Does dysregulated expression of a deregulated viral GPCR trigger Kaposi's sarcomagenesis?

FASEB J. 2004 Mar;18(3):422-7. doi: 10.1096/fj.03-1035hyp.

Abstract

In 1994, the Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) was identified as the etiologic agent of Kaposi's sarcoma (KS). KSHV has since been associated with two additional AIDS-related malignancies: primary effusion lymphomas (PEL) and multicentric Castleman's disease (MCD). Although molecular characterization of the KSHV genome has revealed several candidate oncogenes, infection with KSHV alone is not sufficient to cause KS, suggestive of an accomplice in KS initiation. Recent experimental evidence supports a key role for a particular KSHV gene, a constitutively-active G-protein-coupled receptor (vGPCR), in the development of KS. However, it is unclear how a lytic gene expressed in cells destined to die can cause cancer. Here we propose that dysregulation of the viral gene program may lead to nonlytic vGPCR expression. Several candidate cofactors (e.g., HIV-1 Tat, inflammation, aborted lytic cycle progression) are identified that may trigger vGPCR dysregulation, enabling oncogenic signaling pathways up-regulated by vGPCR, combined with the paracrine secretions from vGPCR-expressing cells, to promote the initiation of KS. If KS is indeed dependent on vGPCR dysregulation, then the development of new therapeutic modalities specifically targeting this viral protein or its downstream targets may ultimately prove to be the most effective treatment strategy for this enigmatic disease.

MeSH terms

  • Animals
  • Apoptosis / physiology
  • Autocrine Communication
  • Cell Transformation, Viral / genetics
  • Cell Transformation, Viral / physiology*
  • Cytokines / physiology
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / virology
  • Gene Expression Regulation, Viral*
  • Gene Products, tat / physiology
  • HIV / physiology
  • Herpesvirus 8, Human / genetics
  • Herpesvirus 8, Human / physiology*
  • Humans
  • Mice
  • Mice, Transgenic
  • Models, Biological
  • Neovascularization, Pathologic / genetics
  • Paracrine Communication
  • Receptors, Chemokine / biosynthesis
  • Receptors, Chemokine / genetics
  • Receptors, Chemokine / physiology*
  • Sarcoma, Kaposi / virology*
  • Signal Transduction
  • Vascular Endothelial Growth Factor Receptor-2 / biosynthesis
  • Vascular Endothelial Growth Factor Receptor-2 / genetics
  • Virus Latency / genetics
  • tat Gene Products, Human Immunodeficiency Virus

Substances

  • Cytokines
  • G protein-coupled receptor, Human herpesvirus 8
  • Gene Products, tat
  • Receptors, Chemokine
  • tat Gene Products, Human Immunodeficiency Virus
  • Vascular Endothelial Growth Factor Receptor-2