Background To investigate the methylation status of the promoter region of RIZ1 gene in human glioma tissues and 4 glioblastoma(GBM)cell lines,and verify the influence of methyltransferase inhibitor 5-Aza-CdR on the transcription of RIZ1 gene and cell proliferation in the cell whose RIZ1 gene promoter region is hypermethylated.Methods and results Methylation-specific PCR(MSP)was performed to detect the methylation status of the RIZ1 promoter in human glioma tissue specimens.The correlation between RIZ1 hypermethylation status and clinicopathological features was also analyzed.Meanwhile,MSP was used to investigate the promoter region methylation status of RIZ1 gene in the four human glioblastoma cell lines.5-Aza-Cdr was treated to the cell line U87,whose RIZ1 gene promoter region hypermethylation was detected.Real-time PCR was used to investigate its influence on the transcription of RIZ1 gene.Brdu was used to detect if 5-Aza-CdR could inhibit the proliferation of the cell line whose RIZ1 gene promoter region was hypermethylated.Among the 51 human glioma specimens,RIZ1 promoter methylation was detected in 23 cases.