"Unless cadmium is unique in its mechanism," NIEHS' Dmitry A. Gordenin, Ph.D., said, "it would seem that environmental factors may cause genetic defects and cancer not only by attacking our DNA directly but also by undermining the mechanisms by which faulty DNA replication is repaired." Dr. Gordenin is the senior author on the paper which he and his colleagues report in today's online issue of the journal Nature Genetics. The report will appear in the print version of the journal in July.
A naturally present white metal, cadmium already is listed in the federal Report on Human Carcinogens as a "known human carcinogen" and has long been known to cause human lung cancer in cadmium-related industry if safeguards are not taken. The new studies, in yeast and human cells, are intended to show how this happens.
Soon after the discovery of the DNA double helix 50 years ago, studies showed environmental chemicals and stresses could cause mutations in the DNA that could result in uncontrolled cell growth, leading to cancer. But the NIEHS group's new contribution is to show that cadmium causes mutations in another way by inhibiting the ability of cells to repair routine errors made when the DNA is copied to make new cells.
Without the repairs, cells mutate "dramatically" and multiply.
The studies were done in yeast cells the living cells used to make bread rise which have proved a useful tool for studying cellular activities. Previous work has demonstrated that what happens in yeast cells generally also happens in more complex life forms, like humans. And the researchers said that their studies with extracts of human cells and initial studies in cultured huma
Contact: Bill Grigg
NIH/National Institute of Environmental Health Sciences