Adaptive resistance to AR inhibitors in hypoxia by GPT1

项目摘要 雄激素受体（AR）在推动人类前列腺癌的发展中起着重要作用。最 目前针对表达AR（AR+）的转移性癌症的治疗旨在抑制AR，例如， 雄激素剥夺治疗（ADT）或AR抑制剂Enzalutamide（Enza）新治疗。 尽管最近取得了进展，但抗AR治疗（ADT/Enza）的疗效和可持续性仍然有限 由于治疗抗性，这导致肿瘤进展和患者死亡。新的认识， 因此，迫切需要抗性机制。肿瘤缺氧常发生在实体癌中 包括转移性前列腺癌，并且长期以来被认为是治疗抗性的原因。然而，在这方面， 确切的机制尚不清楚。最近，我们发现缺氧通过以下途径赋予ADT/Enza抗性： 代谢重编程（Geng et al，Nat. Comm. 2018）。本项目旨在进一步明确 作用集中于胞质谷氨酸-丙酮酸转氨酶（GPT 1）。在文献中，GPT 1被认为是一种 在葡萄糖和谷氨酰胺代谢途径的交汇点的代谢酶，和许多GPT 1- 下游代谢物是致癌的并且对癌细胞具有细胞保护作用。然而，GPT 1在 赋予抗AR治疗抗性的原因是未知的。我们通过代谢和转录组学鉴定了GPT 1， 我们抗AR细胞的筛选。我们新的试验数据进一步表明，i）GPT 1表达和 活性在缺氧时被ADT/Enza上调，ii）在ADT/Enza中上调是一致的。 抗性细胞、异种移植物、PDX和患者样品，和iii）与缺氧相关的临床GPT 1 mRNA， 不良疾病结局和患者ADT/Enza耐药。在本建议中，我们将确定是否和 前列腺癌细胞如何使用GPT 1在缺氧和体内细胞和肿瘤模型中逃避ADT/Enza， 患者样本。我们将确定GPT 1在Aim中赋予ADT/Enza抗性的分子功能。 1、了解目标2的机制，并确认目标3的临床意义。转移性前列 癌症是美国男性癌症死亡的第二大原因。新的机械理解和 治疗策略是未满足的需求。基于GPT 1的研究可能会带来新的机制见解， 为新的预后和治疗策略铺平道路，以预测药物疗效，监测 抵抗，防止或逆转抵抗。

Project Summary Androgen receptor (AR) plays a fundamental role in driving the development of human prostate cancer. Most current treatments against the AR-expressing (AR+) metastatic cancer aim to inhibit AR, e.g. the standard of care with androgen deprivation therapy (ADT), or new treatment with AR inhibitors enzalutamide (Enza). Despite the recent advance, the efficacy and sustainability of anti-AR-treatments (ADT/Enza) are still limited due to treatment resistance, which leads to tumor progression and patient mortality. New understanding in the mechanism of resistance is therefore urgently needed. Tumor hypoxia occurs frequently in solid cancers including metastatic prostate cancer, and has long been considered a cause of treatment resistance. However, the exact mechanism is unclear. Recently, we have found that hypoxia confers ADT/Enza resistance via metabolic reprogramming (Geng et al, Nat. Comm. 2018). This project is to further clarify the mechanism of action centering on the cytosolic glutamate-pyruvate transaminase (GPT1). In literatures, GPT1 is known as a metabolic enzyme at the converging point of glucose and glutamine metabolic pathways, and many GPT1- downstream metabolites are oncogenic and cytoprotective to cancer cells. However, the role of GPT1 in conferring anti-AR-treatment resistance is unknown. We identified GPT1 through metabolic and transcriptomic screenings of our anti-AR-resistant cells. Our new pilot data further showed that i) GPT1 expression and activity were upregulated by ADT/Enza in hypoxia, ii) the upregulation was consistent across ADT/Enza- resistant cells, xenografts, PDX and patient samples, and iii) clinical GPT1 mRNA correlated with hypoxia, poor disease outcomes, and ADT/Enza resistance in patients. In this proposal, we will determine whether and how prostate cancer cells use GPT1 to evade ADT/Enza in hypoxia and in vivo with cell and tumor models and patient samples. We will determine the molecular function of GPT1 in conferring ADT/Enza resistance in Aim 1, understand the mechanisms in Aim 2, and confirm its clinical significance in Aim 3. Metastatic prostate cancer has the 2nd-leading cause of cancer death in American men. New mechanistic understanding and therapy strategy are unmet needs. The GPT1-based studies here may lead to new mechanistic insights, paving ways to new prognosis and treatment strategies to predict drug efficacy, monitor the onset of resistance, and prevent or reverse resistance.