Study on RIZ1 gene promoter methylation status in human esophageal squamous cell carcinoma

AIM:To investigate the promoter region methylation status of retinoblastoma protein-interacting zinc finger gene 1(RIZ1) in the human esophageal squamous cell carcinoma(ESCC) cell lines and tissues and verify the relationship between methylation of RIZ1 and oncogenesis,tumor progression and metastasis etc of ESCC.METHODS:Methylation-specific polymerase chain reaction(MSP) was used to investigate the promoter region methylation status of RIZ1 in 6 ESCC cell lines.One cell line where RIZ1 promoter region methylation was detected was selected for the next study,where the cell line was treated with 5-aza-CdR.Real-time polymerase chain reaction was used to investigate its influence on the transcription of RIZ1.Experiments using frozenpathological specimens from 47 ESCC patients were performed using the same MSP methodology.RESULTS:Promoter methylation of RIZ1 gene was detected in TE13,CaEs17 and EC109 cell lines and the cell line TE13 was chosen for further study.The expression of RIZ1 mRNA in TE-13 was up-regulated after treatment with 5-aza-CdR.The rate of methylation in carcinomas tissues was significantly higher than those in matched neighboring normal and distal ending normal tissue,and the deviation of data was statistically significant(χ 2 = 24.136,P < 0.01).Analysis of the gender,age familial history,tumour deviation,tumour saturation,lymph gland displacement and clinical staging of 47 samples from ESCC patients showed that the fluctuation of data was not statistically significant.CONCLUSION:Promoter methylation may play an important role in the epigenetic silencing of RIZ1 gene expression in human ESCC.RIZ1 is considered to be a potential tumor suppressor gene and may be a biological parameter for testing early stage human ESCC.

Alteration in gene expression profile and oncogenicity of esophageal squamous cell carcinoma by RIZ1 upregulation

AIM:To investigate the effect of retinoblastoma protein-interacting zinc finger gene 1(RIZ1)upregulation in gene expression profile and oncogenicity of human esophageal squamous cell carcinoma(ESCC)cell line TE13.METHODS:TE13 cells were transfected with pcDNA3.1(+)/RIZ1 and pcDNA3.1(+).Changes in gene expression profile were screened and the microarray results were confirmed by reverse transcriptionpolymerase chain reaction(RT-PCR).Nude mice were inoculated with TE13 cells to establish ESCC xenografts.After two weeks,the inoculated mice were randomly divided into three groups.Tumors were injected with normal saline,transfection reagent pcDNA3.1(+)and transfection reagent pcDNA3.1(+)/RIZ1,respectively.Tumor development was quantified,and changes in gene expression of RIZ1 transfected tumors were detected by RT-PCR and Western blotting.RESULTS:DNA microarray data showed that RIZ1transfection induced widespread changes in gene expression profile of cell line TE13,with 960 genes upregulated and 1163 downregulated.Treatment of tumor xenografts with RIZ1 recombinant plasmid significantly inhibited tumor growth,decreased tumor size,and increased expression of RIZ1 mRNA compared to control groups.The changes in gene expression profile were also observed in vivo after RIZ1 transfection.Most of the differentially expressed genes were associated with cell development,supervision of viral replication,lymphocyte costimulatory and immune system development in esophageal cells.RIZ1 gene may be involved in multiple cancer pathways,such as cytokine receptor interaction and transforming growth factor beta signaling.CONCLUSION:The development and progression of esophageal cancer are related to the inactivation of RIZ1.Virus infection may also be an important factor.