Picking the Right Spot

摘要

It has been almost a hundred years since retroviruses first came into the spotlight following the discovery that some tumors are transmissible (1). Although retroviruses can cause cancer through the transfer of oncogenes, in many cases, cell transformation results instead from a phenomenon known as insertional mutagenesis. A hallmark of retroviral replication is the reverse transcription of the viral RNA genome into a DNA copy that becomes integrated into the host cell genome. This recombination event forever links the fates of the invading retro-virus and its target cell, and is one reason why retroviruses are attractive as vectors for gene therapy. However, when transcriptional elements contained in the retrovirus activate a nearby growth-stimulating gene through effects on either the gene promoter or enhancer, a threshold is crossed that can lead to malignant transformation.