LncRNA SNHG22 Sponges miR-128-3p to Promote Progression of Colorectal Cancer through Upregulating E2F3

Abstract

Background: Long non-coding RNA (lncRNA) termed small nucleolar RNA host gene 22 (SNHG22) has been reported as a crucial regulator in several types of human cancers. In this study, we aimed to evaluate the function and mechanism of SNHG22 in colorectal cancer (CRC) progression. Methods: Quantitative RT-PCR (qRT-PCR) was used to detect the expression of SNHG22 in adenoma, tumor tissues (TTs), and adjacent nontumorous tissues (ANTs). The biological behaviors of SNHG22 in CRC cell lines were explored both in vitro (CCK-8 assay, flow cytometry, wound scratch, and transwell assays) and in vivo (nude mouse xenograft model). The interaction between SNHG22 and miR-128-3p, and the target genes of miR-128-3p were explored by online tools, qRT-PCR, western blot, and dual-luciferase reporter assay. Results: SNHG22 expression was gradually upregulated in ANTs, adenoma, and TTs. High expression levels of SNHG22 were significantly related to advanced clinicopathological factors and worse survival in patients with CRC. SNHG22 knockdown markedly prohibited CRC cell proliferation, migration, and invasion; and drove cell apoptosis in vitro; and hindered tumor growth in vivo. Mechanistic investigation showed that SNHG22 could bind to microRNA-128-3p (miR-128-3p) and attenuate its inhibitory effects on the expression levels and activity of E2F3. Rescue experiments exhibited that miR-128-3p inhibition or E2F3 upregulation can offset the functions of SNHG22 knockdown in CRC cells. Conclusion: Our findings support the existence of an interactive regulatory network of SNHG22, miR-128-3p, and E2F3 in CRC cell lines, indicating that the SNHG22/miR-128-3p/E2F3 axis is a novel diagnostic and therapeutic target in CRC.