Maurice Stroun

In the mid 1960s, Stroun along with colleague, Philip Anker, (also in the Department of Plant Physiology at the University of Geneva) began to study the phenomenon of neoplasms in plants. Building on early grafting studies in plants as well as work by other researchers that demonstrated the transfer of genetic material between bacteria, they hypothesized that a similar phenomenon might occur between bacterial cells and plants.^[1] Their research in the late 1960s demonstrated that this process did indeed exist ^[2][3][4] and led them to study whether a similar mechanism occurred in higher-order species, where Stroun published further research showing transfer of genetic material from bacteria to frogs. In an article published in Science, November 10, 1972, bacterial RNA was demonstrated in frog brain cells after a bacterial peritoneal infection.^[5] In the April 1973 issue of the Journal of Bacteriology, Stroun showed transcription of spontaneously released bacterial DNA was found to be incorporated into cellular nuclei of frog auricles.^[6] In one particular experiment published in the same article, Stroun and his group extracted the auricles of frog hearts and dipped them for several hours in a suspension of bacteria. Afterward, they found a high percentage of RNA-DNA hybridization between bacterial DNA extracted from bacteria of the same species as that used in the experiment and titrated DNA extracted from the auricles which had been dipped in the bacterial suspension. The experiment demonstrated that bacterial DNA had been absorbed by the animal cells. Stroun dubbed this phenomenon has trancession. Professor Straun died in Geneva in 2017.

Building on their work and taking notice of the work of Henry G. Kunkel, whose group made the association of higher levels of circulating DNA and lupus,^[7][8] Stroun started studying whether circulating DNA could be associated with malignancies such as cancers in humans.^[9] In a 1977 issue of International Review of Cytology, Volume 51, Anker and Stroun wrote that when foreign DNA is transcribed into a cell of a different organism, "this general biological event is related to the uptake by cells of spontaneously released bacterial DNA, thus suggesting the existence of circulating DNA. In view of the malignant transformations obtained with DNA, the oncogenic (cancer-causing) role of circulating DNA is postulated."^[10]

In the late 1970s, building on the discovery of circulating DNA in human blood by Mandel and Metais,^[11] Leon and his collaborators developed a radioimmunoassay for measuring nanogram quantities of nucleic acids in serum. This technique enabled them to observe that cancer patients tended to possess a greater quantity of circulating DNA in serum (on average) than their healthy counterparts.^[12][13][14] This led Stroun to explore if other methods could be developed to not only detect the overall abundance of nucleic acids in patients with disease (and specifically cancer) but to also detect the disease-specific components of such circulating nucleic acids themselves. Unlike bacterial transformations in plants and animal cells involving clear transfer of separately identifiable nucleic acids, it was not clear how malignancy in cancer arose, although there were many competing theories. Stroun’s postulate that neoplastic malignancy was associated with the presence of tumor specific nucleic acids, led to extensive research by his group of circulating nucleic acids in cancer patients in the late 1980s.^[15][16]