miR-376a/Neuropilin-1 axis mediates the cancer stemness in oral squamous cell carcinoma-an in vitro study

The incidence of oral cancer has been steadily increased over the years. Recent researches indicated that exploring oral cancer stem cells (CSCs) characterized by self-renewal, pluripotency, and aggressiveness have emerged as a promising strategy for predicting oral squamous cell carcinoma (OSCC) recurrence and metastasis. Previous studies have demonstrated that microRNAs regulate cancer stemness. However, the mechanisms that miR-376a/neuropilin-1 (NRP1) axis influences CSC traits have not yet been fully understood. Therefore, an in-depth investigation was conducted in this study.

miR-376a expression in CSCs derived from OSCC cell line SAS was quantified by quantitative real-time polymerase chain reaction. Aldehyde dehydrogenase 1 (ALDH1) activity and CD44 expression were assessed via flow cytometry. The CSC phenotype was characterized through self-renewal, migration, and colony formation assays. A luciferase reporter assay was used to confirm the direct interaction between miR-376a and NRP1.

We found that miR-376a expression was downregulated in SAS-CSCs. Overexpression of miR-376a significantly reduced several CSC phenotypes including ALDH1 activity, CD44 expression, migration, and colony-forming abilities, respectively (P < 0.05). In addition, a luciferase reporter assay substantiated the direct binding of miR-376a to NRP1 (P < 0.05). Moreover, NRP1 overexpression was found to reverse miR-376a-induced the inhibition of migration and self-renewal, respectively (P < 0.05).

Within the limitations of our findings, miR-376a/NRP1 axis may play a crucial role in stemness of OSCC. Targeting this pathway could represent a promising strategy to inhibit OSCC progression.