观察流行病研究提示维生素D缺乏是卵巢癌发病的危险因素。细胞和动物实验也证实维生素D可以抑制卵巢癌的发生。但是维生素D干预的人群试验研究得出的结论却不一致。课题组前期研究发现活性维生素D降解酶CYP24A1在上皮型卵巢癌患者肿瘤组织表达明显升高，而且活性维生素D干预可以引起CYP24A1表达诱导性升高。受上述实验结果的启发，课题组认为减少CYP24A1表达可能会提高维生素D对上皮型卵巢癌增殖和浸润的抑制作用。为验证这一科学问题，本项目使用CRISPR/Cas9技术减少CYP24A1的表达，通过细胞和动物实验以及人上皮型卵巢癌患者术后的肿瘤组织等研究体系，观察CYP24A1对上皮型卵巢癌增殖和浸润能力的影响。同时利用ChiP和pull-down 质谱技术研究与CYP24A1相互作用的关键基因和蛋白质，进一步完善维生素D与卵巢癌联系的理论，为维生素D更合理地用于卵巢癌防治提供理论和实验依据。

The observed epidemiologic studies suggest that deficiency of vitamin D is the risk of epithelial ovarian cancer (EOC). Researches from in vitro and in vivo demonstrate that vitamin D inhibit cell proliferation and migration of EOC. However, some studies on randomized controlled trial agree to differ on this point. Our preliminary results suggest that overexpression CYP24A1, key enzyme of vitamin D metabolic, was inversely associated with of malignancy grade of EOC. Moreover, 1 alpha,25(OH)2D3, active of vitamin D, increased the mRNA expression of CYP24A1 with 15000 times in malignant transformation of ovarian epithelial cells. We hypothesis whether reduced-expression of CYP24A1 enhances effect of vitamin D on development and aggressiveness of EOC. Therefore, in the current project, we are aiming to systematically investigate the effect of CYP24A1 on the proliferation and migration of SKOV-3 and OVCAR-3 cells. We investigate that knockdown expression of CYP24A1 used by CRISPR/Cas9 enhanced 1alpha,25(OH)2D3 -mediated antitumor effect in ovarian cancer cells in vitro and tumorigenicity in vivo. Tumor tissues of patients with EOC are used to verify that inhibition of CYP24A1 enhances 1 alpha,25(OH)2D3 -mediated antitumor effect. We also analysis the change of components (CYP27B1and vitamin D receptor) in vitamin D endocrine system in both increased and decreased expression of CYP24A1. In addition, chromatin immunoprecipitation and pull-down mass spectrometry are used to reveal that key different genes and proteins are correlated with both endogenous and inductive CYP24A1. Our results will be helpful to understand the molecular mechanisms underlying the therapeutic role of vitamin D in development and aggressiveness of EOC, which will provide new clues to find the new measures of preventing and treating ovarian cancer.