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

摘要 尽管治疗有所改善，晚期乳腺癌（BC）的临床结果仍然很差， 是对转移性疾病的新疗法的迫切需要。受体酪氨酸激酶（RTK）过度活化 BC中的信号传导与不良预后相关，但直接RTK抑制剂在临床上的结果好坏参半。 审判RTK信号驱动失巢凋亡抗性，这是一种关键的转移生物学。因此，定义底层 这一过程的机制可以确定新的药物靶点来治疗转移。鞘脂（SL）是一种 生物活性脂质家族，典型地与细胞死亡有关，并且其代谢在癌症中改变。 PI小组正在进行的研究，使用HER 2扩增作为RTK信号传导的模型系统， 鉴定了SL酶二氢神经酰胺去饱和酶1（DES 1）作为SL中关键的HER 2调节节点， 这是HER 2 + BC细胞抗失巢凋亡所需的网络。在临床数据中，高DES 1水平是 与HER 2 + BC的不良结局相关。此外，增加DES 1水平足以推动 HER 2 + BC细胞的体外致瘤性降低，而DES 1 KO降低体内转移。综上所述各项 新的数据使我们提出了一个中心假设，即DES 1是促进RTK的必要和充分的条件。 驱动的失巢凋亡抗性和转移，其将通过追求三个具体目标来测试。第一个目标 将使用Crispr/Cas9在体外和体内确定DES 1在RTK驱动的失巢凋亡抗性中的作用 在RTK驱动的BC细胞中敲除DES 1并确定对体外致瘤性的生物学效应的技术 和循环中的体内细胞存活。第二个目标是定义RTK的机制， 在ECM脱离后，使用功能获得和功能丧失来调节和维持DES 1活性。 直接将DES 1与PI 3 K信号传导和戊糖的致癌激活联系起来的功能途径 磷酸途径第三个目标将确立DES 1作为体内转移的驱动因素， 使用功能获得方法显示， 增加的DES 1足以促进RTK激活的BC中的侵袭性表型，并且可以介导 对靶向HER 2治疗拉帕替尼的耐药性。总的来说，这些研究将确立DES 1作为一个关键 致癌RTK信号的效应子，作为一种新的药物靶点，可有效克服失巢凋亡 并且可用于治疗转移性BC。

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.