Serum lncRNA-ANRIL and SOX9 expression levels in glioma patients and their relationship with poor prognosis

BACKGROUND: lncRNA-CDKN2B antisense RNA 1 (ANRIL) and SRY-box transcription factor 9 (SOX9) has abnormal expression in many tumors including glioma, but the underlying molecular mechanism is unclear. This study set out to investigate the serum lncRNA-ANRIL and SOX9 levels in glioma patients and their effects on prognosis. METHODS: We enrolled 142 glioma patients admitted to our hospital from May 2014 to May 2016 into the research group (RG) and 120 healthy subjects receiving concurrent physical examinations into the control group (CG). Fasting peripheral blood (4 mL each) was sampled from subjects from the two groups. Using the quantitative real-time polymerase chain reaction (qRT-PCR), lncRNA-ANRIL and SOX9 were measured to explore their values in the early diagnosis of glioma. Patients from RG were followed up for 3 years to analyze the influence of lncRNA-ANRIL and SOX9 on patient prognosis. We purchased glioma cell lines U251 and U87 and grouped them according to the transfection of different plasmids. We conducted CCK8 assay to test cell proliferation, Transwell assay to test cell invasion, the flow cytometry to test cell apoptosis, and Western Blot assay to measure bcl-2 and bax protein levels. RESULTS: ANRIL and SOX9 were evidently higher in RG than in CG (P<0.01). The receiver operating characteristic (ROC) curve revealed that the diagnostic sensitivity of ANRIL combined with SOX9 for glioma was 81.62%, and the specificity was 90.83% (P<0.01). ANRIL and SOX9 were closely related to tumor grade, tumor diameter, distant metastasis, and family history of glioma (P<0.01). In total, 135 patients were successfully followed up (95.07%). Patients with high levels of ANRIL and SOX9 had a markedly poorer prognosis than those with low levels (P<0.05). ANRIL and SOX9 were markedly higher in glioma cell lines (U251 and U87) than in normal brain cells (P<0.01). The proliferation and invasion of U251 cells were notably reduced after the transfection of ANRIL and SOX9 inhibitory sequences (P<0.01), but the apoptosis was notably increased (P<0.01). Bcl-2 expression was markedly increased in lncRNA-ANRIL-inhibitor and SOX9-inhibitor (P<0.01), while bax expression was markedly reduced in lncRNA-ANRIL-inhibitor and SOX9-inhibitor (P<0.01). CONCLUSION: lncRNA-ANRIL and SOX9 levels were higher in glioma patients than in healthy people. High-lncRNA-ANRIL and SOX9 levels were strongly associated with unfavorable prognosis of patients. The testing of biological behaviors revealed that lncRNA-ANRIL and SOX9 worked as tumor-promoting genes in glioma.