Sp1-activated Long Noncoding RNA NCK1-AS1 Facilitates Cell Growth of Breast Cancer via Sponging miR-361-5p 

Abstract

Background: Breast cancer (BC) is one of the most lethal and malignant tumors in the world. Accumulating documents have illuminated the vital roles of long noncoding RNAs (lncRNAs) which are closely related to the progression of human cancers, including BC. LncRNA NCK1-AS1 was reported to be an oncogene in some cancers; nevertheless, its functionality is not well elucidated in BC. Methods: NCK1-AS1 expression status was detected in human breast cancer tissues and cell lines by the means of RT-qPCR. The impacts of NCK1-AS1 deficiency on breast cancer cell stemness, viability, proliferation, migration, invasion, and apoptosis were measured in vitro via sphere formation assay, western blot analysis, CCK-8, colony formation, transwell, TUNEL and flow cytometry analysis. Furthermore, luciferase reporter assay, RIP and ChIP were used to verify the mutual effects between molecules.Results: In this study, lncRNA NCK1-AS1 was verified to be elevated in BC tissues and cells. In addition, NCK1-AS1 silencing hampered BC cell growth by inhibiting cell stemness, viability, proliferation, migration and invasion as well as promoting cell apoptosis. Moreover, NCK1-AS1 functioned as a molecular sponge for miR-361-5p and modulated SP1 expression. Rescue experiments signified that SP1 overexpression restored NCK1-AS1 silencing-mediated suppression on BC cell growth. Importantly, SP1 was uncovered to bind with NCK1-AS1 promoter, suggesting a positive feedback loop of NCK1-AS1/miR-361-5p/SP1 in BC cells. Conclusion: Taken together, these findings showed for the first time that NCK1-AS1 served as a carcinogenic gene in BC cells via combining with miR-361-5p to upregulate SP1.