CTCF-Induced lncRNA C5orf66-AS1 Facilitates the Progression of Triple-Negative Breast Cancer via Sponging miR-149-5p to Up-Regulate CTCF and CTNNB1 to Activate Wnt/β-Catenin Pathway

ABSTRACT

Triple-negative breast cancer (TNBC) represents one of the subtypes of breast cancer with high aggressiveness. Long noncoding RNAs (lncRNAs) are well-known to function as crucial regulators in human cancers which include TNBC. Nevertheless, the specific role of the lncRNA C5orf66-AS1 in TNBC is unclear. In this study, we tested C5orf66-AS1 expression in TNBC cells using quantitative real-time PCR (qRT-PCR) and used functional assays to detect cell behaviors, which showed that C5orf66-AS1 was highly expressed in TNBC cells and that C5orf66-AS1 knockdown attenuated cell proliferation, migration, and invasion while promoting cell apoptosis. Through a luciferase reporter assay, RNA immunoprecipitation (RIP) assay, and chromatin immunoprecipitation (ChIP) assay, we identified the binding capacity of C5orf66-AS1 to RNAs. Furthermore, miR-149-5p was proven to be sponged by C5orf66-AS1. CCCTC-binding factor (CTCF) was confirmed as the target of miR-149-5p and could transcriptionally activate C5orf66-AS1 expression in TNBC cells. We also discovered that C5orf66-AS1 activated the Wnt/β-catenin signaling pathway by upregulating catenin beta 1 (CTNNB1). Importantly, CTNNB1 could be targeted by miR-149-5p. In rescue assays, it was proven that overexpressing CTCF and CTNNB1 or inhibiting miR-149-5p could totally reverse the inhibitory effect of silencing C5orf66-AS1 on TNBC progression. In short, the lncRNA C5orf66-AS1 acted as an oncogene to facilitate TNBC malignancy.

KEYWORDS:

• C5orf66-AS1
• miR-149-5p
• CTCF
• CTNNB1
• triple-negative breast cancer

Declaration of Interests

The authors declare no conflict of interest.

SUPPLEMENTAL MATERIAL

Supplemental material is available online only.

ACKNOWLEDGMENTS

We appreciate the support of our experimenters.

This study was supported by the Science and Technology Project of Lianyungang Municipal Health Commission (grant no. 202020).

We have no conflicts of interest to report.