44P - Exploring miR-205 and miR-296 as salivary biomarkers and potential therapeutic targets in oral cancer

Background

Oral cancer (OC) presents a high incidence of recurrences and metastasis. MicroRNA and sphingolipids alterations in plasma and tumors have been linked to many cancers. Sphingosine kinase 2 (SK2), which regulates sphingosine-1-phosphate levels, has been explored as a therapeutic target in cancer. Interestingly, our preliminary data indicate a correlation between SK2 and miRNA levels in OC. This study aimed to investigate miR-205 and miR-296, in the saliva of OC patients and the relationship between these miRNAs and SK2 in OC cells to elucidate further new diagnosis/prognosis and therapy strategies for oral cancer.

Methods

The saliva was collected and processed from 25 OC patients and 15 controls, followed by miRNA extraction. The survival rate of OC patients related to miRNA-205 and miRNA-296 levels in tumor samples was analyzed using the TCGA data. The salivary levels of the 2 miRNAs were determined by qRT-PCR. ROC curves were used to evaluate the potential of the miRNAs as biomarkers. OC cells (HN12 and HN13) without (control) and with SK2 overexpression (HN12-SK2) and SK2 knockdown (HN13-sh-SK2) were selected to evaluate the modulation of the miRNAs by qRT-PCR, as well as to perform migration and spheres assays after transfection with mimic-miRNA-205 and inhibitor for miRNA-296.

Results

The survival rate in OC patients was higher when the miR-205 was high and the miR-296 low. In our cohort, both miR-296 and miRNA-205 presented higher levels in the saliva of OC patients than in the controls. There was a positive correlation between tumor size and miR-296 levels in saliva, opposite to a negative correlation with miR-205. In vitro analysis showed that SK2 overexpression in HN12 cells (HN12-SK2) decreased the expression of miR-205 and increased miR-296, while the knockdown of SK2 in HN13 cells (HN13-sh-SK2) increased the miR-205 and decreased the miR-296. Besides, transfection of a miR-205 mimic and a miRNA-296 inhibitor in HN12/HN13 cells showed decreased cell migration and sphere formation.

Conclusions

We propose that the level of miR-205 and miR-296 in human saliva could be used for the diagnosis and prognosis of OC patients. Moreover, both miRNAs in OC cells may be regulated by sphingosine kinase 2 and explored as therapeutic targets in oral cancer.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

Academic Group.

Funding

Fundação de Amparo e Pesquisa do Estado de São Paulo.

Disclosure

All authors have declared no conflicts of interest.