CircASXL1 knockdown represses the progression of colorectal cancer by downregulating GRIK3 expression by sponging miR-1205

Background: Colorectal cancer (CRC) is a common aggressive tumor that poses a heavy burden to human health. An increasing number of studies have reported that circular RNA (circRNA) is involved in the progression of CRC. In this study, the special profiles of circASXL1 (circ_0001136) in CRC progression were revealed.

Methods: The expression of circASXL1, microRNA-1205 (miR-1205), and glutamate ionotropic receptor kainate type subunit 3 (GRIK3) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression was determined by Western blot or immunohistochemistry. Cell colony-forming ability was investigated by colony formation assay. Cell cycle and apoptosis were demonstrated using cell-cycle and cell-apoptosis analysis assays, respectively. Cell migration and invasion were detected by wound-healing and transwell migration and invasion assays, respectively. The binding sites between miR-1205 and circASXL1 or GRIK3 were predicted by circBank or miRDB online database, and identified by dual-luciferase reporter assay. The impact of circASXL1 on tumor formation in vivo was investigated by in vivo tumor formation assay.

Results: CircASXL1 and GRIK3 expression were apparently upregulated, and miR-1205 expression was downregulated in CRC tissues and cells relative to control groups. CircASXL1 knockdown inhibited cell colony-forming ability, migration and invasion, whereas induced cell arrest at G0/G1 phase and cell apoptosis in CRC cells; however, these effects were attenuated by miR-1205 inhibitor. Additionally, circASXL1 acted as a sponge for miR-1205, and miR-1205 was associated with GRIK3. Furthermore, circASXL1 silencing hindered tumor formation by upregulating miR-1205 and downregulating GRIK3 expression.

Conclusion: CircASXL1 acted an oncogenic role in CRC malignant progression via inducing GRIK3 through sponging miR-1205. Our findings provide a theoretical basis for studying circASXL1-directed therapy for CRC.