Sphingosine kinase 2 controls the aggressive phenotype of oral squamous cell carcinoma by regulating miR-205 and miR-296 through p53.

Alterations in microRNAs, p53, and sphingolipid metabolism have been associated with head and neck squamous cell carcinoma (HNSCC). However, sphingosine kinase 2, a critical enzyme in sphingolipid metabolism, is poorly understood in HNSCC. Our aim was to investigate how SK2 and p53 interact to regulate miR-205 and miR-296. Analysis of small-RNA-seq data from non-tumor oral keratinocytes with SK2 overexpression (NOK-SK2) compared to NOK-control (NOK- Ø) revealed differential expression of more than 100 miRNAs being half regulated by p53. The expression of miR-205 was downregulated, and miR-296 was upregulated in NOK-SK2 cells; however, cells with SK2 knockdown and p53 overexpression showed an opposite profile. Proteins involved in miRNA biogenesis were increased in NOK-SK2 cells while their levels were decreased in NOK-SK2 cells with p53 overexpression. miR-205 mimic and miR-296 inhibitor decreased the aggressiveness and cancer stem-like cells in oral keratinocytes and oral carcinoma cells with SK2 deregulation. Overexpression of miR-205 in HN12-SK2 cells decreased tumor formation capacity and NOK-SK2 cells abrogated the tumor growth in mice. Our results indicate crosstalk between SK2 and p53 in regulating miR-205 and miR-296, which could be potential targets for HNSCC therapy.