Investigation of the potential of miRNA candidates as non-invasive biomarkers for the diagnosis and follow-up of colorectal cancer

Background: Colorectal cancer (CRC) is the third most common cancer worldwide, and despite advances in treatment, molecular biomarkers are needed for both early diagnosis and prognosis monitoring. It is known that microRNAs (miRNA), one of the epigenetic mechanisms, are effective in the initiation and development of cancer by regulating the activity of tumor suppressors and/or oncogenes. In this study, the potential of the molecules let7, miRNA125b, and miRNA30a, which are known to play a role in cellular processes, as biomarkers for colorectal cancer and their molecular mechanisms were investigated in this model. The aim was to evaluate the diagnostic, prognostic, and predictive utility of the target miRNAs in colorectal cancer patients. Material and methods: The expression changes of miRNAs let-7, miRNA125b, and miRNA30a were investigated by miRNAs isolation and cDNA synthesis from the serum samples of 60 patients diagnosed with CRC or from the serum samples of 20 healthy individuals. The calculation was performed using the quantitative real-time polymerase chain reaction method to determine the expression level. The results were compared with clinical parameters. Result: An 8-fold decrease in the expression of let-7 and miRNA125b and a 60-fold decrease in the expression of miRNA30a were found in the serum samples of patients diagnosed with colorectal cancer (CRC) compared to the healthy group. A decrease in let-7 was observed in 53.3%, miRNA125b in 58.3%, and miRNA30a in 55% of patients. A significant correlation was found between the reduced expression status and the stage, lymph nodes, local recurrence, and metastasis (p < 0.05). The ROC analysis showed that the miRNA30a level could be a diagnostic biomarker for CRC (p < 0.001). No significant impact of target miRNA expression changes on overall disease survival was observed. Conclusion: It is thought that the target miRNA30a can be used for early diagnosis and screening and that the target miRNA let-7, miRNA125b, and miRNA30a can be used as non-invasive biomarkers for disease follow-up, with larger patient studies being conducted on CRC patients.