The Study On Plasma MiR-145、miR-20a、miR-21and MiR-223as Non-invasive Biomarkers For Early-stage Non-small Cell Lung Cancer

Objective： Lung cancer is the most common cancer in the world and theleading cause of cancer-related deaths indeveloped countries. Non-small cell lungcancer (NSCLC) accounts for75%to80%of lung cancercases. So far, the mosteffective treatment for NSCLC is surgical resection, which is limited by the fact that65%of patients have advanced disease at the time of diagnosis. Most NSCLCcases,particularly at stages I and II, rarely show symptoms and are difficult to bedetected. To date, the reference gold standard in diagnosing NSCLC is pathologicevidence of malignantcells, which typically requires an invasive strategy such asbronchoscopy, transthoracic needle aspiration, or thoracotomy. Chest X-ray andcomputed tomography screening can detect some lung cancers at an early stage, butthe diagnostic procedures and the hazards of the associated radiation may outweighthe potential benefits. Other methodologies, such as sputum cytology andbronchoalveolar lavage, have not been proven to be effective screening tools. Theseconcerns have led researchers to seek novel biomarkers and new diagnostic assays tonon-invasively assess tumors. Several currently available serum/plasma biomarkersoffer the promise of comprehensively analyzing tumors without the need to carry outa biopsy or a surgical procedure. There are, however, considerable barriers to thebroad implementation of these biomarkers in the clinic. These tumor markers areprimarily proteins, such as CYFRA21-1, CEA, NSE, TPS, chromogranin A, CA125,and CA19-9. The major concern with these markers is their limited sensitivity andspecificity.The discovery of microRNAs(miRNAs) in plasma has opened a new fieldfor molecular diagnosis of cancer. The aim of this study is to investigate whetherplasma miRNAs can be used as biomarkers for early-stage non-small celllung(NSCLC). Methods：we measured the levels of10miRNAs(miR-30d、miR-383、miR-20a、miR-145、miR-221、miR-25、miR-223、miR-21、miR-126、miR-210)in plasma samplesfrom40individuals (20controls and20cases with early-stage NSCLC) in thediscovery set and in validation set of83controls and129cases with early-stageNSCLC using real-time RT-PCR. Receiver operating characteristic (ROC) cuverswere generated for each possible combination of the miRNAs.To prove thecirculating miRNAs in plasma are of tumor origin, their levels were measured in anindependent set of20cases with early-stage NSCLC (before and7~9days aftersurgical removal of the tumors).Results： We found that the experession of plasma miR-145、miR-20a、miR-21and miR-223was significantly increased in the early-stage NSCLC samples with thecontrols. The miRNAs have significant diagnostic value for early-stage NSCLC.miR-145yielded an AUC(the areas under the ROC curve) of0.886、miR-20a yieldedan AUC of0.889、miR-21yielded an AUC of0.838and miR-223yielded an AUC of0.809in discriminating early-stage NSCLC from controls. Combined ROC analysesusing these4miRNAs revealed an elevated AUC of0.897with81.8%sensitivity and90.1%specificity in discriminating early-stage NSCLC. Furthermore,we found thatthese leves of the4miRNAs were significantly reduced in the postoperativeearly-stage NSCLC plasma samples when compared to the preoperativesamples(P<0.05).Conclusion： Altered expressions of the4miRNAs in plasma would havepotential as novel non-invasive biomarkers for early-stage NSCLC,and the miRNAsare of tumor origin. miR-16can be used as reference gene for plasma microRNAdetection. Real-time RT-PCR is a reliable technique for detection of plasmamicroRNA expression.