Plasma miR-21 and miR-31 as Predictive Biomarkers for Evaluation of Therapeutic Efficacy in Metastatic Colorectal Cancer

Introduction. Colorectal cancer (CRC) is the third most common cancer worldwide. Evaluation of patient response to the applied therapy regime is still challenging. Routine laboratory tests during follow-up do not provide necessary information on therapy efficacy. To improve life expectancy and quality of life for patient with CRC ongoing researches is concentrated to discovering new, reliable biomarkers which could contribute to define patients prognosis and choice of therapy. One of topical research field for searching new biomarkers is mi-RNS.

Aim of the study. The aim of this study was to analyze relative expression changes of miR-21 and miR-31 as potential biomarkers for evaluation of therapy efficacy in mCRC.

Material and methods. In the present study seven patients with mCRC diagnosis were included. After surgery all patients received first line therapy with oxaliplatin. Blood samples for present study were collected every 2-3 weeks. Relative expression of miR-31 and miR-21 assessed with real time PCR. Data analysis carried out by delta delta Ct (ΔΔCt) algorithm. Correlation analysis was performed by R programme ver. 3.1.2 using Pearson correlation coefficient.

Results. Our results in the correlation analysis for CEA serum level and relative expression level of miR-21 and miR-31 did not confirm significant correlation. MiR-31 showed increased expression soon after administration of therapy with a drop of relative expression closer to the CDP I. Acquired results revealed trend of increase in relative expression of miR-21 in PFS II compared to PFS I. Correlation analysis for miR-31 and miR-21 did not reach statistical reliability.

Conclusions. The relative expression alteration pattern of miR-31 and miR-21 in plasma during the therapy is promising biomarker for evaluation of therapy efficacy. These findings need to be validated in large cohort sample set.