Involvement of KLRK1 in immune infiltration of head and neck squamous cell carcinoma correlates with favorable prognosis.

Head and neck squamous cell carcinoma (HNSCC) is a malignancy commonly found in the head and neck region, with a low 5-year survival rate. Although immunotherapy has made significant progress, its efficacy in HNSCC treatment remains unsatisfactory. Killer cell lectin-like receptor K1 (KLRK1), a marker highly expressed in immune cells, can bind to its ligands expressed by cancer cells to exert its antitumor effect. However, the role of KLRK1 in HNSCC has yet to be studied extensively. This study aimed to explore the involvement of KLRK1 in immune infiltration of HNSCC and its correlation with prognosis. We analyzed KLRK1 expression data from the Cancer Genome Atlas database. The relationship between KLRK1 and immune cell infiltration has also been investigated. Finally, we analyzed the association between the expression of KLRK1 and its ligands and the prognosis of patients with HNSCC. We found that KLRK1 was highly expressed in HNSCC and correlated with better prognosis. KLRK1 expression was correlated with age, histological grade, HPV infection, pT, pN, pTNM stage, primary site, and survival status. High expression levels of KLRK1 have been linked to high levels of immune cell infiltration, particularly CD4/8 (+) T lymphocytes. Among the ligands of KLRK1, UL16 binding protein (ULBP) 1-3 showed high expression, which was associated with an increased risk of death. Notably, the expression of KLRK1 was negatively correlated with ULBP1-3. Patients with high levels of ULBP2/3 expression in tonsil carcinoma had poorer prognosis than those with low levels (P < .01), whereas ULBP1 expression levels had no significant effect on tonsil carcinoma prognosis (P = .770). The expression levels of ULBP1/3 were correlated with worse prognosis in patients with laryngeal cancer (P < .05), whereas there was no significant correlation between ULBP2 expression levels and overall survival (P = .269). Our study revealed that KLRK1 is highly expressed in HNSCC and is associated with a better prognosis and immune infiltration. Patients with high expression of KLRK1 ligands exhibited worse prognoses, possibly because of the expression of more soluble ligands.