The morphologic distinction of pleomorphic adenoma from other benign or low-grade salivary gland tumors is sometimes difficult and problematic because of their potentially overlapping histological patterns. A subset of pleomorphic adenoma harbors specific gene alterations involving PLAG1 or HMGA2, and the detection of these fusion genes and their products using formalin-fixed, paraffin-embedded (FFPE) tumor specimens may be a useful diagnostic adjunct. In the present study, gene fusions involving PLAG1 or HMGA2 were examined by reverse transcription-polymerase chain reaction (RT-PCR) analysis, with FFPE tumor tissues and immunohistochemical expression of PLAG1 in 45 pleomorphic adenomas, using a commercially available antibody. RT-PCR analyses identified the CTNNB1-PLAG1, LIFR-PLAG1, CHCHD7-PLAG1, and HMGA2-WIF1 fusion transcripts in eight, two, one, and one case, respectively. The TCEA1-PLAG1, HMGA2-FHIT, and HMGA2-NFIB fusion transcripts were not detected. Immunohistochemically, tumor cells in all 45 pleomorphic adenomas were positive for PLAG1, irrespective of PLAG1 rearrangements, even in the case with the HMGA2-WIF1 fusion transcript. Tumor cells displaying myoepithelial or cartilaginous differentiation were almost constantly positive for PLAG1, whereas a limited expression was observed in glandular or keratinizing cells. Among the 46 tumors other than pleomorphic adenoma, 4 carcinomatous components of carcinomas ex pleomorphic adenoma were positive for PLAG1, the other 39 were negative for PLAG1, and the remaining 3 were only faintly and/or focally stained, indicating that the immunohistochemical detection of PLAG1 is diagnostically useful. The present results also suggest that overexpression of PLAG1 is essential for the tumorigenesis of pleomorphic adenomas, although the mechanisms mediating PLAG1 overexpression seem to be variable.

Since the discovery of small non-coding RNAs, the analyses of microRNA (miRNA) expression patterns in human cancer have provided new insights into cancer biology. miRNA-21 has been suggested to be one of the miRNAs that have an important role in the development or biological behavior of a variety of malignancies, including pancreatic cancer. This study was conducted to evaluate the relationship between the expression of miRNA-21 and that of its molecular targets, programmed cell death 4 (PDCD4) and tissue inhibitor of metalloproteinase (TIMP3), in pancreatic ductal adenocarcinoma. The study included 65 pancreatic ductal adenocarcinomas and 5 normal pancreatic tissue specimens for comparison. The miRNA expression profiling of five selected pancreatic ductal adenocarcinomas and five normal pancreatic specimens was performed using a microarray platform, and was evaluated by a hierarchical clustering analysis. The miRNA most highly expressed in pancreatic ductal adenocarcinomas (ie, miRNA-21) was further assessed by quantitative real-time reverse transcription PCR (RT-PCR) assays in the 65 pancreatic ductal adenocarcinoma cases. The expression pattern of its molecular targets (eg, PDCD4 and TIMP3) in pancreatic ductal adenocarcinoma was examined immunohistochemically. In the microarray analyses, 28 miRNAs were upregulated in pancreatic ductal adenocarcinoma compared with normal pancreatic tissue, whereas 48 miRNAs were downregulated. miRNA-21 was the most significantly overexpressed miRNA in the pancreatic ductal adenocarcinomas analyzed, and was also highly expressed in 75% of the 65 pancreatic ductal adenocarcinomas examined by real-time RT-PCR. High miRNA-21 expression was correlated with a worse prognosis in the pancreatic ductal adenocarcinoma patients (P ¼ 0.045). The immunohistochemical expression patterns of PDCD4 (reduced nuclear staining pattern) and TIMP3 (downregulated expression) were significantly associated with both the upregulated miR-21 expression (Po0.05) and the poor survival of the patients (Po0.001 and P ¼ 0.001, respectively). Our data suggest that an overexpression of miRNA-21 is, therefore, associated with the biological behavior of pancreatic ductal adenocarcinoma via the downregulation of the expression of tumor suppressors, PDCD4 and TIMP3, thus resulting in tumor progression and the adverse clinical course of pancreatic ductal adenocarcinoma.

MicroRNAs (miRNAs) are noncoding small RNAs that function as an endogenous regulator of gene expression. Their dysregulation has been implicated in the development of several cancers. However, the status of miRNA in soft tissue sarcomas has not yet been thoroughly investigated. This study examined the global miRNA expression in synovial sarcoma and compared the results to those in another translocation-associated sarcoma, the Ewing family of tumors, and in normal skeletal muscle. The 3D-Gene miRNA microarray platform (Toray, Kamakura, Japan) and unsupervised hierarchical clustering revealed a distinct expression pattern of miRNAs in synovial sarcoma from Ewing tumors and skeletal muscle. Thirty-five of the more than 700 miRNAs analyzed were differentially expressed in synovial sarcomas in comparison to other tissue types. There were 21 significantly up-regulated miRNAs, including some miRNAs, such as let-7e, miR-99b, and miR-125a-3p, clustered within the same chromosomal loci. Quantitative reverse transcription-polymerase chain reaction also demonstrated that these miRNAs were over-expressed in synovial sarcomas. The down-regulation of let-7e and miR-99b by anti-miR miRNA inhibitors resulted in the suppression of the proliferation of synovial sarcoma cells, and modulated the expression of their putative targets, HMGA2 and SMARCA5, suggesting that these molecules have a potential oncogenic role. The unique miRNA expression pattern including the over-expressed miRNA clusters in synovial sarcoma warrants further investigation to develop a better understanding of the oncogenic mechanisms and future therapeutic strategies for synovial sarcoma.

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FLER may identify the future anastomotic site even after repetitive assessments and long-standing bowel ischemia.