Background Lung squamous cell carcinoma (LUSC) accounts for approximately 30% of all lung cancers that possesses the highest occurrence and mortality in all cancer types. determined by luciferase reporter assay and RIP assay. Results MAGI2-AS3 inhibited the proliferative, migratory and invasive capability of BX471 LUSC cells with upregulated expression. Additionally, MAGI2-AS3 overexpression promoted cell apoptosis. We discovered that MAGI2-AS3 was located in the cytoplasm. Hereafter, we found out that MAGI2-AS3 BX471 targeted miR-374a/b-5p. CADM2 was targeted by miR-374a/b-5p. Finally, rescue assays indicated that the promoting effects of miR-374a/b-5p amplification on biological activities were restored by CADM2 addition. Conclusion In conclusion, lncRNA MAGI2-AS3 suppressed LUSC by regulating miR-374a/b-5p/CADM2 axis, which might potentially serve as a therapeutic marker for LUSC patients. Keywords: lung squamous cell carcinoma, LUSC, MAGI2-AS3, miR-374a/b-5p, CADM2 Introduction Lung cancer is one of the top 10 10 malignant tumors with increasing occurrence and mortality.1 Worse still, the incidence and mortality of lung cancer rank the first in all cancer types among the males and the second among the females.2 Small cell lung carcinoma and non-small-cell lung carcinoma (NSCLC) are the common subtypes of lung cancer. And NSCLC can be classified into lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC).3,4 Known factors like smoking, air pollution and ionizing radiation are considered to be associated with the initiation and development of LUSC,5,6 but the pathology of LUSC remains unclear. Long noncoding RNAs (lncRNAs) are a class of molecules with more than 200 nucleotides in length without capability encoding proteins.7 LncRNA dysregulation has been observed in various tumors.8,9 Specifically, downregulated lncRNAs repress tumor development and vice versa. As examples, HCG11 inhibits cell glioma growth by modulating miR-496/CPEB or miR-4425/MTA3 axis.10,11 Up-regulated HEIH promotes colorectal cancer tumorigenesis by cooperating with miR-939 to repress the transcription of Bcl-xl.12 Recently, MAGI2 antisense RNA 3 (MAGI2-AS3) is reported to act as a tumor suppressor in bladder cancer, breast cancer and hepatocellular carcinoma.13C15 Importantly, previous studies have identified that MAGI2-AS3 is down-regulated in NSCLC samples, including LUAD and LUSC samples.16,17 Moreover, we identified through GEPIA NMYC online tool based on TCGA data that MAGI2-AS3 was downregulated in LUSC samples versus normal samples. These findings indicated that MAGI2-AS3 might participate in LUSC. Also, Hao et al delineated that MAGI2-AS3 regulated NSCLC via miR-23a-3p/PTEN axis based on LUAD cell lines (A549, PC9, NCI-H441, and NCI-H1650).18 However, neither the biological function nor the regulatory mechanism of MAGI2-AS3 has been explored in LUSC before, which prompted us to investigate the role of MAGI2-AS3 in LUSC. In mechanism, considerable evidence suggests that lncRNA is capable to regulate gene expression at the transcriptional level or post-transcriptional level.19,20 Additionally, the competitive BX471 endogenous RNA (ceRNA) pattern has attracted abundant attention. In this pattern, lncRNA enhances messenger RNA (mRNA) levels by sponging microRNA (miRNA).21,22 LINC00511 is reported to increase the E2F1 level by interacting with miR-185-3p in breast cancer.23 lncRNA XIST is supposed to modulate BX471 EZH2 expression via acting a molecular sponge of miR-101 in gastric cancer.24 Meanwhile, the regulatory mechanism of MAGI2-AS3 in LUSC remains uncharacterized. To conclude, we attended to explore the biological function and regulatory mechanism of MAGI2-AS3 in LUSC and discovered that lncRNA MAGI2-AS3 suppressed several cellular processes of lung squamous cell carcinoma cells by regulating miR-374a/b-5p/CADM2 axis. Materials and Methods Tissue Samples 41 LUSC tissues and their paired adjacent noncancerous tissues were attained from patients in Peking Union Medical College Hospital by surgery excision between March 2013 and March 2014. No patients received radiotherapy or chemotherapy before surgery. Samples were frozen in liquid nitrogen at ?80C right after resection. Written informed consents were gained from all patients, with the approval of the Ethics Committee of Peking Union Medical College BX471 Hospital. Cell Culture Human bronchial epithelial cell (HBE) and LUSC cells (H2170, H226, SW900, SK-MES-1) were purchased from the American Type Culture Collection (ATCC; Manassas, VA, USA). In a humidified air with 5% CO2, cells were grown routinely at 37C in RPMI-1640 medium (Gibco, Rockville, MD, USA) adding 1% penicillin/streptomycin (Invitrogen) and 10% fetal bovine serum (FBS; Gibco). Cell Transfection The pcDNA3.1/MAGI2-AS3, pcDNA3.1/CADM2 and the.