Inhibition of HIV-1 Tat activity correlates with down-regulation of bcl-2 and results in reduction of angiogenesis and oncogenicity

The Tat protein of the human immunodeficiency virus type 1 promotes survival and growth and inhibits apoptosis of different cell types. These effects of Tat are attributed to the induction of bcl-2 gene expression. In this study we show that the blocking of both intracellular and extracellular Tat correlates with a decrease of bcl-2 transcripts, leading in vitro to a lower growth rate and attenuation of the transformed phenotype and in vivo to a reduced angiogenic and oncogenic activity of Tat-expressing cells. These results support the notion that bcl-2 is an effector of Tat-induced angiogenesis and oncogenesis and indicate that the blocking of Tat functions by immunoprophylactic, pharmacological, and gene therapy approaches may help to control oncogenesis during AIDS.