Abstract 973: The mitochondrial deoxyguanosine kinase regulates lung adenocarcinoma cancer stem-like cells through AMPK/YAP1 signaling
Authors: Lin Shengchen , Huang Chongbiao , Sun Jianwai , Wang Xiuchao , Kang Jiaxin , Taylor Matthew , Fang Bin , Singh Pankaj K , Koomen John , Hao Jihui , Yang Shengyu 
Published: August 2019

Abstract
Metastasis involves the dissemination of tumor cells from primary site to distant organs, and the colonization of disseminated cancer cells to establish distant metastases. Some of the disseminated cancer stem-like cells (CSC) are able to remain in dormancy for years before establishing secondary tumor and triggering metastatic recurrence. The accepted paradigm of cancer therapy aims at eradicating rapidly proliferating cancer cells. However, how to eliminate disseminated metastatic cells in dormancy and to prevent metastatic recurrence remains a major challenge in the clinic. Here, we report that the CSC in non-small cell lung cancer (NSCLC) rely on the mitochondrial deoxyguanosine kinase (dGK) to maintain mitochondrial homeostasis and cancer cell stemness. There is a pool of mitochondrial dNTP in the cell maintained by the mitochondrial deoxynucleoside salvage pathway and dedicated for the mitochondrial DNA (mtDNA) homeostasis in slow-cycling and post-mitotic cells. The role of the mitochondrial deoxynucleoside salvage pathway in tumor initiation and progression is poorly understood. Here, we investigated the role of the mitochondrial dGK, a rate-limiting enzyme in the mitochondrial deoxynucleoside salvage pathway, in the self-renewal of lung adenocarcinoma CSC. Our data support that dGK overexpression strongly correlates with cancer progression and patient survival. Depletion of dGK in lung cancer cells remarkably reduced the proportion of active aldehyde dehydrogenase (ALDH+) CSC, inhibited tumor sphere formation in vitro and prevent tumor-initiation ability of CSC in xenograft mouse models. Mechanistically, dGK controls the biogenesis of respiratory Complex I and mitochondrial oxidative phosphorylation (OXPHOS), which in turn regulates CSC self-renewal through AMPK-YAP1 signaling. The restoration of mitochondrial OXPHOS in dGK depleted lung cancer cells using NDI1, a single subunit yeast NADH : ubiquinone oxidoreductase, was able to rescue AMPK-YAP1 signaling and CSC stemness. Genetic targeting of dGK using doxycycline-inducible CRISPR/Cas9 was able to markedly induce tumor regression. Our findings reveal a novel role for mitochondrial dNTP metabolism in lung cancer tumor growth and progression, and indicate that the mitochondrial deoxynucleotide salvage pathway could be potentially targeted to prevent CSC-mediated therapy resistance and metastatic recurrence.
Citation Format: Shengchen Lin, Chongbiao Huang, Jianwai Sun, Xiuchao Wang, Jiaxin Kang, Matthew Taylor, Bin Fang, Pankaj K Singh, John Koomen, Jihui Hao, Shengyu Yang. The mitochondrial deoxyguanosine kinase regulates lung adenocarcinoma cancer stem-like cells through AMPK/YAP1 signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 973.