CpG2 hypermethylation in the CD95L promoter is associated with survival in patients with glioblastoma

Background and Aim: Blockade of CD95/CD95 ligand (CD95 L) signaling is a promising therapeutic approach for the treatment of glioblastoma (GBM), while methylation of a single cytosine-phosphate-guanine site (CpG2) upstream of the CD95 L promoter has been identified as a prognostic biomarker for GBM. Here, we conducted the first investigation of CD95 L expression and CpG2 methylation levels in the CD95 L promoter in GBM patients. Materials and Methods: In this observational study, tissue samples were collected from 69 patients with a primary diagnosis of World Health Organization Grade IV GBM treated at the Department of Glioma Surgery, Huashan Hospital, Shanghai Medical College, Fudan University and tested for CD95 L expression using immunohistochemistry (IHC). The CpG2 methylation status of the samples was also evaluated, and its impact on overall survival (OS) was assessed by univariate analysis. The study was approved by the Hospital Institutional Review Board (approval No. 220) on July 7, 2015. Results: The IHC results showed a CD95 L detection rate of at least 43.5% for tissue samples with IHC scores of 2 + or 3 + and 78.3% for those with IHC scores of 1 + , 2 + , or 3 + . Patients with high CpG2 methylation levels (≥52% higher than the median value; n = 32) had significantly longer median survival compared with those with low CpG2 methylation levels ( n = 29) (22.95 vs. 14.5 months; P = 0.0084). GBM patients who underwent gross total tumor resection ( n = 57) showed similar results. Those in the high CpG2 methylation group had longer median OS compared with that of patients in the low CpG2 methylation group (23.5 vs. 18.0 months; P = 0.0141). Conclusions: Our results showed a significant prevalence of CD95 L expression in GBM patients, whereas CpG2 hypermethylation within the CD95 L promoter was positively associated with survival. These findings support that CD95/CD95 L signaling blockade has potential as a therapeutic strategy targeting treatment-resistant GBM.