Association of decreased mitochondrial DNA content with the progression of colorectal cancer

Haihong Cui,Ping Huang,Zhijing Wang,Xiaopeng Wang,Xiaoming Guo,Wei Xu,Zhenhua Zhang,Yunxin Zhang,Ying Han

doi:10.1186/1471-2407-13-110

Abstract

BackgroundExperimental data suggest that mitochondria is involved in tumorigenesis. However, little is known about the qualitative and quantitative changes of mtDNA in colorectal cancer tissues. We therefore conducted possible correlations of the mitochondrial DNA (mtDNA) copy number in colorectal cancer (CRC) with clinical and pathological findings and CRC prognosis.MethodsmtDNA copy numbers in CRC cancer tissue and adjacent non-cancerous tissue samples were measured using quantitative real-time polymerase chain reaction analyses from 60 patients admitted to our hospital. We examined the correlation of mtDNA copy numbers and clinicopathologic parameters of CRC patients. The correlation between mtDNA copy number and three-year survival was analyzed.ResultsThe mtDNA copy number was lower in CRC tissue compared with the corresponding non-cancerous colorectal tissue (mean: 108.60 ± 20.11 vs. 153.68 ± 25.72) and was significantly correlated with lymph-node metastasis. Patients with a lower mtDNA copy number tended to have lower 3-year survival than patients with a higher mtDNA copy number assessed by Kaplan–Meier curves, but the correlation was not significant (overall survival, 63.0 vs 83%).ConclusionsThese results suggest that a reduced copy number of mtDNA is correlated with malignant potential in CRC.

Highlights

Experimental data suggest that mitochondria is involved in tumorigenesis
MtDNA copy number of colorectal cancer (CRC) To evaluate if changes in the quantity of mitochondrial DNA (mtDNA) occurred within the tumor tissues of CRC patients, we analyzed the mtDNA copy number of tumor tissues and corresponding non-cancerous colorectal tissues by realtime quantitative polymerase chain reaction (PCR)
Forty-two cases of CRCs (70%) showed reduction of mtDNA copy number compared with non-cancerous colorectal tissues

Summary

Introduction

Little is known about the qualitative and quantitative changes of mtDNA in colorectal cancer tissues. We conducted possible correlations of the mitochondrial DNA (mtDNA) copy number in colorectal cancer (CRC) with clinical and pathological findings and CRC prognosis. Mitochondria are the major intracellular producers of reactive oxygen species (ROS) and are subject to direct attack by ROS in the organelles of mammalian cells. Characteristics such as a lack of introns, inability to bind to histones, and inefficient mtDNA proofreading.

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