Salivary Biomarkers in Oral Cancer

Abstract

Saliva is an easily accessible biofluid with immense diagnostic potential in oral cancer. The identification of potential saliva signatures for early, noninvasive detection of oral squamous cell carcinoma (OSCC) lead to early detection, better outcome, and survival. More than 100 biomarkers have shown differential levels in saliva of patients with OSCC. They encompass a large number of proteins which cover cell surface molecules (CD44sol, CA-125, etc.), cytoskeleton fragments (CYFRA 21-1), intracellular proteins (ZNF-510, Mac-2 binding protein), proteases (MMPs) and inflammation-associated proteins (CRP, defensin-1, IL-6, IL-8), and mRNA signatures (IL-8, IL-1B, DUSP1, OAZ1, SAT, and H3F3A) and recently some noncoding RNA (miRNA and circular RNA). Some of these salivary biomarkers (both RNA and proteins) have displayed high sensitivity and specificity and were shown to reflect the underlying molecular characteristics and severity of OSCC. The salivary-mutated and salivary-methylated DNA, HPV-DNA, telomerase level, certain oral microbiota, metabolic and oxidative stress biomarkers, and inorganic ion concentration have also shown biomarker potential. Moreover, the unstable RNA is protected in exosomes, allowing their stable detection and easy quantification. The salivary transcriptome (coding, noncoding RNAs) has also displayed performance in multiethnic cohorts of oral cancer patients. In this chapter, the potential salivary biomarker signatures, corresponding tissue and serum concentration, and their role in OSCC are discussed.