Abstract

Background and Aim: Both Chronic Obstructive Pulmonary Disease (COPD) and mustard lung victims of chemical injury (unlike asthma and allergy) are known respiratory diseases with a substantial genetic background and there are no highly effective medications for either disease. Considering the many similarities between the two diseases, both can be considered simultaneously under one category. Therefore, we assessed the expression of miR-20a and miR-92a as representatives of the miR-17/92 cluster due to the effective interference of these two miRNAs in the signaling pathways of inflammation and hypoxia in the pulmonary serum (consisting of Mustard Lung and COPD, simultaneously). Methods: Stem-Loop Real-Time Quantitative Polymerase Chain Reaction was used to examine the expression of miR-20a and miR-92a simultaneously in patients with COPD (n=25) and mustard lung (n=50). Results: The results showed that the expression of both miR-20a and miR-92a was significantly downregulated in patients with COPD and chemical injuries when compared to the control group. The expression of each of two miRNAs in the moderate and severe phases of the disease was more downregulated in the mild stage, and miR-92a showed a further downregulation compared to miR-20a (p<0.05). Conclusion: The downregulation of miR-20a and miR-92a might be due to alterations in 1- genomic and/or 2- environmental and/or 3- ecogenomic (affected by epigenomic) factors which requires intensive research in this field. Our results may shed light on new effective strategies for the treatment of respiratory diseases by regulating the mir17/92 cluster by regulating related factors. The members of the oncogenic miR17/92 cluster are significantly upregulated in lung cancer and have the potential to be used as biomarkers in the non-invasive screening of respiratory diseases. Furthermore, these miRNAs can be used for distinguishing respiratory diseases from lung cancer and cardiovascular diseases (also known as COPD comorbities). © 2018 Baqiyatallah University of Medical Sciences. All rights reserved.