John B. Little
James Stevens Simmons Professor of Radiobiology, Emeritus
The long-term goal of this research program is to gain knowledge concerning the mechanisms involved in the response of mammalian cells to ionizing radiation, with particular reference to its carcinogenic and mutagenic effects. The approach is a multifaceted one, and the endpoints under investigation include mutagenesis, malignant transformation, cell survival and the induction of chromosomal abnormalities. The program has the overall purpose of further defining the risks of low-level radiation exposure by gaining a better understanding of the cellular and molecular mechanisms for its effects.
Current research is focused on the bystander effect of radiation. This is based on the discovery made in our laboratory that damage signals may be transmitted from irradiated to non-irradiated cells in a population, leading to genetic changes such as mutations and chromosomal aberrations arising in these non-irradiated “bystander” cells. The signals are transmitted via gap junction mediated intercellular communication, and involve an upregulation of membrane signaling pathways and oxidative stress in the bystander cells. These findings could be of considerable significance in terms of the potential carcinogenic effects of very low doses of alpha radiation, such as those associated with indoor radon exposure.
M.D., 1955, Boston University School of Medicine