1α,25-hydroxyvitamin D/VDR suppresses stem-like properties of ovarian cancer cells by restraining nuclear translocation of β-catenin

Several studies have indicated that 1α,25-hydroxyvitamin D [1α,25(OH)₂D₃] inhibits the proliferation and metastasis of cancer cells through suppressing epithelial-mesenchymal transition. However, its influence on the translocation of β-catenin remains unclear. In the present study, ovarian cancer stem-like cells (CSCs), including side population (SP) and CD44⁺/CD117⁺, were isolated from mouse ovarian surface epithelial (MOSE) cells with malignant transformation. The findings revealed that 1α,25(OH)₂D₃ obviously reduced the sphere-forming ability, as well as Notch1 and Klf levels. Moreover, the limiting dilution assay demonstrated that 1α,25(OH)₂D₃ effectively hindered the tumorigenesis of ovarian CSCs in vitro. Notably, treatment with 1α,25(OH)₂D₃ led to a substantial increase in the cell population of CD44⁺/CD117⁺ forming one tumor from ≤ 100 to 445 in orthotopic transplanted model, indicating a pronounced suppression of stemness of ovarian CSCs. Additionally, 1α,25(OH)₂D₃ robustly promoted the translocation of β-catenin from the nuclear to the cytoplasm through directly binding to VDR, which resulted in decreased levels of c-Myc and CyclinD1 within late MOSE cells. Taken together, these results strongly supported the role of 1α,25(OH)₂D₃ in inhibiting stem-like properties in ovarian cancer cells by restraining nuclear translocation of β-catenin, thereby offering a promising target for cancer therapeutics.