Targeting a non-canonical RAS-driven pathway in pancreatic cancer

项目总结/摘要 >95%的晚期胰腺癌患者发生激活K-RAS突变，最近的研究表明， 将CRAF鉴定为致癌K-RAS下游肿瘤发生所需的激酶。虽然CRAF 激酶活性传统上通过激活MAPK信号传导与肿瘤进展相关， 我们注意到两个非经典的CRAF途径，它们独立于CRAF催化活性， MAPK的激活。几年前，我们建立了丝氨酸338（pS338）上的CRAF磷酸化 驱动CRAF易位到线粒体，在线粒体中与促凋亡蛋白形成复合物并使促凋亡蛋白失活。 激酶ASK 1促进细胞存活。在《自然医学》杂志上出版的一份新手稿中，我们现在报告说， CRAF pS338还与细胞周期激酶Plk 1在有丝分裂纺锤体处形成复合物以影响细胞周期 进展因此，这种丝氨酸对CRAF的遗传或变构抑制驱动细胞凋亡和细胞凋亡。 有丝分裂停滞，不依赖于MAPK途径，并且用MAPK信号传导抑制剂未观察到。 因此，我们的总体目标是靶向CRAF功能，并利用其在细胞存活和有丝分裂中的作用。 进展，以便为胰腺癌患者开发新的治疗方法。拟议 研究将确定CRAF的这两种独特的MAPK独立功能如何促进进展， 致癌K-RAS驱动的胰腺癌转移。在目标1中，我们通过以下方式确定机制： 其中非经典CRAF pS338途径在胰腺癌的独特遗传背景下被激活。 具体地说，我们将关注K-RAS和PAK如何调节CRAF pS338，因为这些分子是 已知在胰腺癌中失调。目标2的目标是评估两者的贡献 非经典CRAF pS338途径对胰腺癌细胞存活（通过ASK 1）和细胞增殖（通过 Plk 1），因为这些与胰腺癌的体内肿瘤生长和转移有关。因为有丝分裂是 在细胞周期的放射敏感阶段，目的3的目标是使用胰腺癌的小鼠模型， 转移，以了解如何最佳地将联合收割机电离辐射与这种新型CRAF pS338的阻断相结合 诱导有丝分裂停滞的途径。我们预计，我们针对肿瘤细胞存活的创新方法， 通过K-RAS/CRAF途径的增殖和放射敏感性将导致令人兴奋的新机会， 转移性胰腺癌

Project Summary/Abstract Activating K-RAS mutations occur in >95% of patients with advanced pancreatic cancer, and recent studies identify CRAF as a kinase required for tumorigenesis downstream of oncogenic K-RAS. Although CRAF kinase activity is traditionally linked to tumor progression via activation of MAPK signaling, we have focused our attention on two non-canonical CRAF pathways which are independent of CRAF catalytic activity and activation of MAPK. Several years ago, we established that CRAF phosphorylation on serine 338 (pS338) drives CRAF translocation to the mitochondria where it forms a complex with and inactivates the pro-apoptotic kinase ASK1 to promote cell survival. In a new manuscript in press at Nature Medicine, we now report that CRAF pS338 also forms a complex with the cell cycle kinase Plk1 at the mitotic spindle to impact cell cycle progression. Accordingly, genetic or allosteric inhibition of this serine on CRAF drives both apoptosis and mitotic arrest that is independent of the MAPK pathway and not observed with inhibitors of MAPK signaling. Our overall objective is therefore to target CRAF function and exploit its role in both cell survival and mitotic progression, in order to develop novel therapeutic approaches for pancreatic cancer patients. The proposed studies will define how these two unique MAPK-independent functions of CRAF contribute to progression and metastasis of pancreatic cancer driven by oncogenic K-RAS. In Aim 1 we determine the mechanisms by which the non-canonical CRAF pS338 pathway is activated in the unique genetic context of pancreatic cancer. Specifically, we will focus on how both K-RAS and PAK regulate CRAF pS338, since these molecules are known to be dysregulated in pancreatic cancer. The goal of Aim 2 is to evaluate the contributions of the two non-canonical CRAF pS338 pathways on pancreatic cancer cell survival (via ASK1) and cell proliferation (via Plk1) as these relate to tumor growth and metastasis of pancreatic cancer in vivo. Since mitosis is the most radiosensitive stage of the cell cycle, the goal of Aim 3 is to use mouse models of pancreatic cancer and metastasis to understand how to optimally combine ionizing radiation with blockade of this novel CRAF pS338 pathway which induces mitotic arrest. We anticipate that our innovative approach to target tumor cell survival, proliferation, and radiosensitivity via the K-RAS/CRAF pathway will lead to exciting new opportunities for metastatic pancreatic cancer.