Knockdown of CYP24A1 Aggravates 1α,25(OH)2D3-Inhibited Migration and Invasion of Mouse Ovarian Epithelial Cells by Suppressing EMT.

Epithelial-mesenchymal transition (EMT) bestows cancer cells with motile and invasive properties. But for ovarian tissues, EMT plays a physiological role in the postovulatory repair of ovary surface epithelial (OSE) cells. Accumulating data indicated that 1α,25(OH)2D3 decreased both the migration and invasion of various cancer cells by suppressing EMT. However, it remains unclear whether 1α,25(OH)2D3 inhibits the process of EMT during different stages of oncogenic transformation in mouse OSE (MOSE) cells. In present study, a spontaneous malignant transformation model of MOSE cells at three sequential stages (early, intermediate and late) was established in vitro first and then subjected to 1α,25(OH)2D3 treatment to investigate the effect of 1α,25(OH)2D3 on the oncogenic transformation of MOSE cells. We found that 1α,25(OH)2D3 significantly reduced the proliferation and invasion of late malignant transformed MOSE (M-L cells) cells by inhibiting EMT both in vitro and in vivo, but not in intermediate transformed (M-I) cells. Importantly, we found that the levels of CYP24A1 in M-I cells were dramatically higher than that in M-L cells following treatment with 1α,25(OH)2D3. Furthermore, we demonstrated that, in both M-I and M-L cells with CYP24A1 knockdown, 1α,25(OH)2D3 suppressed the proliferation and invasion, and reduced the expression of N-cadherin, Vimentin, ß-catenin and Snail. In addition, knockdown of CYP24A1 suppressed EMT by increasing E-cadherin while decreasing N-cadherin, Vimentin, ß-catenin and Snail. These findings provide support for inhibiting CYP24A1 as a potential approach to activate the vitamin D pathway in the prevention and therapy of ovarian cancer.

1α,25­Dihydroxyvitamin D3 restrains stem cell­like 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 cell­like 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,25­dihydroxyvitamin D3 [1α,25(OH)2D3] treatment inhibited the self­renewal 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, Krüppel­like 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 ß­catenin and vitamin D receptor (VDR). Notably, immunofluorescence staining verified that 1α,25(OH)2D3 promoted the expression of ß­catenin 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 ß­catenin expressions in vivo. In conclusion, 1α,25(OH)2D3 restrains the stem cell­like properties of ovarian cancer cells by enhancing the expression of VDR, by promoting the expression of ß­catenin 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.

1α,25(OH)2D3 Suppresses the Migration of Ovarian Cancer SKOV-3 Cells through the Inhibition of Epithelial-Mesenchymal Transition.

Ovarian cancer is the most lethal gynecological malignancy due to its high metastatic ability. Epithelial-mesenchymal transition (EMT) is essential during both follicular rupture and epithelium regeneration. However, it may also accelerate the progression of ovarian carcinomas. Experimental studies have found that 1α,25-dihydroxyvitamin-D3 [1α,25(OH)2D3] can inhibit the proliferation of ovarian cancer cells. In this study, we investigated whether 1α,25(OH)2D3 could inhibit the migration of ovarian cancer cells via regulating EMT. We established a model of transient transforming growth factor-ß1(TGF-ß1)-induced EMT in human ovarian adenocarcinoma cell line SKOV-3 cells. Results showed that, compared with control, 1α,25(OH)2D3 not only inhibited the migration and the invasion of SKOV-3 cells, but also promoted the acquisition of an epithelial phenotype of SKOV-3 cells treated with TGF-ß1. We discovered that 1α,25(OH)2D3 increased the expression of epithelial marker E-cadherin and decreased the level of mesenchymal marker, Vimentin, which was associated with the elevated expression of VDR. Moreover, 1α,25(OH)2D3 reduced the expression level of transcription factors of EMT, such as slug, snail, and ß-catenin. These results indicate that 1α,25(OH)2D3 suppresses the migration and invasion of ovarian cancer cells by inhibiting EMT, implying that 1α,25(OH)2D3 might be a potential therapeutic agent for the treatment of ovarian cancer.

Vitamin D postpones the progression of epithelial ovarian cancer induced by 7, 12-dimethylbenz [a] anthracene both in vitro and in vivo.

PURPOSE: Ovarian cancer is the most lethal malignancy of the female reproductive system, and the prevention and treatment of ovarian carcinoma are still far from optimal. Epidemiological studies reported that ovarian cancer risk was inversely associated with low level of 25-hydroxy vitamin D [25(OH)]. Therefore, this study focuses on exploring the chemoprevention of vitamin D on epithelial ovarian cancer induced by 7, 12-dimethylbenz [a] anthracene (DMBA). METHODS: The mouse ovarian surface epithelial cells were isolated from estrus mice by mild trypsinization and maintained in completed culture medium by repeated passaging. The malignant transformation of mouse ovarian surface epithelial cells was induced by DMBA in vitro. DMBA was directly injected into the bursa of mouse ovary to produce optimized in vivo ovarian cancer model. RESULTS: The results indicate that 1α,25 dihydroxyvitamin D3 may delay malignant transformation of mouse ovarian surface epithelial cells induced by DMBA and significantly decreased the colony formation rate from 18.4% to 3.2% (P<0.05). There was a negative correlation between incidence of DMBA-induced tumor and 25-hydroxy vitamin D level (R (2)=0.978, P<0.05). Vitamin D3 can delay the progression of ovarian cancer induced by DMBA, and the administration of vitamin D3 during the whole process worked more effectively than the administration only during tumor initiation or promotion. Moreover, we found the vitamin D3 increased the expression of E-cadherin and vitamin D receptor while it decreased the expression of ß-catenin. CONCLUSION: We succeeded in establishment of epithelial ovarian cancer models both in vitro and in vivo. The DMBA-implanted model in mice yields high incidence and specificity of epithelial derived tumors. We also found that vitamin D delays the progression of ovarian cancer. However, spontaneous epithelial ovarian carcinoma models are still to be explored for testing the preventive effects of vitamin D on epithelial ovarian cancer.