Upregulation of lncRNA CASC2 Suppresses Cell Proliferation and Metastasis of Breast Cancer via Inactivation of the TGF-β Signaling Pathway

Breast cancer is one of the major malignancies with a mounting mortality rate in the world. Long noncoding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2) has been identified to regulate the initiation and progression of multiple tumorous diseases according to previous studies. However, its biological role has been rarely reported in breast cancer. In the present study, lncRNA CASC2 was found to be significantly downregulated in breast cancer tissues and cell lines using real-time quantitative PCR. Furthermore, gain-of-function assays demonstrated that overexpression of lncRNA CASC2 significantly repressed breast cancer cell proliferation and metastasis. Moreover, CASC2 induced cell cycle arrest and much more early apoptosis of breast cancer. Additionally, based on the above research, we illustrated that inactivation of the TGF-beta signaling pathway was involved in the function of lncRNA CASC2. Collectively, lncRNA CASC2 was a key factor in the tumorigenesis and malignancy of breast cancer, suggesting it may possibly be a potential therapy target for the treatment of breast cancer.