Rational Combination Therapy with PARP Inhibitors in Triple Negative Breast Cancer

三阴性乳腺癌(TNBC)是乳腺癌的一种亚型，经常复发和 导致的结果比激素受体阳性亚型的患者更差。PARP目前是 最有希望的TNBC药物靶点和多种PARP抑制剂(PARPI)已经开发出来， 在临床试验中得到测试。虽然PARPI在携带BRCA突变的患者中显示出更高的应答率， 仍然有很高比例的BRCA突变携带者对PARPI没有反应。因此， 制定策略，使PARPI治疗更有效，并确定生物标志物进行分层 病人是至关重要的。我们最近在《自然医学》(2016)上发表的文章显示，对于反应性 氧物种c-Met在Y907与PARP1相互作用并磷酸化。此外，我们还演示了 C-Met介导的磷酸化是PARPI耐药的关键，c-Met抑制剂增敏 TnBC细胞转化为PARPI。我们研究的长期目标是开发有效的治疗方法 TNBC的战略。为此，我们将寻求新的生物标志物和治疗策略来改进 PARPI的疗效。我们假设PARP1蛋白受其磷酸化调控，并且 PARP1的磷酸化状态和相应的激酶的表达 磷酸化的PARP1将作为联合治疗的合适生物标志物。多重 激酶可以使相同的底物磷酸化，导致信号串扰。此外，TNBC是一种 异质性疾病，不同的激酶在不同的TNBC中起着重要的作用。因此， 我们还假设，与c-Met类似，其他蛋白激酶也具有调节PARP1的功能 在TNBC中通过磷酸化的活性。我们将研究的潜在分子是EGFR，它也 直接与PARP1相互作用并将其磷酸化。我们将研究这些激酶在体内的作用。 PARP1调控与PARPI抗性因此，我们提出了以下三个目标：目标1 系统验证c-Met介导的磷酸化在PARPI耐药中的意义 小鼠模型和TNBC患者样本；目的2.确定EGFR介导的PARP的作用 磷酸化在TNBC对PARPI耐药中的作用；目的3.确定c-Met和EGFR的作用 PARPI在TNBC耐药中的相互作用如果我们的提议成功，几个磷酸化位点 PARP1可作为指导PARPI联合治疗的生物标志物 这是一种激酶抑制剂。我们将特别关注c-Met和EGFR，因为这些激酶的抑制剂是 目前在临床或临床试验中使用，允许我们的生物标记物引导的更快进展 将联合疗法纳入临床试验的基本原理。

Triple negative breast cancer (TNBC) is one subtype of breast cancer that frequently relapses and leads to worse outcome than patients with hormone receptor-positive subtypes. PARP is currently the most promising drug target for TNBC, and multiple PARP inhibitors (PARPi) have been developed and tested in clinical trials. Although PARPi show higher response rate in patients carrying BRCA mutations, there are still high percentage of BRCA mutations carried patients does not respond to PARPi. Thus, developing strategies to make PARPi treatment more effective and to identify biomarkers to stratify patients is critical. Our recent publication in Nature Medicine (2016) showed that in response to reactive oxygen species, c-Met interacts with and phosphorylates PARP1 at Y907. Moreover, we demonstrated that c-Met-mediated phosphorylation is critical for PARPi resistance, and that c-Met inhibitors sensitize TNBC cells to PARPi. The long-term goal of our research is to develop the effective therapeutic strategies for TNBC. To this end, we will seek the novel biomarkers and treatment strategies to improve the efficacy of PARPi. We hypothesized that PARP1 protein is regulated by its phosphorylation, and that phosphorylation status of PARP1 and the expression of the corresponding kinases that phosphorylate PARP1 will serve as appropriate biomarkers for combinational treatment. Multiple kinases can phosphorylate the same substrates, resulting in signal crosstalk. Also, TNBC is a heterogeneous disease, and the distinct kinases play an important role in different TNBC. Therefore, we also hypothesize that similar to c-Met, other protein kinases also have functions to regulate PARP1 activity through phosphorylation in TNBC. Potential molecules we will study are EGFR, which also directly interacts with PARP1 and phosphorylate it. We will investigate the role of these kinases in PARP1 regulation and PARPi resistance. Thus, we propose the following three aims; Aim 1. To systematically validate the significance of c-Met–mediated phosphorylation in PARPi resistance in mouse models and TNBC patient samples; Aim 2. To determine the role of EGFR-mediated PARP phosphorylation in PARPi resistance in TNBC; Aim 3. To determine the role of c-Met and EGFR interplay in PARPi resistance in TNBC. If our proposal is successful, several phosphorylation sites in PARP1 can be used as biomarkers to guide the combinational treatment of PARPi and correlated kinase inhibitors. We will particularly focus on c-Met and EGFR because inhibitors of these kinases are currently used in the clinic or in clinical trials, allowing for faster progression of our biomarker-guided rationale combination therapy into clinical trials.