April 28, 2005
Although the DNA double helix in the cell nucleus grabs all of the attention, there is another type of genetic material in our cells. It’s the DNA of our energy-generating mitochondria, and scientists have discovered in recent years that alterations in mitochondrial DNA occur in several types of tumors linked to smoking, including head and neck cancer. Building on this earlier work, a team of NIDCR grantees and colleagues hypothesized that people with oral squamous cell carcinoma may have elevated levels of mitochondrial DNA in their saliva, and this elevation would be independent of other possible contributing factors, such as age and how often one smokes. To test this hypothesis, the scientists evaluated levels of two mitochondrial DNA genes called Cox I and Cox II in the saliva of 94 people with oral squamous cell carcinoma and 656 healthy volunteers. As reported in the April 1 issue of the journal Clinical Cancer Research, they found Cox I and Cox II levels were on average significantly higher in those with head and neck cancer, and this difference was independent of other contributory factors. The authors speculated that in the cancer patients, their primary tumors might shed their own increased levels of mitochondrial DNA into the saliva.