BACKGROUND: It is well documented that long non-coding RNAs (lncRNAs) are involved in the progression of multiple human tumors by sponging microRNAs (miRNAs). However, whether lncRNA TFAP2A-AS1 plays a role in the tumorigenesis of breast cancer (BC) remains undetermined.

MATERIAL AND METHODS: Real-time PCR (qRT-PCR) assay was performed to detect the relative mRNA expression of TFAP2A-AS1 and miR-933. Flow cytometry analysis, CCK-8 assay, and Transwell assay were applied to detect the effects of TFAP2A-AS1 overexpression on cell cycle, apoptosis, viability, and invasion of BC cells. In vivo proliferation assay was performed to evaluate the effects of TFAP2A-AS1 overexpression on tumor growth. Bioinformatics methods, dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays were used to predict and validate the interaction between TFAP2A-AS1 and miR-933, as well as SMAD2 and miR-933. Western blot assay was performed to examine the protein expression of SMAD2 in treated BC cells.

RESULTS: TFAP2A-AS1 expression was significantly lower in BC tissues and cell lines, and patients with high TFAP2A-AS1 expression exhibited a better prognosis than those with low TFAP2A-AS1 expression. Overexpression of TFAP2A-AS1 in BC cells caused cell cycle arrest, promoted cell apoptosis, suppressed cell ability, and attenuated cell invasion in vitro, and inhibited tumor growth in vivo. TFAP2A-AS1 was revealed to act as a miRNA sponge for miR-933 and then regulated the expression of Smad2.

CONCLUSIONS: Results from the present study suggest that TFAP2A-AS1 acts as a tumor suppressor in BC via the miR-933/SMAD2 axis.

Keywords: Breast Neoplasms, carcinogenesis, Cell Cycle Checkpoints, MCF-7 cells, Transcription Factor AP-2