TBK1 mediated regulation of E2F1 as a therapeutic target in non-small cell lung cancer

 描述（由申请人提供）：TBK 1（Tank Binding Kinase 1）在介导先天免疫中起主要作用，是NF kB介导的转录调节途径的已知调节因子。TBK 1激活由NFkB介导的存活途径，并且是K-Ras依赖性致癌事件的重要下游介质。最近的研究表明，RalB信号模块和外囊复合物通过直接磷酸化Akt激活TBK 1并促进K-Ras突变癌细胞的存活。我们早期的研究表明，暴露于尼古丁（烟草烟雾的成瘾成分）的细胞激活Akt并稳定XIAP，使非小细胞肺癌（NSCLC）细胞对化疗药物诱导的细胞凋亡具有抗性。这种生存机制也参与诱导E2 F1介导的转录活性，导致生存素表达升高。我们还发现尼古丁可促进小鼠非小细胞肺癌的生长和转移，并以E2 F1依赖的方式诱导MMP 9、MMP 14和MMP 15等多种基质金属蛋白酶的表达。Rb-Raf-1相互作用的破坏剂抑制E2 F1的转录活性，可以抑制MMPs的表达，并阻止小鼠细胞的侵袭、迁移和转移。有趣的是，我们最近的研究表明，细胞暴露于尼古丁激活TBK 1，促进尼古丁介导的细胞增殖。水平 活性磷酸-TBK 1在人肿瘤样品以及暴露于尼古丁的小鼠肿瘤中升高。此外，TBK 1与E2 F1转录因子物理相互作用并有效磷酸化它，增强E2 F1介导的转录。TBK 1还可以以E2 F1依赖的方式诱导MMP启动子，并且TBK 1的消耗降低了MMP 9和14的内源性水平。基于这些观察结果，我们假设TBK 1是K-Ras以及烟碱乙酰胆碱受体（nAChR）介导的信号传导的重要下游靶点，并且它通过E2 F1调节促进肺癌的进展和转移。基于这一假设，我们提出TBK 1和E2 F1的小分子抑制剂的组合在抑制非小细胞肺癌的生长和转移方面将是高效的。我们相信，这些研究具有高度创新性，将对我们抗击非小细胞肺癌的努力产生重大影响。

 DESCRIPTION (provided by applicant): TBK1 (Tank Binding Kinase 1) plays a major role in mediating innate immunity and is a known regulator of NF kB mediated transcriptional regulatory pathway. TBK1 activates survival pathways mediated by NFkB, and is an important downstream mediator of K-Ras-dependent oncogenic events. Recent studies have shown that the RalB signaling module and the exocyst complex activate TBK1 and promote survival of K-Ras mutant cancer cells through direct phosphorylation of Akt. Our earlier studies had shown that exposure of cells to nicotine, the addictive component of tobacco smoke, activates Akt and stabilizes XIAP, rendering non-small cell lung cancer (NSCLC) cells resistant to apoptosis induced by chemotherapeutic agents. This survival mechanism is also involved in induction of E2F1-mediated transcriptional activity, resulting in elevated expression of survivin. We had also found that nicotine could promote the growth and metastasis of NSCLC in mice, and could induce the expression of multiple matrix metalloproteinases including MMP9, MMP14 and MMP15 in an E2F1-dependent manner. A disruptor of the Rb-Raf-1 interaction, which inhibits the transcriptional activity of E2F1, could inhibit the expression of MMPs and prevent cell invasion, migration and metastasis in mice. Interestingly, our recent studies show that exposure of cells to nicotine activates TBK1 and facilitates nicotine-mediated cell proliferation. Levels of active phospho-TBK1 are elevated in human tumor samples as well as in tumors from mice that are exposed to nicotine. Further, TBK1 physically interacts with E2F1 transcription factor and phosphorylates it efficiently, enhancing E2F1-mediated transcription. TBK1 could also induce MMP promoters in an E2F1-dependent fashion, and depletion of TBK1 reduces the endogenous levels of MMP9 and 14. Based on these observations, we hypothesize that TBK1 is a vital downstream target of K-Ras as well as nicotinic acetylcholine receptor (nAChR)-mediated signaling and it facilitates the progression and metastasis of lung cancer through E2F1 regulation. Based on this hypothesis, we propose that the combination of small molecule inhibitors of TBK1 and E2F1 would be highly efficient in inhibiting the growth and metastasis of non-small cell lung cancers. We believe that these studies are highly innovative and will have a significant impact on our efforts to combat non-small cell lung cancer.