Long noncoding RNA DLX6-AS1 promotes tumorigenesis by modulating miR-497-5p/FZD4/ FZD6/Wnt/β-catenin pathway in pancreatic cancer

Jiyong Yang,1* Zhen Ye,1* Dan Mei,2 Honggang Gu,1 Jingzhe Zhang1 1Department of General Surgery, Longhua Hospital Shanghai University of Traditional Chinese Medicine, Shanghai 210000, China; 2Department of General Surgery, Wuxi Hospital of Traditional Chinese Medicine, Wuxi 214000, China *These authors contributed equally to this work Background: Long noncoding RNAs (lncRNAs) are abnormally expressed in various human tumors and play an important role in multiple tumorigeneses, including pancreatic cancer (PC). Materials and methods: The present study was designed to evaluate the role of lncRNA DLX6-AS1 in tumorigenesis of PC. The expression of DLX6-AS1 and its effect on proliferation, apoptosis, migration, and invasion was investigated in vitro. Its effect on tumor growth and metastasis in vivo and its potential targets were also examined. Results: We observed that DLX6-AS1 was highly expressed in PC tissues and PC cell lines, and was negatively correlated with the survival of PC patients. We found that overexpression of DLX6-AS1 promoted proliferation, migration, and invasion of PC cells, inhibited apoptosis, increased Bcl-2, cyclin D1, and MMP-2 expression, and decreased cleaved caspase 3, p27, and E-cadherin expression in PC cells. In addition, overexpression of DLX6-AS1 promoted PC growth by increasing tumor volume and weight and increasing the number of liver and lung metastatic foci. Knockdown of DLX6-AS1 showed an opposite effect in all the experiments. miR-497-5p was demonstrated to be a direct target of DLX6-AS1 and was regulated by DLX6-AS1. We also demonstrated that miR-497-5p targeted FZD4 and FZD6 and decreased their expression. miR-497-5p mimics also decreased the expression of FZD4, FZD6, and β-catenin; the expression of FZD4 or FZD6 was reversed by the overexpression of vectors FZD4 or FZD6, respectively, while the expression of β-catenin was reversed by either vector. Finally, the effect of DLX6-AS1 on proliferation, cell cycle, migration, invasion, and apoptosis of cells and expression of FZD4, FZD6, and β-catenin was neutralized by overexpression of vectors of miR-497-5p, FZD4, or FZD6, totally or partially. Conclusion: Collectively, these findings suggested that DLX6-AS1/miR-497-5p/FZD4/FZD6/Wnt/β-catenin signaling pathway is involved in the pathogenesis of PC, and DLX6-AS1 could be a potential biomarker and target for PC treatment. Keywords: pancreatic cancer, DLX6-AS1, long noncoding RNAs, miR-497-5p, FZD