Vitamin D postpones the progression of epithelial ovarian cancer induced by 7, 12-dimethylbenz [a] anthracene both in vitro and in vivo Lizhi Liu,1,* Zhiyong Hu,2,* Hemei Zhang,3 Yongfeng Hou,1 Zengli Zhang,4 Guangming Zhou,5 Bingyan Li1,5 1School of Public Health, Medical College of Soochow University, Suzhou, 2Department of Chronic Disease Management, Lishui Center for Disease Control and Prevention, Lishui, 3Department of Chronic Disease Management, Wenzhou Center for Disease Control and Prevention, Wenzhou, 4Department of Labor Hygiene and Environmental Health, School of Public Health, Soochow University, Suzhou, 5School of Radiation Medicine and Protection, Soochow University, Suzhou, People’s Republic of China *These authors contributed equally to this work 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 (R2=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 β-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. Keywords: vitamin D, epithelial ovarian cancer, DMBA, experimental animal model, chemoprevention, vitamin D receptor

1α,25-Dihydroxyvitamin D3 [1,25(OH)2D3] has been demonstrated to inhibit the growth of cancer cells. However, carboplatin is the most widely used chemotherapeutic agent to treat cancer. We hypothesized that vitamin D may enhance the antiproliferative effects of carboplatin, and tested this hypothesis in ovarian cancer SKOV‑3 cells treated with carboplatin and 1,25(OH)2D3. Cell viability was determined by Cell Counting Kit‑8, while cell cycle distribution, apoptosis, reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were analyzed by flow cytometry. In these experiments, 1,25(OH)2D3 and carboplatin each provided dose‑dependent suppression of SKOV‑3 growth, and synergy was demonstrated between 10 nM 1,25(OH)2D3 and carboplatin. The proportion of cells in G0/G1 phase was markedly reduced by the drug combination, while the proportion of cells in G2/M phase was increased. Apoptosis did not increase in ovarian cancer cells treated with 10 nM 1,25(OH)2D3 alone; however, 1,25(OH)2D3 evidently enhanced carboplatin‑induced apoptosis. Similarly, ROS production was evidently higher and MMP was lower in cells treated with the two drugs than in those treated with each drug alone. The results suggested that 1,25(OH)2D3 suppresses SKOV‑3 growth and enhances the antiproliferative effect of carboplatin. The drugs function synergistically by inducing cell cycle arrest, increasing apoptosis and ROS production, and reducing MMP.

Objective. To investigate the effect of single nucleotide polymorphisms (SNPs) of the key genes in vitamin D metabolic pathway on the serum 25(OH)D level after long-term vitamin D₃ supplementation and provide a theoretical basis for rational vitamin D₃ supplementation in diabetic patients with different genetic backgrounds. Methods. Patients with type 2 diabetes (T2DM) who met the inclusive criteria were given 800 IU of vitamin D₃ daily for 30 consecutive months. Serum 25(OH)D levels was measured at enrollment and every 6 months after enrollment. The average value of four-time measurements represented individual serum 25(OH)D level during vitamin D₃ supplementation. Multiplex TaqMan genotyping was used to determine the distribution of eight candidate SNPs in genes of DHCR7, CYP2R1, CYP27B1, CYP24A1, and VDR, which are key genes in the vitamin D metabolic pathway, in diabetic patients. Results. At baseline, the average serum 25(OH)D level was 22.71±6.87 ng/mL, and 17.9% of patients had a ≥30 ng/mL level. During supplementation, the level of 25(OH)D increased significantly at each time point, and the average 25(OH)D level increased to 30.61±5.04 ng/mL; however, there were 44.6% of patients whose serum 25(OH)D levels were still below 30 ng/mL. In the patients with CYP27B1 (rs10877012) G/T genotype, 71.79% achieved sufficient level of 25(OH)D, which was significantly higher than the other two genotypes (P<0.05). Compared with those with T/T genotype, the RR of the patients with rs10877012 for <30 ng/mL level was 0.544 (95% CI: 0.291-0.917), and the RR after adjusting age and outdoor activity was 0.560 (95% CI: 0.292-0.970). Conclusion. The serum 25(OH)D level in patients with diabetes mellitus after long-term vitamin D₃ supplementation is associated with CYP27B1 polymorphism. Patients with rs10877012 G/T allele have a better response to vitamin D₃ supplementation. Trial Registration. This trial is registered with ChiCTR-IPC-17012657.

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