Mitochondria: Endosymbiont bacteria DNA sequence as a target against cancer

Mitochondrial DNA copy numbers in gastric cancer tissues: a possible biomarker for estimating cancer progression

BACKGROUND

Mitochondria have their own genome (mtDNA), which in humans is a circular multi-copy genome consisting of 16 569 base pairs. Abnormalities in the mtDNA have been reported to correlate with various age-related pathophysiologies.

METHODS

Based on a total of 182 DNA samples extracted from gastric cancer tissues, we measured mtDNA copy numbers (mtDNA-CN) using real-time polymerase chain reaction (PCR) and then examined alongside sex, age, tumor stage, Laurén classification, and the overexpression of Human Epidermal Growth Factor Receptor 2 (HER2).

RESULTS

We found no sex differences in mtDNA-CN and no correlation with age, but significant differences according to tumor stage. The mtDNAcn of intestinal type by Laurén classification was significantly larger than that of diffuse type. There was no significant difference in mtDNA-CN between HER2-positive and -negative tissues. Multiple regression analyses showed that only the tumor stage was a significant variable, while Laurén classification was not.

CONCLUSION

These results indicate that mitochondrial genomic abnormalities contribute the progression of gastric cancer independently of HER2 overexpression, and may shed light on the emerging role of mtDNA-CN in situ as a possible biomarker for estimating cancer progression.

The Entanglement between Mitochondrial DNA and Tumor Metastasis

Simple Summary

Mitochondrial dysfunction is one of the main features of cancer cells. As genetic material in mitochondria, mitochondrial DNA (mtDNA) variations and dysregulation of mitochondria-encoded genes have been shown to correlate with survival outcomes in cancer patients. Cancer metastasis is often a major cause of treatment failure, which is a multi-step cascade process. With the development of gene sequencing and in vivo modeling technology, the role of mtDNA in cancer metastasis has been continuously explored. Our review systematically provides a summary of the multiple roles of mtDNA in cancer metastasis and presents the broad prospects for mtDNA in cancer prediction and therapy.

Abstract

Mitochondrial DNA, the genetic material in mitochondria, encodes essential oxidative phosphorylation proteins and plays an important role in mitochondrial respiration and energy transfer. With the development of genome sequencing and the emergence of novel in vivo modeling techniques, the role of mtDNA in cancer biology is gaining more attention. Abnormalities of mtDNA result in not only mitochondrial dysfunction of the the cancer cells and malignant behaviors, but regulation of the tumor microenvironment, which becomes more aggressive. Here, we review the recent progress in the regulation of cancer metastasis using mtDNA and the underlying mechanisms, which may identify opportunities for finding novel cancer prediction and therapeutic targets.