Apatinib Inhibits Stem Properties and Malignant Biological Behaviors of Breast Cancer Stem Cells by Blocking Wnt/β-catenin Signal Pathway through Downregulating LncRNA ROR

Background: Cancer stem cells could influence tumor recurrence and metastasis. Objective: To develop a new effective treatment modality targeting breast cancer stem cells (BCSCs) and to explore the role of Apatinib in BCSCs. Methods: BCSCs were isolated from MDA-MB-231 cells by the immune magnetic beads method. BCSCs were treated with Apatinib, lentiviral plasmids (lncRNA ROR), and iCRT-3 (Wnt pathway inhibitors). Viability, colony numbers, sphere numbers, apoptosis, migration, invasion of BCSCs were detected by MTT, colony formation, tumorsphere, flow cytometry, wound-healing, transwell assays, respectively. The expressions of markers (ABCG2, CD44, CD90, and CD24), epithelial-mesenchymal transition (EMT)-related molecules (Ecadherin, N-cadherin, Vimentin, MMP-2, MMP-9), and Wnt/β-catenin pathway-related proteins (Wnt3a, Wnt5a, β-catenin) in breast cancer stem cells were determined by performing Western blot and qRT-PCR analysis. Results: Apatinib decreased the viability and colony numbers of BCSCs in a concentration-dependent manner, and it also reduced sphere numbers, suppressed migration, invasion and lncRNA ROR expression, and induced apoptosis of BCSCs. However, these results were partially reversed by lncRNA ROR overexpression. Apatinib suppressed stem property, EMT process, and Wnt/β-catenin pathway in BCSCs, which was partially reversed by lncRNA ROR overexpression. Moreover, lncRNA ROR overexpression increased the colony and sphere numbers and promoted the cell viability, apoptosis inhibition, migration, and invasion of BCSCs, but these effects were partially reversed by iCRT-3. LncRNA ROR overexpression increased the stem property, EMT process, and Wnt/β-catenin pathway, which were partially counteracted by iCRT-3. Conclusion: Apatinib inhibited stem property and malignant biological behaviors of BCSCs by blocking the Wnt/β-catenin signal pathway through down-regulating lncRNA ROR.