Salivary Exosomal microRNAs: Discovery and Potential Biomarkers for Human Papillomavirus-Associated Oral Squamous Cell Carcinoma

SUMMARY Exosomes are small, membrane bound vesicles secreted by many types of cancers including oral squamous cell carcinoma (OSCC), and have been found to contain various cargo, including microRNAs (miRNAs). miRNAs are short, single-stranded noncoding RNAs that can post-ranscriptionally regulate gene expression. OSCC, the sixth most common cancer in the world, has a dismal survival rate of only 50% over five years. This is in part due to the late diagnosis of the cancer because it is very difficult to identify a lesion at risk during the earliest stages of the disease as well as due to its high recurrence rate. The goal of this study is to identify and exploit the presence of exosomal miRNAs secreted in bodily fluids such as saliva to diagnose early stages of OSCC. The development of a technique to detect the presence of this disease during its early onset will help provide timely and effective treatment to patients all around the world and thus increase the overall survival rate. In this paper, we discuss whether infection with HPV results in the release of specific miRNA biomarkers in exosomes and if these miRNAs of interest are able to be detected in saliva during the early stages of the cancer. We also explore the possibility of detecting other HPVassociated cancers using these miRNAs in order to streamline the cancer screening process and to detect the presence and progression of multiple cancers in a non-invasive manner using only one or two types of bodily fluids as samples. This field of “liquid biopsies”, where bodily fluid samples are examined for biomarkers to identify the presence of a disease is quickly becoming the favoured approach to diagnosing many different health complications, especially cancer, and has a lot of potential in the future for screening patients in a relatively non-invasive manner. Identification of potential salivary microRNA biomarkers for HPVassociated OSCC will revolutionize cancer diagnostics and allow patients throughout the world to have increased life expectancy.