Overexpression of the miR-143/145 and reduced expression of the let-7 and miR-126 for early lung cancer diagnosis.

INTRODUCTION Lung cancer is the leading cause of cancer-related deaths worldwide. For this reason, huge efforts are being invested in discovering suitable blood biomarkers that would allow early diagnosis and treatment. One of the possible promising candidates for this role are microRNA molecules (miRNAs). The aim of the study was to identify individual blood miRNAs that could be used as potential biomarkers for early diagnosis of lung cancer. METHODS This prospective study analyzed blood samples of 60 patients with early-stage lung cancer, and blood samples of 60 healthy individuals. All study patients with lung cancer had undergone radical pulmonary resection at the University Hospital Ostrava within the study period (2015-2017). Definitive diagnosis of lung cancer was confirmed by histopathology examination of the resected pulmonary specimen. We investigated relative expressions in selected 13 blood miRNAs; the examined miRNAs were miR-126, miR-155, miR-221, miR-21, miR-143, miR-145, miR-133a, let-7a, miR-146a, miR-31, miR-182, let-7g and miR-19b. RESULTS The outcome of this study showed that the levels of the majority of the tested circulating miRNA in lung cancer patients are significantly altered. The most significant serum miRNA biomarkers for the early detection of lung cancer are as follows: miR-143, let-7g, miR-126, let-7a, and miR-145 (miR-143 and miR-145 have oncogene functions, while miR-126, let-7g and let-7a have suppressor functions). CONCLUSIONS We have demonstrated the excellent diagnostic value of several miRNAs (miR-126, miR-143, miR-145, let-7a and let7g). These have an estimated sensitivity and specificity of 75-85% and 0.90-0.93 AUC. However, these individual miRNA biomarkers require further validation in larger prospective cohorts.