Identification of Novel Mechanisms of Autophagy Regulation for Cancer

描述（由申请人提供）：我在西北大学Vincent Cryns博士的实验室获得博士学位，主要研究乳腺癌中凋亡细胞死亡的机制。目前，我是新泽西州罗格斯癌症研究所Eileen White博士实验室的博士后，在那里我正在研究自噬在体外和体内肺肿瘤发生中的作用。我发现自噬通过维持线粒体谷氨酰胺代谢来维持brafv600e驱动的肿瘤的生长。这些动物的自噬消融导致有缺陷线粒体的积累，肿瘤细胞命运从腺癌转变为良性嗜酸细胞瘤，总体生存期增加。这项工作建立了自噬与肺肿瘤持续生长之间的功能联系，表明自噬抑制将是这些肿瘤的一种有价值的治疗策略。作为一名独立调查员，我想进一步阐述这些令人兴奋的结果。我的研究项目将致力于研究癌症中的自噬，重点是如何调节这一途径作为癌症的治疗方式。我已经在这个方向上迈出了重要的一步，通过对自噬调节剂进行shRNA筛选，以确定自噬调节的新机制。我发现了许多囊泡运输成分，特别是Rab gtpase的一个子集，细胞内运输的中心组织者，以及代谢相关基因，如参与脂质代谢的激酶，这些基因被预测为自噬相关疾病和癌症的治疗靶点。我目前正在研究自噬调控机制，研究这些基因在非小细胞肺癌小鼠模型中抑制自噬的功能意义。在我职业生涯的这个阶段，获得K22奖将为我提供保护时间，以获得额外的经验，进入新的研究领域，以及生成成功竞争R01所需的额外数据和论文，从而确保我作为一名独立研究者的成功。

DESCRIPTION (provided by applicant): I earned my Ph.D. in the laboratory of Dr. Vincent Cryns at Northwestern University where I focused on mechanisms of apoptotic cell death in breast cancer. Currently, I am a postdoctoral fellow in the laboratory of Dr. Eileen White at the Rutgers Cancer Institute of New Jersey where I am studying the role of autophagy in lung tumorigenesis in vitro and in vivo. I discovered that autophagy sustains the growth of BrafV600E-driven tumors by maintaining mitochondrial glutamine metabolism. Autophagy ablation in these animals results in an accumulation of defective mitochondria, alteration in tumor cell fate from adenocarcinomas to benign oncocytomas, and an increase in overall survival. This work establishes a functional link between autophagy and the continued growth of lung tumors, suggesting that autophagy inhibition would be a valuable therapeutic strategy in these tumors. I would like to expand on these exciting results as an independent investigator. My research program will be devoted to the study of autophagy in cancer, with an emphasis on how to modulate the pathway as a therapeutic modality in cancer. I have already taken a significant step in this direction by conducting an shRNA screen for autophagy modulators to identify novel mechanisms of autophagy regulation. I identified many vesicle trafficking components, in particular a subset of the Rab GTPases, central organizers of intracellular trafficking, and metabolically relevant genes, such as kinases involved in lipid metabolism, which are predicted to be therapeutic targets for autophagy related diseases and cancer. I am now studying the mechanisms of autophagy regulation and investigating the functional significance of suppressing autophagy by these genes in mouse models of NSCLC. Receipt of the K22 award at this point in my career would provide protected time to gain additional experience and move into new research areas, as well as generate additional data and papers necessary to successfully compete for an R01, thus ensuring my success as an independent investigator. Project Summary Autophagy is a catabolic process that sustains metabolism by recycling intracellular components for use in biosynthetic processes and eliminating damaged proteins and organelles whose accumulation is toxic. It is increasingly clear that tumor cells exploit autophagy as a means to meet their elevated metabolic demands. I discovered that autophagy is required to support mitochondrial metabolism and growth of lung tumors driven by oncogenic BrafV600E. Autophagy ablation resulted in alteration of tumor cell fate and prolonged survival. Similar results have been obtained with lung tumors driven by Kras; and mammary tumorigenesis is blunted in mouse models with deficiencies in components required for nucleation of the autophagosome suggesting that autophagy inhibition is likely to be a powerful therapeutic approach for cancer. This project determines the mechanism of autophagy inhibition by two of the most promising novel autophagy regulators identified by my shRNA screen, the small GTPase Rab9 and the pseudokinase Trib3, and evaluates whether these genes can alter tumor progression and survival in a mouse model of NSCLC. Rab9, a member of the Ras-related small GTPase superfamily, regulates traffic between the late endosome and the trans Golgi network. I hypothesize that it inhibits autophagy by diverting components needed for phagophore nucleation to the endosomal pathway, or by interfering with lipid donation to the expanding autophagosome. The pseudokinase Trib3 plays a central role in lipid homeostasis by controlling the stability of acetyl-coA carboxylase (ACC) and by inhibiting the master regulator of adipogenesis, PPARγ. I hypothesize that Trib3 enhances cellular energy levels to obviate the need for autophagy. These studies are important, and have the potential to identify novel biological mechanisms and approaches to lung cancer therapy as well as extend our understanding of the mechanics and regulation of autophagy.