pp71-stimulated genes in U87 stable cells

Glioblastoma multiforme (GBM) is a highly malignant primary central nervous neoplasm characterized by tumor cell invasion, robust angiogenesis, and a mean survival of 15 months. Human cytomegalovirus (HCMV) infection is present in > 90% of GBMs, although the role the virus plays in GBM pathogenesis is unclear. We report here that a majority of human GBM tumors express HCMV pp71, which has previously been found to promote cell cycle progression and viral replication, and that pp71 is expressed preferentially within the CD133+ cancer stem cell-like subpopulation. Overexpression of pp71 in adult neural precursor cells (NPCs) resulted in a dramatic induction of stem cell factor (SCF) gene expression, which has been identified as an important pro-angiogenic factor in GBM. We further demonstrate that pp71 induces a pro-inflammatory response via NFΚB activation, which drives SCF upregulation. In summary, we show for the first time that HCMV pp71 is expressed in a majority of human GBMs and that pp71 activates NFΚB signaling, resulting in increased expression and secretion of SCF, an important paracrine modulator of GBM angiogenesis. U87 GBM cells were transduced with either pLXSN-pp71 or pLXSN empty vector retroviruses and selected with G418 for selection of stable cells. Total RNA was isolated from both cell lines and hybridized to Affymetric microarrays. The fold change in expression for all cellular genes in pp71 stable cell lines versus the empty vector control was then calculated.