Mitochondrial DNA mutations in exhaled breath condensate of patients with lung cancer.

INTRODUCTION

Lung cancer is a leading cause of cancer mortality worldwide. Non-invasively collected biofluids such as exhaled breath condensate (EBC) present a potential sampling medium to detect and study pathological changes implicated in tumourigenesis. Mitochondrial DNA changes have been implicated in the carcinogenesis process. Consequently, the detection of mitochondrial changes in EBC could expand our understanding of lung carcinogenesis as well as identifying specific markers for future studies.

METHODS

EBC and saliva was collected from newly diagnosed subjects with lung cancer and control subjects in a cross-sectional study. The EBC and saliva was analysed for mitochondrial DNA D-loop changes using a PCR sequencing approach. The sequences obtained were compared to paired salivary DNA and the revised Cambridge Reference Sequence (rCRS) to identify somatic mutations, and quantitative and qualitative differences in mutations were analysed between groups.

RESULTS

A total of 25 subjects (9 NSCLC patients, 10 smokers/ex-smokers and 6 non-smokers) were recruited. A significantly elevated D-loop mutation rate in the lung cancer group compared to the control groups was present (7 vs 3.5 for smokers/ex-smokers, and 7 vs. 4 for non-smokers, p = 0.034). The recognised mutation T16217C showed specificity for lung cancer.

CONCLUSIONS

Mitochondrial DNA mutations are more common in the EBC of patients with lung cancer. This suggests that these processes are associated with the carcinogenesis of lung cancer and may be a marker of the disease.