Can cigarette smoke and the saliva of heavy smokers influence the metabolism of cancer–inhibiting chemicals found in strawberries and expression of genes associated with oral cancer risk?

A new pilot study conducted at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James) hypothesized that they can, and initial data reveals some intriguing differences in the oral microenvironment of smokers versus non–smokers.

Researchers reported their findings at the American Association for Cancer Research (AACR) 2017 Annual Meeting.

For this study, a multidisciplinary team made up of experts in functional foods, oncology, and public health conducted an early phase clinical trial to establish the differences in salivary enzyme activities on the phytochemical components of strawberries between smokers and non–smokers. Researchers also analyzed the expression of a select group of genes associated smoking and increased risk of oral cancer.

Strawberries were administered using a novel confection designed to enhance delivery in the oral cavity to phytochemicals, including anthocyanins, the family of purple and red pigments found in fruits and vegetables.

Previous laboratory studies suggest that dietary administration of whole strawberries has substantial potential as a strategy for oral and esophageal cancer prevention.

“When people eat strawberries, they chew and swallow the fruit quickly. We wanted to develop a method of increasing exposure in the mouth to the beneficial phytochemicals that have linked with oral cancer prevention, and look for potential differences in that way the salivary enzymes in smokers versus non–smokers metabolize them.” explains study first author Jennifer Ahn–Jarvis, PhD, a postdoctoral fellow in The Ohio State Colleges of Dentistry.

To do this, Ahn–Jarvis and team designed a pilot clinical trial to analyzed the effects of an Ohio State–developed strawberry confection – a small candy with the nutritional equivalent of 2 ½ cups of whole strawberries – in a group of heavy smokers compared with an equal group of never–smokers.

Study participants were asked to consume the strawberry confection or a placebo four times a day for one week and follow a diet absent of other red and purple fruits and vegetables.

The team then collected saliva and tissue samples from inside the mouth to measure levels and activities of salivary enzymes that metabolize strawberry phytochemicals and the expression of a select panel of 44 genes associated with cigarette smoke and oral cancer risk, respectively.

Researchers observed significant differences between smokers and non–smokers in salivary enzyme activity and strawberry metabolites in the mouth following administration of the strawberry confection. They also validated seven genes (ALOX12B, CD207, HTR3A, KRT10, LOR, PNLIPRP3, TRNP1) independently associated with smokers versus non–smokers. The combination effect of smoking/strawberry exposure on oral cancer risk and its relation to gene expression remains unclear, and is currently under investigation.

“This initial data confirmed that something is very different about the oral environment of smokers which may ultimate influence not only cancer risk but also the potential effectiveness of food–based cancer prevention strategies,” adds Ahn–Jarvis. “Successful development and use of our novel confection delivery system paves the way for its use in a larger study, which will allow us to more precisely evaluate the effects of smoking and strawberries on molecular endpoints related to oral cancer development.”

Additional analysis of study data is underway to determine if there is a correlation between oral exposure time to anthocyanins and reduced oral cancer risk among smokers.