Mesothelioma epidemiology, carcinogenesis, and pathogenesis

Malignant peritoneal mesothelioma presenting with persistent high fever

Malignant peritoneal mesothelioma (MPM) is a rare tumor that develops in the peritoneum. In this paper, we describe an extremely rare case of MPM metastasizing to the appendix in a 48-year-old female who initially presented with a persistent high fever. The woman reported a slight lower abdominal discomfort which had been relieved by urination for four months. She had lost 5 kg of weight. There was no nausea, vomiting, diarrhea, abdominal pain, or abdominal distension. Many broad spectrum antibiotics were given without relief of fever. Computed tomography (CT) scans revealed a thickened omentum majus and diffused multiple omental nodules. An omentectomy, appendectomy, and adnexectomy were carried out. A gross pathologic specimen of omentum tissue revealed a firm gray-white mass. Microscopic and immunohistochemical examinations confirmed the diagnosis of appendiceal and bilateral adnexal metastases of an MPM. These results suggest that MPM should be considered in the differential diagnosis of unexplained persistent high fever. Awareness of such atypical presentations of mesothelioma may help to make a correct diagnosis.

Receptor tyrosine kinase inhibitors and cytotoxic drugs affect pleural mesothelioma cell proliferation: insight into EGFR and ERK1/2 as antitumor targets

Malignant pleural mesothelioma (MPM) is an aggressive chemotherapy-resistant cancer. Up-regulation of epidermal growth factor receptor (EGFR) plays an important role in MPM development and EGFR-tyrosine kinase inhibitors (TKIs) may represent novel therapeutic options. We tested the effects of the EGFR TKIs gefitinib and erlotinib and TKIs targeted to other growth factors (VEGFR and PDGFR), in comparison to standard antineoplastic agents, in two human MPM cell lines, IST-Mes2 and ZL55. All drugs showed IC(50) values in the micromolar range: TKIs induced cytostatic effects at concentrations up to the IC(50,) while conventional drug growth-inhibitory activity was mainly cytotoxic. Moreover, the treatment of IST-Mes2 with TKIs (gefitinib and imatinib mesylate) in combination with cisplatin and gemcitabine did not show additivity. Focusing on the molecular mechanisms underlying the antiproliferative and pro-apoptotic effects of EGFR-TKIs, we observed that gefitinib induced the formation and stabilization of inactive EGFR homodimers, even in absence of EGF, as demonstrated by EGFR B(max) and number of sites/cell. The analysis of downstream effectors of EGFR signaling demonstrated that EGF-induced proliferation, reverted by gefitinib, involved ERK1/2 activation, independently from Akt pathway. Gefitinib inhibits MPM cell growth and survival, preventing EGF-dependent activation of ERK1/2 pathway by blocking EGFR-TK phosphorylation and stabilizing inactive EGFR dimers. Along with the molecular definition of TKIs pharmacological efficacy in vitro, these results may contribute to delve deep into the promising but still controversial role for targeted and conventional drugs in the therapy of MPM.

Transforming growth factor-β-induced protein (TGFBI) suppresses mesothelioma progression through the Akt/mTOR pathway

As an uncommon cancer, mesothelioma is very hard to treat with a low average survival rate owing to its usual late detection and being highly invasive. The link between asbestos exposure and the development of mesothelioma in humans is unequivocal. TGFBI, a secreted protein that is induced by transforming growth factor-β in various human cell types, has been shown to be associated with tumorigenesis in various types of tumors. It has been demonstrated that TGFBI expression is markedly suppressed in asbestos-induced tumorigenic cells, while an ectopic expression of TGFBI significantly suppresses tumorigenicity and progression in human bronchial epithelial cells. In order to delineate a potential role of TGFBI in mediating the molecular events that occur in mesothelioma tumorigenesis, we generated stable TGFBI knockdown mutants from the mesothelium cell line Met-5A by using an shRNA approach, and secondly created ectopic TGFBI overexpression mutants from the mesothelioma cell line H28 in which TGFBI is absent. We observed that in the absence of TGFBI, the knockdown mesothelial and mesothelioma cell lines exhibited an elevated proliferation rate, enhanced plating efficiency, increased anchorage-independent growth, as well as an increased cellular protein synthesis rate as compared with their respective controls. Furthermore, cell cycle regulatory proteins c-myc/cyclin D1/phosphor-Rb were upregulated; a more active PI3K/Akt/mTOR signaling pathway was also detected in TGFBI-depleted cell lines. These findings suggest that TGFBI may repress mesothelioma tumorigenesis and progression via the PI3K/Akt signaling pathway.

Detection of integrin-linked kinase in the serum of patients with malignant pleural mesothelioma

OBJECTIVE

Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in malignant pleural mesothelioma. Recently, detection of integrin-linked kinase in serum of patients with ovarian cancer has been reported. This study asks whether integrin-linked kinase can also be detected in serum of patients with malignant pleural mesothelioma and whether serum level has diagnostic or prognostic relevance for that disease.

METHODS

A sandwich enzyme-linked immunosorbent assay was designed to detect integrin-linked kinase and applied to serum samples from 46 patients with malignant pleural mesothelioma, 98 patients with other malignant chest disease, and 23 patients with benign chest disease. Integrin-linked kinase serum concentration and clinical data were correlated statistically.

RESULTS

Median serum integrin-linked kinase concentration was significantly higher in malignant pleural mesothelioma (8.89 ng/mL) than in other malignant chest disease (0.66 ng/mL) or benign chest disease (0.78 ng/mL, P < .001). There was no relevant correlation of serum integrin-linked kinase with cell lysis parameters (R(2) < 0.1). Serum integrin-linked kinase concentration greater than 2.48 ng/mL had diagnostic sensitivity of 80%, specificity of 95%, positive predictive value of 85.7%, negative predictive value of 92.7%, and overall accuracy of 91% for distinction between malignant pleural mesothelioma and other diseases. Serum integrin-linked kinase concentration in malignant pleural mesothelioma was independent of histologic subtype or asbestos exposure. There was no statistically significant impact of serum integrin-linked kinase concentration on prognosis.

CONCLUSIONS

Integrin-linked kinase can be detected in serum of patients with malignant pleural mesothelioma and may be a diagnostic marker for the disease.

Summary of presentations from the 46th Annual Meeting of the American Society of Clinical Oncology (2010) focus on tumor biology and biomarkers related to lung cancer

Globally, lung cancer remains the most common cause of cancer-related death. In recent years, it has become clear that development of rational molecular targeted therapies is critical to improve the outcomes of patients with lung cancer. A better understanding of the tumor biology is crucial to achieve this goal. Several new findings in the field of tumor biology were presented at the 46th Annual Meeting of the American Society of Clinical Oncology. Novel genetic mutations were identified in pleural mesothelioma using array-based technologies. Several studies on the development and testing of new molecular diagnostic tests to detect epidermal growth factor receptor tyrosine kinase mutations and EML4-ALK (Echinoderm Microtubule-associated Protein like 4 Anaplastic Lymphoma Receptor Tyrosine Kinase) fusion gene were presented as well.

Solid cancer mortality associated with chronic external radiation exposure at the French atomic energy commission and nuclear fuel company

Studies of nuclear workers make it possible to directly quantify the risks associated with ionizing radiation exposure at low doses and low dose rates. Studies of the CEA (Commissariat à l'Energie Atomique) and AREVA Nuclear Cycle (AREVA NC) cohort, currently the most informative such group in France, describe the long-term risk to nuclear workers associated with external exposure. Our aim is to assess the risk of mortality from solid cancers among CEA and AREVA NC nuclear workers and its association with external radiation exposure. Standardized mortality ratios (SMRs) were calculated and internal Poisson regressions were conducted, controlling for the main confounding factors [sex, attained age, calendar period, company and socioeconomic status (SES)]. During the period 1968-2004, there were 2,035 solid cancers among the 36,769 CEA-AREVA NC workers. Cumulative external radiation exposure was assessed for the period 1950-2004, and the mean cumulative dose was 12.1 mSv. Mortality rates for all causes and all solid cancers were both significantly lower in this cohort than in the general population. A significant excess of deaths from pleural cancer, not associated with cumulative external dose, was observed, probably due to past asbestos exposure. We observed a significant excess of melanoma, also unassociated with dose. Although cumulative external dose was not associated with mortality from all solid cancers, the central estimated excess relative risk (ERR) per Sv of 0.46 for solid cancer mortality was higher than the 0.26 calculated for male Hiroshima and Nagasaki A-bomb survivors 50 years or older and exposed at the age of 30 years or older. The modification of our results after stratification for SES demonstrates the importance of this characteristic in occupational studies, because it makes it possible to take class-based lifestyle differences into account, at least partly. These results show the great potential of a further joint international study of nuclear workers, which should improve knowledge about the risks associated with chronic low doses and provide useful risk estimates for radiation protection.

HER1-targeted 86Y-panitumumab possesses superior targeting characteristics than 86Y-cetuximab for PET imaging of human malignant mesothelioma tumors xenografts

Malignant mesothelioma (MM), a rare form of cancer is often associated with previous exposure to fibrous minerals, such as asbestos. Asbestos exposure increases HER1-activity and expression in pre-clinical models. Additionally, HER1 over-expression is observed in the majority of MM cases. In this study, the utility of HER1-targeted chimeric IgG₁, cetuximab, and a human IgG₂, panitumumab, radiolabeled with ⁸⁶Y, were evaluated for PET imaging to detect MM non-invasively in vivo, and to select an antibody candidate for radioimmunotherapy (RIT).

Methods

Radioimmunoconjugates (RICs) of cetuximab and panitumumab were prepared by conjugation with CHX-A’’-DTPA followed by radiolabeling with ⁸⁶Y. The HER1 expression of NCI-H226, NCI-H2052, NCI-H2452 and MSTO-211H human mesothelioma cells was characterized by flow cytometry. In vivo biodistribution, pharmacokinetic analysis, and PET imaging were performed in tumor bearing athymic mice.

Results

In vivo studies demonstrated high HER1 tumor uptake of both RICs. Significant reduction in tumor uptake was observed in mice co-injected with excess mAb (0.1 mg), demonstrating that uptake in the tumor was receptor specific. Significant differences were observed in the in vivo characteristics of the RICs. The blood clearance T_½α of ⁸⁶Y-cetuximab (0.9–1.1 h) was faster than ⁸⁶Y-panitumumab (2.6–3.1 h). Also, the tumor area under the curve (AUC) to liver AUC ratios of ⁸⁶Y-panitumumab were 1.5 to 2.5 times greater than ⁸⁶Y-cetuximab as observed by the differences in PET tumor to background ratios, which could be critical when imaging orthotopic tumors and concerns regarding radiation doses to normal organs such as the liver.

Conclusion

This study demonstrates the more favorable HER1-targeting characteristics of ⁸⁶Y-panitumumab than ⁸⁶Y-cetuximab for non-invasive assessment of the HER1 status of MM by PET imaging. Due to lower liver uptake, panitumumab based immunoconjugates may fare better in therapy than corresponding cetuximab based immunoconjugates.

Toxicoproteomic evaluation of carbon nanomaterials in vitro

Carbon nanotubes (CNTs) have already been successfully implemented in various fields, and they are anticipated to have innovative applications in medical science. However, CNTs have asbestos-like properties, such as their nanoscale size and high aspect ratio (>100). Moreover, CNTs may persist in the body for a long time. These properties are thought to cause malignant mesothelioma and lung cancer. However, based on conventional toxicity assessment systems, the carcinogenicity of asbestos and CNTs is unclear. The reason for late countermeasures against asbestos is that reliable, long-term safety assessments have not yet been developed by toxicologists. Therefore, a new type of long-term safety assessment, different from the existing methods, is needed for carbon nanomaterials. Recently, we applied a proteomic approach to the safety assessment of carbon nanomaterials. In this review, we discuss the basic concept of our approach, the results, the problems, and the possibility of a long-term safety assessment for carbon nanomaterials using the toxicoproteomic approach.

Epidermal growth factor receptor overexpression in malignant pleural mesothelioma: prognostic correlations

BACKGROUND

To evaluate epidermal growth factor receptor (EGFR) phenotypic expression and related gene status in malignant pleural mesothelioma (MPM) and to correlate the results with patients' prognosis.

METHOD

Eighty-three cases of MPM specimens were submitted to immunohistochemical (IHC) staining to evaluate the expression of EGFR protein; positive cases were submitted to fluorescence in situ hybridization (FISH) to investigate the gene status. Results were correlated with clinico-pathological characteristics and long-term survival.

RESULTS

Thirty-eight cases (46%) demonstrated a positive IHC reaction [30/57 (52%) epithelial and 8/20 (40%) biphasic whereas sarcomatous MPM were negative]. No association was recorded between EGFR IHC positive staining and age, gender, or asbestos exposure. Three out of 38 (8%) cases submitted to FISH were positive revealing gene amplification or polysomy. Mean follow-up was 15.4  months (range 2-44). Epithelial subtype only was confirmed to affect prognosis (2-years survival rate 40 vs. 18% for non-epithelial subtype, P = 0.042). When epithelial MPM patients were considered, IHC EGFR positive staining was demonstrated to be a negative prognostic factor (2-years survival rate 26 vs. 60% for IHC EGFR negative staining; P = 0.026).

CONCLUSIONS

EGFR overexpression is identified by IHC in 52% of epithelial MPM and is demonstrated to be a factor negatively affecting prognosis. Phenotypic overexpression seems not to be related to gene status alteration.

Malignant pleural mesothelioma risk among nuclear workers: a review

Exposure to ionising radiation has been suggested as a causal risk factor for malignant pleural mesothelioma (MPM). Studies of patients treated by radiotherapy for primary cancers have suggested that radiation contributes to the development of secondary MPM. Here we examined the risk to nuclear workers of MPM related to exposure to low doses of occupational radiation at low dose rates. All results concerning MPM risk in published studies of nuclear workers were examined for their association with radiation exposure and potential confounders. We found 19 relevant studies. Elevated risks of pleural cancer were reported in most (15/17) of these studies. Eight reported risks higher for radiation monitored workers than for other workers. However, of 12 studies that looked at associations with ionising radiation, only one reported a significant dose-risk association. Asbestos was an important confounder in most studies. We conclude that studies of nuclear workers have not detected an association between ionising radiation exposure and MPM. Further investigations should improve the consideration of asbestos exposure at the same time as they address the risk of MPM related to occupational exposure of nuclear workers to low doses of ionising radiation at low dose rates.

Onconase mediated NFKβ downregulation in malignant pleural mesothelioma

Purpose

Treatment of malignant pleural mesothelioma (MPM) with Ranpirnase (Onconase) results in disruption of protein translation and cell apoptosis. We hypothesize that Onconase acts via down regulation of nuclear factor kappa B (NFKβ) by specific microRNAs (miRNA) and that interference of this pathway could have implications for MPM resistance to chemotherapy.

Experimental Design

Three immortalized MPM cell lines (H2959, H2373, and H2591) were exposed to Onconase at 0–20 µg/mL. Cell counts were measured at 48 and 72 hours. Gene expression in miRNA-enriched RNA was validated by RT-PCR. The functional implications of miRNA expression were evaluated by transfecting miRNA mimics or inhibitors into MPM cell lines, and performing Matrigel™ invasion, cell proliferation, soft agar colony formation, and scratch closure assays. Effects on NFKβ expression and downstream targets including ABC transporters, BCL-xl, and IAP were assessed by RT-PCR and Western Blotting.

Results

Treatment with 20µg/mL of Onconase significantly decreased cell count and invasion. Hsa-miR-17* was significantly upregulated and hsa-miR-30c significantly down-regulated by Onconase treatment in all cell lines. Forced expression of hsa-miR-17* mimic and hsa-miR-30c inhibitor each significantly decreased functional activity of Onconase in all assays. NFKB1(p50) expression and downstream targets were also decreased with Onconase treatment as well as with forced expression miRNA mimic and inhibitors.

Conclusions

Onconase treatment caused a significant decrease in cell proliferation, invasion, and in expression of certain miRNAs. Recapitulation of the resultant miRNA expression pattern with hsa-miR-17* mimic and hsa-miR-30c inhibitor resulted in downregulation of NFKB1 and reduced malignant behavior in functional assays. Thus, Onconase likely exerts its anti-tumor effect through these miRNAs.

Telomerase activity in pleural malignant mesotheliomas

New treatments are needed for malignant pleural mesothelioma (MPM), which currently has a poor prognosis. Cellular immortalisation, one of the hallmarks of cancer, depends on the activity of a telomere length maintenance mechanism (TMM) - either telomerase or alternative lengthening of telomeres (ALT). The TMMs are widely regarded as potential targets for cancer therapies and telomerase inhibitors have entered clinical trials. The aim of this study was to determine what proportion of MPMs use ALT and/or telomerase. Forty-three MPMs from 42 patients were examined for telomerase and ALT activity. Telomerase activity was detected by immunoaffinity purification followed by the telomere repeat amplification protocol (TRAP), and ALT activity was determined by the C-circle assay and by assessing telomere lengths using terminal restriction fragment analyses. We found that 43 of 43 MPMs were telomerase-positive[+] and ALT-negative[-]. Therefore, to investigate whether pleural mesothelial cells are unusually susceptible to activation of telomerase, we examined activation of the TMMs in an in vitro model of cellular immortalisation, in which normal pleural mesothelial cells were transduced with simian virus 40 (SV40) oncogenes. We found that normal mesothelial cells were TMM-negative, and that expression of the SV40 oncogenes did not directly activate telomerase or ALT. Immortalisation, which in this experimental system results from additional genetic changes that have not yet been identified, was accompanied by activation of either TMM. Therefore, pleural mesothelial cells are capable of activating either TMM in vitro, and the observation that 100% of MPMs were telomerase[+] suggests that there are factors in vivo that select for telomerase activity during oncogenesis of this tumour type. We conclude that MPM is a tumour that could be considered for anti-telomerase therapy.

LATS2 is a tumor suppressor gene of malignant mesothelioma

Malignant mesothelioma (MM) is an aggressive neoplasm associated with asbestos exposure. We carried out genome-wide array-based comparative genomic hybridization analysis with 14 MM cell lines. Three cell lines showed overlapping homozygous deletion at chromosome 13q12, which harbored the LATS2 (large tumor suppressor homolog 2) gene. With 6 other MM cell lines and 25 MM tumors, we found 10 inactivating homozygous deletions or mutations of LATS2 among 45 MMs. LATS2 encodes a serine/threonine kinase, a component of the Hippo tumor-suppressive signaling pathway, and we transduced LATS2 in MM cells with its mutation. Transduction of LATS2 inactivated oncoprotein YAP, a transcriptional coactivator, via phosphorylation, and inhibited MM cell growth. We also analyzed LATS2 immunohistochemically and found that 13 of 45 MM tumors had low expression of LATS2. Because NF2 is genetically mutated in 40% to 50% of MM, our data indicate that Hippo pathway dysregulation is frequent in MM cells with inactivation of LATS2 or an upstream regulator of this pathway, Merlin, which is encoded by NF2. Thus, our results suggest that the inactivation of LATS2 is one of the key mechanisms for constitutive activation of YAP, which induces deregulation of MM cell proliferation.

Computerized segmentation and measurement of malignant pleural mesothelioma

PURPOSE

The current linear method to track tumor progression and evaluate treatment efficacy is insufficient for malignant pleural mesothelioma (MPM). A volumetric method for tumor measurement could improve the evaluation of novel treatments, but a fully manual implementation of volume measurement is too tedious and time-consuming. This manuscript presents a computerized method for the three-dimensional segmentation and volumetric analysis of MPM.

METHODS

The computerized MPM segmentation method segments the lung parenchyma and hemithoracic cavities to define the pleural space. Nonlinear diffusion and a k-means classifier are then implemented to identify MPM in the pleural space. A database of 31 computed tomography scans from 31 patients with pathologically confirmed MPM was retrospectively collected. Three observers independently outlined five randomly selected sections in each scan. The Jaccard similarity coefficient (J) between each of the observers and between the observer-defined and computer-defined segmentations was calculated. The computer-defined and the observer-defined segmentation areas (averaged over all observers) were both calculated for each axial section and compared using Bland-Altman plots.

RESULTS

The median J value among observers averaged over all sections was 0.517. The median J between the computer-defined and manual segmentations was 0.484. The difference between these values was not statistically significant. The area delineated by the computerized method demonstrated variability and bias comparable to the tumor area calculated from manual delineations.

CONCLUSIONS

A computerized method for segmentation and measurement of MPM was developed. This method requires minimal initialization by the user and demonstrated good agreement with manually drawn outlines and area measurements. This method will allow volumetric tracking of tumor progression and may improve the evaluation of novel MPM treatments.

Epidemiology of mesothelioma in Egypt. A ten-year (1998-2007) multicentre study

INTRODUCTION

Mesothelioma is a cancer strongly linked to exposure to carcinogenic minerals, especially asbestos. The aim of the study was to detect the incidence of malignant pleural mesothelioma (MPM) in Egypt, to clarify the impact of occupational and environmental risk factors, and to characterise its demographic features.

MATERIAL AND METHODS

They were 584 cases diagnosed as MPM detected in Cairo University Hospitals and National Cancer Institute from 1998 to 2007. Unfortunately, full epidemiological data were only available for 165 cases due to absence of a reliable registration system.

RESULTS

A steady increase in the number of cases was detected, from 24 in 1998, peaking at 82 cases in 2005, followed by a gradual decline (though still high) with 68 cases in 2006 and 51 cases in 2007. Male/female ratio was 1.35/1 (p > 0.05). The occupational exposure to asbestos was 13.9%. Residential exposure plays a major role in two regions, Helwan and Shoubra (27.3% and 20.6% respectively), while in Upper and Lower Egypt the level was 12.7% and 17.5% respectively. Kaplan-Meier survival for sex, residence and the pathological types epithelioid, biphasic and sarcomatoid was insignificant. The median survival for different grades and treatment modalities was significant (P < 0.001).

CONCLUSIONS

There was a steady increase in the incidence of MPM from 1998 to 2005 followed by a decline during 2006-2007. Mesothelioma in Egypt is mainly concentrated in areas of high environmental pollution. The decline within the last 2 years may be attributed to recent strict industrial preventive measures. However, a better environmental control programme would benefit Egypt.

Estrogen receptor β exerts tumor repressive functions in human malignant pleural mesothelioma via EGFR inactivation and affects response to gefitinib

BACKGROUND

The role of estrogen and estrogen receptors in oncogenesis has been investigated in various malignancies. Recently our group identified estrogen receptor beta (ERβ) expression as an independent prognostic factor in the progression of human Malignant Pleural Mesothelioma (MMe), but the underlying mechanism by which ERβ expression in tumors determines clinical outcome remains largely unknown. This study is aimed at investigating the molecular mechanisms of ERβ action in MMe cells and disclosing the potential translational implications of these results.

METHODS

We modulated ERβ expression in REN and MSTO-211H MMe cell lines and evaluated cell proliferation and EGF receptor (EGFR) activation.

RESULTS

Our data indicate that ERβ knockdown in ER positive cells confers a more invasive phenotype, increases anchorage independent proliferation and elevates the constitutive activation of EGFR-coupled signal transduction pathways. Conversely, re-expression of ERβ in ER negative cells confers a more epithelioid phenotype, decreases their capacity for anchorage independent growth and down-modulates proliferative signal transduction pathways. We identify a physical interaction between ERβ, EGFR and caveolin 1 that results in an altered internalization and in a selective reduced activation of EGFR-coupled signaling, when ERβ is over-expressed. We also demonstrate that differential expression of ERβ influences MMe tumor cell responsiveness to the therapeutic agent: Gefitinib.

CONCLUSIONS

This study describes a role for ERβ in the modulation of cell proliferation and EGFR activation and provides a rationale to facilitate the targeting of a subgroup of MMe patients who would benefit most from therapy with Gefitinib alone or in combination with Akt inhibitors.

A diagnostic assay based on microRNA expression accurately identifies malignant pleural mesothelioma

The definitive identification of malignant pleural mesothelioma (MPM) has significant clinical implications, yet other malignancies often involve the lung pleura, confounding the diagnosis of MPM. In the absence of accurate markers, MPM can be difficult to distinguish from peripheral lung adenocarcinoma and metastatic epithelial cancers. MicroRNA expression is tissue-specific and highly informative for identifying tumor origin. We identified microRNA biomarkers for the differential diagnosis of MPM and developed a standardized microRNA-based assay. Formalin-fixed, paraffin-embedded samples of 33 MPM and 210 carcinomas were used for assay development. Using microarrays, we identified microRNAs differentially expressed between MPM and various carcinomas. Hsa-miR-193-3p was overexpressed in MPM, while hsa-miR-200c and hsa-miR-192 were overexpressed in peripheral lung adenocarcinoma and carcinomas that frequently metastasize to lung pleura. We developed a standardized diagnostic assay based on the expression of these microRNAs. The assay reached a sensitivity of 100% and a specificity of 94% in a blinded validation set of 68 samples from the lung and pleura. This diagnostic assay can provide a useful tool in the differential diagnosis of MPM from other malignancies in the pleura.

Programmed necrosis induced by asbestos in human mesothelial cells causes high-mobility group box 1 protein release and resultant inflammation

Asbestos carcinogenesis has been linked to the release of cytokines and mutagenic reactive oxygen species (ROS) from inflammatory cells. Asbestos is cytotoxic to human mesothelial cells (HM), which appears counterintuitive for a carcinogen. We show that asbestos-induced HM cell death is a regulated form of necrosis that links to carcinogenesis. Asbestos-exposed HM activate poly(ADP-ribose) polymerase, secrete H(2)O(2), deplete ATP, and translocate high-mobility group box 1 protein (HMGB1) from the nucleus to the cytoplasm, and into the extracellular space. The release of HMGB1 induces macrophages to secrete TNF-alpha, which protects HM from asbestos-induced cell death and triggers a chronic inflammatory response; both favor HM transformation. In both mice and hamsters injected with asbestos, HMGB1 was specifically detected in the nuclei, cytoplasm, and extracellular space of mesothelial and inflammatory cells around asbestos deposits. TNF-alpha was coexpressed in the same areas. HMGB1 levels in asbestos-exposed individuals were significantly higher than in nonexposed controls (P < 0.0001). Our findings identify the release of HMGB1 as a critical initial step in the pathogenesis of asbestos-related disease, and provide mechanistic links between asbestos-induced cell death, chronic inflammation, and carcinogenesis. Chemopreventive approaches aimed at inhibiting the chronic inflammatory response, and especially blocking HMGB1, may decrease the risk of malignant mesothelioma among asbestos-exposed cohorts.

Asbestos, carbon nanotubes and the pleural mesothelium: a review of the hypothesis regarding the role of long fibre retention in the parietal pleura, inflammation and mesothelioma

The unique hazard posed to the pleural mesothelium by asbestos has engendered concern in potential for a similar risk from high aspect ratio nanoparticles (HARN) such as carbon nanotubes. In the course of studying the potential impact of HARN on the pleura we have utilised the existing hypothesis regarding the role of the parietal pleura in the response to long fibres. This review seeks to synthesise our new data with multi-walled carbon nanotubes (CNT) with that hypothesis for the behaviour of long fibres in the lung and their retention in the parietal pleura leading to the initiation of inflammation and pleural pathology such as mesothelioma. We describe evidence that a fraction of all deposited particles reach the pleura and that a mechanism of particle clearance from the pleura exits, through stomata in the parietal pleura. We suggest that these stomata are the site of retention of long fibres which cannot negotiate them leading to inflammation and pleural pathology including mesothelioma. We cite thoracoscopic data to support the contention, as would be anticipated from the preceding, that the parietal pleura is the site of origin of pleural mesothelioma. This mechanism, if it finds support, has important implications for future research into the mesothelioma hazard from HARN and also for our current view of the origins of asbestos-initiated pleural mesothelioma and the common use of lung parenchymal asbestos fibre burden as a correlate of this tumour, which actually arises in the parietal pleura.

Respiratory chest pain: diagnosis and treatment

Chest pain from respiratory causes is a common complaint and may indicate the presence of a serious or even life-threatening pathologic condition. Most chest pains are the result of irritation or inflammation of the parietal pleura, as the visceral pleura is insensate, although pain may arise from direct malignant invasion or trauma to the chest wall. Rapid recognition with appropriate understanding of the anatomy and physiology of chest pain from respiratory causes is vital to ensure timely and appropriate therapy.

hsa-miR-29c* is linked to the prognosis of malignant pleural mesothelioma

The inability to forecast outcomes for malignant mesothelioma prevents clinicians from providing aggressive multimodality therapy to the most appropriate individuals who may benefit from such an approach. We investigated whether specific microRNAs (miR) could segregate a largely surgically treated group of mesotheliomas into good or bad prognosis categories. A training set of 44 and a test set of 98 mesothelioma tumors were analyzed by a custom miR platform, along with 9 mesothelioma cell lines and 3 normal mesothelial lines. Functional implications as well as downstream targets of potential prognostic miRs were investigated. In both the training and test sets, hsa-miR-29c* was an independent prognostic factor for time to progression as well as survival after surgical cytoreduction. The miR was expressed at higher levels in epithelial mesothelioma, and the level of this miR could segregate patients with this histology into groups with differing prognosis. Increased expression of hsa-miR-29c* predicted a more favorable prognosis, and overexpression of the miR in mesothelioma cell lines resulted in significantly decreased proliferation, migration, invasion, and colony formation. Moreover, major epigenetic regulation of mesothelioma is mediated by hsa-miR-29c* and was shown through downregulation of DNA methyltransferases as well as upregulation of demethylating genes. A single miR has the potential to be a prognostic biomarker in mesothelioma, and validation of these findings as well as investigation of its downstream targets may give insight for potential therapies in the future.

Utilization of gene profiling and proteomics to determine mineral pathogenicity in a human mesothelial cell line (LP9/TERT-1)

Identifying and understanding the early molecular events that underscore mineral pathogenicity using in vitro screening tests is imperative, especially given the large number of synthetic and natural fibers and particles being introduced into the environment. The purpose of the work described here was to examine the ability of gene profiling (Affymetrix microarrays) to predict the pathogenicity of various materials in a human mesothelial cell line (LP9/TERT-1) exposed to equal surface area concentrations (15 x 10(6) or 75 x 10(6) microm(2)/cm(2)) of crocidolite asbestos, nonfibrous talc, fine titanium dioxide (TiO(2)), or glass beads for 8 or 24 h. Since crocidolite asbestos caused the greatest number of alterations in gene expression, multiplex analysis (Bio-Plex) of proteins released from LP9/TERT-1 cells exposed to crocidolite asbestos was also assessed to reveal if this approach might also be explored in future assays comparing various mineral types. To verify that LP9/TERT-1 cells were more sensitive than other cell types to asbestos, human ovarian epithelial cells (IOSE) were also utilized in microarray studies. Upon assessing changes in gene expression via microarrays, principal component analysis (PCA) of these data was used to identify patterns of differential gene expression. PCA of microarray data confirmed that LP9/TERT-1 cells were more responsive than IOSE cells to crocidolite asbestos or nonfibrous talc, and that crocidolite asbestos elicited greater responses in both cell types when compared to nonfibrous talc, TiO(2), or glass beads. Bio-Plex analysis demonstrated that asbestos caused an increase in interleukin-13 (IL-13), basic fibroblast growth factor (bFGF), granulocyte colony-stimulating factor (G-CSF), and vascular endothelial growth factor (VEGF). These responses were generally dose-dependent (bFGF and G-CSF only) and tumor necrosis factor (TNF)-alpha independent (except for G-CSF). Thus, microarray and Bio-Plex analyses are valuable in determining early molecular responses to fibers/particles and may directly contribute to understanding the etiology of diseases caused by them. The number and magnitude of changes in gene expression or "profiles" of secreted proteins may serve as valuable metrics for determining the potential pathogenicity of various mineral types. Hence, alterations in gene expression and cytokine/chemokine changes induced by crocidolite asbestos in LP9/TERT-1 cells may be indicative of its increased potential to cause mesothelioma in comparison to the other nonfibrous materials examined.

Genomic abnormalities and signal transduction dysregulation in malignant mesothelioma cells

Malignant mesothelioma (MM) is a tumor with poor prognosis associated with asbestos exposure. While it remains to be clarified how asbestos fibers confer genetic/epigenetic alterations and induce cellular transformation in normal mesothelial cells, the understanding of key molecular mechanisms of MM cell development, proliferation, and invasion has progressed. MM shows frequent genetic inactivation of tumor suppressor genes of p16(INK4a)/p14(ARF) and neurofibromatosis type 2 (NF2) which encodes Merlin, and epigenetic inactivation of RASSF1A. However, no frequent mutations of well-known oncogenes such as K-RAS and PIK3CA have been identified. Activation of multiple receptor tyrosine kinases including the epidermal growth factor receptor (EGFR) family and MET, and subsequent deregulations of mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K)-AKT signaling cascades are frequently observed in most MM cells. The tumor suppressive function of Merlin in MM cells is also being investigated by dissecting its possible downstream signaling cascade called the Hippo pathway. Further comprehensive delineation of dysregulated signaling cascades in MM cells will lead to identification of key addiction pathways for cell survival and proliferation of MM cells, which strongly promote establishment of a new molecular target therapy for MM.

French cohort of the uranium processing workers: mortality pattern after 30-year follow-up

OBJECTIVE

To investigate mortality among nuclear workers with potential internal exposure to uranium.

METHODS

The cohort included 2,709 workers employed at the AREVA NC Pierrelatte plant for at least 6 months (72,787 person-years). This plant processed uranium enrichment during the period 1960-1996 and chemical conversion since 1980. Mortality was compared to the national and regional mortality rates available for the period 1968-2005. For causes of death of interest with respect to occupational exposure, mortality trends according to occupational characteristics were assessed.

RESULTS

As expected, an important healthy worker effect (all causes SMR = 0.55 (95% CI: 0.50-0.61), n = 411; all cancers SMR = 0.70 (95% CI: 0.60-0.81), n = 193) was observed. Among cancer sites a priori related to uranium exposure, only mortality for lymphatic cancer was increased among potentially exposed workers (SMR = 1.49 (95% CI: 0.68-2.82); n = 9). An important increase in mortality from pleural cancer was observed (SMR = 2.85 (95% CI: 0.93-6.66), n = 5); none of the deceased workers were exposed to radiation whereas all handled asbestos.

CONCLUSION

In spite of limited statistical power, results show consistency with previous studies of nuclear workers potentially exposed to uranium. Further investigation based on more precise uranium exposure data should allow the estimation of uranium hazard effects among this cohort.

Belmont™ Hyperthermia Pump in the conduct of intra-operative heated chemotherapy

Intra–operative heated chemotherapy (IOHC) has been performed in the Thoracic surgical department of Brigham and Women’s Hospital (BWH, Boston, MA, USA) for over a decade. A “home-grown” system was developed for this purpose with limited improvements made to it through the years. This technology is used for neo-adjuvant therapy in the conduct of extra-pleural pneumonectomy and pleurectomy for treatment of mesothelioma. Improvements to the traditional BWH system were sought due to the hazardous nature of the chemotherapy solution and the relative complexity of the IOHC circuit. Belmont Instrument (Belmont Instrument Corporation, Billerica, MA, USA) applied their proprietary infusion/warming technology to develop the Belmont™ Hyperthermia Pump. The Hyperthermia Pump was designed to recirculate large volumes of fluid while maintaining perfusate temperatures up to 46oC at a flow rate of up to 750 ml/min. Approval from the FDA for clinical use of this device was granted June 2007. Parameters were defined and investigated to determine if the Hyperthermia Pump would meet or exceed the performance characteristics of the traditional BWH system. Our investigation resulted in the replacement of the traditional BWH circuit. The Belmont™ Hyperthermia Pump is a compact, easy to use, extremely safe means to deliver intra-operative hyperthermic chemotherapy in the conduct of surgical treatment of mesothelioma.

A mutation in the mouse Chd2 chromatin remodeling enzyme results in a complex renal phenotype

BACKGROUND AND AIMS

Glomerular diseases are the third leading cause of kidney failure worldwide, behind only diabetes and hypertension. The molecular mechanisms underlying the cause of glomerular diseases are still largely unknown. The identification and characterization of new molecules associated with glomerular function should provide new insights into understanding the diverse group of glomerular diseases. The Chd2 protein belongs to a family of enzymes involved in ATP-dependent chromatin remodeling, suggesting that it likely functions as an epigenetic regulator of gene expression via the modification of chromatin structure.

METHODS

In this study, we present a detailed histomorphologic characterization of mice containing a mutation in the chromodomain helicase DNA-binding protein 2 (Chd2).

RESULTS

We show that Chd2-mutant mice present with glomerulopathy, proteinuria, and significantly impaired kidney function. Additionally, serum analysis revealed decreased hemoglobin and hematocrit levels in Chd2-mutant mice, suggesting that the glomerulopathy observed in these mice is associated with anemia.

CONCLUSION

Collectively, the data suggest a role for the Chd2 protein in the maintenance of kidney function.

An evolutionary perspective on parasitism as a cause of cancer

For the past half-century, the dominant paradigm of oncogenesis has been mutational changes that disregulate cellular control of proliferation. Parasitic causes of cancer were first incorporated into this paradigm by suggesting mechanisms through which parasitism might increase mutational damage, such as generation of mutagenic compounds during immunological activity. The growing recognition of the molecular mechanisms of pathogen-induced oncogenesis and the difficulty of generating oncogenic mutations without first having large populations of dysregulated cells, however, suggests that pathogens, particularly viruses, are major initiators of oncogenesis for many if not most cancers, and that the traditional mutation-driven process becomes the dominant process after this initiation. Molecular phylogenies of individual cancers should facilitate testing of this idea and the identification of causal pathogens.