ABSTRACT
@#[Abstract] Objective: To explore the effect of lncRNA HOTAIR/miR-519d-3p/cyclin D1 (CCND1) axis on the proliferation and metastasis of breast cancer cells and its underlying mechanism. Methods: A total of 50 pairs of breast cancer tissues and corresponding para-cancer tissues resected from breast cancer patients in the Department of Breast Surgery, the Third Hospital of Nanchang from March 2017 to February 2019 were collected for this study. The expression level of HOTAIR in breast cancer tissues and paired paracancer tissues was detected by qPCR, in addition, the expressions of HOTAIR and miR-519d-3p in normal breast epithelial cells and breast cancer cell lines were also detected. Breast cancer SKBR3 cells were divided into NC group (without any treatment), si-HOTAIR group, mir-519d-3p mimics group, miR-519d-3p mimic+pcHOTAIR group, miR-519d-3p mimic+pcCCND1 group, and si-HOTAIR+ pcCCND1 group. The proliferation ability of SKBR3 cells was detected by CCK-8. Invasion and migration of SKBR3 cells were detected by Transwell. The expression levels of E-cadherin, N-cadherin, Vimentin and CCND1 in SKBR3 cells were detected by Western blotting. The targeting relationship between HOTAIR and miR-519d-3p, miR-519d-3p and CCND1 was detected by Dualluciferase reporter gene system. Results: HOTAIR was highly expressed in breast cancer tissues and cell lines, with the highest expression in SKBR3 cells. HOTAIR knockdown significantly inhibited the proliferation, invasion and migration of SKBR3 cells, as well as increased the expression level of E-cadherin and decreased the expression levels of N-cadherin and Vimentin. Dual-luciferase reporter gene assay showed that HOTAIR targetedly down-regulated the expression of miR-519d-3p, and miR-519d-3p targetedly downregulated the expression of CCND1. Further studies showed that knockout of HOTAIR inhibited the EMT, proliferation, invasion and migration of SKBR3 cells through enhancing the inhibitory effect of miR-519d-3p on CCND1 expression (all P<0.05). Conclusion: HOTAIR knockdown inhibits proliferation and metastasis of SKBR3 cells by regulating the axis of miR-519d-3p/CCND1.