Abstract: Objective To study the effect of circ_0086414 on biological behavior of oral squamous cell carcinoma (OSCC) via miR-498/PCK1 axis. 
Methods In total, 27 pairs of surgically resected OSCC tissues and paired paracancerous tissues were collected. Real-time quantitative PCR(qRT-PCR) was used to detect the expression of circ_0086414 and PCK1 in tissues. SJG-1 cells were divided into pcDNA group, pcDNA circ_0086414 group, miR-498 NC group, miR-498 mimic group, OE-NC group, OE-PCK1 group, miR-498 NC+pcDNA group, miR-498 NC+pcDNA circ_0086414 group, miR-498 mimic+pcDNA group, and miR-498 mimic+pcDNA circ_0086414 group. Cell counting kit (CCK8) was used to detect SJG-1 cell proliferation. Flow cytometry was used to detect SJG-1 cell apoptosis, and Transwell assay was used to detect SJG-1 cell invasion. Western bloting (WB) assay was used to detect epithelial messtimal transformation. The relationship between circ_0086414 and miR-498 and between miR-498 and PCK1 was detected by dual luciferase reporter gene. 
Results The relative expression of circ_0086414 in OSCC tissues was significantly lower than that in paracancerous tissues (P＜0.001). Compared with HOK in normal human oral keratinocytes, the expression of circ_0086414 in human OSCC cell lines HEK293T, SJG-1, SCC-15 and HSC-2 was significantly decreased (P＜0.001). Compared with pcDNA group, SJG-1 cells in pcDNAcirc_0086414 group had significantly decreased proliferation ability, significantly increased apoptosis rate, significantly decreased invasion ability, and there was significantly decreased N-cadherin expression level, and significantly increased E-cadherin expression level (P＜0.001). Compared with miR-498 NC group, miR-498mimic group had significantly increased proliferation ability, significantly decreased apoptosis rate and significantly increased invasion ability in SJG-1 cells, as well as significantly increased expression level of N-cadherin, and significantly decreased expression level of E-cadherin (all P＜0.001). Compared with the miR-498 NC+pcDNA group, the proliferation ability of SJG-1 cells in the miR-498 NC+pcDNAcirc_0086414 group was decreased significantly, the apoptosis rate was increased significantly, and the invasion ability was decreased significantly. The expression level of N-cadherin was decreased significantly, and the expression level of E-cadherin was increased significantly. The proliferation ability of SJG-1 cells in miR-498 mimic+pcDNA group was increased significantly, the apoptosis rate was decreased significantly, and the cell invasion ability was increased significantly. The expression level of N-cadherin was increased significantly, while the expression level of E-cadherin was significantly decreased (all P＜0.001). Compared with the miR-498 mimic+pcDNA group, the proliferation capacity of SJG-1 cells in miR-498 mimic+pcDNAcirc_0086414 group was significantly reduced, the apoptosis rate was significantly increased, and the invasion ability was significantly decreased. The expression level of N-cadherin was significantly decreased, while the expression level of E-cadherin was significantly increased (all P＜0.001). Compared with the OE-NC group, the proliferation ability of SJG-1 cells in the OE-PCK1 group was significantly decreased, the apoptosis rate was significantly increased, and the invasion ability of SJG-1 cells was significantly decreased. The expression level of N-cadherin was significantly decreased, the expression level of E-cadherin was significantly increased, and the relative expression level of PCK1 was significantly increased (all P＜0.001). 
Conclusion The expression of circ_0086414 is down-regulated in OSCC cells and tissues, and overexpression of circ_0086414 inhibits the malignant behavior of OSCC cells. By regulating the miR-498/PCK1 axis to stimulate apoptosis, it provides a meaningful experimental basis for exploring biomarkers for diagnosis and treatment of OSCC, and provides a new diagnosis and treatment idea for OSCC.

Key words: oral neoplasms, carcinoma, squamous cell, RNA, circular