Esophageal 3D organoids of MPV17-/- mouse model of mitochondrial DNA depletion show epithelial cell plasticity and telomere attrition.

Manti Guha,Koji Tanaka,Gordon Ruthel,Narayan G Avadhani,Satish Srinivasan,Andres Klein-Szanto,Maura M Sheehan,Prasanna M Chandramouleeswaran,Kelly Whelan,Takashi Kijima,Hiroshi Nakagawa

doi:10.18632/oncotarget.27264

Abstract

Esophageal squamous cell carcinoma (ESCC) is an aggressive cancer with late-stage detection and poor prognosis. This emphasizes the need to identify new markers for early diagnosis and treatment. Altered mitochondrial genome (mtDNA) content in primary tumors correlates with poor patient prognosis. Here we used three-dimensional (3D) organoids of esophageal epithelial cells (EECs) from the MPV17-/- mouse model of mtDNA depletion to investigate the contribution of reduced mtDNA content in ESCC oncogenicity. To test if mtDNA defects are a contributing factor in ESCC, we used oncogenic stimuli such as ESCC carcinogen 4-nitroquinoline oxide (4-NQO) treatment, or expressing p53R175H oncogenic driver mutation. We observed that EECs and 3D-organoids with mtDNA depletion had cellular, morphological and genetic alterations typical of an oncogenic transition. Furthermore, mitochondrial dysfunction induced cellular transformation is accompanied by elevated mitochondrial fission protein, DRP1 and pharmacologic inhibition of mitochondrial fission by mDivi-1 in the MPV17-/- organoids reversed the phenotype to that of normal EEC organoids. Our studies show that mtDNA copy number depletion, activates a mitochondrial retrograde response, potentiates telomere defects, and increases the oncogenic susceptibility towards ESCC. Furthermore, mtDNA depletion driven cellular plasticity is mediated via altered mitochondrial fission-fusion dynamics.

Highlights

Esophageal Squamous Cell Carcinoma (ESCC) is one of the most aggressive squamous cell cancers and is the sixth leading cause of cancer-related mortality in the world [1]
We recently reported that mitochondrial DNA (mtDNA) depletion and mitochondrial dysfunction in immortalized cells activates mitochondrial retrograde signaling (MtRS) which plays a causal role in telomere attrition similar to that observed in tumor cells [21]
We assessed the telomere length in primary esophageal epithelial cells (EEC) using real time PCR approach [21, 22] and observed that the median telomere length is markedly reduced in MPV17-/- esophageal tissues and esophageal cells compared to that of WT or MPV17-/+ (Figure 1B)

Summary

Introduction

Esophageal Squamous Cell Carcinoma (ESCC) is one of the most aggressive squamous cell cancers and is the sixth leading cause of cancer-related mortality in the world [1]. Esophageal cancer comprises of two main histological subtypes: esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma [2]. ESCC is the major histological type and accounts for >80% of esophageal cancer incidences worldwide [1]. The most prevalent genetic alterations identified in ESCC include TP53R175H or EGFR mutations [4]. Carcinogens such as 4-NitroQuinoline Oxide (4NQO) are reported to cause ESCC in mouse models [5]. ESCC is often diagnosed at advanced stage, accounting for its poor

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Results

Conclusion