miR-210在卵巢肿瘤中的功能研究

Hypoxia, the condition of insufficient oxygen supply to tissues, is a hallmark of solid tumors. HIF1α is a major transcription factor regulating genes for cellular adaptation and survival under hypoxia. Recently, miR-210 was found to be the most robustly induced microRNA by HIF1α under hypoxia. Among the miR-210 targets identified to date, several genes are involved in mitochondria electron transfer function, indicating miR-210 as a major factor in regulating mitochondria oxidative phosphorylation and overall cellular energy metabolism under hypoxic conditions. However, miR-210’s functional role in tumorigenesis remains to be controversial. The goal of this proposed project is to elucidate the mechanism of miR-210 function in the tumorigenesis of epithelial ovarian cancer, the most lethal gynecologic cancer. In our preliminary studies, we have found that loss of miR-210 copy number in ovarian cancer cell lines does not lead to decreased expression and attenuated hypoxia induction. We have also identified a new miR-210 target gene, NDUFA4, regulating mitochondria respiratory function. In the proposed studies, we will utilize biochemical and genetic approaches to dissect miR-210 function in regulation mitochondrial respiration and the mechanism of a positive feedback regulation to HIF1α, linking oxidative phosphorylation and glycolysis. In addition, we will establish a novel miR-210 ovarian cancer mouse model to elucidate its function in ovarian cancer tumorigenesis. At the end of the study, we will have a clear understanding of miR-210’s function in ovarian cancer tumorigenesis and its contribution to tumor hypoxia phenotypes.

缺氧是实体瘤的一个重要标志。最近，miR-210被发现是HIF1α在缺氧条件下诱导最强烈的microRNA。在迄今发现的miR-210靶基因中，有多个是在线粒体电子转移链上发挥重要功能的基因，表明miR-210是调节线粒体氧化磷酸化和缺氧条件下细胞能量代谢的一个重要因素。然而，miR-210在肿瘤发生中的作用仍富有争议。本课题的目标是阐明miR-210功能在上皮性卵巢肿瘤发生中所起的作用及其分子机理。我们将分析miR-210功能在调节线粒体呼吸中的作用，并且阐明一个miR-210对HIF1α的正反馈调节的分子机制，从而揭示一个把细胞氧化磷酸化和糖酵解连接起来的一个新途径。此外，我们还将建立一个全新的miR-210卵巢癌小鼠模型，以阐明其在卵巢癌肿瘤发生中的功能。通过本课题我们将清楚地了解miR-210在卵巢癌肿瘤发生中的功能，并阐明miR-210对肿瘤在缺氧微环境下细胞能量代谢转换的作用。

卵巢癌是女性生殖系统常见的恶性肿瘤之一，死亡率高居妇科肿瘤首位，对妇女生命和健康造成严重威胁。上皮性卵巢癌（EOC）组织中含有缺氧区域，这些缺氧微环境能够促进 EOC 的血管生成，转移和增加肿瘤细胞的免疫耐受性，直接导致降低EOC 病人的生存率。因此，针对肿瘤缺氧的治疗手段有希望有效地消除对于化疗和放疗具有耐受性的癌细胞。miR-210是低氧条件下诱导表达最明显的微小RNA，所以我们假设深入理解miR-210功能可能为卵巢癌的治疗带来新的方法。.本课题在研究期间发现 EOC 肿瘤细胞主要通过miR-210/NDUFA4轴来抑制急性低氧条件下线粒体有氧呼吸功能，并且建立了脂质体纳米微球（micelle）在体内递送miR-210反向寡核酸以抑制xenograft肿瘤中miR-210表达而进行肿瘤治疗的策略，发现对EOC肿瘤的生长有显著抑制作用，提示miR-210是 EOC代谢靶向治疗的潜在的新治疗靶点。此外，我们建立了肿瘤领域中首个具有卵巢肿瘤背景的 miR-210 条件性基因敲除小鼠，发现miR-210基因的缺失显著降低了肿瘤的发生，提示miR-210对肿瘤的发生有促进作用，同时也支持了我们在卵巢癌细胞株中靶向miR-210阻碍细胞生长的实验结果。