脂肪组织分泌肽OATSP2调控卵巢上皮癌恶性进展的作用及机制研究

OATSP2, a new active peptide, secreted by omental adipose tissue, which is identified by peptidomics techniques. It is highly conserved among species and high stability. Previous studies have not reported about OATSP2, our previous study preliminary indicated that OATSP2 can inhibit the proliferation, invasion and metastasis of ovarian cancer in vitro and in vivo. FASN was found to be a potential target of OATSP2 by pull-down assay. FASN, as a key enzyme in fatty acid synthesis, play as important regulatory role in many cancer. Accordingly, we propose a hypothesis that OATSP2 inhibits the expression of FASN and regulates the malignant behavior of ovarian cancer cell. In this study we will further systematically evaluate the function of OATSP2 both in vitro and in vivo. Using FASN as a mechanism clue, we will demonstrate the interaction between OATSP2 and FASN through physical methods and rescue experiments. We also optimize the stability and targeted modification of OATSP2 to enhance its effect in inhibiting tumor. If successful, this study may provide a new method for ovarian cancer treatment.

OATSP2是我们借助多肽组学从腹腔大网膜脂肪组织分泌成分中获得的一条新的活性肽，具有物种间高度保守且稳定性高的特征。既往未有研究报道，前期通过体内体外实验初步证实OATSP2具有抑制卵巢上皮癌细胞增殖及侵袭转移的作用，pull-down实验揭示FASN可能是其发挥作用的关键分子，FASN作为脂肪酸合成关键酶，在多种肿瘤中扮演着重要的调控角色。据此我们提出“OATSO2通过抑制FASN调控卵巢上皮癌恶性行为”的假说。本研究拟通过体外和体内两方面系统评估多肽OATSP2的作用。以FASN为机制线索，通过物理学方法、挽救实验等多方面论证OATSP2与FASN蛋白之间的关系，并通过对其稳定性和靶向性等理化修饰以提高其抗肿瘤应用的可行性。如获成功，本研究有望为临床治疗卵巢癌提供新手段。

卵巢上皮癌是一种致死率较高的肿瘤，研究表明，卵巢癌可优先转移到大网膜脂肪组织。因此大网膜脂肪组织与卵巢癌的关系需要我们进一步探讨。OATSP2（Omental Adipose Tissue Secreted Peptide 2）是我们前期筛选的低表于高级别浆液性卵巢癌患者（HGSOC）和高表达于良性浆液性卵巢囊肿（BSOC）网膜脂肪组织分泌的多肽。体外功能实验表明，OATSP2可明显抑制SKOV3及OVCAR3的增殖、迁移能力，并明显促进其凋亡。除此之外，OATSP3可显著抑制卵巢癌细胞SKOV3和OVCAR3在网膜脂肪组织的粘附。裸鼠皮下移植瘤和腹腔移植瘤模型显示，OATSP2腹腔注射可显著抑制卵巢癌在体内的生长速度。裸鼠体内毒性试验结果显示OATSP2对机体的肝肾功能无明显影响。多肽Pull down实验及质谱结果显示，真核翻译起始因子2B亚基（eukaryotic translation initiation factor 2B subunit epsilon，eIF2B5）可能是介导OATSP2发挥抑癌作用的重要分子。WB及IF共定位实验证实OATSP2可能通过与eIF2B5结合。进一步IP实验证实eIF2B5确实是与OATSP2结合的蛋白，OATSP2结合eIF2B5后通过eIF2α抑制总蛋白合成并促进肿瘤细胞死亡。因此OATSP2可作为卵巢上皮癌治疗的一种候选药物。