The comet assay: A sensitive method for detecting DNA damage in individual cells

The comet assay is a sensitive and rapid method for DNA strand break detection in individual cells, and the year 2009 represents the 25th anniversary of the first description of this methodology in 1984. Over time this method has been improved, but is still not completely standardized, and variations are currently in widespread use with emphasis on applications in research and genetic toxicology. Here we review the principles of the comet assay and cite key studies that have focused on this assay in the past 25 years. In addition, we present an example of how the comet assay was used in our laboratory for studying the induction of DNA damage in human lung cancer cells after differing doses of the cytosine analog 5-aza-2′-deoxycytidine (5-aza-CdR). Finally, some insights into the potential of this assay in cancer research and work in related fields are offered.