The mitochondrial deoxyguanosine kinase is required for cancer cell stemness in lung adenocarcinoma.

Shengchen Lin,Xiuchao Wang,Oana Bollt,Jihui Hao,Pankaj K Singh,Jiaxin Kang,Matthew D Taylor,Eric Martine,John Koomen,Jianwei Sun,Shengyu Yang,Bin Fang,Chongbiao Huang

doi:10.15252/emmm.201910849

Abstract

The mitochondrial deoxynucleotide triphosphate (dNTP) is maintained by the mitochondrial deoxynucleoside salvage pathway and dedicated for the mtDNA homeostasis, and the mitochondrial deoxyguanosine kinase (DGUOK) is a rate‐limiting enzyme in this pathway. Here, we investigated the role of the DGUOK in the self‐renewal of lung cancer stem‐like cells (CSC). Our data support that DGUOK overexpression strongly correlates with cancer progression and patient survival. The depletion of DGUOK robustly inhibited lung adenocarcinoma tumor growth, metastasis, and CSC self‐renewal. Mechanistically, DGUOK is required for the biogenesis of respiratory complex I and mitochondrial OXPHOS, which in turn regulates CSC self‐renewal through AMPK‐YAP1 signaling. The restoration of mitochondrial OXPHOS in DGUOK KO lung cancer cells using NDI1 was able to prevent AMPK‐mediated phosphorylation of YAP and to rescue CSC stemness. Genetic targeting of DGUOK 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 implicate that the mitochondrial deoxynucleotide salvage pathway could be potentially targeted to prevent CSC‐mediated therapy resistance and metastatic recurrence.

Highlights

The mitochondrial deoxynucleotide triphosphate is maintained by the mitochondrial deoxynucleoside salvage pathway and dedicated for the mitochondrial DNA (mtDNA) homeostasis, and the mitochondrial deoxyguanosine kinase (DGUOK) is a rate-limiting enzyme in this pathway
DGUOK overexpression is required for lung adenocarcinoma tumor growth and metastasis To understand the role of mitochondrial deoxynucleoside salvage pathway in lung cancer progression, we evaluated the correlation between Thymidine kinase 2 (TK2) and DGUOK mRNA transcripts with the survival of lung cancer patients in a previously published meta-analysis dataset
DGUOK staining in lung adenocarcinoma tissues appeared as punctate or diffuse cytosolic staining in lung adenocarcinoma specimens and formalin-fixed paraffin-embedded H1650 cells (Fig EV1B and C), which is consistent with its mitochondrial localization in the cell

Summary

Introduction

The mitochondrial deoxynucleotide triphosphate (dNTP) is maintained by the mitochondrial deoxynucleoside salvage pathway and dedicated for the mtDNA homeostasis, and the mitochondrial deoxyguanosine kinase (DGUOK) is a rate-limiting enzyme in this pathway. We investigated the role of the DGUOK in the self-renewal of lung cancer stem-like cells (CSC). The depletion of DGUOK robustly inhibited lung adenocarcinoma tumor growth, metastasis, and CSC self-renewal. DGUOK is required for the biogenesis of respiratory complex I and mitochondrial OXPHOS, which in turn regulates CSC self-renewal through AMPKYAP1 signaling. The restoration of mitochondrial OXPHOS in DGUOK KO lung cancer cells using NDI1 was able to prevent AMPK-mediated phosphorylation of YAP and to rescue CSC stemness. Genetic targeting of DGUOK using doxycycline-inducible CRISPR/Cas 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 implicate that the mitochondrial deoxynucleotide salvage pathway could be potentially targeted to prevent CSCmediated therapy resistance and metastatic recurrence

Methods

Results

Conclusion