Genomic gains and losses in malignant mesothelioma demonstrated by FISH analysis of paraffin-embedded tissues

Benign Mesothelial Proliferations of the Tunica Vaginalis Testis

The correct diagnosis of mesothelial proliferations is a classic problem for pathologists, and one which has important clinical implications. A significant number of such cases appear associated with recurrent hydrocele, as an irritative/reactive response to this condition. The morphological spectrum of mesothelial lesions in this topography is broad, and a set of benign conditions may appear, sometimes with florid gross features and cytologic pseudo-atypia. Here, we present two different examples in which malignancy was initially considered in the differential diagnosis.

Usefulness of NF2 hemizygous loss detected by fluorescence in situ hybridization in diagnosing pleural mesothelioma in tissue and cytology material: A multi-institutional study

OBJECTIVES

BAP1, CDKN2A, and NF2 are the most frequently altered genes in pleural mesotheliomas (PM). Discriminating PM from benign mesothelial proliferation (BMP) is sometimes challenging; it is well established that BAP1 loss, determined by immunohistochemistry (IHC), and CDKN2A homozygous deletion (HD), determined by fluorescence in situ hybridization (FISH), are useful. However, data regarding the diagnostic utility of NF2 FISH in PM is limited. Thus, we performed a multi-institutional study examining the utility of NF2 alterations determined by FISH for diagnosing PM in combination with BAP1 loss and CDKN2A HD.

MATERIALS AND METHODS

Multi-institutional PM cases, including 106 surgical and 107 cell block samples as well as 37 tissue cases of benign mesothelial proliferation (BMP) and 31 cell block cases with reactive mesothelial cells (RMC), were collected and analyzed using IHC for BAP1 and FISH for CDKN2A and NF2.

RESULTS

In PM, NF2 FISH revealed hemizygous loss (HL) in 54.7% of tissue cases (TC) and 49.5% of cell block cases (CBC), with about 90% of HL being monosomy. CDKN2A HD or BAP1 loss were detected in 75.5%/65.4% TC or 63.6%/60% CBC, respectively. BMP or RMC showed no BAP1 loss, CDKN2A HD, or NF2 HL. For discriminating PM from BMP, a combination of BAP1 loss, CDKN2A HD, and NF2 HL yielded enhanced sensitivity of 98.1% TC/94.4% CBC. BAP1 loss, CDKN2A HD, or NF2 HL were observed in 69%, 70%, or 58% of epithelioid PM, but in 9%, 91%, or 27% of sarcomatoid PM, respectively. Histotype, histological gradings, and CDKN2A deletion status showed significant differences in overall survival, while BAP1 loss and NF2 HL did not.

CONCLUSION

NF2 HL, consisting predominantly of monosomy, can be detected by FISH in both TC and CBC of PM, and is effective for distinguishing PM from BMP, especially when combined with BAP1 loss and CDKN2A HD.

Malignant pleural mesothelioma: an update

Malignant mesotheliomas are rare types of cancers that affect the mesothelial surfaces, usually the pleura and peritoneum. They are associated with asbestos exposure, but due to a latency period of more than 30 years and difficult diagnosis, most cases are not detected until they reach advanced stages. Treatment options for this tumor type are very limited and survival ranges from 12 to 36 months. This review discusses the molecular physiopathology, current diagnosis, and latest therapeutic options for this disease.

Adenomatoid Tumor: A Review of Pathology With Focus on Unusual Presentations and Sites, Histogenesis, Differential Diagnosis, and Molecular and Clinical Aspects With a Historic Overview of Its Description

Adenomatoid tumors have been described almost a century ago, and their nature has been the subject of debate for decades. They are tumors of mesothelial origin usually involving the uterus, the Fallopian tubes, and the paratesticular region. Adenomatoid tumors of the adrenal gland, the liver, the extragenital peritoneum, the pleura, and the mediastinum have been rarely reported. They are usually small incidental findings, but large, multicystic and papillary tumors, as well as multiple tumors have been described. Their pathogenesis is related to immunosuppression and to TRAF7 mutations. Despite being benign tumors, there are several macroscopic or clinical aspects that could raise diagnostic difficulties. The aim of this review was to describe the microscopic and macroscopic aspects of adenomatoid tumor with a special focus on its differential diagnosis and pathogenesis and the possible link of adenomatoid tumor with other mesothelial lesions, such as the well-differentiated papillary mesothelioma and the benign multicystic mesothelioma, also known as multilocular peritoneal cysts.

Hemizygous loss of NF2 detected by fluorescence in situ hybridization is useful for the diagnosis of malignant pleural mesothelioma

Neurofibromatosis type 2 (NF2) gene, a tumor suppressor gene located on chromosome 22q12.2, is frequently abnormal in mesothelioma. Recent studies have revealed the effectiveness of diagnostic assays for differentiating malignant pleural mesothelioma from reactive mesothelial hyperplasia. These include detection of homozygous deletion of the 9p21 locus by fluorescence in situ hybridization (FISH) (9p21 FISH), loss of expression of BAP1 as detected by immunohistochemistry, and loss of expression of methylthioadenosine phosphorylase (MTAP) as detected by immunohistochemistry. However, the application of FISH detection of NF2 gene deletion (NF2 FISH) in differentiation of malignant pleural mesothelioma from reactive mesothelial hyperplasia has not been fully evaluated. In this study, we investigated whether NF2 FISH, either alone or in a combination with other diagnostic assays (9p21 FISH, MTAP immunohistochemistry, and BAP1 immunohistochemistry), is effective for distinguishing malignant pleural mesothelioma from reactive mesothelial hyperplasia. This study cohort included malignant pleural mesothelioma (n = 47) and reactive mesothelial hyperplasia cases (n = 27) from a period between 2001 and 2017. We used FISH to examine deletion status of NF2 and 9p21 and immunohistochemistry to examine expression of MTAP and BAP1 in malignant pleural mesothelioma and in reactive mesothelial hyperplasia. Hemizygous NF2 loss (chromosome 22 monosomy or hemizygous deletion) was detected in 25 of 47 (53.2%) mesothelioma cases. None of the mesothelioma cases showed homozygous NF2 deletion. Hemizygous NF2 loss showed 53.2% sensitivity and 100% specificity in differentiating malignant pleural mesothelioma from reactive mesothelial hyperplasia. A combination of NF2 FISH, 9p21 FISH, and BAP1 immunohistochemistry yielded greater sensitivity (100%) than that detected for either diagnostic assay alone (53.2% for NF2 FISH, 78.7% for 9p21 FISH, 70.2% for MTAP immunohistochemistry, or 57.4% for BAP1 immunohistochemistry). Thus, NF2 FISH in combination with other diagnostic assays is effective for distinguishing malignant pleural mesothelioma from reactive mesothelial hyperplasia.

Evaluation of gene expression levels in the diagnosis of lung adenocarcinoma and malignant pleural mesothelioma

Background

This study aims to evaluate gene expression levels in the diagnosis of lung adenocarcinoma and malignant pleural mesothelioma both which have a distinct treatment and prognosis.

Methods

Between January 2012 and January 2014, 12 newly diagnosed patients with a lung adenocarcinoma, 12 patients with malignant pleural mesothelioma, and eight healthy individuals as the control group were included. After treatment of the fresh samples of lung adenocarcinoma stored at -80°C for ribonucleic acid isolation, and paraffin-embedded tissues of patients with malignant pleural mesothelioma were deparaffinized, complementary deoxyribonucleic acid synthesis and expression of 84 genes associated with deoxyribonucleic acid repair were analyzed via real-time polymerase chain reaction assay. According to the expression of tumor cells, expression of each fold change was calculated.

Results

The BRCA1, BRCA2, CDK7, MLH3, MSH4, NEIL3, SMUG1, UNG, XRCC2, and XRCC4 genes showed more than five-fold higher expression in the patients with lung adenocarcinomas, compared to the control group. The patients with malignant pleural mesothelioma showed a five-fold higher expression in the APEX2, BRCA1, BRCA2, CDK7, MLH1, MLH3, MSH3, MSH4, NEIL3, PARP2, PARP3, PMS1, RAD50, RAD51, RAD51B, RAD51D, RAD52, RPA3, SMUG1, UNG, XPA, XRCC2, and XRCC4 genes, compared to the control group. Comparing malignant pleural mesothelioma with lung adenocarcinoma cases, we found that CDK7, MLH1, TREX1, PRKDC, XPA, PMS1, UNG, and RPA3 genes were overexpressed.

Conclusion

Our study results showed differences between expression profiles of deoxyribonucleic acid repair genes in lung adenocarcinoma and malignant pleural mesothelioma cells. Based on our study results, we suggest that TREX1, PRKDC, and PMS1 genes may play a key role in the differential diagnosis of these two entities.

Mesothelium and Malignant Mesothelioma

The mesothelium is an epithelial structure derived from the embryonic mesoderm. It plays an important role in the development of a number of different organs, including the heart, lungs, and intestines. In this publication, we discuss aspects of the development of the mesothelium, where mesothelial structures can be found, and review molecular and cellular characteristics associated with the mesothelium. Furthermore, we discuss the involvement of the mesothelium in a number of disease conditions, in particular in the pathogenesis of mesotheliomas with an emphasis on malignant pleural mesothelioma (MPM)—a primary cancer developing in the pleural cavity.

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

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

Diagnostic value of microRNAs in asbestos exposure and malignant mesothelioma: systematic review and qualitative meta-analysis

Background

Asbestos is a harmful and exceptionally persistent natural material. Malignant mesothelioma (MM), an asbestos-related disease, is an insidious, lethal cancer that is poorly responsive to current treatments. Minimally invasive, specific, and sensitive biomarkers providing early and effective diagnosis in high-risk patients are urgently needed. MicroRNAs (miRNAs, miRs) are endogenous, non-coding, small RNAs with established diagnostic value in cancer and pollution exposure. A systematic review and a qualitative meta-analysis were conducted to identify high-confidence miRNAs that can serve as biomarkers of asbestos exposure and MM.

Methods

The major biomedical databases were systematically searched for miRNA expression signatures related to asbestos exposure and MM. The qualitative meta-analysis applied a novel vote-counting method that takes into account multiple parameters. The most significant miRNAs thus identified were then subjected to functional and bioinformatic analysis to assess their biomarker potential.

Results

A pool of deregulated circulating and tissue miRNAs with biomarker potential for MM was identified and designated as “mesomiRs” (MM-associated miRNAs). Comparison of data from asbestos-exposed and MM subjects found that the most promising candidates for a multimarker signature were circulating miR-126-3p, miR-103a-3p, and miR-625-3p in combination with mesothelin. The most consistently described tissue miRNAs, miR-16-5p, miR-126-3p, miR-143-3p, miR-145-5p, miR-192-5p, miR-193a-3p, miR-200b-3p, miR-203a-3p, and miR-652-3p, were also found to provide a diagnostic signature and should be further investigated as possible therapeutic targets.

Conclusion

The qualitative meta-analysis and functional investigation confirmed the early diagnostic value of two miRNA signatures for MM. Large-scale, standardized validation studies are needed to assess their clinical relevance, so as to move from the workbench to the clinic.

Targeting microRNA to improve diagnostic and therapeutic approaches for malignant mesothelioma

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

Association Between Clinicopathological Factors and Genomic Abnormalities Detected by FISH Analysis in Epithelioid Diffuse Malignant Pleural Mesothelioma

BACKGROUND

Abnormality of genes including 9p21 is known in malignant mesothelioma and we have examined the frequency of gene deletion and amplification using the fluorescence in situ hybridization (FISH) method. We formerly reported that abnormality of the genes was more common in the sarcomatoid type than epithelioid type. In this study, we compared the clinicopathological factors including nuclear grade (NG) and genomic abnormality in epithelioid malignant pleural mesothelioma (MPM).

METHODS

Using paraffin-embedded tissues of 31 epithelioid MPMs, we investigated the presence of gene abnormalities in the genes 9p21, 1p36, 14q32, 22q12, 5p15, 6p, 8q24, and 7p12 by the FISH method, and compared the results with NG, clinical stage, and prognosis.

RESULTS

In the higher NG group of epithelioid MPM, more gene amplifications [in particular 5p15 and 8q24(MYC)] were observed, and clinical stage was more advanced. Cases with the amplification of 7p12(EGFR) tended to exhibit a worse prognosis. The significant correlation between histological differentiation and clinical features such as prognosis was not confirmed.

CONCLUSIONS

NG status in epithelioid MPM may be related to gene alteration and clinical features.

Overexpression of Functional SLC6A3 in Clear Cell Renal Cell Carcinoma

Purpose: Renal cell carcinoma (RCC) is derived from a tissue with a remarkable capacity for vectorial transport. We therefore performed an unbiased exploration of transporter proteins in normal kidney and kidney cancer to discover novel clinical targets.Experimental Design: Using The Cancer Genome Atlas (TCGA) database, we investigated differences in membrane transporter expression in clear cell RCC (ccRCC) and normal kidney. We identified the dopamine transporter SLC6A3 as a specific biomarker for ccRCC. To investigate the functionality of SLC6A3, we used a [³H]-dopamine uptake assay on ccRCC cells. We further explored the effect of hypoxia-inducible factor (HIF) proteins on SLC6A3 expression by introducing siRNA in ccRCC cells and by hypoxic treatment of nonmalignant cells.Results: We show that ccRCC expresses very high transcript levels of SLC6A3 in contrast to normal kidney tissue and other tumor types, which do not express appreciable levels of this transporter. Importantly, we demonstrate that the elevated expression of SLC6A3 in ccRCC cells is associated with specific uptake of dopamine. By targeting the expression of HIF-1α and HIF-2α, we could show that SLC6A3 expression is primarily influenced by HIF-2α and that hypoxia can induce SLC6A3 expression in normal renal cells.Conclusions: We conclude that the dopamine transporter SLC6A3 constitutes a novel biomarker that is highly specific for ccRCC. We further postulate that the protein can be exploited for diagnostic or therapeutic purposes for detection or treatment of ccRCC. Clin Cancer Res; 23(8); 2105-15. ©2016 AACR.

The legacy of the F344 rat as a cancer bioassay model (a retrospective summary of three common F344 rat neoplasms)

The Fischer 344 (F344) rat was used by the National Toxicology Program (NTP) for over 5 decades for toxicity and carcinogenicity studies. However, in 2006, the NTP decided to switch to a different rat stock due largely to high background control incidences of Leydig cell tumors (LCTs) and mononuclear cell leukemia (MNCL), also known as large granular lymphocytic (LGL) leukemia. In the current review, we aim (1) to provide a summary of NTP bioassays with treatment-associated effects involving MNCL and LCTs in addition to male F344-specific tunica vaginalis mesothelioma (TVM); (2) to describe important pathobiological differences between these F344 rat tumor responses and similar target tissue-tumor response in humans; and (3) to present the NTP reasons for switching away from the F344 rat. We show that due to the highly variable background incidence of F344 MNCL, more reliance on historical control data than is usual for most tumor responses is warranted to evaluate potential effect of any chemical treatment in this rat strain. The high spontaneous incidence of LCTs in the testes of male F344 rats has made this tumor endpoint of little practical use in identifying potential testicular carcinogenic responses. TVM responses in F344 rats have a biological plausible relationship to LCTs unlike TVM in humans. Given their high spontaneous background incidence and species-specific biology, we contend that MNCL and LCT, along with TVM responses, in F344 rat carcinogenicity studies are inappropriate tumor types for human health risk assessment and lack relevance in predicting human carcinogenicity.

Comparative genetic analysis of a rare synchronous collision tumor composed of malignant pleural mesothelioma and primary pulmonary adenocarcinoma

Background

Although asbestos acts as a potent carcinogen in pleural mesothelial and pulmonary epithelial cells, it still remains unclear whether asbestos causes specific and characteristic gene alterations in these different kinds of target cells, because direct comparison in an identical patient is not feasible. We experienced a rare synchronous collision tumor composed of malignant pleural mesothelioma (MPM) and primary pulmonary adenocarcinoma (PAC) in a 77-year-old man with a history of long-term smoking and asbestos exposure, and compared the DNA copy number alteration (CNA) and somatic mutation in these two independent tumors.

Methods

Formalin-fixed paraffin-embedded (FFPE) tissues of MPM and PAC lesions from the surgically resected specimen were used. Each of these MPM and PAC lesions exhibited a typical histology and immunophenotype. CNA analysis using SNP array was performed using the Illumina Human Omni Express-12_FFPE (Illumina, San Diego, CA, USA) with DNA extracts from each lesion. Somatic mutation analysis using next-generation sequencing was performed using the TruSeq Amplicon Cancer Panel (Illumina).

Results

The CNA analysis demonstrated a marked difference in the frequency of gain and loss between MPM and PAC. In PAC, copy number (CN) gain was detected more frequently and widely than CN loss, whereas in MPM there was no such obvious difference. PAC did not harbor CNAs that have been identified in asbestos-associated lung cancer, but did harbor some of the CNAs associated with smoking. MPM exhibited CN loss at 9p21.2-3, which is the most common genetic alteration in mesothelioma.

Conclusion

In this particular case, asbestos exposure may not have played a primary role in PAC carcinogenesis, but cigarette smoking may have contributed more to the occurrence of CN gains in PAC. This comparative genetic analysis of two different lesions with same amount of asbestos exposure and cigarette smoke exposure has provided information on differences in the cancer genome related to carcinogenesis.

Non-coding RNA repertoires in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare malignancy, with extremely poor survival rates. There are limited treatment options, with no second line standard of care for those who fail first line chemotherapy. Recent advances have been made to characterise the underlying molecular mechanisms of mesothelioma, in the hope of providing new targets for therapy. With the discovery that non-coding regions of our DNA are more than mere junk, the field of research into non-coding RNAs (ncRNAs) has exploded in recent years. Non-coding RNAs have diverse and important roles in a variety of cellular processes, but are also implicated in malignancy. In the following review, we discuss two types of non-coding RNAs, long non-coding RNAs and microRNAs, in terms of their role in the pathogenesis of MPM and their potential as both biomarkers and as therapeutic targets in this disease.

DNA copy number gains in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor with an extremely poor prognosis. The incidence of MPM is increasing as a result of widespread exposure to asbestos. The molecular pathogenesis of MPM remains unclear. The present study analyzed the frequency of various genomic copy number gains (CNGs) in MPM using reverse transcription-quantitative polymerase chain reaction. A total of 83 primary MPMs and 53 primary lung adenocarcinomas were analyzed to compare the CNGs of EGFR, KRAS, MET, FGFR1 and SOX2. In MPM, the CNGs of EGFR, KRAS, MET, FGFR1 and SOX2 were detected in 12 (14.5%), 8 (9.6%), 5 (6.0%), 4 (4.8%) and 1 (1.2%) of the samples, respectively. In lung adenocarcinomas, the CNGs of EGFR, KRAS, MET, FGFR1 and SOX2 were detected in 21 (39.6%), 12 (22.6%), 5 (9.4%), 10 (18.9%) and 0 (0.0%) of the samples, respectively. The CNGs of EGFR, KRAS and FGFR1 were significantly less frequent in the MPMs compared with the lung adenocarcinomas (P=0.0018, 0.048 and 0.018, respectively). Overall, the MPMs exhibited these CNGs less frequently compared with the lung adenocarcinomas (P=0.0002). The differences in CNGs between the two tumor types suggested that they are genetically different.

Overview of the biochemical and genetic processes in malignant mesothelioma

Malignant mesothelioma (MM) is a highly aggressive form of cancer, has a long latency period, and is resistant to chemotherapy. It is extremely fatal, with a mean survival of less than one year. The development of MM is strongly correlated with exposure to asbestos and with other factors, such as erionite and simian virus 40 [corrected]. Although various countries have banned the use of asbestos, MM has proven to be difficult to control and there appears to be a trend toward an increase in its incidence in the years to come. In Brazil, MM has not been widely studied from a genetic or biochemical standpoint. In addition, there have been few epidemiological studies of the disease, and the profile of its incidence has yet to be well established in the Brazilian population. The objective of this study was to review the literature regarding the processes of malignant transformation, as well as the respective mechanisms of tumorigenesis, in MM.

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

Context

Immunohistochemistry has become an indispensable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome in the era of personalized medicine. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

Objective

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

Data Sources

Literature review, authors' research data, and personal practice experience.

Conclusions

This review article has shown that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. The discovery of new mutation-specific antibodies identifying a subset of specific gene-arranged lung tumors provides a promising alternative and cost-effective approach to molecular testing. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoiding potential diagnostic errors.

Comparison of genomic abnormality in malignant mesothelioma by the site of origin

AIMS

Malignant mesothelioma (MM) results from the accumulation of a number of acquired genetic events at the onset. In MM, the most frequent changes are losses in 9p21, 1p36, 22q12 and 14q32, and gains in 5p, 7p and 8q24 by comparative genomic hybridisation analysis. We have examined various genomic losses and gains in MM and benign mesothelial proliferation by fluorescence in situ hybridisation (FISH) analysis. 9p21 deletion was reported to be less frequent in peritoneal than in pleural MMs. This study analysed various genomic losses and gains in MM by the site of origin using FISH analysis.

MATERIALS AND METHODS

We performed FISH analysis using paraffin-embedded tissues from 54 cases (40 pleural and 14 peritoneal) of MMs and compared the frequency of genomic abnormality by the site of origin.

RESULTS

9p21 deletion was shown in 34 of 40 cases (85%) of pleural MMs, and was less frequent in five of 14 cases (36%) of peritoneal MMs (p<0.001) by FISH analysis. By contrast, 5p15 and 7p12 amplification was more significantly frequent in peritoneal than in pleural MMs. No difference between the two sites of MM in other genes was found.

CONCLUSIONS

9p21 homozygous deletion assessed by FISH has been reported to be useful for differentiating MM from reactive mesothelial proliferation, but it should be noted that 9p21 deletion was less frequent in peritoneal MM. Our study suggests that the pathway of the genetic abnormality might vary between pleural and peritoneal MM.

The role of key genes and pathways involved in the tumorigenesis of Malignant Mesothelioma

Malignant Mesothelioma (MM) is a very aggressive cancer with low survival rates and often diagnosed at an advanced stage. Several players have been implicated in the development of this cancer, such as asbestos, erionite and the simian virus 40 (SV40). Here, we have reviewed the involvement of erionite, SV40, as well as, the role of several genes (p16(INK4a), p14(ARF), NF2, LATS2, SAV, CTNNB1 and among others), the pathways (RAS, PI3K, Wnt, BCL and Hippo), and their respective roles in the development of MM.

Comparative immunohistochemical analysis of IMP3, GLUT1, EMA, CD146, and desmin for distinguishing malignant mesothelioma from reactive mesothelial cells

OBJECTIVES

To identify useful biomarkers for differentiating between malignant mesothelioma (MM) and reactive mesothelial cells (RMCs).

METHODS

Formalin-fixed, paraffin-embedded (FFPE) tissues from 34 MM and 40 RMC samples were analyzed using immunohistochemistry, and the findings were compared.

RESULTS

Positive markers for MM included insulin-like growth factor 2 messenger RNA binding protein 3 (IMP3), glucose transporter 1 (GLUT1), epithelial membrane antigen (EMA), and CD146, which showed sensitivities of 94%, 85%, 79%, and 71% and specificities of 78%, 100%, 88%, and 98%, respectively. In sarcomatoid MM, EMA had significantly lower expression than did IMP3, GLUT1, and CD146 (P < .001). The areas under receiver operating characteristic curves were the highest for IMP3 (0.95), followed by GLUT1 (0.93). When the optimal cutoff points for IMP3 (30%) and GLUT1 (10%) were used, the sensitivity of IMP3 and GLUT1 for MM was 100%, and the specificity of both for MM was 95%.

CONCLUSIONS

The combination of IMP3 and GLUT1 is most appropriate for distinguishing MM from RMC using FFPE sections.

Diagnostic value of fluorescence in situ hybridization assay in malignant mesothelioma: a meta-analysis

The diagnosis of malignant mesothelioma (MM) remains a clinical challenge and the fluorescence in situ hybridization (FISH) assay has been reported to be one promising tool. The present meta-analysis aimed to establish the overall diagnostic accuracy of FISH for diagnosing MM. After a systematic review of English language studies, the sensitivity, specificity and other measures of accuracy of FISH in the diagnosis of MM were pooled using random-effects models. Summary receiver operating characteristic curves were applied to summarize overall test performance. Nine studies met our inclusion criteria, the pooled sensitivity and specificity for FISH for diagnosing MM being 0.72 (95% CI 0.67-0.76) and 1.00 (95% CI 0.98-1.00), respectively. The positive likelihood ratio was 34.5 (95% CI 14.5-82.10), the negative likelihood ratio was 0.24 (95% CI 0.16-0.36), and the diagnostic odds ratio was 204.9 (95% CI 76.8-546.6), the area under the curve being 0.99. Our data suggest that the FISH assay is likely to be a useful diagnostic tool for confirming MM. However, considering the limited studies and patients included, further large scale studies are needed to confirm these findings.

Diagnostic usefulness of p16/CDKN2A FISH in distinguishing between sarcomatoid mesothelioma and fibrous pleuritis

The distinction between sarcomatoid mesothelioma and fibrous pleuritis is difficult based on histology, especially when the amount of tumor tissue examined via biopsy is small and immunohistochemical examination is inconclusive. We studied the usefulness of deletion of p16 with fluorescence in situ hybridization (FISH) and p16 hypermethylation with polymerase chain reaction for the diagnosis and prognosis of malignant pleural mesothelioma (MPM). We analyzed 50 MPMs, including 22 sarcomatoid mesothelioma cases and 10 fibrous pleuritis cases. We set the cutoff value of homozygous deletion pattern as 14.4% based on FISH signaling patterns using samples of fibrous pleuritis. The percentage of homozygous deletion pattern was higher than 14.4% in 55.6% of the epithelioid mesotheliomas (10/18) and in all of the sarcomatoid mesotheliomas (22/22). Methylation of p16 was observed in 7 (20.6%) of 34 informative cases. p16 FISH analysis can be a reliable test for distinguishing between sarcomatoid mesothelioma and fibrous pleuritis and a prognostic factor for MPM.

Applications of array-CGH for lung cancer

This chapter summarizes the current knowledge on gene copy number changes found in lung tumors, and their application in the diagnosis, prognostication, and prediction of response to chemotherapy. Examples of the identification of specific "driver" oncogenes within amplified DNA segments are described. A model of how array-CGH could be integrated clinically into the routine workup of lung cancers in clinical laboratory is proposed.

Molecular testing in melanoma

Melanoma is the deadliest form of skin cancer and is increasing in incidence. Recent treatment advances have been made, but there remains a need for continued development of effective therapy options, as treatment rarely leads to cure. Many melanomas contain somatic mutations involved in tumor pathogenesis. Accurate identification of these mutations is necessary to stratify patients for the purpose of treatment and potential for clinical trials, given the absence or presence of a specific mutation. There are a number of techniques available that will identify genetic mutations and genomic aberrations present within melanoma tumor samples which are reviewed here. The type of mutation and sample number will drive selection of a given mutation detection strategy. The strengths and weaknesses, along with limitations, of the various methods will also be discussed. The discovery of somatic mutations integral in melanoma will increase our understanding of tumor pathogenesis and should facilitate identification of mutations relevant to clinical treatment decisions, advancing progress toward personalized medicine.