Harold Eliot Varmus

(b. 1939)

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(1939–) American microbiologist

Born at Oceanside, New York, Varmus was educated at Amherst College, Harvard, and at Columbia University, where he studied medicine. After working at the Presbyterian Hospital, New York (1966–68), he joined the National Institutes of Health, Bethesda, as clinical associate (1968–70) before moving to the Department of Microbiology at the University of California at San Francisco. He was appointed full professor in 1979.

In the 1970s, working in collaboration with Michael Bishop, Dominique Stehelin, and Peter Vogt, Varmus made a crucial breakthrough in our understanding of cancer. The Rous sarcoma virus, which causes cancer in chickens, was known to have a particular gene (called an ‘oncogene’) associated with its cancer-causing capability. Varmus and his colleagues prepared a molecular probe for this gene – a fragment of DNA with a base sequence complementary to the gene and capable of pairing with it – and demonstrated that the gene was present in the cells of normal chickens.

This showed for the first time that viral oncogenes are derived from genes of the virus's host, incorporated into the genetic material of the virus in a modified form. This breakthrough led to the discovery of a large number of similar cellular genes, subsequently termed ‘proto-oncogenes’, that acted as a source of oncogenes. The key to understanding how viral oncogenes transform a normal cell into a cancerous one thus lies in determining how their equivalent proto-oncogenes function in normal cells. Several roles have been elucidated for these genes, principally the regulation of cell growth, division, and differentiation. Interference or disturbance in these processes, as may occur in the presence of an oncogene, could lead to uncontrolled cell proliferation, as in cancer.

The results of Varmus's work were published in 1976 and opened the door to a major new field in cancer research. For this work Varmus and Bishop were jointly awarded the 1989 Nobel Prize for physiology or medicine.

Subjects: Science and Mathematics.

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