Assessment of Minimal Residual Disease in Ewing Sarcoma

Advances in molecular pathology now allow for identification of rare tumor cells in cancer patients. Identification of this minimal residual disease is particularly relevant for Ewing sarcoma, given the potential for recurrence even after complete remission is achieved. Using RT-PCR to detect specific tumor-associated fusion transcripts, otherwise occult tumor cells are found in blood or bone marrow in 20–30% of Ewing sarcoma patients, and their presence is associated with inferior outcomes. Although RT-PCR has excellent sensitivity and specificity for identifying tumor cells, technical challenges may limit its widespread applicability. The use of flow cytometry to identify tumor-specific antigens is a recently described method that may circumvent these difficulties. In this manuscript, we compare the advantages and drawbacks of these approaches, present data on a third method using fluorescent in situ hybridization, and discuss issues affecting the further development of these strategies

Lack of cyclophilin D protects against the development of acute lung injury in endotoxemia.

Sepsis caused by LPS is characterized by an intense systemic inflammatory response affecting the lungs, causing acute lung injury (ALI). Dysfunction of mitochondria and the role of reactive oxygen (ROS) and nitrogen species produced by mitochondria have already been proposed in the pathogenesis of sepsis; however, the exact molecular mechanism is poorly understood. Oxidative stress induces cyclophilin D (CypD)-dependent mitochondrial permeability transition (mPT), leading to organ failure in sepsis. In previous studies mPT was inhibited by cyclosporine A which, beside CypD, inhibits cyclophilin A, B, C and calcineurin, regulating cell death and inflammatory pathways. The immunomodulatory side effects of cyclosporine A make it unfavorable in inflammatory model systems. To avoid these uncertainties in the molecular mechanism, we studied endotoxemia-induced ALI in CypD-/- mice providing unambiguous data for the pathological role of CypD-dependent mPT in ALI. Our key finding is that the loss of this essential protein improves survival rate and it can intensely ameliorate endotoxin-induced lung injury through attenuated proinflammatory cytokine release, down-regulation of redox sensitive cellular pathways such as MAPKs, Akt, and NF-kappaB and reducing the production of ROS. Functional inhibition of NF-kappaB was confirmed by decreased expression of NF-kappaB-mediated proinflammatory genes. We demonstrated that impaired mPT due to the lack of CypD reduces the severity of endotoxemia-induced lung injury suggesting that CypD specific inhibitors might have a great therapeutic potential in sepsis-induced organ failure. Our data highlight a previously unknown regulatory function of mitochondria during inflammatory response

Aberrant maturation of mutant perforin underlies the clinical diversity of hemophagocytic lymphohistiocytosis

Missense mutations in perforin, a critical effector of lymphocyte cytotoxicity, lead to a spectrum of diseases, from familial hemophagocytic lymphohistiocytosis to an increased risk of tumorigenesis. Understanding of the impact of mutations has been limited by an inability to express human perforin in vitro. We have shown, for the first time to our knowledge, that recombinant human perforin is expressed, processed appropriately, and functional in rat basophilic leukemia (RBL) cells following retroviral transduction. Subsequently, we have addressed how perforin missense mutations lead to absent perforin detection and impaired cytotoxicity by analyzing 21 missense mutations by flow cytometry, immunohistochemistry, and immunoblot. We identified perforin missense mutations with partial maturation (class 1), no apparent proteolytic maturation (class 2), and no recognizable forms of perforin (class 3). Class 1 mutations exhibit lytic function when expressed in RBL cells and are associated with residual protein detection and variable cytotoxic function in affected individuals, suggesting that carriers of class 1 alleles may exhibit more subtle immune defects. By contrast, class 3 mutations cause severely diminished perforin detection and cytotoxicity, while class 2 mutations have an intermediate phenotype. Thus, the pathologic mechanism of perforin missense mutation likely involves a protein dosage effect of the mature protein

Superficial malignant ossifying fibromyxoid tumors harboring the rare and recently described ZC3H7B‐BCOR and PHF1‐TFE3 fusions

Ossifying fibromyxoid tumor (OFMT) is a rare soft tissue neoplasm of uncertain differentiation and intermediate biologic potential. Up to 85% of OFMTs, including benign, atypical, and malignant forms, harbor fusion genes. Most commonly, the PHF1 gene localized to 6p21 is fused with EP400, but other fusion partners, such as MEAF6, EPC1, and JAZF1 have also been described. Herein, we present two rare cases of superficial OFMTs with ZC3H7B‐BCOR and the very recently described PHF1‐TFE3 fusions. The latter also exhibited moderate to strong diffuse immunoreactivity for TFE3. Reciprocally, this finding expands the entities with TFE3 rearrangements. Accumulation of additional data is necessary to determine if OFMTs harboring these rare fusions feature any reproducible clinicopathologic findings or carry prognostic and/or predictive implications

Recurrent t(2;2) and t(2;8) translocations in rhabdomyosarcoma without the canonical PAX-FOXO1 fuse PAX3 to members of the nuclear receptor transcriptional coactivator family

The fusion oncoproteins PAX3-FOXO1 [t(2;13)(q35;q14)] and PAX7-FOXO1 [t(1;13)(p36;q14)] typify alveolar rhabdomyosarcoma (ARMS); however, 20-30% of cases lack these specific translocations. In this study, cytogenetic and/or molecular characterization to include FISH, RT-PCR and sequencing analyses of five rhabdomyosarcomas [four ARMS and one embryonal rhabdomyosarcoma (ERMS)] with novel, recurrent t(2;2)(p23;q35) or t(2;8)(q35;q13) revealed that these non-canonical translocations fuse PAX3 to NCOA1 or NCOA2 respectively. The PAX3-NCOA1 and PAX3-NCOA2 transcripts encode chimeric proteins composed of the paired-box and homeodomain DNA-binding domains of PAX3, and the CID domain, the Q-rich region and the AD2 domain of NCOA1 or NCOA2. To investigate the biological function of these recurrent variant translocations, the coding regions of PAX3-NCOA1 and PAX3-NCOA2 cDNA constructs were introduced into expression vectors with tetracycline-regulated expression. Both fusion proteins showed transforming activity in the soft agar assay. Deletion of the AD2 portion of the PAX3-NCOA fusion proteins reduced the transforming activity of each chimeric protein. Similarly, but with greater impact, CID domain deletion fully abrogated the transforming activity of the chimeric protein. These studies: (1) expand our knowledge of PAX3 variant translocations in RMS with identification of a novel PAX3-NCOA2 fusion; (2) show that both PAX3-NCOA1 and PAX3-NCOA2 represent recurrent RMS rearrangements; (3) confirm the transforming activity of both translocation events and demonstrate the essentiality of intact AD2 and CID domains for optimal transforming activity; and, (5) provide alternative approaches (FISH and RT-PCR) for detecting PAX-NCOA fusions in nondividing cells of RMS. The latter could potentially be utilized as aids in diagnostically challenging cases

Usher Syndrome Type III: Revised Genomic Structure of the USH3 Gene and Identification of Novel Mutations

Usher syndrome type III is an autosomal recessive disorder characterized by progressive sensorineural hearing loss, vestibular dysfunction, and retinitis pigmentosa. The disease gene was localized to 3q25 and recently was identified by positional cloning. In the present study, we have revised the structure of the USH3 gene, including a new translation start site, 5′ untranslated region, and a transcript encoding a 232–amino acid protein. The mature form of the protein is predicted to contain three transmembrane domains and 204 residues. We have found four new disease-causing mutations, including one that appears to be relatively common in the Ashkenazi Jewish population. We have also identified mouse (chromosome 3) and rat (chromosome 2) orthologues, as well as two human paralogues on chromosomes 4 and 10