CircSFMBT2 Plays an Oncogenic Role in Lung Adenocarcinoma Depending on the miR-1305/SALL4 Axis

Circular RNAs (circRNAs) exhibit significant functions in diverse malignant tumors, including lung adenocarcinoma (LUAD). In this study, we aimed to elucidate the role of circRNA scm like with four mbt domains 2 (circSFMBT2) in LUAD. Quantitative real-time polymerase chain reaction (qRT-PCR), western blot assay or immunohistochemistry (IHC) assay was performed for quantification of circSFMBT2, microRNA-1305 (miR-1305), spalt like transcription factor 4 (SALL4), proliferating Cell Nuclear Antigen (PCNA) or Ki-67. 5-ethynyl-2’-deoxyuridine (EdU) assay, transwell assay and flow cytometry analysis were applied to analyze cell proliferation, metastasis and apoptosis, respectively. Mouse xenograft model was established to explore the function of circSFMBT2. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were used to estimate the relationship between miR-1305 and circSFMBT2 or SALL4. CircSFMBT2 was upregulated in LUAD and related to advanced TNM stage and poor prognosis. CircSFMBT2 knockdown suppressed cell proliferation, metastasis, glycolysis and induced apoptosis in LUAD cells in vitro as well as tumor formation in vivo. CircSFMBT2 directly targeted miR-1305, and miR-1305 inhibition reversed circSFMBT2 knockdown-mediated inhibitory effects on LUAD malignant behaviors. SALL4 was the target gene of miR-1305. MiR-1305 overexpression repressed the malignant phenotypes of LUAD cells, while SALL4 enhancement abated the effects. CircSFMBT2 aggravated the progression of LUAD by the miR-1305/SALL4 axis, which might provide a diagnostic and prognostic marker for LUAD.