RESUMEN
Aim: The miR-138-5p promoter-methylated DNA level, miR-138-5p and PDL1 expression were investigated in colorectal cancer (CRC) patients. Materials & methods: miR-138-5p promoter methylation status and miR-138-5p expression were investigated using the MethyLight and qPCR method, respectively. For measuring PDL-1, we applied the Bioassay Technology Elisa kit. Results: The percentage of methylated reference values of plasma and tissue samples from patients was higher than control groups. The area under curve presented a sensitivity of 55% and a specificity of 82.5% for plasma samples. Compared with the control groups, lower expression of miR-138-5p and higher concentration of PDL1 protein were observed in the patients group. Conclusion: CRC may be detected early by identifying miR-138-5p methylated DNA in plasma as a diagnostic biomarker.
Unfortunately, most patients with colorectal cancer (CRC) are diagnosed late in advanced stages. Genetic alterations due to a person's behavior or environment, such as miRNA dysregulation and methylation, occur in the initial phases of tumorigenesis. This study investigated the disease causing role of methylation of the miR-138-5p gene and its target protein, PDL1, in CRC as well as their potential ability to be used in the early diagnosis of this cancer. Using molecular techniques, higher methylated miR-138-5p as well as a higher PDL1 concentration were found in patients. This suggested a link between PDL1 protein and hyper methylation of the miR-138-5p gene. On the other hand, the hypermethylation of miR-138-5p happened before the increase of PDL1 protein, which resulted in decreased miR-138-5p and as a result decreased PDL1 protein. Compared with other biomarkers, miR-138-5p methylation and PDL1 had high diagnostic accuracy (acceptable sensitivity and specificity). Thus, the methylated miR-138-5p and PDL1 are proposed as diagnostic biomarkers for CRC.