Presentation Speech by Professor Erling Norrby of the Karolinska Institute

Translation from the Swedish text

Your Majesties, Your Royal Highnesses, Ladies and Gentlemen.

Our body is composed of independent living entities, which we call cells. The number of cells in a single individual is about 1000 times larger than the number of all individuals on this planet. Still, all these cells can interact in a remarkably controlled fashion. The orchestration of this interaction is one of the great wonders of biology.

When we cut one of our fingers, wound-healing is initiated. By a marvellously controlled process of cell division, the skin and neighboring tissues at the wound are restored to their original condition. The discovery which is being honored with this year’s Nobel Prize in Physiology or Medicine has given us completely new insights into the mechanisms that control cell growth and division. However, this discovery was not made by studying the balanced growth of normal cells, but through investigations of a virus which causes tumors in chickens.

In 1966, Peyton Rous was awarded the Nobel prize in Physiology or Medicine for his discovery 55 years earlier of a tumor-inducing virus, which was later named after him. It was known in the mid-1970s that the Rous virus has a separate part of its genetic material – a gene – which determines whether tumors occur. This gene is not required for virus replication. This year’s prize-winners, Michael Bishop and Harold Varmus, and their collaborators managed to develop a molecular probe, which could selectively identify the tumor-inducing gene in the Rous virus. By use of this probe it was demonstrated that the critical gene was present in normal cells from all species. To their own great surprise and that of the scientific community, they had to draw the conclusion that the tumor-inducing gene in the Rous virus was of cellular origin. Does this mean that we are carrying cancer genes in our cells? Obviously not. However, in our cells there is a family of probably several hundred genes which are old in evolutionary terms and which control the normal growth and division of cells. Disruptions in the functioning of one or more of these genes can cause one cell to slip out of the network of growth control. The cell runs amok and a tumor may be the result.

As so often in medical research, we gained new insights into the normal functioning of a biological system through studies of the unbalanced state. The abnormal is the mirror image of the normal, or to quote the 19th century Swedish poet Erik Johan Stagnelius, “chaos is the neighbor of God”. Since the family of growth-controlling genes, of which we have now identified more than 60, was demonstrated in tumor cells, they were given the somewhat illogical name oncogenes. This name derives from the Greek term onkos meaning tumor. Our knowledge of the proteins synthesized under the direction of oncogenes has given us broad insights into the complicated growth-controlling signal systems in cells. These signal chains include growth factors, receptors for these factors on the cell surface, substances which transmit signals from the cell surface into the genetic material in the cell nucleus, and finally, substances which directly influence the genetic material.

Cancer originates in disturbances in the genetic material of cells. Yet in most cases a single disturbance is not sufficient, but instead an accumulation of several critical injuries is required. This is the reason why cancers usually occur relatively late in life. Abnormally functioning oncogenes have now been demonstrated in many types of tumors in man. For the first time we are beginning to comprehend the complicated mechanisms behind the development of this group of diseases. New opportunities for diagnosis and treatment of various forms of cancer are now becoming available.

Michael Bishop and Harold Varmus,

Through your discovery of the cellular origin of retroviral oncogenes you set in motion an avalanche of research on factors that govern the normal growth of cells. This research has given us a new perspective on one of the most fundamental phenomena in biology and as a consequence also new insights into the complex group of diseases that we call cancer. On behalf of the Nobel Assembly of the Karolinska Institute I would like to convey to you our warmest congratulations and I now ask you to step forward to receive your Nobel Prizes from the hands of His Majesty the King.