lncRNA DLEU2 Accelerates Oral Cancer Progression via miR-30a-5p/RAP1B Axis to Regulate p38 MAPK Signaling Pathway

BACKGROUND: Oral cancer (OC) is common cancer in the world. Long noncoding RNAs (lncRNAs) have been shown to be involved in cancer regulation, including oral cancer (OC). The aim of this study was to investigate the role of lncRNA deleted in lymphocytic leukemia 2 (DLEU2) in oral cancer. METHOD: The Gene Expression Omnibus database was used to analyze differentially expressed lncRNA/microRNA (miRNA, miR)/mRNA. The expression levels of DLEU2, miR-30a-5p, and RAP1B in OC cells were detected by RT-qPCR. Dual-luciferase was used to analyze the binding of lncRNA/miRNA/mRNA. Cell Counting Kit-8 was used to measure cell proliferation. Transwell assay was used to inspect cell migration and invasion abilities. Western blot was used to detect MAPK pathway-related protein levels. RESULT: Our research shows that, in contrast to miR-30a-5p, DLEU2 or RAP1B was upregulated in OC cells, and high expression of DLEU2 or RAP1B was associated with poorer overall survival. Inhibiting the expression of DLEU2 slowed the proliferation and reduced the ability of migration and invasion of Tca8113 and CAL-27 cells. miR-30a-5p was predicted to interact with DLEU2 or RAP1B by bioinformatics, and dual-luciferase analysis confirmed this interaction. Notably, si-DLEU2 suppressed RAP1B expression and protein level, and after overexpression of RAP1B in OC cells, reversal of suppressed DLEU2 expression was observed. Furthermore, the inhibitory effect of si-DLEU2 on MAPK signaling was reversed by overexpression of RAP1B. Therefore, si-DLEU2 regulates MAPK signaling through the miR-30a-5p/RAP1B axis and inhibits OC development. CONCLUSION: DLEU2 contributed to proliferation, migration and invasion via miR-30a-5p/RAP1B axis to regulate MAPK signaling pathway in OC cells.