Association Of Mutation And Methylation In The Promoter Region Of Tif1γ With Non-small Cell Lung Cancer

Background and Objective:TIF1γ (Transcription intermediary factor1gamma), which belongs to transcription intermediary factor1family, is an inhibitor of the TGF-β/Smad signaling pathway and could inhibit the signal transduction mediated by TGF-β. The deficiency of TIF1γ expression in a variety of tumor cells suggests that TIFly may play as a tumor suppressor gene in cancer development. The aim of this study is to confirm the relationship between TIF1γ and non-small cell lung cancer (NSCLC) through exploring the expression of TIF1γ in NSCLC cells and tissues, and investigate the regulation mechanism of TIF1γy expression in NSCLC cells.Methods:Thirteen NSCLC and the paired corresponding para-cancerous lung tissue samples and three cell lines (a normal bronchial epithelial cell line HBE and two NSCLC cell lines A549and95C) were selected. The quantitative Real-time PCR and western blotting were used to determine the expression of TIF1γ, and ImageJ was used to evaluate the relative expression of TIF1γ. Direct sequencing was performed to detect mutations within the promoter region of the TIF1γ gene and then Bisulfite-sequencing PCR (BSP) and cloning sequencing were carried out to test the methylation status of the promoter region of TIF1γ gene in the selected cell lines.Results:Both mRNA and protein expression of TIFly were found significantly decreased in A549and95C compared with that in HBE (P<0.05). And in9pairs (69.2%) of tissues among the13pairs, the mRNA expression of TIF1γ gene was higher in the cancer tissues than that in the paired paracancerous lung tissues (P<0.05). The result of promoter activity analysis shows that the core promoter of TIF1γ gene locates in the region of-282--30. No abnormal mutation was found in the region of-287to-5which include the core promoter of the TIF1γ gene in the three cell lines. Moreover, five CpG sites (including-214bp,-128bp,-124bp,-65bp and-55bp) were detected in the promoter of TIF1γ gene by using BSP, and the methylation profiles in these CpG sites showed similar pattern between NSCLC cells and HBE cells. Conclusion:TIF1γ may play a tumor suppressor role in the progression of NSCLC. the core promoter of TIF1γy gene locates in the region of-282--30. No mutation was found in the-287--5region of which include the core promoter of the TIF1γ gene in a normal bronchial epithelial cell line and two NSCLC cell lines. But there are five CpG sites which can be methylated located in this region.