Spit Diagnostics

The Salivary Proteome Knowledge Base

If spit could talk, it might tell us whether we’re sick or healthy.


According to David Wong, DMD, DMSc—professor and associate dean of research at the School of Dentistry at the University of California, Los Angeles—the protein profile in our saliva might distinguish a person with oral cancer or breast cancer from one who has neither disease. That’s why the National Institute of Dental and Craniofacial Research last fall funded grants to Wong’s group and two others who will identify all of the proteins in human saliva.


Because spit can be collected non-invasively, Wong says, it is ideal for diagnostic testing. But there’s a hitch: “Saliva contains all the information we know is in blood, but at much lower magnitudes,” Wong says. “So you need different tools to measure it.”


In recent years, those tools have been developed. Seven groups around the country, including at UCLA, have been building biosensors for saliva diagnostics.


Wong and his colleagues have already determined that the RNA transcriptome profile in the saliva of people with oral cancer is markedly different from that of healthy controls. So why bother with the proteome? “At the end of the day, we’ll have genomic, proteomic, and transcriptomic information,” Wong says. “The question will be which information by itself or in combination is most sensitive to predicting disease processes.”


Already, Wong’s group has identified 310 proteins in saliva. They expect to find 1500 to 2000 before they are through. Once they have the full list, Wong and his colleagues will be identifying the protein signatures of ten high-impact systemic diseases that might be detectable in saliva, starting with oral cancer, breast cancer, and adult-onset diabetes.


When the project is complete, a web-based Salivary Proteome Knowledge Base will contain the researchers’ proteomic data along with annotations of protein function and links to other databases.


In the long run, Wong expects that people will spit into a vial to be tested for oral cancer, breast cancer, or other diseases. “It’s not that far away,” Wong says. “The proof of concept is there.” Biotech companies are now interested in the possibility of saliva diagnostics. “Our guess—in a year there will be a commercially available system for specific selected diseases and, eventually, many more,” Wong says. “And the test will be painless.”


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