MED12 Alterations in Both Human Benign and Malignant Uterine Soft Tissue Tumors

The relationship between benign uterine leiomyomas and their malignant counterparts, i.e. leiomyosarcomas and smooth muscle tumors of uncertain malignant potential (STUMP), is still poorly understood. The idea that a leiomyosarcoma could derive from a leiomyoma is still controversial. Recently MED12 mutations have been reported in uterine leiomyomas. In this study we asked whether such mutations could also be involved in leiomyosarcomas and STUMP oncogenesis. For this purpose we examined 33 uterine mesenchymal tumors by sequencing the hot-spot mutation region of MED12. We determined that MED12 is altered in 66.6% of typical leiomyomas as previously reported but also in 11% of STUMP and 20% of leiomyosarcomas. The mutated allele is predominantly expressed in leiomyomas and STUMP. Interestingly all classical leiomyomas exhibit MED12 protein expression while 40% of atypical leiomyomas, 50% of STUMP and 80% of leiomyosarcomas (among them the two mutated ones) do not express MED12. All these tumors without protein expression exhibit complex genomic profiles. No mutations and no expression loss were identified in an additional series of 38 non-uterine leiomyosarcomas. MED12 mutations are not exclusive to leiomyomas but seem to be specific to uterine malignancies. A previous study has suggested that MED12 mutations in leiomyomas could lead to Wnt/β-catenin pathway activation however our immunohistochemistry results show that there is no association between MED12 status and β-catenin nuclear/cytoplasmic localization. Collectively, our results show that subgroups of benign and malignant tumors share a common genetics. We propose here that MED12 alterations could be implicated in the development of smooth muscle tumor and that its expression could be inhibited in malignant tumors

ETV4 is a useful marker for the diagnosis of CIC-rearranged undifferentiated round-cell sarcomas: a study of 127 cases including mimicking lesions

International audienceSubsets of primitive round-cell sarcomas remain difficult to diagnose and classify. Among these is a rare round-cell sarcoma that harbors a CIC gene rearrangement known as CIC-rearranged undifferentiated round-cell sarcoma, which is most commonly fused to the DUX4 gene. Owing to its aggressive clinical behavior and potential therapeutic implications, accurate identification of this novel soft tissue sarcoma is necessary. Definitive diagnosis requires molecular confirmation, but only a few centers are as yet able to perform this test. Several studies have shown that PEA3 subfamily genes, notably ETV4 (belonging to the family of ETS transcription factors), are upregulated in CIC-rearranged undifferentiated round-cell sarcomas. We performed a detailed immunohistochemical analysis to investigate ETV4 expression in CIC-rearranged undifferentiated round-cell sarcomas and their potential mimics (especially Ewing sarcomas). The study cohort included 17 cases of CIC-rearranged undifferentiated round-cell sarcomas, and 110 tumors that morphologically mimic CIC-rearranged undifferentiated round-cell sarcomas: 43 Ewing sarcomas, 25 alveolar rhabdomyosarcomas, 20 poorly differentiated round-cell synovial sarcomas, 10 desmoplastic round-cell tumors, 5 BCOR-CCNB3 sarcomas, 5 lymphoblastic lymphomas, and 2 rhabdoid tumors. All CIC-rearranged undifferentiated round-cell sarcomas (on core needle biopsies and open biopsies) were ETV4-positive with a strong diffuse nuclear pattern. Among the other 110 tumors, only six cases (four Ewing sarcomas, one alveolar rhabdomyosarcoma, and one desmoplastic round-cell tumor) showed focal (o5% of tumor cells) and very weak nuclear expression of ETV4; all other tumors were completely negative for ETV4. We conclude that systematic immunohistochemical analysis of ETV4 makes it possible to diagnose undifferentiated round-cell sarcomas (with no molecular markers for sarcoma-associated translocation) such as CIC-rearranged undifferentiated round-cell sarcoma

Tetraploidization of Immortalized Myoblasts Induced by Cell Fusion Drives Myogenic Sarcoma Development with DMD Deletion

Whole-genome doubling is the second most frequent genomic event, after TP53 alterations, in advanced solid tumors and is associated with poor prognosis. Tetraploidization step will lead to aneuploidy and chromosomic rearrangements. The mechanism leading to tetraploid cells is important since endoreplication, abortive cytokinesis and cell fusion could have distinct consequences. Unlike processes based on duplication, cell fusion involves the merging of two different genomes, epigenomes and cellular states. Since it is involved in muscle differentiation, we hypothesized that it could play a role in the oncogenesis of myogenic cancers. Spontaneous hybrids, but not their non-fused immortalized myoblast counterparts they are generated from, induced tumors in mice. Unstable upon fusion, the hybrid genome evolved from initial mitosis to tumors with a highly rearranged genome. This genome remodeling finally produced targeted DMD deletions associated with replicative stress, isoform relocalization and metastatic spreading, exactly as observed in human myogenic sarcomas. In conclusion, these results draw a model of myogenic oncogenesis in which cell fusion and oncogene activation combine to produce pleomorphic aggressive sarcomas

Identification of a recurrent STRN/ALK fusion in thyroid carcinomas.

Thyroid carcinoma is the most common endocrine malignant tumor and accounts for 1% of all new malignant diseases. Among all types and subtypes of thyroid cancers that have been described so far, papillary thyroid carcinoma is the most frequent. The standard management treatment of these tumors consists of surgery, followed by radioiodine treatment in case of high risk of relapse. The most aggressive forms are commonly treated by chemotherapy, radiotherapy or experimental drug testing. We recently reported the case of a patient presenting an anaplastic thyroid carcinoma with lung metastases. Fluorescence in situ hybridization analysis allowed us to detect a rearrangement of the anaplastic lymphoma kinase (ALK) gene in both tumors. The patient was treated with crizotinib and presented an excellent drug response. We present here the subsequent investigations carried out to further characterize this genetic alteration and to assess the prevalence of ALK rearrangements in thyroid lesions. High resolution array-comparative genomic hybridization data complemented by RT-PCR and sequencing analyses, allowed us to demonstrate the presence of a STRN/ALK fusion. The STRN/ALK transcript consisted of the fusion between exon 3 of STRN and exon 20 of ALK. Subsequent screening of 75 various thyroid tumors by RT-PCR revealed that 2 out of 29 papillary thyroid carcinomas exhibited the same fusion transcript. None was detected in other types of malignant or benign thyroid lesions analyzed. These findings could pave the way for the development of new targeted therapeutic strategies in the treatment of papillary thyroid carcinomas and point to ALK inhibitors as promising agents that merit rapid evaluation

RCBTB1 Deletion Is Associated with Metastatic Outcome and Contributes to Docetaxel Resistance in Nontranslocation-Related Pleomorphic Sarcomas

Half of soft-tissue sarcomas are tumors with complex genomics, which display no specific genetic alterations and respond poorly to treatment. It is therefore necessary to find new therapeutic targets for these sarcomas. Despite genetic heterogeneity across samples, oncogenesis may be driven by common pathway alterations. Therefore, genomic and transcriptomic profiles of 106 sarcomas with complex genomics were analyzed to identify common pathways with altered genes. This brought out a gene belonging to the “cell cycle” biological pathway, RCBTB1 (RCC1 And BTB Domain Containing Protein 1), which is lost and downregulated in 62.5% of metastatic tumors against 34% of non-metastatic tumors. A retrospective study of three sarcoma cohorts revealed that low RCBTB1 expression is prognostic for metastatic progression, specifically in patients that received chemotherapy. In vitro and in vivo, RCBTB1 overexpression in leiomyosarcoma cells specifically sensitized to docetaxel-induced apoptosis. This was associated with increased mitotic rate in vitro and higher growth rate of xenografts. By contrast, RCBTB1 inhibition decreased cell proliferation and protected sarcoma cells from apoptosis induced by docetaxel. Collectively, these data evidenced that RCBTB1 is frequently deleted in sarcomas with complex genomics and that its downregulation is associated with a higher risk of developing metastasis for patients receiving chemotherapy, likely due to their higher resistance to docetaxel

Recurrent \textitTRIO Fusion in Nontranslocation\textendashRelated Sarcomas

International audienc

Chromosome Instability Accounts for Reverse Metastatic Outcomes of Pediatric and Adult Synovial Sarcomas

PURPOSESynovial sarcoma (SS) occurs in both children and adults, although metastatic events are much more common in adults. Whereas the importance of the t(X;18) translocation in SS oncogenesis is well established, the genetic basis of SS metastasis is still poorly understood. We recently reported expression (CINSARC; Complexity Index in Sarcoma) and Genomic Index prognostic signatures related to chromosome integrity in sarcomas and GI stromal tumors. Here we investigate whether these signatures can also predict outcomes in SS.Patients And methodsOne hundred patients who had primary untreated SS tumors were selected for expression and genomic profiling in a training/validation approach.ResultsCINSARC and Genomic Index have strong independent and validated prognostic values (P < .001). By comparing expression profiles of tumors with or without metastasis, 14 genes that are common to the CINSARC signature were identified, and the two top-ranked genes, KIF14 and CDCA2, were validated as prognostic markers in an independent cohort. Comparing genomic profiles of adult versus pediatric SS, we show that metastasis is associated with genome complexity in both situations and that the adult genome is more frequently rearranged. Accordingly, pediatric patients with an even genomic profile do not develop metastasis. CONCLUSIONMetastasis development in SS is strongly associated with chromosome complexity, and CINSARC and Genomic Index are validated independent prognostic factors. The differences in metastasis frequency between adults and children are associated with genome instability, which is much more frequent in adults. Genomic Index is potentially the best overall biomarker and clearly the most clinically relevant, considering that genome profiling from formalin-fixed samples is already used in pathology.status: publishe

ALK Interphase fluorescence <i>in situ</i> hybridization and immunohistochemistry.

<p>(A) On the representative picture of the FISH, realized using the LSI ALK Dual Color Break Apart Rearrangement Probe, we could observe <i>ALK</i> probe break-aparts highlighted by arrows in the two positive PTC cases. Magnification: X1000. (B) Pictures of immunohistochemical labeling for ALK in the two PTC samples. Pictures of hematoxylin, eosin and safran (HES) staining of the two samples are also presented. Magnification for HES: X200, Magnification for IHC: X400.</p

<i>ALK</i>, <i>STRN</i> and <i>STRN/ALK</i> fusion status at mRNA and genomic DNA levels in positive PTC.

<p>(A) Expression profiles of <i>ALK</i>, <i>STRN</i> and <i>STRN/ALK</i> fusion transcript obtained by RT-PCR in two PTC samples and in one control sample (C1) are presented. L: molecular weight ladder, bp: base-pair. (B) Chromatogram showing the sequence of <i>STRN/ALK</i> fusion transcript at the breakpoint observed in the two PTC samples. The <i>STRN</i> exon 3 (NM_003162) at the 5′ part of the transcript is fused to the <i>ALK</i> exon 20 (NM_004304) at the 3′ portion. (C) Products obtained after PCR on genomic DNA using first <i>ALK</i> and <i>STRN</i> forward and reverse primers and then the combination of a <i>STRN</i> forward primer with an <i>ALK</i> reverse primer for case 5 and one control sample (C1). (D) Chromatogram showing the sequence of <i>STRN/ALK</i> fusion at the genomic breakpoint observed in the case 5. One nucleotide at the intronic junction (C) is identical in both fused genes and might be contributed by either of them.</p

Genomic profile.

<p>(A) CGH profile obtained from a pulmonary metastasis of the initial case. Genomic alterations are presented and organized on the X axis from chromosome 1 to 22 and X, Y. Log2 ratio values are reported on the Y axis. Significant gains or losses are indicated by blue lines and blue areas above or below each profile, respectively. Chromosome 2 is highlighted with a black box. (B) Enlargements of chromosome 2 and <i>ALK</i> chromosomal region. The chromosome 2 region containing <i>ALK</i> locus is highlighted with a black box. The log2 ratio values of probes covering the proximal regions of <i>ALK</i> and the gene itself are presented. The arrow indicates the breakage region. (C) Enlargements of chromosome 2 and <i>STRN</i> chromosomal region. The chromosome 2 region containing <i>STRN</i> locus is highlighted with a black box. The log2 ratio values of probes covering the proximal regions of <i>STRN</i> and the gene itself are presented. The arrow indicates the breakage region. (D) Schematic representation of potential breakpoints into the two genes at the genomic level (gDNA) according to the CGH data. Agilent CGH probes surrounding the different breakpoints are indicated.</p