The Evaluation of miR-21 Level in Lung Tissue and Plasma of Nsclc Patients

Background: Lung cancer is one of the most common malignant tumors with poor survival, which is usually diagnosed at advanced stages. In recent years, increasing evidence has revealed that circulating miRNAs exhibit great potential in screening and early detection of various types of cancers including lung cancer. miR-21 is one of the most highly expressed members of the microRNA family in many human cancer types. Methods: The authors analyzed miR-21 expression in matched tumor and normal tissues and plasma in 17 patients affected with non-small cell lung cancer. Samples were collected from the NSCLC patients before surgery, radiotherapy or chemotherapy. Expression levels of tissue miR-21 were assessed, using TaqMan RT-PCR assay. Expression levels of plasma miR-21 were assessed, using LNA™ RT microRNA PCR primer set and SYBR green qRT-PCR assay. Results: miR-21 expression was higher in 9 out of 17 patients’ plasma samples. No change in miR-21 expression was observed in 8 plasma samples. In lung tissues, ten patients showed up-regulation of miR-21 and six patients were down-regulated. One patient had no change in miR-21 expression level in tissue samples. The expression level of mir-21 in tissue and plasma was concordant in 6 patients. Conclusion: It seems that the level of miR-21 in plasma samples of NSCLC patients as a marker for screening needs more investigation.