Circ_0000218 plays a carcinogenic role in laryngeal cancer through regulating microRNA-139-3p/Smad3 axis

Background: Laryngeal squamous cell carcinoma (LSCC) accounts for about 85%-90% of all cases of laryngeal cancer. So far, the role and molecular mechanism of circular RNA 0,000,218 (circ_0000218)/microRNA (miR)-139-3p in laryngeal cancer are not clear. The present study aimed to investigate the role and regulatory mechanism of circ_0000218/miR-139-3p in laryngeal cancerin vitro and in vivo.

Methods: quantitative real time polymerase chain reaction (qRT-PCR) was used to detect the expression of circ_0000218/miR-139-3p in LSCC cells. Dual luciferase reporter assay and RNA immunoprecipitation (RIP) assay were used to confirm binding sites between miR-139-3p and smad family member 3 (Smad3), and circ_0000218 and miR-139-3p. Cell Counting Kit-8 (CCK-8) and cell apoptosis analysis were used to detect cell viability and apoptosis. Xenograft experiment was performed to show in vivo effect of circ_0000218/miR-139-3p on the growth of LSCC.

Results: Circ_0000218 was highly expressed in LSCC cells. miR-139-3p, lower expressed in LSCC cells, was negatively regulated by circ_0000218 in LSCC cells. Besides, the findings suggested that circ_0000218 silencing inhibited the LSCC cell viability and promoted apoptosis by negatively regulating miR-139-3p expression. Furthermore, the data indicated that miR-139-3p inhibited the viability of LSCC cells and promoted apoptosis, and these effects were reversed by Smad3 over-expression. In addition, the in vivo effects of circ_0000218/miR-139-3p on LSCC were consistent with the in vitro study.

Conclusions: circ_0000218 inhibition inhibited the growth of LSCC by targeting miR-139-3p/Smad3 axis. Our present study provided a new target for laryngeal cancer treatment.