The Expression and Biological Function of DKK1 in Oral Squamous Cell Carcinomas by Bioinformatics Analysis

Background: To investigate the expression of transcription factor Dickkopf-1 (DKK1) in oral squamous cell carcinomas (OSCC) by bioinformatics analysis and to clarify the connection between expression of DKK1 and clinicopathological features of OSCC, so as to elucidate the early diagnosis and prognostic significance of OSCC by DKK1. Methods: This study used the GEPIA database in conjunction with the TCGA database to analyze the expression level of DKK1 in OSCC tissues and then verify it by QRTPCR and Western-blot analysis in vitro. The LinkedOmics database was used to describe the correlation between DKK1 expression and clinical pathological parameters of OSCC and its impact on prognosis. DKK1 was knocked down by RNA interference approach in SCC-4 and SCC-25 OSCC cell lines. In addition, the proliferation ability was assessed by MTT assay. Results: DKK1 was highly expressed in OSCC and positively correlated with OSCC pathological grade and T stage. The results of TCGA showed that high DKK1 mRNA expression was associated with overall survival in OSCC. Besides, both DKK1 mRNA and protein expression was confirmed increased significantly in oral squamous cell carcinomas SCC-25 and SCC-4. Furthermore, MTT analysis investigated that knockdown of DKK1 caused reduced proliferation ability of OSCC cells. Conclusions: The TCGA database analysis found that DKK1 is highly expressed in OSCC and is associated with multiple pathological indicators of OSCC, which will provide important theoretical guidance for subsequent oral squamous cell carcinoma research.