Background: Human herpesvirus 8 (HHV-8) has been implicated in the etiology of Kaposi's sarcoma (KS), a highly angiogenic tumor of complex histology, and two lymphoproliferative diseases, primary effusion lymphoma (PEL) and multicentric Castleman's disease (MCD). A number of HHV-8 encoded genes have been proposed to be involved in the pathogenesis of KS and PEL and a few have been shown to be oncogenic in heterologous systems (Reyes GR, LaFemina R, Hayward SD, Hayward GS. Morphological transformation by DNA fragments of human herpesviruses: evidence for two distinct transforming regions in herpes simplex virus types 1 and 2 and lack of correlation with biochemical transfer of the thymidine kinase gene. Cold Spring Harbor Symp Quant Biol 1980;44:629-641; Moore PS, Boshoff C, Weiss RA, Chang Y. Molecular mimicry of human cytokine and cytokine response pathway genes by KSHV. Science 1996;274:1739-1744; Cheng EH, Nicholas J, Bellows DS, Hayward GS, Guo HG, Reitz MS, Hardwick JM. A Bcl-2 homolog encoded by Kaposi sarcoma-associated virus, human herpesvirus 8, inhibits apoptosis but does not heterodimerize with Bax or Bak. Proc Natl Acad Sci USA 1997;94:690-694; Li M, Lee H, Yoon DW, Albrecht JC, Fleckenstein B, Neipel F, Jung JU. Kaposi's sarcoma-associated herpesvirus encodes a functional cyclin. J Virol 1997;71:1984-1991; Neipel F, Albrecht J-C, Fleckenstein B. Cell-homologous genes In the Kaposi's sarcoma-associated rhadinovirus human herpesvirus 8: determinants of its pathogenicity? J Virol 1997;71:4187-4192; Nicholas J, Ruvolo VR, Burns WH, Sandford G, Wan X, Ciufo D, Hendrickson SB, Guo HG, Hayward GS, Reitz MS. Kaposi's sarcoma-associated human herpesvirus-8 encodes homologues of macrophage inflammatory protein-1 and interleukin-6. Nat Med 1997;3:287-292; Nicholas J, Zong J, Alcendor DJ, Ciufu DM, Poole LJ, Sarisky RT, Chiuo C, Zhang X, Wan X, Guo H, Reitz MS, Hayward GS. Novel organizational features, captured cellular genes, and strain variability within the genome of KSHV/HHV-8. JNCI Monographs 1998;23:79-88; Muralidhar S, Pumfery AM, Hassani M, Sadaie MR, Azumi N, Kishishita M, Brady JN, Doniger J, Medveczky P, Rosenthal LJ. Identification of kaposin (ORF K12) as a human herpesvirus 8 (Kaposi's sarcoma associated herpesvirus) transforming gene. J Virol 1998;72:4980-4988). The kaposin gene (ORF K12) encoded by the abundant latency-associated HHV-8 transcript, T0.7, has been previously shown to induce tumorigenic transformation of Rat-3 cells (Muralidhar S, Pumfery AM, Hassani M, Sadaie MR, Azumi N, Kishishita M, Brady JN, Doniger J, Medveczky P, Rosenthal LJ. Identification of kaposin (ORF K12) as a human herpesvirus 8 (Kaposi's sarcoma associated herpesvirus) transforming gene. J Virol 1998;72:4980-4988). The current study is a further characterization of kaposin protein.
Objectives: Characterization of kaposin expression in transformed and tumor-derived Rat-3 cells as well as PEL cell lines, BCBL-1, BC-3 and KS-1 and analysis of mechanism(s) of transformation.
Design: The presence of kaposin DNA in transformed cells was determined by fluorescent in situ hybridization (FISH). Expression of kaposin protein was analyzed by Western blot analysis and indirect immunofluorescence assay (IFA). (ABSTRACT TRUNCATED)