title: The role of the retinoblastoma protein-interacting zinc finger gene 1 tumor suppressor gene in human esophageal squamous cell carcinoma cells.
abstract: The tumor suppressor protein retinoblastoma protein-interacting zinc finger gene 1 (RIZ1) is downregulated in several types of cancer, including esophageal squamous cell carcinoma (ESCC). The present study used twoin vitromethods to re-express RIZ1 in the human ESCC TE13 cell line in order to induce apoptosis. RIZ1 was re-expressed in the TE13 cells by reintroducing the gene through transfection or by removal of transcriptional repression through treatment with a DNA methyltransferase (DNMT) inhibitor. To reintroduce the gene, the open reading frame of the RIZ1 gene was inserted into the eukaryotic expression pcDNA3.1(+) vector and pcDNA3.1(+)/RIZ1 was purified and transfected into the TE13 ESCC cells. Removing transcriptional repression involved treating the TE13 cells with 5-aza-2'-deoxycytidine (5-aza-CdR), a DNMT inhibitor. RIZ1 mRNA and protein expression were determined by quantitative polymerase chain reaction (qPCR) and western blotting. The rate of apoptosis of the cells was determined by flow cytometry. A recombinant eukaryotic human RIZ1 expression plasmid, pcDNA3.1(+)/RIZ1, was constructed and confirmed by sequencing. RIZ1 mRNA and protein expression increased in pcDNA3.1(+)/RIZ1 stably transfected cells. Treatment with 5-aza-CdR for 48 and 72 h resulted in increased RIZ1 protein expression and increased the rate of apoptosis in the TE13 cells (P<0.01). In conclusion, transfection of the TE13 cells with the eukaryotic pcDNA3.1(+)/RIZ1 expression vector and reversal of transcriptional repression of RIZ1 using 5-aza-CdR demonstrate that it is possible to re-express RIZ1 in TE13 cells. Furthermore, the re-expression of RIZ1 led to an increased rate of apoptosis and this method may provide new therapeutic possibilities.
authors.affiliation: Department of Cardiothoracic Surgery, Tianjin Medical University General Hospital, Heping, Tianjin 300052, P.R. China.
authors.forename: Shangwen
authors.initials: S
authors.lastname: Dong
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.forename: Shaojie
authors.initials: S
authors.lastname: Liang
authors.forename: Shuo
authors.initials: S
authors.lastname: Wang
authors.forename: Pei
authors.initials: P
authors.lastname: Sun
authors.forename: Yuanguo
authors.initials: Y
authors.lastname: Wang
keywords: 5-aza-2′-deoxycytidine; esophageal squamous cell carcinoma; pcDNA3.1(+); retinoblastoma protein-interacting zinc finger gene 1; transfection