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.

Variation in gene coding sequence represents a significant factor in predisposition to disease, including cancer. Variants of some DNA repair genes (e.g. MLH1, MSH2 and MSH6) are known to predispose to cancer. We identified single nucleotide polymorphisms (SNPs) in five DNA repair genes in 142 healthy individuals using a DNA sequencing protocol optimized for the direct detection of single nucleotide polymorphisms. This approach, called the heterozygote sequencing protocol (HSP), enables moderate-scale population surveys of SNPs. HSP uses fluorescently tagged primers and exploits the large dynamic range and low background of automated fluorescent sequencing. HSP may be used for any sequence that can be amplified by PCR. A total of 12 SNP variants in MGMT, ERCC1, CDK7, CCNH and XRCC4 were identified, 11 at polymorphic frequencies, with an average frequency of 0.22 (95% confidence interval 0.20-0.24). Among the 82 individuals for whom complete SNP profiles were available, no one person carried the GenBank reference sequence for all five genes. The extensive heterogeneity observed in these five genes is intriguing. All variants are in Hardy-Weinberg equilibrium, although the meaning of this equilibrium is unclear. Using this approach, possible associations of sequence variation, and hence of variation in DNA repair, with disease risk can be assessed.

ERCC1 plays an essential role in the nucleotide excision repair (NER) of DNA. We compare 37 kb of sequence from the ERCC1 region on human chromosome 19q13.3 to the orthologous region on mouse chromosome 7. In addition to showing the conserved gene structure between ERCC1, ASE-1, and their murine counterparts, this genomic comparison reveals a highly conserved 497 bp segment found 5 kb upstream of ERCC1 exon 1 that contains a CpG island and previously unidentified "classical" promoter elements. Additional putative regulatory elements are also found within a conserved LINE-1 (long interspersed nuclear element) sequence 800 bp upstream of exon 1 in both human and mouse. Expressed sequence tag (EST) assemblies for human ERCC1 identified numerous splice variants involving exons 1, 2, 3, 7, 8, and 9 that could affect DNA repair efficiencies of ERCC1. A previously undescribed transcript that reads through exon 9 and utilizes the polyadenylation signal of a neighboring Alu element accounts for nearly half of the total splice variants identified in the human EST database. This transcript would theoretically translate to a larger ERCC1 protein product containing a novel C-terminal end. Overall, approximately 18% of publicly available ERCC1 cDNA sequences were determined to be splice variants, while no variants were found in the mouse. The ability to assess novel transcripts and identify candidate regulatory regions demonstrates the potential utility for a catalogue archiving comparative analyses for all genes involved in DNA repair. Our comparative genomic analysis of ERCC1 can be viewed at http://web.uvic.ca/-bioweb/laj.html.

In preclinical studies, mesenchymal stromal cells (MSCs) exhibit robust potential for numerous applications. To capitalize on these benefits, cell manufacturing and delivery protocols have been scaled up to facilitate clinical trials without adequately addressing the impact of these processes on cell utility nor inevitable regulatory requirements for consistency. Growing evidence indicates that culture‐aged MSCs, expanded to the limits of replicative exhaustion to generate human doses, are not equivalent to early passage cells, and their use may underpin reportedly underwhelming or inconsistent clinical outcomes. Here, we sought to define the maximum expansion boundaries for human umbilical cord‐derived MSCs, cultured in chemically defined xeno‐ and serum‐free media, that yield consistent cell batches comparable to early passage cells. Two male and two female donor populations, recovered from cryostorage at mean population doubling level (mPDL) 10, were serially cultivated until replicative exhaustion (senescence). At each passage, growth kinetics, cell morphology, and transcriptome profiles were analyzed. All MSC populations displayed comparable growth trajectories through passage 9 (P9; mPDL 45) and variably approached senescence after P10 (mPDL 49). Transcription profiles of 14,500 human genes, generated by microarray, revealed a nonlinear evolution of culture‐adapted MSCs. Significant expression changes occurred only after P5 (mPDL 27) and accumulated rapidly after P9 (mPDL 45), preceding other cell aging metrics. We report that cryobanked umbilical cord‐derived MSCs can be reliably expanded to clinical human doses by P4 (mPDL 23), before significant transcriptome drift, and thus represent a mesenchymal cell source suited for clinical translation of cellular therapies. Stem Cells Translational Medicine 2019;8:945&958

No abstract