Abstract: Objective To investigate the effect of long non-coding RNA (lncRNA) homeobox transcription factor 6 antisense RNA1 (DLX6-AS1) regulating miR-181b/interleukin-6 (IL-6) axis on the proliferation, migration and invasion of esophageal cancer Eca-109 cells. Methods The human esophageal epithelial cell line HEEC and human esophageal squamous cell carcinoma cell line Eca-109 were selected, and the expression levels of lncRNA DLX6-AS1, miR-181b and IL-6 were detected by qRT-PCR. The si-DLX6-AS1, miR-181b mimics, pcDNA-IL-6, pcDNA-IL-6+miR-181b mimics and their corresponding negative controls were transfected into Eca-109 cells, respectively, and the transfection effect was detected by qRT-PCR. The CCK-8 assay and EdU staining assay were used to detect cell proliferation ability. The Transwell assay was used to detect cell migration and invasion ability, and dual luciferase reporter assay was used to verify the targeting relationship between lncRNA DLX6-AS1 and miR-181b, miR-181b and IL-6. Results Compared with those of HEEC cells, the expression levels of lncRNA DLX6-AS1 and IL-6 mRNA were increased in Eca-109 cells (P=0.005, 0.006), but the expression level of miR-181b was decreased (P=0.004). Compared with the corresponding negative control group, the cell proliferation activity and EdU positive cell rate in the si-DLX6-AS1 group and miR-181b mimics group were decreased (all P<0.05), and the number of cell migration and invasion were decreased (all P<0.05 ), while the cell proliferation activity and EdU positive cell rate in the pcDNA-IL-6 group were increased (both P<0.05), and the number of cell migration and invasion were increased (both P<0.05). IncRNA DLX6-AS1 had a targeted binding relationship with miR-181b. After co-transfection of miR-181b mimics and wild-type DLX6-AS1 vector, the intracellular luciferase activity was significantly decreased in cells (P=0.006). The expression level of miR-181b in Eca-109 cells was increased after down-regulation of DLX6-AS1 expression (P=0.010). miR-181b had a targeted binding relationship with IL-6. After co-transfection of miR-181b mimics and wild-type IL-6 vector, the intracellular luciferase activity was significantly decreased (P<0.05). The expression level of IL-6 in Eca-109 cells decreased after overexpression of miR-181b mimics (P<0.05). Compared with those of the pcDNA-IL-6 group, the expression levels of IL-6 mRNA and protein in Eca-109 cells, the cell proliferation activity, the EdU positive cell rate, the number of cell migration and invasion were decreased (all P<0.05), after co-transfection of pcDNA-IL-6 and miR-181b mimics. Conclusions LncRNA DLX6-AS1 promotes the proliferation, migration and invasion of esophageal cancer Eca-109 cells through miR-181b targeting and negatively regulating IL-6 expression.

Key words: Esophageal cancer, Long non-coding RNA homeobox transcription factor 6 antisense RNA1, miR-181b, Interleukin-6