Deletions on Chromosome Y and Downregulation of the SRY Gene in Tumor Tissue Are Associated with Worse Survival of Glioblastoma Patients

SIMPLE SUMMARY: Glioblastoma (GBM) is one of the most common and most aggressive brain tumors with higher prevalence among men than women. Loss of chromosome Y (LOY) in the peripheral blood cells has been associated with increased risk of developing cancer. However, there is a lack of data about LOY in GBM tumor tissue and the potential impact on patients’ prognosis. Through droplet digital PCR (ddPCR) analysis of 10 markers spread throughout chromosome Y in 105 male GBM patients, we were able to identify deletion of SRY gene as a factor strongly correlating with reduced overall survival. This finding was later corroborated by the analysis of GBM gene expression data collected in TCGA, showing correlation between decreased SRY expression and shortened overall survival. ABSTRACT: Background: Biological causes of sex disparity seen in the prevalence of cancer, including glioblastoma (GBM), remain poorly understood. One of the considered aspects is the involvement of the sex chromosomes, especially loss of chromosome Y (LOY). Methods: Tumors from 105 isocitrate dehydrogenase (IDH) wild type male GBM patients were tested with droplet digital PCR for copy number changes of ten genes on chromosome Y. Decreased gene expression, a proxy of gene loss, was then analyzed in 225 IDH wild type GBM derived from TCGA and overall survival in both cohorts was tested with Kaplan–Meier log-rank analysis and maximally selected rank statistics for cut-off determination. Results: LOY was associated with significantly shorter overall survival (7 vs. 14.6 months, p = 0.0016), and among investigated individual genes survival correlated most prominently with loss of the sex-determining region Y gene (SRY) (10.8 vs. 14.8 months, p = 0.0031). Gene set enrichment analysis revealed that epidermal growth factor receptor, platelet-derived growth factor receptor, and MYC proto-oncogene signaling pathways are associated with low SRY expression. Conclusion: Our data show that deletions and reduced gene expression of chromosome Y genes, especially SRY, are associated with reduced survival of male GBM patients and connected to major susceptibility pathways of gliomagenesis.