| But when the researchers exposed cells in culture to cigarette smoke, they found that the fused chromosomes were being pulled simultaneously from both directions much like a piece of taffy, forming so-called anaphase bridges between its two ends. Eventually, these chromosomes either tear apart, leaving two broken pieces, or if they don't break apart, the abnormal, elongated chromosomes may persist after anaphase is completed. Either way, a major change in the structure of the chromosomes is the end result. "Others have found the presence of anaphase bridges is correlated with chromosome instability in cancer cells. Because cigarette smoking is linked to oral, larynx, lung, bladder and esophageal cancers, our results showing that cigarette smoke can produce anaphase bridges and destabilize a cell's chromosomes have added significance," said Dr. Saunders. "The failure of the cell to accurately repair the cigarettes smoke condensate-induced double-stranded breaks probably leads to anaphase bridge formation and chromosomal instability," added Li Z. Luo, Ph.D., a graduate student in the department of biological sciences, who will present the data. According to their results, which also are detailed in an upcoming article in the journal Mutation Research, the development of anaphase bridges and chromosome instability is most likely due to reactive oxygen species that form as the cell is exposed to the various chemicals in smoke. Treating the smoke-exposed cells with different antioxidants, agents that block formation of reactive oxygen species, prevented most occurrences of anaphase bridge formation and significantly reduced genomic imbalances. "Unfortunately, no amount of scientific evidence arguing against smoking will get everyone to stop or not begin to smoke in the first place. So, perhaps one long-term goal should be to develop cigarettes that somehow prevent what we've seen happen to the cells in our lab," remarked Dr. Saunders. In addition to Drs. Luo and Saunders, other authors of the abstract and paper are Kristen M. Werner, Ph.D., a former undergraduate student in the department of biological sciences; and Susanne M. Gollin, Ph.D., professor of human genetics at the University of Pittsburgh Graduate School of Public Health and co-investigator at the Oral Cancer Center of Discovery at the University of Pittsburgh Cancer Institute. |