Early detection of lung cancer in exhaled breath condensate using miRNA markers

Abstract

Background: Lung cancer is the leading cause of death by cancer worldwide. Since 5-year survival rate increases significantly when lung cancer is diagnosed at early stages, the development of accurate non-invasive biomarkers for early lung cancer diagnosis is of utmost importance. Over the last years, several tumour biomarkers based on microRNAs (miRNAs) determined in exhaled breath condensate (EBC) have been evaluated and could be applied to early diagnosis of lung cancer. Rationale: miRNA signatures for surgical specimens of lung cancer have been determined providing a panel of differentially expressed miRNAs that were able to discriminate lung cancer patients from normal subjects. Using these miRNAs, we hypothesised that the miRNAs expression pattern is similar in lung cancer tissue and in EBC, indicating that EBC is a good surrogate of lung tissue and can be used for non-invasive diagnosis of lung cancer. Methods: Expression of miR-1, mir-200b, miR-21, miR-486, miR-375 was assessed in normal and tumour tissues and EBC obtained from 19 lung cancer patients and 18 healthy subjects. Results: Our results indicate that all miRNAs analysed were differentially expressed in normal and the corresponding lung cancer tissue. miR-1 and miR-486 were down-regulated in lung cancer tissues whereas miR-200b, miR-21 and miR-375 were significantly higher in lung cancer tissues. Interestingly, EBC miRNAs follow the same trend as that observed in the tissues. Conclusions: Our data indicate that a panel of miRNAs can be reliably determined in EBC, which could be considered as surrogate of lung cancer, indicating that these biomarkers could be useful in early diagnosis of lung cancer.