title: Gene regulation and functional alterations induced by Kaposi's sarcoma-associated herpesvirus-encoded ORFK13/vFLIP in endothelial cells.
abstract: Kaposi's sarcoma (KS) is an angioproliferative inflammatory disorder induced by endothelial cell infection with the KS-associated herpesvirus (KSHV). ORFK13/vFLIP, one of the KSHV genes expressed in KS, encodes a 188-amino-acid protein which binds to the Ikappab kinase (IKK) complex to activate NF-kappaB. We examined ORFK13/vFLIP contribution to KS phenotype and potential for therapeutic targeting. Retroviral transduction of ORFK13/vFLIP into primary human endothelial cells induces the spindle morphology distinctive of KS cells and promotes the formation of abnormal vascular networks typical of KS vasculature; upregulates the expression of proinflammatory cytokines, chemokines, and interferon-responsive genes; and stimulates the adhesion of inflammatory cells characteristic of KS lesions. Thymidine phosphorylase, a cellular enzyme markedly induced by ORFK13/vFLIP, can metabolize the prodrug 5-fluoro-5-deoxyuridine (5-dFUrd) to 5-fluouridine (5-FU), a potent thymidine synthase inhibitor, which blocks DNA and RNA synthesis. When tested for cytotoxicity, 5-dFUrd (0.1 to 1 microM) selectively killed ORFK13/vFLIP-expressing endothelial cells while sparing control cells. These results demonstrate that ORFK13/vFLIP directly and indirectly contributes to the inflammatory and vascular phenotype of KS and identify 5-dFUrd as a potential new drug that targets KSHV latency for the treatment of KS and other KSHV-associated malignancies.
authors.affiliation: Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 4134, Bethesda, MD 20892, USA. sakakibs@mail.nih.gov
authors.forename: Shuhei
authors.initials: S
authors.lastname: Sakakibara
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Pise-Masison
authors.forename: John N
authors.initials: JN
authors.lastname: Brady
authors.forename: Giovanna
authors.initials: G
authors.lastname: Tosato
mesh_terms: D048430:Cell Shape; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000821:virology*; D005786:Gene Expression Regulation; D019288:Herpesvirus 8, Human / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D012514:Sarcoma, Kaposi / Q000235:genetics* / Q000821:virology; D014161:Transduction, Genetic; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D014764:Viral Proteins; C481275:viral FLIP protein, Human herpesvirus 8