By uncovering causes, we set the stage for cures. In fields as diverse as cancer, cystic fibrosis, and bowel disease, our researchers are finding ways to reduce the impact of disease on our patients. Gene D. Block Vice President for Research and Public Service Fighting Cancer with Retroviruses Thomas Parsons Chair of the Department of Microbiology Retroviruses have been implicated as a cause of cancer for most of this century-and indeed the relationship between retroviruses and tumors is a logical one. Inducing a host cell to multiply rapidly is an ideal strategy for an organism bent on perpetuating itself as widely as possible. The typical retrovirus genome is limited and unstable.
Viruses evolve and change form by capturing genes from host cells.
In the case of retroviruses that stimulate tumors, the genes they capture or mimic are oncogenes, or genes that cause cancer in human beings and other higher organisms. Thomas Parsons, chair of the department of microbiology, studies the Rous sarcoma virus, a classic cancer-inducing retrovirus discovered by Nobel Prize winner Peyton Rous in 1911. Thanks to natural selection, retroviruses that mimic the activities of human oncogenes make an ideal model that Parsons and his colleagues have been using to unravel this mechanism. The viral oncogene in the Rous sarcoma virus produces an enzyme called Src that modifies other proteins in the cell by a process known as phosphorylation. It is only when these proteins are phosphorylized that the cell becomes cancerous.