Effect Of Silencing Of Circular RNA Hsa_circ₀004491 On Migration And Invasion Of Oral Squamous Cell Carcinoma

Objective: Oral squamous cell carcinoma（OSCC）is one of the most common oral malignant tumors,and its incidence rate ranks eighth among different cancers.The fiveyear survival rate of patients has remained at around 63%.However,the pathogenesis and prognosis of oral squamous cell carcinoma are still ambiguous.Circular RNA（circ RNA）has been widely detected in mammals in recent years,and more and more data have confirmed the correlation between circ RNA and cancer.In this study,we aimed to investigate the expression of the circular RNA hsa_circ₀004491 in oral squamous cell carcinoma cell lines,and to explore its effects on the migration and invasion of oral squamous cell carcinoma cell lines,and to explore its possible molecular mechanisms.Methods: Quantitative PCR（qRT-PCR）was used to detect the relative expression of hsa_circ₀004491 in oral squamous cell carcinoma cell lines（SCC-15,SCC-25,CAL-27）and human oral keratinocytes（HOK）.Oral squamous cell carcinoma cell line with low expression of circular RNA hsa_circ₀004491 was used as a follow-up study.Si RNA and Ctrl-si were designed and transfected into cells,the silencing efficiency was detected at 24 hours after transfection by qRT-PCR,the effect of silencing hsa_circ₀004491 on the proliferative capacity of oral squamous cell carcinoma was detected by CCK-8 and EDU proliferation assay,the effect of silencing hsa_circ₀004491 on the invasion and migration by scratch test and transwell assay,detection of cell migration and invasion-related protein expression by silencing hsa_circ₀004491 by Western blot.RESULTS: The expression levels of hsa_circ₀004491 in four cell lines（HOK,SCC-15,SCC-25,CAL-27）were detected by qRT-PCR,and the relative expression levels in SCC-15 and CAL-27 were significantly reduce.Si RNA and ctrl-si were designed and transfected into SCC-15 and CAL-27 cell lines,the silencing efficiencies were 80% of SCC-15 cell line and 65% of CAL-27 cell line,respectively,compared to the control group.Both results of CCK-8 and EDU proliferation experiments showed that the number of cells in the proliferative phase of the treatment group with low expression of circ RNA was not significantly different from that of the control group,and that was statistically meaningless.The scratch results showed that the number of scratchtransplanting cells in the treatment group with low expression of circ RNA increased and the migration distance increased than the control group.The results of Transwell migration assay showed that the number of cells in the SCC-15 and CAL-27 cell lines was higher than that in the control group（**,P<0.01）.The results of Transwell invasion experiment indicated that the number of cells in the interference group was significantly higher than that in the control group in the SCC-15 and CAL-27 cell lines（***,P<0.001）.The results of Western blot showed that the expression level of E-cadherin was significantly lower in the SCC-15 and CAL-27 cell lines than in the control group,and the expression of vimentin was significantly increased.Conclusion: The migration and invasion of OSCC cell lines SCC-15 and CAL-27 could be improved by silencing the circular RNA hsa_circ₀004491.Hsa_circ₀004491 may play a role in the development of oral squamous cell carcinoma.