Comprehensive bioinformatics analysis targeting sphingosine-related genes in head and neck cancer

A comprehensive bioinformatics analysis of the expression of sphingosine-related genes and prognosis of patients with head and neck squamous cell carcinoma (HNSCC) was performed using TCGA data and TIMER. A keyword search using sphingosine identified 29 genes, 10 of which were associated with patient survival. The expression of CERS2, CERS5, PLPP3, SGPP1, and S1PR4 significantly differed between tumors and normal tissue. A protein-protein interaction analysis revealed a dense network of these genes. Survival rates decreased in patients with the high expression of CERS2, CERS5, and SGPP1, and increased in those with the high expression of PLPP3 and S1PR4. An examination of the relationship between the expression of these five genes and classical clinical risk factors revealed that the high expression of CESR5 negatively correlated with survival for all classical clinical risk factors, while that of S1PR4 positively correlated with survival. The TIMER analysis showed that CERS5 and S1PS4 expression on tumor-infiltrating immune cells from HNSCC patients was associated with survival. Collectively, these results indicate the potential of CERS5 as a marker of a poor prognosis, and the contribution of S1PR4 to a favorable prognosis through its expression on immune cells. Therefore, the expression of sphingosine-related genes on tumor cells and infiltrating immune cells is important for the prognosis of HNSCC patients.