Iron, Ferroptosis and Ovarian Cancer

摘要 在美国，卵巢癌是导致死亡人数最多的妇科癌症。令人沮丧的预后 在过去的30年里，晚期疾病患者的变化仍然很小。需要新的方法。 在上一个资助周期中，我们的实验室发现卵巢肿瘤细胞和卵巢癌的启动 细胞(癌症干细胞)获得和保留的铁显著多于非恶性细胞--a 这种现象我们称之为“铁瘾”。这种增强的铁获取和保留促进了 卵巢癌。然而，我们发现，这种增强的铁滞留也使卵巢癌细胞 对引发铁下垂的药物非常敏感，铁下垂是一种铁依赖的细胞死亡形式。 虽然铁是铁性上睑下垂的中心，但人们对铁是如何导致这种易感性知之甚少的。在这 应用程序中，我们检验了以下假设，即铁在 以及我们最近发现的铁下垂途径中的新靶点可能会导致 卵巢癌的成功干预。我们处理这个问题有两个广泛的目标：1)更好地 了解铁在铁性下垂中的作用；2)确定特定的靶点，以增强铁的活性 铁下垂诱导剂通过在卵巢癌本身和在卵巢癌中培养前铁下垂通路 卵巢癌微环境。 我们的具体目标就是针对这些目标。在目标1中，我们继续进行铁下垂诱因的试点观察 触发信号网络，促进多不饱和过氧化脂质(近端)的产生 铁性下垂的“刽子手”)。我们认为，铁性下垂是通过1)转录激活的 铁依赖的前铁链蛋白，增加不稳定的铁，以及2)前馈环路的参与， 禁用铁依赖的脂质去饱和酶SCD1，我们最近展示了对铁下垂的保护作用。我们 将使用细胞培养和卵巢癌小鼠模型来验证我们的假设。在目标2中，我们使用状态- 最先进的NanoSIMS成像和MALDI-MSI来探测铁链死亡信号的起源部位，共同- 用氧化的脂类定位铁，这是铁性下垂的典型特征。我们使用以下工具确认和扩展这些发现 细胞器--靶向铁络合剂。在目标3中，我们评估了卵巢肿瘤微环境中的细胞如何改变 卵巢癌对引起铁性下垂的药物的反应。我们专注于巨噬细胞和成纤维细胞， 我们在初步研究中发现，与卵巢癌转移密切相关的细胞 旁分泌影响卵巢铁性下垂程度的脂和铁代谢 癌细胞。 总的来说，这些实验将增强对卵巢癌铁代谢的了解，探索调控 以前没有与铁性下垂相关的通路，并定义了肿瘤微环境对 铁性下垂-将有助于在卵巢癌治疗中更有效地使用铁性下垂诱导剂。

Summary Ovarian cancer causes more deaths than any other gynecologic cancer in the US. The dismal prognosis of patients with advanced disease remains little changed in the past 30 years. New approaches are needed. In the last grant cycle, our laboratory discovered that ovarian tumor cells and ovarian cancer tumor-initiating cells (`cancer stem cells') acquire and retain substantially more iron than their non-malignant counterparts – a phenomenon we named “iron addiction”. This enhanced iron acquisition and retention facilitates growth of ovarian cancer. However, we found that this enhanced iron retention also makes ovarian cancer cells exquisitely susceptible to drugs that trigger ferroptosis, an iron-dependent form of cell death. Although iron is central to ferroptosis, little is known about how iron actually confers this susceptibility. In this application, we test the hypothesis that iron plays critical, novel, and previously undescribed roles in ferroptosis, and that new targets in the ferroptosis pathway that we recently discovered might lead to successful interventions in ovarian cancer. We approach this problem with two broad objectives: 1) to better understand the role of iron in ferroptosis; 2) to identify specific targets that will enhance the activity of ferroptosis inducers by fostering pro-ferroptotic pathways both in ovarian cancers themselves and in the ovarian cancer microenvironment. Our Specific Aims are directed at these goals. In Aim 1, we pursue pilot observations that ferroptosis inducers trigger a signaling network that fosters the generation of polyunsaturated lipid peroxides (the proximal `executioners' of ferroptosis). We propose that ferroptosis is propagated by both 1) transcriptional activation of iron-dependent pro-ferroptotic proteins that increase labile iron, and 2) engagement of a feed forward loop that disables the iron-dependent lipid desaturase SCD1 that we recently showed protects against ferroptosis. We will test our hypothesis using cell culture as well as murine models of ovarian cancer. In Aim 2, we use state- of-the-art NanoSIMS imaging and MALDI-MSI to probe the sites of origin of the ferroptotic death signal, co- localizing iron with the oxidized lipids that typify ferroptosis. We confirm and expand these findings using organelle-targeted iron chelators. In Aim 3, we assess how cells in the ovarian tumor microenvironment modify the response of ovarian cancers to drugs that induce ferroptosis. We focus on macrophages and fibroblasts, cells that are critically involved in ovarian cancer metastasis, which we discovered in pilot studies exert paracrine effects on lipid and iron metabolism that dramatically affect the degree of ferroptosis in ovarian cancer cells. Collectively, these experiments will enhance knowledge of ovarian cancer iron metabolism, explore regulatory pathways not previously linked to ferroptosis, and define the contribution of the tumor microenvironment to ferroptosis - efforts that will help to direct more effective use of ferroptosis inducers in ovarian cancer therapy.