Long non-coding RNAs (lncRNAs) serve critical roles in the pathogenesis of various cancers, including lung adenocarcinoma (LUAD). Herein, in this study, we aimed to investigate the biological and clinical significance of lncRNA DiGeorge syndrome critical region gene 5 (DGCR5) in LUAD. It was observed that DGCR5 was upregulated in LUAD tissues and LUAD cell lines. Inhibition of DGCR5 can prevent LUAD progression via playing anti-apoptosis roles. Both mRNA expression and protein levels of BCL-2 were increased by DGCR5 downregulation while reversely BAX was increased. Additionally, a novel microRNA target of DGCR5, hsa-mir-22-3p was identified through bioinformatics search and confirmed by dual-luciferase reporter system. Gain and loss-of-function studies were performed to verify whether DGCR5 exerts its biological functions through regulating hsa-mir-22-3p in vitro. Overexpression of DGCR5 was able to reverse the tumor inhibitory effect of hsa-mir-22-3p mimics. Furthermore, in vivo tests tumor xenografts were established to detect the function of DGCR5 in LUAD tumorigenesis. Downregulated DGCR5 expression was greatly associated with smaller tumor size, implying a favorable prognosis of LUAD patients. Taken these together, DGCR5 could be considered as a prognostic biomarker and therapeutic target in LUAD diagnosis and treatment.

Non-coding RNAs can exert significant roles various cancers, including NSCLC. Previously, we indicated that lncRNA DGCR5 can promote lung cancer progression through inhibiting hsa-mir-22-3p. In our current study, we investigated the role of DGCR5 in cancer stem cell-like properties of NSCLC. CSCs have been recognized as the frequent cause of tumor metastasis, tumor recurrence, and chemotherapy resistance. Here, lung cancer stem cells were successfully enriched from the parental NSCLC A549, H460, and H1299 cells by using tumor sphere formation assays and side population (SP) assays. We observed that DGCR5 was up-regulated in the enriched CSCs of NSCLC. DGCR5 can inhibit the stemness of NSLCL while overexpression of DGCR5 promoted CSC-like traits. In addition, miR-330-5p was predicted as target of DGCR5 and the correlation between them was validated by dual-luciferase reporter assay, RIP assay, and RNA pull-down assay. Meanwhile, it was found that miR-330-5p was decreased in CSCs of NSCLC. miR-330-5p mimics repressed the stemness while miR-330-5p inhibition enhanced CSC-like properties by targeting CD44. Taken these together, DGCR5 can act as a crucial regulator of CSCs in NSCLC by modulating miR-330-5p/CD44 axis.