Head and neck squamous cell carcinoma (HNSCC) represents an aggressive and heterogenous group of cancers whose pathologies remain largely unresolved. Exosomes are a subtype of extracellular vesicles secreted by a variety of cells that have begun to spark significant interest in their roles in cancer. As membranous vesicles, spanning from 30–150 nm in diameter, exosomes mediate the transport of various molecules, such as proteins, nucleic acids, and lipids, intercellularly throughout the body. In doing so, exosomes not only act to deliver materials to cancer cells but also as signals that can confer their progression. Accumulating evidence shows the direct correlation between exosomes and the aggressiveness of HNSCC.
How a tumor induces PMN formation in a specific organ remains to be determined. The suppressive nature of immune cells in the TME is critical to the regulation of anti-tumor immune responses. One of the possible mechanisms is that TDEs mediate tumor PMN remodeling to establish a supportive and receptive niche to promote tumor cell colonization and metastasis. Maybruck et al. have found, however, that head and neck cancer cells can induce a suppressive phenotype in human CD8+ T cells through the release of TDEs . Specifically, the group revealed through mass spectrometry that the immunoregulatory protein galectin-1 was present in these exosomes and played a key role in inducing this suppressive phenotype. The purification of exosomal RNA and subsequent CD8+ T cell suppression analysis also implicated RNAs in T cell dysfunction. This study suggests that tumor immunosuppressive exosomes could be a potential therapeutic target to preserve T cell function in anti-tumor immune responses .
Early diagnosis and treatment are critical determinants in a cancer patient’s prognosis. The application of biomarkers in HNSCC detection, as well as factors such as staging, treatment efficacy, and prognosis, have consequently garnered attention in recent years . Biomarkers represent a diverse range of molecules, and abnormalities in their levels or makeup can be detected in bodily fluids, like urine, saliva, and blood, as well as tumors themselves. In particular, exosomal biomarkers may be roughly divided into nucleic acids, proteins, lipids, and metabolites (Figure 2).