The role of ghrelin in cisplatin-induced infertility

描述(申请人提供)：接受顺铂化疗的男性癌症患者中，超过50%会长期不育。这是一个非常令人担忧的问题，因为这些患者中有许多是儿童或年轻人，他们在癌症中幸存下来，希望以后能生育。然而，目前还没有针对化疗引起的不孕不育的药物治疗。生殖细胞凋亡是顺铂致不育的一个关键因素，而促凋亡介质P53和核因子kappaB的激活也参与了这一过程。Ghrelin是一种新的激素，具有抗细胞凋亡的特性，并在其他组织中抑制核因子？B。我们的初步研究表明，它可以减少顺铂诱导的生殖细胞凋亡。然而，Ghrelin在这种情况下的作用机制(S)及其对生育的影响尚不清楚。这项应用的长期目标是：a)开发新的策略来保护接触化疗药物的个人的生育能力，以及b)建立在这种情况下Ghrelin的影响的调节机制。假设：我们假设Ghrelin可以预防顺铂诱导的不育，并下调顺铂诱导的睾丸核因子？B和P53的激活。我们的具体目标是：1)确定Ghrelin对顺铂诱导的不育的影响；2)确定Ghrelin和顺铂对睾丸P53和NF-B活性的影响。设计和方法：在我们的顺铂诱导的性腺损伤的啮齿动物模型中，我们观察到Ghrelin阻止了顺铂诱导的睾丸细胞凋亡和核因子？B的激活。我们现在提议通过开发一种新的转基因小鼠系来测试ghrelin和顺铂对生育力、p53和NF？B活性的影响。该转基因小鼠系已经被设计成在含有NF？B共识结合位点的启动子的控制下表达荧光素酶和绿色荧光蛋白。基于我们成人模型中产生的数据，我们还将建立一个青春期前不孕症模型的可行性。意义：在癌症化疗的长期幸存者中，超过80%的儿童和男性的主要生活方式是生育问题。因此，研究Ghrelin对生育力、生殖细胞凋亡及核因子B和P53活性的影响，对于寻找预防或逆转顺铂等化疗药物所致不孕症的方法具有重要意义。这样的追求将与保持长期生育力相关，这些男性暴露在化疗药物、化学物质或辐射中。与公共卫生有关：接受癌症化疗的儿童和男子有相当大比例的生殖器官受损，导致不孕不育。我们目前还没有办法预防或预测谁会在接受化疗后不育；然而，我们的初步工作首次表明，一种名为Ghrelin的新激素可以防止这种因化疗而对生殖器官造成的损害。我们在这里提出的实验将确定Ghrelin对生育的影响，并将引导我们开发预防或治疗不孕不育的新方法。

DESCRIPTION (provided by applicant): More than 50% of male cancer patients subjected to cisplatin-based chemotherapy will suffer from long-term infertility. This is a significant concern because many of these patients are children or young men who survive their cancer and would hope to later reproduce. However, medical treatment for chemotherapy-induced infertility is not currently available. A key factor in the development of cisplatin-induced infertility is germ cell apoptosis, and activation of the proapoptotic mediators p53 and Nuclear Factor kappa B (NF?B) has been implicated in its development. Ghrelin, a novel hormone, has anti-apoptotic properties and suppresses NF?B in other tissues. Our preliminary studies indicate that it reduces cisplatin-induced apoptosis in germ cells. However, ghrelin's mechanism(s) of action in this setting and its effect on fertility are unknown. The long-term objectives of this application are: a) to develop new strategies for preserving fertility in individuals exposed to chemotherapeutic drugs and b) to establish the mechanisms mediating ghrelin's effects in this setting. Hypothesis: We hypothesize that ghrelin will prevent cisplatin-induced infertility and downregulate testicular NF?B and p53 activation induced by cisplatin. Our specific aims are: 1) To determine the effect of ghrelin administration on cisplatin-induced infertility and 2) To establish the effects of ghrelin and cisplatin on testicular p53 and NF?B activity. Design and methods: In our rodent model of cisplatin-induced gonadal damage we have observed that ghrelin prevents cisplatin-induced testicular apoptosis and NF?B activation. We are now proposing to test the effects of ghrelin and cisplatin on fertility, p53 and NF?B activity by exploiting a new transgenic mouse line that has been engineered to express luciferase and green fluorescent protein under control of a promoter that contains NF?B consensus binding sites. Based on the data generated in our adult model, we also will establish the feasibility of a prepubertal model of infertility. Significance: Fertility is the major life-style concern in more than 80% of children and men who are long-term survivors of cancer chemotherapy. Establishing the mechanisms and effects of ghrelin on fertility, germ cell apoptosis and NF?B and p53 activity in this setting will be important to develop methods to prevent or reverse the infertility caused by cisplatin and other chemotherapeutic agents. Such a pursuit will have relevance for maintaining long-term fertility in men who are exposed to chemotherapeutic agents, chemicals or radiation. PUBLIC HEALTH RELEVANCE: A significant proportion of children and men receiving chemotherapy for the treatment of cancer suffer damage to their reproductive organs leading to infertility. We currently do not have a way to prevent or predict who will become infertile after receiving chemotherapy; however, our preliminary work shows for the first time that a new hormone called "ghrelin" prevents this damage to the reproductive organs due to chemotherapy. The experiments we propose here will determine the effects of ghrelin on fertility and will lead us to the development of new ways to prevent or treat infertility.