Tenosynovial giant-cell tumor (TGCT) and pigmented villonodular synovitis (PVNS) are related conditions with features of both reactive inflammatory disorders and clonal neoplastic proliferations. Chromosomal translocations involving chromosome 1p13 have been reported in both TGCT and PVNS. We confirm that translocations involving 1p13 are present in a majority of cases of TGCT and PVNS and show that CSF1 is the gene at the chromosome 1p13 breakpoint. In some cases of both TGCT and PVNS, CSF1 is fused to COL6A3 (2q35). The CSF1 translocations result in overexpression of CSF1. In cases of TGCT and PVNS carrying this translocation, it is present in a minority of the intratumoral cells, leading to CSF1 expression only in these cells, whereas the majority of cells express CSF1R but not CSF1, suggesting a tumor-landscaping effect with aberrant CSF1 expression in the neoplastic cells, leading to the abnormal accumulation of nonneoplastic cells that form a tumorous mass.pigmented villonodular synovitis ͉ receptor tyrosine kinase ͉ macrophage ͉ COL6A3

Gastrointestinal stromal tumors (GIST) occur primarily in the wall of the intestine and are characterized by activating mutations in the receptor tyrosine kinases genes KIT or PDGFRA. The diagnosis of GIST relies heavily on the demonstration of KIT/CD117 protein expression by immunohistochemistry. However, KIT expression is absent in approximately 4% to 15% of GIST and this can complicate the diagnosis of GIST in patients who may benefit from treatment with receptor tyrosine kinase inhibitors. We previously identified DOG1/TMEM16A as a novel marker for GIST using a conventional rabbit antipeptide antiserum and an in situ hybridization probe. Here, we describe 2 new monoclonal antibodies against DOG1 (DOG1.1 and DOG1.3) and compare their staining profiles with KIT and CD34 antibodies on 447 cases of GIST. These included 306 cases with known mutational status for KIT and PDGFRA from a molecular consultation service. In addition, 935 other mesenchymal tumors and 432 nonsarcomatous tumors were studied. Both DOG1 antibodies showed high sensitivity and specificity for GIST, with DOG1.1 showing some advantages. This antibody yielded positive staining in 370 of 425 (87%) scorable GIST, whereas CD117 was positive in 317 of 428 (74%) GIST and CD34 in 254 of 430 (59%) GIST. In GIST with mutations in PDGFRA, 79% (23/29) showed DOG1.1 immunoreactivity while only 9% (3/32) and 27% (9/33) stained for CD117 and CD34, respectively. Only 1 of 326 (0.3%) leiomyosarcomas and 1 of 39 (2.5%) synovial sarcomas among the 935 soft tissue tumors examined showed positive immunostaining for DOG1.1. In addition, DOG1.1 immunoreactivity was seen in fewer cases of carcinoma, melanoma, and seminoma as compared with KIT.

BackgroundColon cancer arises from the accumulation of multiple genetic and epigenetic alterations to normal colonic tissue. microRNAs (miRNAs) are small, non-coding regulatory RNAs that post-transcriptionally regulate gene expression. Differential miRNA expression in cancer versus normal tissue is a common event and may be pivotal for tumor onset and progression.MethodsTo identify miRNAs that are differentially expressed in tumors and tumor subtypes, we carried out highly sensitive expression profiling of 735 miRNAs on samples obtained from a statistically powerful set of tumors (n = 80) and normal colon tissue (n = 28) and validated a subset of this data by qRT-PCR.ResultsTumor specimens showed highly significant and large fold change differential expression of the levels of 39 miRNAs including miR-135b, miR-96, miR-182, miR-183, miR-1, and miR-133a, relative to normal colon tissue. Significant differences were also seen in 6 miRNAs including miR-31 and miR-592, in the direct comparison of tumors that were deficient or proficient for mismatch repair. Examination of the genomic regions containing differentially expressed miRNAs revealed that they were also differentially methylated in colon cancer at a far greater rate than would be expected by chance. A network of interactions between these miRNAs and genes associated with colon cancer provided evidence for the role of these miRNAs as oncogenes by attenuation of tumor suppressor genes.ConclusionColon tumors show differential expression of miRNAs depending on mismatch repair status. miRNA expression in colon tumors has an epigenetic component and altered expression that may reflect a reversion to regulatory programs characteristic of undifferentiated proliferative developmental states.

The discovery of microRNAs (miRNAs) has led to a paradigm shift in our basic understanding of gene regulation. Competing endogenous RNAs (ceRNAs) are the recent entrants adding to the complexities of miRNA mediated gene regulation. ceRNAs are RNAs that share miRNA recognition elements (MREs) thereby regulating each other. It is apparent that miRNAs act as rheostats that fine-tune gene expression and maintain the functional balance of various gene networks. Thus MREs in coding and non-coding transcripts have evolved to become the crosstalk hubs of gene interactions, affecting the expression levels and activities of different ceRNAs. Decoding the crosstalk between MREs mediated by ceRNAs is critical to delineate the intricacies in gene regulation, and we have just begun to unravel this complexity.

Intraepithelial tumor-infiltrating T cells have been correlated with improved outcomes in ovarian carcinoma, however, it is not known whether there is an association with disease stage, histological subtype, or BRCA mutation/expression. Two case series of ovarian carcinomas were included in the study; a retrospective series of 500 patients, and 40 prospectively collected cases fully characterized for BRCA1 mutation status and expression. Intraepithelial immune cells were assessed as present or absent by immunohistochemical staining of tissue microarrays. In the retrospective case series, the presence of intraepithelial CD8 þ T-cells correlated with improved disease-specific survival (P ¼ 0.027), whereas intraepithelial CD3 þ T cells did not (P ¼ 0.49). For serous ovarian carcinomas, the presence of intraepithelial CD3 þ and CD8 þ T-cells correlated with improved disease-specific survival (P ¼ 0.0016 and Pr0.0001, respectively). The presence of intraepithelial CD8 þ T cells was not associated with improved survival in endometrioid or clear cell carcinomas. On multivariate analysis, disease stage and CD8 þ T cells were found to be independently predictive of improved disease-specific survival, whereas grade, age at surgery, and type of adjuvant treatment were not. In the prospective patient cohort, intraepithelial CD8 þ T-cells correlated with the presence of mutation or loss of expression of BRCA1 through promoter methylation (P ¼ 0.019). Intraepithelial CD8 þ tumor-infiltrating T-cells correlate with improved clinical outcomes for all stages of ovarian cancer; this association is restricted to the serous ovarian cancer subtype, and is an independent prognostic factor on multivariate analysis. The presence of intraepithelial CD8 þ T cells also significantly correlates with loss of BRCA1. rates to chemotherapy and the demonstrated improvements in median overall survival, fewer than 40% of patients with advanced disease survive to 5 years. 3 Many potential molecular prognostic factors in ovarian cancer have been investigated (eg HER2, TP53). 4 Most factors were identified in small studies and have not been reproduced or independently validated, precluding clinical utility. In addition, mutations of the BRCA1 and 2 tumor suppressor genes have been associated with improved clinical outcomes 5-7 but the biologic mechanisms underlying these findings are not well understood to date.The prognostic significance of the host immune response, as defined by the presence of tumor-infiltrating lymphocytes, has been studied in ovarian

The transcription factor EGR1 is a tumor suppressor gene that is downregulated in many cancer types. Clinically, loss of EGR1 translates to increased tumor transformation and subsequent patient morbidity and mortality. In synovial sarcoma, the SS18-SSX fusion protein represses EGR1 expression through a direct association with the EGR1 promoter. However, the mechanism through which EGR1 becomes downregulated in other tumor types is unclear. Here, we report that EGR1 is regulated by microRNA (miR)-183 in multiple tumor types including synovial sarcoma, rhabdomyosarcoma (RMS), and colon cancer. Using an integrative network analysis, we identified that miR-183 is significantly overexpressed in these tumor types as well as in corresponding tumor cell lines. Bioinformatic analyses suggested that miR-183 could target EGR1 mRNA and this specific interaction was validated in vitro. miR-183 knockdown in synovial sarcoma, RMS, and colon cancer cell lines revealed deregulation of a miRNA network composed of miR-183-EGR1-PTEN in these tumors. Integrated miRNA-and mRNA-based genomic analyses indicated that miR-183 is an important contributor to cell migration in these tumor types and this result was functionally validated to be occurring via an EGR1-based mechanism. In conclusion, our findings have significant implications in the mechanisms underlying EGR1 regulation in cancers. miR-183 has a potential oncogenic role through the regulation of 2 tumor suppressor genes, EGR1 and PTEN, and the deregulation of this fundamental miRNA regulatory network may be central to many tumor types. Cancer Res; 70(23); 9570-80. Ó2010 AACR.

Synovial sarcoma is a soft tissue malignancy defined by the SYT-SSX fusion oncogene. Demonstration of the t(X;18) by cytogenetics, fluorescence in situ hybridization or reverse-transcriptase polymerase chain reaction has become the gold standard for diagnosis, but practical considerations limit the availability of these methods. Gene expression profiling studies performed by several independent groups have consistently identified TLE1 as an excellent discriminator of synovial sarcoma from other sarcomas, including histologically similar tumors such as malignant peripheral nerve sheath tumor. TLE proteins (human homologues of Groucho) are transcriptional corepressors that inhibit Wnt signaling and other cell fate determination signals, and so have an established role in repressing differentiation. We examined the expression of TLE proteins in synovial sarcoma and in a broad range of mesenchymal tumors using tissue microarrays to assess the value of anti-TLE antibodies in the immunohistochemical confirmation of synovial sarcoma. We demonstrate that TLE expression is a consistent feature of synovial sarcoma using both a well-characterized monoclonal antibody recognizing the TLE family of proteins and a commercially available polyclonal antibody raised against TLE1. Both antibodies gave intense and/or diffuse nuclear staining in 91/94 molecularly confirmed synovial sarcomas. Moderate staining is occasionally seen in schwannoma and solitary fibrous tumor/hemangiopericytoma. In contrast, TLE staining is detected much less frequently and at lower levels, if at all, in 40 other mesenchymal tumors. Our findings establish TLE as a robust immunohistochemical marker for synovial sarcoma, and may have implications for understanding the biology of synovial sarcoma and for developing experimental therapies for this cancer.

MicroRNAs (miRNAs) are B22 nucleotide-long noncoding RNAs involved in several biological processes including development, differentiation and proliferation. Recent studies suggest that knowledge of miRNA expression patterns in cancer may have substantial value for diagnostic and prognostic determinations as well as for eventual therapeutic intervention. We performed comprehensive analysis of miRNA expression profiles of 27 sarcomas, 5 normal smooth muscle and 2 normal skeletal muscle tissues using microarray technology and/or small RNA cloning approaches. The miRNA expression profiles are distinct among the tumor types as demonstrated by an unsupervised hierarchical clustering, and unique miRNA expression signatures were identified in each tumor class. Remarkably, the miRNA expression patterns suggested that two of the sarcomas had been misdiagnosed and this was confirmed by reevaluation of the tumors using histopathologic and molecular analyses. Using the cloning approach, we also identified 31 novel miRNAs or other small RNA effectors in the sarcomas and normal skeletal muscle tissues examined. Our data show that different histological types of sarcoma have distinct miRNA expression patterns, reflecting the apparent lineage and differentiation status of the tumors. The identification of unique miRNA signatures in each tumor type may indicate their role in tumorigenesis and may aid in diagnosis of soft tissue sarcomas.