1α,25‑Dihydroxyvitamin D3 restrains stem cell‑like properties of ovarian cancer cells by enhancing vitamin D receptor and suppressing CD44.

Scientific evidence linking vitamin D with various cancer types is growing, but the effects of vitamin D on ovarian cancer stem cell‑like cells (CSCs) are largely unknown. The present study aimed to examine whether vitamin D was able to restrain the stemness of ovarian cancer. A side population (SP) from malignant ovarian surface epithelial cells was identified as CSCs, in vitro and in vivo. Furthermore, 1α,25‑dihydroxyvitamin D3 [1α,25(OH)2D3] treatment inhibited the self‑renewal capacity of SP cells by decreasing the sphere formation rate and by suppressing the mRNA expression levels of cluster of differentiation CD44, NANOG, OCT4, SOX2, Krüppel‑like factor 4 and adenosine triphosphate binding cassette subfamily G member 2. Additionally, 1α,25(OH)2D3 treatment decreased the expression of Cyclin D1, whereas it increased the expression of β‑catenin and vitamin D receptor (VDR). Notably, immunofluorescence staining verified that 1α,25(OH)2D3 promoted the expression of β‑catenin in the cytoplasm. Furthermore, vitamin D3 delayed the onset of tumor formation derived from injection of ovarian CSCs to nude mice, by reducing CD44 and enhancing β‑catenin expressions in vivo. In conclusion, 1α,25(OH)2D3 restrains the stem cell‑like properties of ovarian cancer cells by enhancing the expression of VDR, by promoting the expression of β‑catenin in the cytoplasm, and by suppressing the expression of CD44. These findings provide a novel insight into the functions of vitamin D in diminishing the stemness of cancer CSCs.