br A miRNA can contain multiple
A miRNA can contain multiple target genes, and multiple miRNAs can also regulate the same gene; thus, miRNAs are involved in the complex gene and pathway regulations in cancers. Genome-wide
Details of over-represented KEGG pathways associated with miRNA target genes.
miRNA and mRNA expression analyses have been used to identify the functional involvement of miRNAs in the development and pathogen-esis of cancers . Thus, we conducted pathway enrichment analysis based on the predicted targets and found that the dysregulated miRNAs
miRNA Description of pathway P adj. P Gene count Gene
adj. P:adjusted P value.
(miR-144-3p and miR-425-5p) in CRC were functionally involved in several key cancer-related pathways, such as axonal guidance, PI3K, cGMP, and calcium signaling pathways (Fig. 5). Wu et al. reported that the significant upregulation of miR-144-3p can inhibit the activation of PI3K signaling pathway by downregulating the expression of IRS1, which suppresses the growth and metastasis of laryngeal squamous cell carcinoma . Other researchers found that miR-144-3p promotes cell proliferation, migration, and invasion in nasopharyngeal carcinoma by repressing the expression of phosphatase and tensin homolog (PTEN) to activate the PI3K pathway . These results were consistent with our finding that the PI3K pathway is one of the primary signal transduction pathways in miR-144-3p to predict target genes. In addition, a large number of reports suggested that the Ca2+ signaling pathway played an important role in tumor occurrence and development. Tumor 13(S)-HODE showed markedly higher Ca2+ concentration compared with normal cells and elevated expression levels of L-type and T-type Ca2+ channels . miR-425-5p was mainly enriched in the Ca2+, cyclic adenosine monophosphate (cAMP), and cGMP signaling pathways, indicating that the same miRNA regulates a variety of target genes. Ca2+-dependent activation of adenosine 5′-monophosphate activated protein kinase (AMPK) in cancer cells causes G1-phase cell cycle arrest and enhances cell viability or survival .
We demonstrated that seven miRNAs may function as noninvasive biomarkers to detect CRC. The consistency check results showed good agreement between miRNAs and the golden standard paraﬃn pa-thology to diagnose CRC. In particular, the panel of three miRNAs (miR-144-3p, miR-425-5p, and miR-1260b) yielded an AUC of 0.954, with 93.8% sensitivity and 91.3% specificity, which demonstrated higher diagnostic performance compared with the single-factor index. Furthermore, miRNA target prediction and pathway enrichment ana-lysis indicated that the dysregulated miRNAs in CRC are functionally involved in several key cancer-related pathways, such as axonal gui-dance, PI3K, and calcium signaling pathways. Thus, the plasma 3-miRNA panel may serve as a novel noninvasive biomarker for CRC diagnosis and may be related to CRC development. However, further studies are needed to highlight the theoretical strengths of this ap-proach.
The experiments were designed by L.F.R. and Y.X.F., T.Y. performed the majority of the experiments and data analysis. L.J.J. assisted with data analysis and wrote the paper. Y.X.F., G.D.M., and F.L.W. provided materials and made critical suggestions during the course of this work.
Ethics approval and consent to participate
This study was approved by the Institutional Ethics Committees at Shenzhen People’s Hospital (Shenzhen, China) and Sun Yat-sen University Cancer Center, and written informed consent was obtained from all study participants.
Availability of data and materials
All data generated or analyzed during this study were included in this article and its supplementary information files. And the datasets used and analyzed during the current study are available from the corresponding author on reasonable request, the TCGA dataset (http:// gdac.broadinstitute.org/), and CTD dataset (http://ctdbase.org/).