Ionising radiation can cause cells to turn cancerous

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IT is well established that exposure to ionizing radiation can result in mutations or other genetic damage that cause cells to turn cancerous. Now a new study led by researchers with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has revealed another way in which radiation can promote cancer development.
Working with cultures of human breast cells, the researchers discovered that radiation exposure can alter the environment surrounding the cells so that future cells are more likely to become cancerous.
“Our work shows that radiation can change the microenvironment of breast cells, and this in turn can allow the growth of abnormal cells with a long-lived phenotype that has a much greater potential to be cancerous,” says Paul Yaswen, a cell biologist and breast cancer research specialist with Berkeley Lab’s Life Sciences Division. A cell’s phenotype is its full complement of observable physical or biochemical characteristics. Different cells can have phenotypes that look dramatically different or exhibit radically different behaviour even though their genetic makeup (genotype) is identical.
Signals from outside the cell can alter a cell’s phenotype by regulating (or de-regulating) the cell’s use of its genes. Studies have shown that if a cell develops a pre-cancerous phenotype, it can pass on these “epigenetic” changes to its daughters, just as it can pass on genetic mutations.
“Many in the cancer research community, especially radiobiologists, have been slow to acknowledge and incorporate in their work the idea that cells in human tissues are not independent entities, but are highly communicative with each other and with their microenvironment,” Yaswen says. “We provide new evidence that potential cancer agents and their effects must be evaluated at a systems level.”
Yaswen is the corresponding author of a paper describing this study that appears in the on-line journal Breast Cancer Research. Co-authoring the paper were Rituparna Mukhopadhyay, Sylvain Costes, Alexey Bazarov, William Hines and Mary Helen Barcellos-Hoff.
“The work we did was performed with non-lethal but fairly substantial doses of radiation, unlike what a woman would be exposed to during a routine mammogram,” says Yaswen, who is also a member of the Bay Area Breast Cancer and the Environment Research Center. “However, the levels of radiation involved in other procedures, such as CT scans or radiotherapy, do start to approach the levels used in our experiments and could represent sources of concern.”