Molecular characterization of colorectal cancer: Insights from miRNA, mRNA, and protein analysis

Recent research highlights the significant roles of microRNAs (miRNAs) in various diseases, particularly cancer, where they serve as diagnostic and prognostic markers. This study focuses on colorectal cancer (CRC) by examining the expression of six specific miRNAs, miR-20a, miR-21, miR-29a, miR-31, miR-92a, and miR-224, in 81 tumor samples compared to matched normal tissues. We assessed the expression levels of six target genes, SMAD4, PTEN, TGFBRII, BCL2, KLF4, and RASA1, using reverse transcription quantitative polymerase chain reaction and immunohistochemistry. Our results indicated a significant upregulation of miR-20a, miR-21, miR-29a, and miR-31 in tumor samples, alongside a decrease in TGFBRII mRNA expression. Correlation analyses demonstrated that high levels of miR-20a were inversely related to both mRNA and protein levels of PTEN. Elevated expressions of miR-21 and miR-224 were associated with lower mRNA and protein levels of TGFBRII. Furthermore, increased levels of miR-29a and miR-31 showed an inverse relationship with mRNA and protein levels of RASA1. These findings suggest a strong link between upregulated miRNAs and downregulated target genes, indicating their significant roles in CRC carcinogenesis. Notably, the upregulation of miR-20a, miR-21, miR-29a, and miR-31 may serve as effective biomarkers for differentiating CRC from normal mucosa, potentially enhancing screening strategies in the general population.