Down-regulated long non-coding RNA RNAZFHX4-AS1 suppresses invasion and migration of breast cancer cells via FAT4-dependent Hippo signaling pathway

Breast cancer is ranked as the second leading cause of cancer-related deaths among women. Accumulating evidences have revealed that long non-coding RNAs (lncRNAs) are involved in human tumorigenesis owing to the regulation of essential pathways for tumor initiation and progression. Herein, the current study aimed to explore the regulatory mechanism of lncRNA ZFHX4-AS1 in breast cancer in relation to the Hippo signaling pathway. Initially, microarray analysis was conducted to screen out differentially expressed lncRNAs related to breast cancer. Next, the functional role of lncRNA ZFHX4-AS1 in breast cancer was determined using ectopic expression, knockdown, and reporter assay experiments. Subsequently, lncRNA ZFHX4-AS1, TAF4, TAZ, and YAP expressions were determined, followed by verification of the targeting relationship between lncRNA ZFHX4-AS1 and TAF4. Then cell proliferation, invasion, migration, cell cycle, and apoptosis were measured. Lastly, tumor growth and metastasis were detected by tumor xenograft in nude mice. LncRNA ZFHX4-AS1 was found to be highly expressed while FAT4 was poorly expressed in breast cancer tissues. FAT4 was the target gene of lncRNA ZFHX4-AS1, and lncRNA ZFHX4-AS1 silencing increased FAT4 expressions, while decreased YAP and TAZ expressions. In addition, knockdown of lncRNA ZFHX4-AS1 suppressed breast cancer cell proliferation, migration, and invasion as well as tumor growth, blocked cell cycle entry, while promoted cell apoptosis by inhibiting the Hippo signaling pathway. In conclusion, our findings reveal that lncRNA ZFHX4-AS1 silencing exerts an inhibitory effect on breast cancer development by suppressing the activation of the Hippo signaling pathway via FAT4.