Mitochondrial DNA Levels Linked to Cancer Mutation Burden

MITOCHONDRIAL DNA copy number was associated with mutation burden and cancer-related gene expression in a multicancer analysis.

The findings add to research exploring how the genetic material within mitochondria relates to tumour biology. They suggest that mitochondrial measurements could help explain differences between cancer samples, while leaving their potential clinical use to further investigation.

Looking Beyond Nuclear DNA

Most human DNA is located in the cell nucleus, but mitochondria contain a separate, much smaller genome. These structures generate much of the chemical energy needed for cellular activity.

Mitochondrial DNA copy number describes the abundance of this genetic material in a sample. It is a different measurement from the DNA sequence itself: researchers can examine how many copies are present as well as whether the sequence contains mutations.

Cancer biology also involves changes in how cells obtain and use energy. Studying mitochondrial variation alongside genetic alterations may therefore help connect two aspects of tumour behaviour that are often examined separately.

Examining Cancer Samples

Researchers analysed whole-genome data across multiple cancer types and compared mitochondrial DNA copy number with mutation burden and gene expression.

Higher copy numbers were associated with greater mutation burden. The analysis also identified patterns consistent with compensation for impaired mitochondrial function.

Samples with lower mitochondrial DNA levels generally showed increased expression of cancer-promoting genes, including genes involved in cell migration and epithelial–mesenchymal transition. That process concerns changes in cellular characteristics associated with the ability to move and invade surrounding tissue.

These observations describe relationships within the data, rather than showing that one measurement directly causes another.

From Association to Biological Understanding

The distinction between copy number and function is important. Measuring more mitochondrial DNA does not, by itself, show that a tumour has healthier mitochondria or that a patient has a better prognosis.

Likewise, differences in gene expression can suggest biological activity without establishing the eventual course of disease in an individual patient.

The results provide hypotheses that can be tested experimentally: for example, whether altered mitochondrial DNA abundance contributes to tumour behaviour or reflects other changes already taking place.

Clinical Questions Remain

Before a measurement can guide care, researchers need to establish that it provides reliable information relevant to a defined clinical decision.

For this approach, future work could examine whether mitochondrial DNA measurements add useful information beyond existing tumour assessments and whether findings remain consistent across independent patient groups.

The study does not establish a validated diagnostic test, a treatment-selection tool or a benefit from changing mitochondrial DNA copy number. Its contribution is to identify connections that may help researchers understand cancer metabolism and progression more precisely.

Reference

Acharyya A and Dhar R. Multicancer analysis reveals mtDNA copy number as a key determinant of mutational load and cancer progression. FEBS J. 2026. doi:10.1111/febs.70736.