en Investigation of MicroRNA-21 Expression Levels in Serum and Stool as a Potential Non-Invasive Biomarker for Diagnosis of Colorectal Cancer Cancer Biology Cancer Biology مقاله کامل Full Length/Original Article <p><strong>Background:</strong> Most cancer studies focus on exploring non-invasive biomarkers for cancer detection. In the present study, we sought to investigate the expression level of microRNA-21 (miR-21), as a potential diagnostic marker, in serum and stool samples from 40 patients with colorectal cancer (CRC) and 40 healthy controls. <strong>Methods: </strong>Quantitative real-time RT-PCR was applied to determine the relative expression level of miR-21 in serum and stool. At the same time, the sensitivity and specificity of this marker was evaluated by receiver operating characteristic (ROC) curve analysis. <strong>Results:</strong> miR-21 expression levels of serum and stool were up-regulated 12.1 (<em>P</em><0.05, 95% CI: 5.774-34.045) and 10.0 (<em>P</em><0.05, 95% CI: 0.351-16.260) times in CRC patients, respectively, when compared to the control group. The sensitivity and specificity of miR-21 was found to be 86.05% and 72.97%, respectively (an area under the ROC curve [AUC] of 0.783). The stool miR-21 level in CRC patients was much higher than that in the healthy controls, showing a sensitivity of 86.05% and a specificity of 81.08% (AUC: 0.829). The expression level of miR-21 in stool was able to significantly distinguish CRC <em>tumor, node, metastasis</em> stages III-IV from stages I-II, with a sensitivity and specificity of 88.1% and 81.6%, respectively (AUC: 0.872). <strong>Conclusion: </strong>The results of this study indicated that miR-21 expression levels in serum and stool can be considered as a potential diagnostic biomarker for the diagnosis of CRC patients. However, more studies are required to confirm the validity of miR-21 as a valuable non-invasive diagnostic tool for CRC.</p> Serum, Stool, miR-21, Biomarker, Colorectal Cancer (CRC) 106 113 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-622&slc_lang=en&sid=1 Saiyad Bastaminejad No Department of Molecular Medicine and Genetics, Research Center for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; Morovat Taherikalani No Razi Herbal Medicines Research Center, Department of Microbiology, School of Medicine Lorestan University of Medical Sciences, Khorramabad, Iran Reza Ghanbari No Digestive Oncology Research Center, Digestive Disease Research Institute, Tehran University of Medical Science, Tehran, Iran Akbar Akbari No Abadan School of Medical Sciences, Abadan, Iran Nooshin Shabab No Department of Molecular Medicine and Genetics, Research Center for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; Massoud Saidijam sjam110@yahoo.com Yes Department of Molecular Medicine and Genetics, Research Center for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran;