FOXM1介导FSH促卵巢癌血管生成拟态及其分子机制研究

Vasculogenic mimicry(VM)is a new method of cancer angiogenesis. The mechanism of vasculogenic mimicry in ovarian cancer is not fully elucidated. Two important regulation genes in vasculogenic mimicry: VEGFA, MMP2, are both proved as downstream genes of FSH/FSHR and direct targets of FOXM1. We found that FSH and FOXM1 both promoted vasculogenic mimicry in ovarian cancer, FSH-induced FOXM1 nuclear transportation and VEGFA expression were spatio-temporally consistent, knockdown of FOXM1 by siRNA significantly attenuated the increase of VEGFA expression by FSH stimulation. Based on the above, our hypotheses are: (1)FOXM1 is a key gene which mediates FSH-stimulated VEGFA and MMP2 expression, (2)FSH/FSHR promotes vasculogenic mimicry by phosphorylating FOXM1 and triggering its nuclear transportation, then increasing VEGFA and MMP2 expression. Through clinical investigation, in vitro assay and animal model, we expect to characterize the role of FOXM1 in FSH-stimulated vasculogenic mimicry, define the mechanism of FOXM1 transactivation after FSH stimulation, and illuminate the relationship between FOXM1 and vasculogenic mimicry as well as malignant progress in ovarian cancer. The obtained results will form basis for full understand of the mechanism of vasculogenic mimicry and malignant progress, and provide new candidate for molecular targeted therapy in ovarian cancer.

血管生成拟态(VM)是一种新的肿瘤血管生成方式，卵巢癌VM的具体调控机制未完全阐明。文献提示VM的两个重要调控基因（VEGFA、MMP2）同为FSH的下游基因和FOXM1的直接靶基因。我们前期研究发现FSH和FOXM1均能促进卵巢癌VM发生，FSH可促进FOXM1入核转运与VEGFA表达,抑制FOXM1的表达可减弱FSH对VEGFA表达的促进作用。据此提出假设： FSH通过激活FOXM1直接促进VEGFA、MMP2表达，发挥促VM作用。课题拟从分子、细胞、组织、动物水平多层次证明FOXM1在FSH促进VM发生中的关键性作用，揭示FSH激活FOXM1的机制，阐明FOXM1磷酸化对VEGFA、MMP2表达的作用及其与卵巢癌VM发生和恶性进展之间的关系。为揭示卵巢癌VM发生和恶性进展的机制奠定基础。

本项目结合临床病理标本免疫组化、细胞体外实验和分子生物学实验等多个层次的方法，研究了FOXM1在上皮性卵巢癌组织和细胞中的表达情况、FSH对卵巢癌细胞中FOXM1表达的影响及其机制，FSH/FOXM1轴在肿瘤血管生成拟态中的作用，以及靶向FOXM1对卵巢癌顺铂敏感性的影响。我们的研究发现： （1）FOXM1在卵巢癌组织中高表达并与预后不良有关；（2） FSH对FOXM1的表达有明显的促进作用，FOXM1在FSH促卵巢癌细胞血管生成拟态中起到重要的作用，FSH通过磷酸化PKA和ERK促进FOXM1的表达；（3）FSH通过促进FOXM1的表达，增强下游MMP7/VEGFA等效应分子的表达；（4）FOXM1通过调控DNA修复在卵巢癌中对顺铂的细胞毒性有保护作用；（5）靶向FOXM1可以增强卵巢癌细胞对顺铂的敏感性，FOXM1可以调控卵巢癌细胞的DNA修复能力，FOXM1可以转录激活EXO1基因的表达，靶向FOXM1和EXO1可以增强卵巢癌细胞对顺铂的敏感性；（6）设计可穿透细胞膜的ARF短肽可以抑制FOXM1的转录活性，下调FOXM1下游靶基因的表达，并增强卵巢癌细胞对顺铂的敏感性，并在动物实验中得到验证。上述研究结果表明：FOXM1是卵巢癌的一个重要的促癌转录因子，不仅促进卵巢癌细胞的血管生成拟态，也参与调控卵巢癌对顺铂化疗的敏感性，具有潜在的靶向治疗价值。