Several markers have been studied in biofluids, such as serum, plasma and pleural effusions, especially using ELISA, and some of them are still under investigation. However, only mesothelin and ostepontin have proven levels of sensitivity and specificity that are worth testing in the clinical setting.

Feasibility of large-scale screening using N-ERC/mesothelin levels in the blood for the early diagnosis of malignant mesothelioma

A large-scale screening involving the measurement of N-ERC/mesothelin levels in blood using an ELISA system for the early diagnosis of malignant mesothelioma (MM) was carried out in individuals with a history of employment at construction sites. Approximately 30,000 subjects were screened. Of the 80 subjects with high-risk values, one male patient was diagnosed as having MM based on a PET study and histopathology. This is the first report of the pre-clinical diagnosis of MM based on blood test screening. In addition, plasma levels of N-ERC/mesothelin may be effectively used for monitoring relapse after surgery.

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

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

Development of positron emission tomography imaging by 64Cu-labeled Fab for detecting ERC/mesothelin in a mesothelioma mouse model

BACKGROUND

Malignant mesothelioma is a highly aggressive form of cancer. Curative surgery is the only effective therapy for mesothelioma, and therefore early diagnosis is important. However, early diagnosis is difficult using current diagnostic imaging techniques, and a new imaging method for early diagnosis is urgently required. We evaluated the affinity of radiolabeled monoclonal antibodies to the C-terminal fragment of ERC/mesothelin for this purpose.

METHODS

In-labeled or I-labeled IgG against C-terminal fragment of ERC and its Fab fragment were evaluated in vitro by cell binding, competitive inhibition, and cellular internalization assays, and in vivo by biodistribution in mice bearing ERC-expressing tumors. Next, the Fab fragment was labeled with the positron emitter Cu and evaluated by positron emission tomography (PET).

RESULTS

Radiolabeled IgG and Fab showed specific binding to ERC-expressing mesothelioma cells with high affinity. Both radiolabeled IgG and Fab internalized into cells after binding to ERC on the cell surface. In-labeled IgG accumulated in ERC-expressing tumors and resulted in a moderate tumor-to-blood ratio at 4 days after injection. Furthermore, PET using Cu-labeled Fab visualized the tumor at 6 h after injection.

CONCLUSION

Cu-labeled Fab can be useful for ERC-specific PET imaging, and can thus facilitate improved diagnosis of patients with early-stage mesothelioma.

Serum level of expressed in renal carcinoma (ERC)/ mesothelin in rats with mesothelial proliferative lesions induced by multi-wall carbon nanotube (MWCNT)

Expressed in renal carcinoma (ERC)/mesothelin is a good biomarker for human mesothelioma and has been investigated for its mechanistic rationale during the mesothelioma development. Studies are thus ongoing in our laboratories to assess expression of ERC/mesothelin in sera and normal/proliferative/neoplastic mesothelial tissues of animals untreated or given potentially mesothelioma-inducible xenobiotics, by an enzyme-linked immunosorbent assay (ELISA) for N- and C-(terminal fragments of) ERC/mesothelin and immunohistochemistry for C-ERC/mesothelin. In the present paper, we intend to communicate our preliminary data, because this is the first report to show how and from what stage the ERC/mesothelin expression changes during the chemical induction of mesothelial proliferative/neoplatic lesions. Serum N-ERC/mesothelin levels were 51.4 +/- 5.6 ng/ml in control male Fischer 344 rats, increased to 83.6 +/- 11.2 ng/ml in rats given a single intrascrotal administration of 1 mg/kg body weight of multi-wall carbon nanotube (MWCNT) and bearing mesothelial hyperplasia 52 weeks thereafter, and further elevated to 180 +/- 77 ng/ml in rats similarly treated and becoming moribund 40 weeks thereafter, or killed as scheduled at the end of week 52, bearing mesothelioma. While C-ERC/mesothelin was expressed in normal and hyperplastic mesothelia, the protein was detected only in epithelioid mesothelioma cells at the most superficial layer. It is thus suggested that ERC/mesothelin can be used as a biomarker of mesothelial proliferative lesions also in animals, and that the increase of levels may start from the early stage and be enhanced by the progression of the mesothelioma development.

Mesothelin (MSLN) promoter is hypomethylated in malignant mesothelioma, but its expression is not associated with methylation status of the promoter

Gene methylation leads to malignant progression in some tumors. The mechanism by which mesothelin is expressed in malignant mesothelioma (MM) is not well understood. MM is histologically divided into 3 subtypes, that is, the epithelioid, sarcomatoid, and biphasic types, and it was shown that mesothelin expression was restricted to the epithelioid type and the epithelioid component of the biphasic type of MM. However, its regulatory mechanism of expression has not been clarified. Here, we studied the expression of mesothelin by immunohistochemistry along with the methylation status of 20 CpG sites in the promoter of the mesothelin gene (MSLN) in 118 lung specimens, including 39 MM, 41 lung carcinoma, 26 nonneoplastic pulmonary lesions, and 12 normal lung tissue samples by the methylation-sensitive single nucleotide primer extension technique. We confirmed that mesothelin was expressed in the epithelioid type and epithelioid component of the biphasic type of MM but neither in the sarcomatoid type nor sarcomatous component of the biphasic type. Surprisingly, the MSLN promoter was significantly hypomethylated in the MM cases regardless of its subtype, compared with the other pulmonary lesions and normal lung tissue samples. These findings suggested that hypomethylation of the MSLN promoter may be specifically associated with the formation of MM, regardless of its expression status, and that the expression of mesothelin protein was lost in the sarcomatoid type by some unknown posttranscriptional regulatory mechanism. We also identified 4 CpG sites, among the 20 sites studied, to be more specifically hypomethylated in MM cases.

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.

Antitumor activity of anti-C-ERC/mesothelin monoclonal antibody in vivo

Mesothelioma is an aggressive cancer often caused by chronic asbestos exposure, and its prognosis is very poor despite the therapies currently used. Due to the long latency period between asbestos exposure and tumor development, the worldwide incidence will increase substantially in the next decades. Thus, novel effective therapies are warranted to improve the prognosis. The ERC/mesothelin gene (MSLN) is expressed in wide variety of human cancers, including mesotheliomas, and encodes a precursor protein cleaved by proteases to generate C-ERC/mesothelin and N-ERC/mesothelin. In this study, we investigated the antitumor activity of C-ERC/mesothelin-specific mouse monoclonal antibody, 22A31, against tumors derived from a human mesothelioma cell line, ACC-MESO-4, in a xenograft experimental model using female BALB/c athymic nude mice. Treatment with 22A31 did not inhibit cell proliferation of ACC-MESO-4 in vitro; however, therapeutic treatment with 22A31 drastically inhibited tumor growth in vivo. 22A31 induced antibody-dependent cell-mediated cytotoxicity by natural killer (NK) cells, but not macrophages, in vitro. Consistently, the F(ab')(2) fragment of 22A31 did not inhibit tumor growth in vivo, nor did it induce antibody-dependent cell mediated cytotoxicity (ADCC) in vitro. Moreover, NK cell depletion diminished the antitumor effect of 22A31. Thus, 22A31 induced NK cell-mediated ADCC and exerted antitumor activity in vivo. 22A31 could have potential as a therapeutic tool to treat C-ERC/mesothelin-expressing cancers including mesothelioma.

Diagnostic performance of soluble mesothelin and megakaryocyte potentiating factor in mesothelioma

RATIONALE

Soluble mesothelin (SM) is currently the reference serum biomarker of malignant pleural mesothelioma (MPM). Megakaryocyte potentiating factor (MPF), which originates from the same precursor protein, is potentially more sensitive, yet lacks validation.

OBJECTIVES

To analyze the diagnostic performance of MPF as an MPM biomarker and compare this performance with SM.

METHODS

A total of 507 participants were enrolled in six cohorts: healthy control subjects (n = 101), healthy asbestos-exposed individuals (n = 89), and patients with benign asbestos-related disease (n = 123), benign respiratory disease (n = 46), lung cancer (n = 63), and MPM (n = 85). Sera were analyzed for SM and MPF levels using the Mesomark and Human MPF ELISA kit, respectively.

MEASUREMENTS AND MAIN RESULTS

SM and MPF levels differed significantly between patients with MPM and participants from each other cohort (P < 0.001). Receiver operating characteristics curve analysis did not reveal a significant difference between both markers in area under curve (AUC) for distinguishing MPM from all cohorts jointly (SM = 0.871, MPF = 0.849; P = 0.28). At 95% specificity, SM and MPF had a sensitivity of 64% (cutoff = 2.00 nmol/L) and 68% (cutoff = 12.38 ng/ml), respectively. Combining both markers did not improve the diagnostic performance.

CONCLUSIONS

In this prospective multicenter study, MPF is validated as a highly performant MPM biomarker. The similar AUC values of SM and MPF, together with the limited difference in sensitivity, show that both serum biomarkers have an equivalent diagnostic performance.

Diagnostic value of soluble mesothelin-related peptides for malignant mesothelioma: a meta-analysis

BACKGROUND

Serum concentrations of soluble mesothelin-related peptides (SMRP) have been reported to be higher in patients with malignant mesothelioma than in healthy subjects and in patients with non-malignant mesothelioma diseases. The aim of the present meta-analysis was to establish the overall diagnostic accuracy of the measurement of SMRPs for diagnosing malignant mesothelioma.

METHODS

After a systematic review of English language studies, sensitivity, specificity, and other measures of accuracy of serum SMRPs in the diagnosis of malignant mesothelioma were pooled using random-effects models. Summary receiver operating characteristic curves were used to summarize overall test performance.

RESULTS

Eleven publications from 12 studies met our inclusion criteria. The summary estimates for SMRPs in the diagnosis of malignant mesothelioma in the studies included were sensitivity 0.64 (95% confidence interval 0.61-0.68), specificity 0.89 (0.88-0.90), positive likelihood ratio 7.10 (4.44-11.35), negative likelihood ratio 0.39 (0.31-0.48), and diagnostic odds ratio 19.35 (10.95-34.17).

CONCLUSIONS

Serum SMRP determination plays a role in the diagnosis of malignant mesothelioma. The results of SMRP assays should be interpreted in parallel with clinical findings and the results of conventional tests.

An animal model of preclinical diagnosis of pancreatic ductal adenocarcinomas

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal disease, which is usually diagnosed in an advanced stage. Animal PDA models which reflect the human condition are clearly necessary to develop early diagnostic tools and explore new therapeutic approaches. We have established transgenic rats carrying a mutated H- or K-ras gene (Hras250 and Kras327) controlled by Cre/loxP activation. These animals develop PDA which are histopathologically similar to that in humans. We utilized this model to identify biomarkers to detect early PDA. We report here that serum levels of Erc/Mesothelin are significantly higher in rats bearing PDA than in controls. Importantly, the levels are significantly elevated in rats before grossly visible carcinomas develop. Even in rats with very small microscopic ductal carcinoma lesions, elevated serum Erc/Mesothelin can be detected. We believe this is the first report of a pancreas tumor animal model in which pre-symptomatic lesions can be diagnosed.

Biomarkers for malignant pleural mesothelioma: current status

Malignant pleural mesothelioma (MPM) is an aggressive tumor with poor prognosis, whose main etiology is exposure to asbestos fibers. The incidence of MPM is anticipated to increase worldwide during the first half of this century. For various reasons, MPM is difficult to diagnose and is notoriously refractory to most treatments. However, recently two active chemotherapy regimens have been demonstrated to significantly increase survival in patients with MPM, and several therapeutic agents and strategies are currently under evaluation.Researchers have actively sought MPM biomarkers for more than 20 years. Biomarkers would be helpful in managing three clinical aspects of MPM: early diagnosis, prognosis, and treatment outcome prediction. The aims of the present review are to summarize the published and recently presented data on MPM biomarkers and to identify the prospects for future translational research projects.Among the 'classical' diagnostic biomarkers measured in biological fluids, such as cytokeratins and cell surface antigens, none discriminate patients with MPM from those with other malignancies and nonmalignant diseases. Osteopontin, soluble mesothelin, and megakaryocyte potentiating factor (MPF) appear to be the most promising of the recent biomarkers, but are still subject to some limitations. Osteopontin lacks specificity for mesothelioma, while both soluble mesothelin and MPF lack sensitivity for detecting non-epithelial subtypes. Panels consisting of a small set of biomarkers do not improve the diagnostic yield, and results from molecular profiling are too preliminary to be brought into daily clinical practice. While a large number of biomarkers have been assessed in biological fluids and tumor tissue for their prognostic value, none have had a widespread impact on clinical practice. In contrast, data concerning predictive biomarkers are very limited, even though they are most interesting from the perspective of clinicians.Additional prospective studies, in large and independent samples of patients, with rigorous statistical methodology and standardized laboratory techniques are now warranted to validate and define the precise value of diagnostic and prognostic MPM biomarkers. Future research efforts should focus on biomarkers predictive of the efficacy and toxicity of standard chemotherapy. Translational research should be systematically incorporated into the design of clinical trials assessing new targeted agents in MPM.

Assessment of biomarkers in asbestos-exposed workers as indicators of cancer risk

Epidemiological studies have shown that mortality from malignant mesothelioma (MM) and lung cancer have increased with increasing cumulative exposure to asbestos. To investigate whether tumour-related biomarkers can contribute towards the evaluation of the carcinogenic risk in populations exposed to asbestos, the DNA adduct 8-hydroxy-2'-deoxyguanosine (80HdG), interleukine-6 (IL-6), platelet-derived growth factor (PDGF-BB), hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGFbeta) and soluble mesothelin-related peptides (SMRPs) were analysed in a cohort of workers differently exposed to asbestos fibres at the workplace. To document biomarker levels in an unexposed population, 54 age-matched subjects were enrolled. A total of 119 subjects with a history of occupational exposure to asbestos underwent clinical examination and were interviewed by trained personnel, responding to a detailed questionnaire related to duration of asbestos exposure, smoking, and occupational task. According to the occupational tasks, asbestos-exposed subjects were analysed for their asbestos cumulative dose and the association with the biomarkers was evaluated. Among the occupational groups, maintenance workers, pipe fitters and electricians were exposed to a higher cumulative dose of asbestos fibres. Exposure to asbestos significantly increased the steady-state content of 80HdG in DNA. Elevated levels of 80HdG and IL-6 best reflected a high level of SMRPs, which is related to cell transformation. Subjects heavily exposed to asbestos [> 60(ff/cm3) x years] showed also a higher level of angiogenic factors. A combination of angiogenic biomarkers with a specific mesothelioma-biomarker such as SMRPs could be used for close surveillance of workers with a history of asbestos exposure.

siRNA-mediated Erc gene silencing suppresses tumor growth in Tsc2 mutant renal carcinoma model

Silencing of gene expression by small interfering RNAs (siRNAs) is rapidly becoming a powerful tool for genetic analysis and represents a potential strategy for therapeutic product development. However, there are no reports of systemic delivery of siRNAs for stable treatment except short hairpin RNAs (shRNAs). On the other hand, there are many reports of systemic delivery of siRNAs for transient treatment using liposome carriers and others. With regard to shRNAs, a report showed fatality in mice due to oversaturation of cellular microRNA/short hairpin RNA pathways. Therefore, we decided to use original siRNA microspheres instead of shRNA for stable treatment of disease. In this study, we designed rat-specific siRNA sequences for Erc/mesothelin, which is a tumor-specific gene expressed in the Eker (Tsc2 mutant) rat model of hereditary renal cancer and confirmed the efficacy of gene silencing in vitro. Then, by using siRNA microspheres, we found that the suppression of Erc/mesothelin caused growth inhibition of Tsc2 mutant renal carcinoma cells in tumor implantation experiments in mice.