Preliminary study of microRNA expression profiling in non-metastatic colorectal cancer

e15528 Background: MicroRNAs (miRNAs) are non-coding single-stranded RNAs (18–25 nucleotides in length) that regulate gene expression at the posttranscriptional level by promoting the degradation of mRNAs or by blocking mRNA translation. However, the clinical significance in colon cancer is not yet determined. This study aims to identify differentially expressed miRNAs in colorectal cancer by comparing colon cancerous tissues with normal tissues, exploring the potential roles. Methods: The miRNA expression microarray was employed on tumors from patients diagnosed with adenocarcinoma of the colon. The pilot study included samples from 6 patients (3 women and 3 men), aged 55 to 72 years (mean 62.5±8.4 years). The tumour was located in the rectum, TNM status was as follows: cT (all patients at stage T3), cN (3 patients – N1, 3 patients – Nx), cM (all patients at stage M0). Average tumor size 4.6±2.5 cm. Normal colon tissue was used as a control. The studies were performed with the consent of the patient and according to the protocol accepted by the Bioethics Committee at the Medical University of Lublin No. KE-0254/12/2018. The material was collected during tumor removal surgery, then transported and stored in RNAlater. In the next step, microRNAs were isolated using the RNeasy Micro Kit (Qiagen). The quality and quantity of isolated RNA was assessed with NanoDrop 2000c followed by Bioanalyzer 2100 (Agilent), for the next step samples with RIN above 7. The microRNA expression profile was then evaluated using the GeneChip™ miRNA 4.0 Array (Applied Biosystems). Results: On the basis of a pilot microarray study, the profile of differentially expressed miRNAs was successfully screened. 1.39% of 36 222 tested genes showed a significant at least twofold increase in expression, while 1.75% showed a significant at least twofold decrease in expression. Three novel, not yet described in literature, miRNAs i.e. miR-3154 (p-value 0.015), miR-3921 (p-value 0.036), and miR-5006 (p-value 0.007) appeared to be involved in colorectal carcinogenesis. Conclusions: The present study suggests that mentioned miRNAs after confirmation on a greater group of patients may be used as diagnostic markers for the detection of early stage colon cancer in the general population. This paper was created as part of the project “The Best of the Best! 4. 0.” implemented under the Operational Programme: Knowledge Education Development 2014-2020 and co-financed by the European Social Fund.