Expression Analysis of Circulating miR-21 in Iranian Patients with Hereditary Colorectal Cancer

Background and objectives: Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality in the world. MicroRNAs (miRNAs) have potential as diagnostic biomarkers for various diseases including cancer. This study was undertaken to investigate expression of miR-21 before and after surgery in patients with hereditary CRC. Methods: After collecting blood samples from 39 patients and 39 healthy controls, total RNA was extracted by the TRIzol method. Following cDNA synthesis, expression of miR-21 in serum of subjects was evaluated using real-time PCR, along with two reference genes, let-7d and let-7g. The real-time expression results and Ct values were collected and analyzed based on the 2-∆∆ct method. Results: In spite of tumor removal, serum miR-21 expression levels was significantly higher in hereditary CRC patients compared with controls (P=0.022). Conclusion: Our results confirmed that samples from hereditary cases of CRC must not be included in experiments on the diagnostic potential of miRNAs.