Versican G1 domain enhances adenoviral-mediated transgene expression and can be modulated by inhibitors of the Janus kinase (JAK)/STAT and Src family kinase pathways.

To examine the biochemical influences that may contribute to the success of gene therapy for ocular disorders, the role of versican, a vitreous component, in adenoviral-mediated transgene expression was examined. Versican is a large chondroitin sulfate-containing, hyaluronic acid-binding proteoglycan present in the extracellular matrix and in ocular vitreous body. Y79 retinoblastoma cells and CD44-negative SK-N-DZ neuroblastoma cells transduced with adenoviral vectors in the presence of versican respond with an activation of transgene expression. Proteolysis of versican generates a hyaluronan-binding G1 domain. The addition of recombinant versican G1 to SK-N-DZ cells results in a similar activation of transgene expression, and treatment with dasatinib, an inhibitor of Src family kinases, also mimics the effects of versican. Enhancement is accompanied by an increase in signal transducer and activator of transcription 5 (STAT5) phosphorylation and is abrogated by treatment with C188-9, a STAT3/5 inhibitor, or with ruxolitinib, a Janus kinase 1/2 (JAK1/2) inhibitor. These data implicate versican G1 in enhancing adenoviral vector transgene expression in a hyaluronic acid-CD44 independent manner that is down-regulated by inhibitors of the JAK/STAT pathway and enhanced by inhibitors of the Src kinase pathway.

Late Presentation of Retinoblastoma in a Teen with Aicardi Syndrome.

BACKGROUND/AIMS: Retinoblastoma (Rb) generally presents in children <8 years of age. Aicardi syndrome (AS) is a congenital, neurodevelopmental disorder that has been associated with various ophthalmic abnormalities, but no reports have related it to a delayed presentation of Rb. This report describes the late presentation of Rb in a teenage patient with AS and suggests modifications in ophthalmic screening to facilitate early detection. METHODS: A chart review was conducted of a patient with AS. We examined the ophthalmic history, fundus images and B-scan ultrasonography. Histopathological analysis was conducted on globe sections. RESULTS: The patient's ophthalmic history was consistent with normal findings of AS: fundus images and B-scan ultrasonography revealed chorioretinal lacunae and an area of retinal detachment, respectively. The patient presented with chronic irritation and mydriasis of the blind left eye. This was enucleated as treatment. Histopathology revealed a focally differentiated Rb. Immunohistochemistry demonstrated that the tumor cells were positive for synaptophysin and negative for the wild-type Rb protein, and a high Ki-67 proliferation index was shown. CONCLUSION: Our patient was diagnosed with Rb at age 16. AS has been associated with numerous ophthalmic findings, but this is the first report relating it to a late Rb presentation. Meticulous ophthalmic examinations should be considered through the teenage years and early adulthood of AS patients.

Tumorspheres but not adherent cells derived from retinoblastoma tumors are of malignant origin.

Verification that cell lines used for cancer research are derived from malignant cells in primary tumors is imperative to avoid invalidation of study results. Retinoblastoma is a childhood ocular tumor that develops from loss of functional retinoblastoma protein (pRb) as a result of genetic or epigenetic changes that affect both alleles of the RB1 gene. These patients contain unique identifiable genetic signatures specifically present in malignant cells. Primary cultures derived from retinoblastoma tumors can be established as non-adherent tumorspheres when grown in defined media or as attached monolayers when grown in serum-containing media. While the RB1 genotypes of tumorspheres match those of the primary tumor, adherent cultures have the germline RB1 genotype. Tumorspheres derived from pRb-negative tumors do not express pRb and express the neuroendocrine tumor markers synaptophysin and microtubule-associated protein 2 (MAP2). Adherent cells are synaptophysin-negative and express pRb, the epithelial cell marker cytokeratin that is expressed in the retinal pigmented epithelium and the vascular endothelial cell marker CD34. While tumorspheres are of malignant origin, our results cast doubt on the assumption that adherent tumor-derived cultures are always valid in vitro models of malignant cells and emphasize the need for validation of primary tumor cultures.

A small-molecule inhibitor targeting the mitotic spindle checkpoint impairs the growth of uterine leiomyosarcoma.

PURPOSE: Uterine leiomyosarcoma (ULMS) is a poorly understood cancer with few effective treatments. This study explores the molecular events involved in ULMS with the goal of developing novel therapeutic strategies. EXPERIMENTAL DESIGN: Genome-wide transcriptional profiling, Western blotting, and real-time PCR were used to compare specimens of myometrium, leiomyoma, and leiomyosarcoma. Aurora A kinase was targeted in cell lines derived from metastatic ULMS using siRNA or MK-5108, a highly specific small-molecule inhibitor. An orthotopic model was used to evaluate the ability of MK-5108 to inhibit ULMS growth in vivo. RESULTS: We found that 26 of 50 gene products most overexpressed in ULMS regulate mitotic centrosome and spindle functions. These include UBE2C, Aurora A and B kinase, TPX2, and Polo-like kinase 1 (PLK1). Targeting Aurora A inhibited proliferation and induced apoptosis in LEIO285, LEIO505, and SK-LMS1, regardless of whether siRNA or MK-5108 was used. In vitro, MK-5108 did not consistently synergize with gemcitabine or docetaxel. Gavage of an orthotopic ULMS model with MK-5108 at 30 or 60 mg/kg decreased the number and size of tumor implants compared with sham-fed controls. Oral MK-5108 also decreased the rate of proliferation, increased intratumoral apoptosis, and increased expression of phospho-histone H3 in ULMS xenografts. CONCLUSIONS: Our results show that dysregulated centrosome function and spindle assembly are a robust feature of ULMS that can be targeted to slow its growth both in vitro and in vivo. These observations identify novel directions that can be potentially used to improve clinical outcomes for this disease.