Oral cancer has a high mortality rate, making early diagnosis crucial for effective treatment and prognosis. Unlike other cancers, oral cancer develops in the oral cavity, enabling direct contact between saliva and cancer cells. Therefore, saliva is a more useful diagnostic tool than serum or tissue. When DNA, RNA, or proteins produced by cancer cells enter the saliva, they can be easily detected as tumor markers. Therefore, salivary biomarkers can serve as a noninvasive alternative to serum- or tissue-based biomarkers. Early diagnosis is essential for increasing the treatment success rate, improving prognosis, and enhancing post-treatment recovery, ultimately improving the quality of life. Proteins are essential molecules involved in key processes, such as the development, growth, death, and metastasis of oral cancer. Recent advancements in molecular biology and salivary proteomics have enabled the detection and analysis of numerous proteins in saliva. Many of these protein molecules are currently the focus of extensive research. This article aims to review the potential of saliva as a diagnostic tool, techniques for detecting protein biomarkers, and salivary protein biomarkers for oral cancer diagnosis.

Coronavirus disease 2019 (COVID-19) is a highly contagious illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This disease is characterized by a wide spectrum of symptoms, ranging from mild to severe, including fatal outcomes. This study aims to review gustatory and salivary secretion dysfunctions and determine their potential pathogenic mechanisms. Gustatory impairment and salivary dysfunction are prevalent among patients with acute COVID-19 and those recovering from the disease. The mouth serves as a critical entry route for SARS-CoV-2. The cells within the oral epithelium, taste buds, and minor and major salivary glands express key entry factors for SARS-CoV-2, including angiotensin-converting enzyme 2, transmembrane serine protease 2, and furin. The co-occurrence of gustatory and salivary secretion dysfunctions possibly has pathogenetic association with the following factors: the expression of SARS-CoV-2 cellular entry receptors in the taste buds and salivary glands and SARS-CoV-2–induced zinc deficiency, which is crucial for normal taste perception and saliva secretion. Furthermore, the cytokine storm triggered by COVID-19 contributes to secondary damage affecting gustatory and salivary functions.

Autophagy is an evolutionarily well-conserved cellular homeostasis program that responds to various cellular stresses and degrades unnecessary or harmful intracellular materials in lysosomes. Accumulating evidence has shown that autophagy dysfunction often results in various human pathophysiological conditions, including metabolic disorders, cancers, and neurodegenerative diseases. The discovery of an autophagy machinery protein network has revealed underlying molecular mechanisms of autophagy, and advances in the understanding of its regulatory mechanism have provided novel therapeutic targets for treating human diseases. Recently, reports have emerged on the involvement of autophagy in oral squamous cell carcinoma (OSCC). Although the role of autophagy in cancer therapy is controversial, the beneficial use of the induction of autophagic cell death in OSCC has drawn significant attention. In this review, the types of autophagy, mechanism of autophagosome biogenesis, and modulating molecules and therapeutic candidates affecting the induction of autophagic cell death in OSCC are briefly described.