BackgroundDespite improvements in nasopharyngeal carcinoma (NPC) treatment, patients with recurrence and metastasis still have a poor prognosis. Thus, the identification of novel biomarkers is urgently needed to predict outcomes and tailor treatment for NPC.MethodsFour data sets were downloaded from Gene Expression Omnibus, and one data set GSE68799 of which was applied to filtrate key modules and hub genes by construction of a co-expression network. Other data sets (GSE12452 and GSE53819) were used to verify hub genes. The data set GSE102349 was devoted to identify prognostic hub genes by survival analysis. To explored whether prognostic hub genes are related to hypoxia signatures in NPC, correlation analysis was carried out, and followed by functional verification experiments of those genes in vitro.ResultsBy co-expression network analysis, blue module was regarded as a key module in the benign and malignant group, and IGSF9 of the blue module was identified as a prognostic hub gene. Moreover, IGSF9 is expected to be a innovative hypoxia-related gene in NPC based on the strong associativity between expression of IGSF9 and hypoxia scores of three signatures (99-gene, 26-gene and 15-gene). Further functional studies verified that down-regulated expression of IGSF9 could reduce the proliferation, migration and invasion ability of NPC cells, and hypoxia could induce the expression of IGSF9.ConclusionIGSF9 was identified to be relevant to prognosis and involved in hypoxia in NPC. IGSF9 might serve as one novel prognostic indicator of NPC in the future.