卵巢癌在发达国家中病死率居妇科生殖道恶性肿瘤之首位。随着手术技术的发展和化疗药物的更新，卵巢癌患者的5年生存率仍没有显著提高，因此探求常规治疗方法之外的免疫治疗和分子靶向基因治疗方法成为目前卵巢癌治疗的研究热点问题。近期有研究表明NK4除了通过拮抗肝细胞生长因子和抑制血管生成双重作用抑制肿瘤的生长和转移之外，还具有提高机体抗肿瘤免疫作用，但其机制尚不清楚。肿瘤免疫与肿瘤的发生发展关系密切，免疫抑制酶IDO通过参与免疫耐受可促进卵巢癌腹腔内转移进而促进卵巢癌的发展。本课题前期预实验结果证明NK4在卵巢癌细胞SKOV-3中可抑制IDO表达，本研究拟通过基因转染、蛋白检测、流式细胞仪技术、种植瘤模型建立、免疫组织化学等方法证明NK4通过抑制IDO表达在卵巢癌中增强抗肿瘤免疫作用，并研究其分子机制，为卵巢癌免疫治疗和分子靶向基因治疗提供新思路。

Ovarian cancer is the leading cause of cancer death among female genital malignancies in developed countries. The five-year survival rate has not been improved with the development of surgical technique and improvement of chemotherapeutic drugs. Therefore, researches are focusing on investigating the immunotherapeutic and molecular gene therapeutic strategies. It has been reported recently that NK4 has the ability to enhance host anti-tumor immunity distinct from its bifunctional activity of HGF antagonist and anti-angiogenesis. However, the mechanism of it is still unknown. Anti-tumor immunity has the key role in the development and progression of malignancies. Immunosuppressive enzyme indoleamine 2, 3-dioxygenase (IDO) takes part in the induction of immunotolerance to promote peritoneal dissemination and tumor progression of ovarian cancer. Our preliminary results show that NK4 inhibits IDO expression in the ovarian cancer cell line SKOV-3 and the purpose of this research is to prove our hypothesis that NK4 can enhance anti-tumor immunity via inhibition of IDO expression in SKOV-3 and to elucidate the mechanism of NK4 inhibiting IDO expression in SKOV-3. The results of this research are expected to investigate novel immunotherapeutic and molecular targeted gene therapeutic strategies for ovarian cancer.