HMGA2 Regulates Circular RNA ASPH to Promote Malignant Phenotypes in Lung Adenocarcinoma

Abstract

Background: The HMGA2 gene has been identified as an oncogene in many malignancies. The regulatory effects of HMGA2 on protein-coding oncogenes have been demonstrated by multiple studies. However, the effects of HMGA2 on circular RNAs (circRNAs) in malignancies remain unclear. Methods: CircRNA high-throughput sequencing analysis was performed on stable HMGA2-overexpressing A549 cells. qRT-PCR analysis in A549 cells and tissue samples was used to screen for the candidate circRNA. The effects of HMGA2 on circular RNA ASPH (circASPH) and its host gene were evaluated using RT-PCR. A chromatin immunoprecipitation assay was performed to detect DNA-protein complexes. Co-IP followed by mass spectrometry was used to determine the proteins interacting with HMGA2. The proliferation, migration, and invasion of lung adenocarcinoma cell lines were examined by EdU, wound scratch, and transwell invasion assays, respectively. The effect of circASPH on tumor growth in vivo was verified using a mouse xenograft assay. Luciferase, RNA FISH, and biotin-coupled miRNA capture assays were used to evaluate the interaction between circASPH and microRNAs. Findings: CircASPH expression levels were significantly higher in cancerous tissues. Patients with higher levels of circASPH had a shorter overall survival. CircASPH was found to be directly regulated by HMGA2 and Twist1. CircASPH promoted the malignant phenotypes of lung adenocarcinoma. CircASPH acted as a molecular sponge for miR-370 and abrogated miR-370-mediated inhibition of HMGA2. The oncogenic function of circASPH was HMGA2-dependent. Interpretation: These findings reveal the oncogenic functions of the HMGA2-circASPH-HMGA2 axis and may be useful in developing circRNA-based therapeutic strategies for lung adenocarcinoma. Funding Statement: The National Natural Science Foundation of China (grant 81702287 to Dr. Wei-Lin Liao and grant 81800443 to Dr. Ye Ma). Declaration of Interests: The authors stated: None. Ethics Approval Statement: All the study protocols were approved by the Institutional Review Boards of General Hospital of Western Theater Command. For examinations utilizing human lung tissue specimens, all patients gave written informed consent. The animal studies were performed in accordance with the institutional ethics guidelines for animal experiments.