Abstract
BackgroundCircular RNAs (circRNAs) feature prominently in tumor progression. However, the biological function and molecular mechanism of circ_0003266 in colorectal cancer (CRC) require further investigation.MethodsCirc_0003266 expression in 46 pairs CRC tissues / adjacent tissues, and CRC cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR); after circ_0003266 was overexpressed or knocked down in CRC cells, cell proliferation, apoptosis, migration, and invasion were evaluated by the cell counting kit-8 (CCK-8), flow cytometry, and Transwell assays, respectively; the interaction among circ_0003266, miR-503-5p, and programmed cell death 4 (PDCD4) was confirmed using bioinformatics analysis and dual-luciferase reporter assay; PDCD4 protein expression in CRC cells was quantified using Western blot.ResultsCirc_0003266 was significantly lowly expressed in CRC tissues and cell lines. Circ_0003266 overexpression markedly repressed CRC cell proliferation, migration, and invasion, and accelerated the cell apoptosis, but its overexpression promoted the malignant phenotypes of CRC cells. PDCD4 was a direct target of miR-503-5p and circ_0003266 promoted PDCD4 expression by competitively sponging miR-503-5p.ConclusionCirc_0003266 suppresses the CRC progression via sponging miR-503-5p and regulating PDCD4 expressions, which suggests that circ_0003266 may serve as a novel target for the treatment of CRC.
Highlights
Circular RNAs feature prominently in tumor progression
Circ_0003266 is lowly expressed in colorectal cancer (CRC) The expression profile of circRNAs in 5 pairs of CRC tissue and normal tissue samples were analyzed by circRNA microarray (GSE142837)
To verify the circular structure of circ_0003266, RNase R resistance assay was performed, and it was found that only linear mRNA (GAPDH) expression level was decreased after RNA R treatment, implying that circ_0003266 has a loop structure (Fig. 1c)
Summary
Circular RNAs (circRNAs) feature prominently in tumor progression. The biological function and molecular mechanism of circ_0003266 in colorectal cancer (CRC) require further investigation. Colorectal cancer (CRC) is a common cancer, and its mortality ranks among cancers worldwide, with nearly 900,000 deaths each year [1]. Great progress has been made in the diagnosis and treatment in recent years, the therapeutic effect of some patients with CRC is not good due to high frequency of metastasis and recurrence [2]. The research on CircRNA is a class of non-coding RNA derived from the reverse splicing of the precursor mRNA, which is with a covalent closed-loop structure formed by splicing the 5′ end of one exon with the 3′ end of another exon [6]. Hsa_circ_0013958 expression is up-regulated in lung adenocarcinoma tissues, cells, and plasma of the patients, which is positively correlated with TNM stage and lymphatic
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