The Expression Of LZTFL1in Gastric Cancer And Its Mechanism

Objective:To investigate the expression level of the leucine zipper transcription factor-like1(LZTFL1) in gastric cancer tissue and cancer cells, as well as methylation status of LZTFL1promoter. Roles of LZTFL1on the proliferation and migration of gastric cancer cells and the regulatory mechanism of LZTFL1expression were also investigated.Methods:1.30cases gastric cancer specimens together with corresponding normal gastric mucosa were collected to investigate the expression level of LZTFL1by immunohistochemical method.2. mRNA and protein levels of LZTFL1were checked by real-time quantitative PCR(RT-PCR) and Western Blotting in four human gastric cancer cell lines(AGS, MKN28, MKN45and BGC823).3. LZTF1was overexpressed in AGS cell line by plasmid transfection, the proliferation and migration ability of cells were investigated by MTS, Flow cytometry and transwell methods.4. LZTF1expression was downregulated by siRNA transfection in GES-1cell line, and the proliferation and migration ability of cells were investigated by MTS, Flow cytometry and transwell methods. 5. YY1expression was downregulated in AGS cell line and overexpressed in GES-1cell line, RT-PCR and Western Blotting were employed to detect the LZTFL1mRNA and Protein levels.6. The promoter region of LZTFL1gene was analyzed and the regulation effect of transcription factor YY1on LZTFL1promoter was studied by chromatin immunoprecipitation (Chromatin immunoprecipitation, CHIP).7. The methylation status of LZTFL1promoter was analyzed by bisulfite sequencing (Bisulfite GenomicSequencing sulfide, BGS) and isulfite methylation specific PCR (Methylation specific PCR,MSP). And methylation inhibitor Aza to employed to reverse the methylation of LZTFL1promoter and the expression level changes of LZTFL1gene were detected by RT-PCR and Western-blotting.Results:1. Compared with normal gastric mucosa, the expression levels of LZTFL1gene were significantly lower in gastric cancer tissues as well as in various gastric cancer cell lines.2. LZTFL1gene overexpression inhibits the proliferation and migration ability of gastric cancer cell, and vice versa.3. The transcriptional factor YY1regulates the promoter of LZTFL1direct binding.4. The promoter of the LZTFL1gene in the human gastric cancer cell line AGS were high methylated which was correlated with the low expression of LZTFL1in gastric cancer.Conclusion:1. The expression levels of LZTFL1gene were significantly lower in gastric cancer tissues and cell lines.2. LZTFL1gene overexpression inhibits the proliferation and migration ability of gastric cancer cell, and vice versa.3. The low expression level of LZTFL1gene in gastric cancer may due to its hypermethylation.