Role of microRNA 204-5p (miR-204) as putative diagnostic marker in Non Small Cell Lung Cancer

Abstract

T he leading cause of deaths related to cancer in men and women worldwide is the lung cancer (Fitzmaurice et al., 2015). Non–small cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancers. At initial diagnosis, 20% of patients have localized disease, 25% of patients have regional metastasis, and 55% of patients have distant spread of disease. Symptoms depend on the location of cancer (Rivera et al., 2013). MicroRNAs are small, regulating, non-coding RNAs that regulate, above all, the transcription by binding to the untranslated regions (UTR) of 3' of the targeted mRNAs (Shukla et al., 2011). In the current study, we aimed to evaluate the efficacy of miR-204 as a novel early diagnostic marker in NSCLC via comparing its value in both serum and bronchial tissue samples and correlates its expression levels with the histopathological features. This study included 50 subjects, they were divided into two groups. Group I included 25 patients with non small cell lung cancer. The 2nd group included 25 non malignant subjects. Under the ethical legislation and rules of Ain Shams University the biological samples were collected in form of tissue and serum samples. For serum sample, 3 ml whole blood samples were collected in plain “without anticoagulant” sterile vacutainer, centrifuged at 4000 rpm for 20 minutes, the serum was separated in a 1.5 sterile plastic Eppendorf, and fresh tissue samples were collected and stored in phosphate –buffer saline (pH 7.4), labeled and stored at -80 C until analyzed. For tissue samples, bronchial biopsies were collected by bronchoscope after taking a written consent from all subjects. MiRNA was extracted from serum and tissue homogenized samples using a miRNeasy Mini Kit followed by reverse transcription then miR-204 was relatively expressed by using quantitative real-time polymerase chain reaction (qRT-PCR) The expression of miR-204-5p biomarker; was compared in NSCLC cancer patients versus the non-cancerous tissue in both serum and tissue samples. The data normalization was tested by normality test which shows that the biomarker expression is not normally distributed; thus, a Mann-Whitney test for non -parametric values was applied. Results showed a high significant difference in the expression of miR-204-5p (p<0.01). The miR-204-5p gene expression is downregulated by two folds in NSCLC cancer patients (median: 19.2; range: 10.2 –52.4) compared to control group.