Deciphering the miR-200a-3p/RUNX1 Axis: A Novel Oncogene Signature in Colorectal Cancer

Background The dual role of carcinogenic or tumor suppressor makes Runt related transcription factor 1 (RUNX1) a new diagnostic markers or therapeutic target for colorectal cancer (CRC). In CRC, the relationship between RUNX1 and prognosis, biological function, and potential microRNA directly involved in the regulation of RUNX1 are unclear. Methods Gene expression of RUNX1 in colorectal cancer (CRC) was comprehensively analyzed using data from The Cancer Genome Atlas (TCGA) and Oncomine databases. Kaplan-Meier survival curves were constructed to assess the clinical and prognostic status associated with RUNX1 expression in CRC patients. The correlation between clinical features and RUNX1 expression was analyzed in the GSE17536 dataset using the Chi-square test. The relationship between RUNX1 expression and overall survival (OS) in CRC was investigated through both univariate and multivariate Cox regression analyses. Genes co-expressed with RUNX1 were identified using Spearman correlation analysis. The potential functions of RUNX1 in CRC were elucidated through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. MiRNAs that negatively regulate RUNX1 expression were identified using TargetScan, ENCORI, and miRDB databases. The relationship between miR-200a-3p expression levels and clinicopathologic characteristics, as well as the prognosis of CRC patients, was analyzed using the Chi-square test. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was employed to determine the expression levels of RUNX1 and miR-200a-3p in CRC cell lines (HCT-116, HT-29, SW480, and SW620). The interaction between RUNX1 and miR-200a-3p was confirmed through a luciferase reporter assay. Results Compared with normal tissues, RUNX1 mRNA expression was up-regulated in most cancer tissues, including CRC. RUNX1 expression was closely correlated with TNM stage in CRC patients (P < 0.05). The high expression level of RUNX1 mRNA (HR: 2.198, 95%CI: [1.200, 4.027]) could be used as an independent risk factor for overall survival (OS) in CRC patients. The mRNA level of RUNX1 in CRC patients was significantly correlated with OS (P < 0.01), disease-free survival (DFS) (P < 0.01), and disease-specific survival (DSS) (P < 0.001). RUNX1 co-expressed genes are mainly involved in GO entries such as development and growth, differentiated cell morphogenesis, and KEGG signaling pathways such as adhesion plaques and adhesion junctions. miR-200a-3p may be the miRNAs with direct regulatory role of RUNX1. The expression of miR-200a-3p was significantly correlated with T stage (P = 0.03) and M stage (P = 0.026). Low expression of miR-200a-3p was significantly associated with poor prognosis in CRC patients (P = 0.02). The expression levels of RUNX1 and miR-200a-3p in CRC cell lines were negatively correlated. RUNX1 has specific binding sites with miR-200a-3p. The results of dual luciferase reporter gene detection showed that compared with three groups, Luc-3'UTR + mimic-NC, Luc-NC + miR-200a-3p mimic and Luc-NC + mimic-NC, luciferase activity of Luc-3'UTR + miR-200a-3p mimic group was significantly decreased (P < 0.05), suggesting that miR-200a-3p may be a direct negative regulator of RUNX1. Conclusion High expression of RUNX1 might function as an oncogene in CRC. The up-regulated expression of RUNX1 is associated with poor prognosis after CRC, which can be used as a biomarker of prognosis in CRC patients. This study is the first to report that RUNX1 is a direct negative regulatory target of miR-200a-3p in CRC and can be used as a potential therapeutic target for CRC patients.