Long noncoding RNA DLX6-AS1 promotes breast cancer progression via miR-505-3p/RUNX2 axis

The dysregulation of long non-coding RNA (lncRNA) DLX6-AS1 has been identified to be involved in the development of several cancers, but its functional role and the underlying mechanism of DLX6-AS1 in breast cancer (BC) remains unknown. In the current study, the expression of DLX6-AS1 in the BC tissue samples was evaluated and the correlation between DLX6-AS1 expression and clinicopathological parameters were also analyzed. We found that DLX6-AS1 expression was much higher in tumor tissues than that in adjacent normal tissues and was positively associated with poor prognosis in BC patients. DLX6-AS1 knockdown significantly suppressed BC cell proliferation, invasion, migration, and promoted apoptosis. Moreover, luciferase reporter assay validated that DLX6-AS1 acted as an endogenous sponge to miR-505-3p and negatively regulated its expression. Additionally, miR-505-3p inhibited runt-related transcription factor 2 (RUNX2) expression by directly bind to its 3'- untranslated region (3'-UTR) and overexpression of RUNX2 partially reversed the effect of miR-505-3p mimics on BC cell proliferation and invasion. Furthermore, in BC tissues, miR-505-3p expression level was inversely associated with DLX6-AS1 and RUNX2, respectively. In conclusion, these findings demonstrated that DLX6-AS1 functioned as an oncogenic role that promoted BC proliferation and invasion through miR-505-3p/RUNX2 axis, which might serve as a potential therapeutic target for BC treatment.