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

项目摘要/摘要 激活K-RAS突变发生在95%的晚期胰腺癌患者中，最近的研究 确定CRAF是致癌K-RAS下游肿瘤发生所需的一种激酶。虽然CRAF 传统上，激酶活性通过激活MAPK信号与肿瘤进展联系在一起，我们关注 我们关注两个非典型的CRAF途径，它们独立于CRAF的催化活性和 MAPK的激活。几年前，我们建立了CRAF丝氨酸338(PS338)的磷酸化 推动CRAF易位到线粒体，在那里它与促凋亡细胞形成复合体并使其失活 激活ASK1以促进细胞存活。在自然医学出版社的一份新手稿中，我们现在报道 CRAF pS338还与有丝分裂纺锤体上的细胞周期蛋白激酶Plk1形成复合体，影响细胞周期 进步。因此，这种丝氨酸对CRAF的遗传或变构抑制会导致细胞凋亡和 有丝分裂停滞不依赖于MAPK信号通路，也不能用MAPK信号的抑制剂观察到。 因此，我们的总体目标是针对CRAF功能，并利用其在细胞存活和有丝分裂中的作用 进展，以开发胰腺癌患者的新治疗方法。建议数 研究将确定CRAF的这两个独特的不依赖MAPK的功能如何促进进展和 癌基因K-RAS在胰腺癌转移中的作用在目标1中，我们通过以下方式确定机制 其中，非典型的CRAF pS338通路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是如何调节CRAF pS338的，因为这些分子 已知在胰腺癌中存在调节失调。目标2的目标是评估两者的贡献 非典型CRAF pS338途径对胰腺癌细胞存活(通过ASK1)和细胞增殖(通过 PLK1)，因为它们与胰腺癌体内的肿瘤生长和转移有关。因为有丝分裂是最多的 在细胞周期的放射敏感阶段，目标3的目标是使用胰腺癌和 了解如何最佳结合电离辐射和阻断这种新型CRAF pS338的转移 诱导有丝分裂停止的途径。我们预计，我们针对肿瘤细胞存活的创新方法， 通过K-RAS/CRAF途径的增殖和辐射敏感性将带来令人兴奋的新机会 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.