Dihydroceramide desaturase (DES1) as a mediator of receptor tyrosine kinase-driven metastasis in breast cancer

摘要 尽管治疗方法有所改进，晚期乳腺癌(BC)的临床结果仍然很差 是对转移性疾病新疗法的迫切需要。受体酪氨酸激酶(RTK)过度激活 BC中的信号与预后不良有关，然而直接的RTK抑制剂在临床上的结果好坏参半 审判。RTK信号驱动失巢耐药，这是一种关键的肿瘤转移生物学。因此，定义基础的 这一过程的机制可以确定新的治疗转移的药物靶点。鞘脂(SL)是一种 生物活性脂类家族，经典的与细胞死亡有关，其新陈代谢在癌症中改变。 PI小组正在进行的研究使用HER2扩增作为RTK信号的模型系统 确定SL酶二氢神经酰胺脱饱和酶1(DES1)是SL中HER2调控的关键节点 HER2+BC细胞抗失巢凋亡所需的网络。在临床数据中，高DES1水平是 与HER2+BC的预后更差有关。此外，提高DES1水平足以驱车进入 HER2+BC细胞的体外致瘤性，而DES1KO降低了体内转移。这些加在一起， 新的数据使我们得出了一个中心假设，即DES1是促进RTK- 驱动失巢耐药和转移，这将通过追求三个具体目标来测试。第一个目标 将利用Crispr/Cas9在体外和体内确定DES1在RTK驱动的失巢凋亡抵抗中的作用 在RTK驱动的BC细胞中敲除DES1的技术及其对体外致瘤性的生物学效应 体内细胞在循环中存活。第二个目标将定义RTK的机制(S) 在ECM脱离后利用功能获得和丢失来调节和维持DES1活性 直接连接DES1与PI3K信号和戊糖致癌激活的功能途径 磷酸盐途径。第三个目标是建立DES1作为体内转移和转移的驱动因素 用功能增益方法研究携带RTK高激活的BC细胞的化疗耐药性 在RTK激活的BC中，增加的DES1足以促进侵袭性表型，并可以介导 对靶向HER2疗法拉帕替尼的耐药性。总体而言，这些研究将把DES1确立为关键 致癌RTK信号的效应者和作为一种新的药物靶点，有效地克服失巢凋亡 耐药，可用于转移性结直肠癌的治疗。

ABSTRACT Despite improvements in treatment, clinical outcomes for late stage breast cancer (BC) remain poor and there is a critical need for new therapies for metastatic disease. Hyperactivation of receptor tyrosine kinase (RTK) signaling in BC is associated with poor prognosis yet direct RTK inhibitors have had mixed results in clinical trials. RTK signaling drives anoikis resistance, a key metastasis-enabling biology. Thus, defining the underlying mechanisms of this process could identify new druggable targets to treat metastasis. Sphingolipids (SL) are a family of bioactive lipids, classically implicated in cell death, and whose metabolism is altered in cancer. Ongoing studies from the PI’s group, using HER2 amplification as a model system of RTK signaling have identified the SL enzyme dihydroceramide desaturase 1 (DES1) as a key HER2-regulated node in the SL network that was required for anoikis resistance of HER2+ BC cells. In clinical data, high DES1 levels were associated with worse outcomes in HER2+ BC. Moreover, increasing DES1 levels was sufficient to drive in vitro tumorigenicity of HER2+ BC cells whereas DES1 KO reduced in vivo metastasis. Taken together, these novel data have led us to the central hypothesis that DES1 is necessary and sufficient to promote RTK- driven anoikis resistance and metastasis which will be tested by pursuing three specific aims. The first aim will define the role of DES1 in RTK-driven anoikis resistance in vitro and in vivo using Crispr/Cas9 technology to knockout DES1 in RTK-driven BC cells and defining biological effects on in vitro tumorigenicity and in vivo cell survival in the circulation. The second aim will define the mechanism(s) by which RTKs regulate and maintains DES1 activity following ECM detachment using gain of function and loss of function approaches to directly connect DES1 with oncogenic activation of PI3K signaling and the pentose phosphate pathway. The third aim will establish DES1 as a driver of in vivo metastasis and chemoresistance in BC harboring RTK hyperactivation using gain of function approaches to show that increased DES1 is sufficient to promote an aggressive phenotype in RTK-activated BC and can mediate resistance to the targeted HER2 therapy lapatinib. Collectively, these studies will establish DES1 as a key effector of oncogenic RTK signaling and as a novel druggable target, effective at overcoming anoikis resistance and useful for treatment of metastatic BC.