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P1.02 - Biology/Pathology (ID 614)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Biology/Pathology
- Presentations: 2
- Coordinates: 10/16/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
P1.02-002 - Diagnostic Utility of MUC4 Expression to Differentiate Epithelioid Mesothelioma from Lung Adenocarcinoma and Squamous Cell Carcinoma (ID 8372)
09:30 - 16:00 | Author(s): A.S. Mawas
Malignant mesothelioma is a highly aggressive asbestos related cancer with poor prognosis and its diagnosis and differentiatiation from various cancers is challenging. In addition to histological features, many positive and negative immunohisotchemical markers are needed to differentiate epitheioid mesothelioma from lung adenocarcinoma and/or squamous cell carcinoma. The positive mesothelial markers calretinin, WT-1, D2-40, CK5/6; positive lung adenocarcinoma markers, TTF-1, Napsin-A, Claudin-4, CEA; and positive squamous cell markers, P40, P63, CK5/6, MOC31 are routinely used. However, these markers are not sufficient and novel markers have to be identified.
Patients and Histologic Samples Pathological specimens (formalin-fixed paraffin-embedded tissue blocks) of 65 epithelioid mesothelioma and 60 lung adenocarcinoma and 57 squamous cell carcinoma were obtained from the archives of the Department of Pathology, Hiroshima University. All histological sections were reviewed and reclassified according to recent 2015 WHO classification and was confirmed by histologic findings and an immunohistochemical marker panel recommended by 2012 IMIG update to practical guidelines Immunohistochemical Procedures and Evaluation of Expression of MUC4 Immunohistochemical staining was performed using the Ventana Benchmark GX automated immunohistochemical station (Roche Diagnostics, Tokyo, Japan). Cells showing nuclear staining for calretinin, WT1, p40, p63, and TTF-1, cytoplasmic staining for MUC4 and napsin A, membranous staining for D2-40, MOC-31, and claudin-4 or membranous and/or cytoplasmic staining for CK5/6 and CEA were regarded as ‘positive’. Positive Immunoreactivity was semiquantified scored from 0 to 3+.
MUC4 positivity was present in 50/60(83.3%) cases, case of adenocarcinoma and 50/56(89.3%) cases of squamous cell carcinoma but none of 65 epithelioid mesotheliomas (0%). Among lung adenocarcinoma cases, 21 cases showed score 3+, 9 cases 2+ and 20 cases score +1. In lung squamous cell carcinoma, 21 cases score 3+, 10 cases score 2+ and 19 cases score 1+. The sensitivity and specificity of MUC4 to differentiate epithelioid mesothelioma from lung adenocarcinoma were 100% and 83.3% respectively with accuracy rate of 92%. Similarly, sensitivity and specificity of MUC4 to differentiate epithelioid mesothelioma from lung squamous cell carcinoma 100% and 89.3% respectively with accuracy rate of 95%. MUC4 expression showed sensitivity of 100%, but lower specificity of 86.2% and accuracy rate of 91.2% than CEA or Claudin-4 expression. However, it showed better sensitivity, specificity and accuracy rate than that of MOC-31.
MUC4 is an additional negative immunohistochemical marker to differentiate epithelioid mesothelioma from lung adenocarcinoma and/or squamous cell carcinoma.
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P1.02-052 - Identification of DAB2 and Intelectin-1 as Novel Positive Immunohistochemical Markers of Epithelioid Mesothelioma (ID 9299)
09:30 - 16:00 | Author(s): A.S. Mawas
Malignant mesothelioma is a fatal malignant tumor. It is often difficult to diagnose and to differentiate from other carcinomas, especially pulmonary adenocarcinoma. As there are currently no absolute immunohistochemical positive markers for the definite diagnosis of epithelioid mesothelioma, the identification of additional “positive” markers that may facilitate this diagnosis becomes of clinical importance.
Gene Expression Analysis Formalin-fixed paraffin-embedded tissue sections from 6 epithelioid mesothelioma and 6 pulmonary adenocarcinoma cases were used for gene expression analysis. RNA extraction for gene expression analysis was performed from papillary or solid growth of tumor cells in each specimen. The Human Transcriptome 2.0 GeneChip Array containing gene transcript sets of 44,699 protein coding and 22,829 nonprotein coding clusters was used to analyze gene expression profiles. Validation by Real-time RT PCR & Western Blotting The increased mRNA expression of DAB2 and Intelectin-1 was validated by reverse transcriptase polymerase chain reaction of RNA from tumor tissue and protein expression was validated by Western blotting of 5 mesothelioma cell lines. Immunohistochemical Procedures and Evaluation of Expression of DAB2 and Intelectin-1 The utility of DAB2 and Intelectin-1 in the differential diagnosis of epithelioid mesothelioma and pulmonary adenocarcinoma was examined by an immunohistochemical study of 75 cases of epithelioid mesothelioma and 67 cases of pulmonary adenocarcinoma.
Differential Gene Expression Of the 44,699 protein coding and 22,829 nonprotein coding transcripts on the Human Transcriptome 2.0 GeneChip Array, 902 statistically significant mRNA transcripts were differentially expressed, with a greater than 1.3-fold difference, between epithelioid mesothelioma and pulmonary adenocarcinoma. Validation Realtime RT-PCR showed relative mRNA expression of DAB2 and Intelectin-1 was significantly higher in epithelioid mesothelioma than that in pulmonary adenocarcinoma. Western blot analysis showed DAB2 and Intelectin-1 protein expression in all 5 commercially available mesothelioma cells lines with anti-DAB2 and anti-Intelectin-1 antibody. Immunohistochemical Expression Profiles in Epithelioid Mesothelioma and Pulmonary Adenocarcinoma The expression of DAB2 and Intelectin-1 was localized in the cytoplasm of tumor cells in epithelioid mesothelioma cases. Positive DAB2 expression was observed in 60 of 75 epithelioid mesotheliomas (80.0%) and 2 of 67 pulmonary adenocarcinomas (3.0%). In half of epithelioid mesotheliomas, DAB2 immunoreactivity was generally strong and diffuse (score 3+). In contrast, pulmonary adenocarcinomas showing DAB2 expression was focal (score 1+).
We identified 2 novel positive markers of epithelioid mesothelioma, DAB2 and Intelectin-1, by using gene expression microarray analysis and confirmed their utility to differentiate epithelioid mesothelioma from pulmonary adenocarcinoma by immunohistochemical study.