Dai Limeng, Fu Liyuan, Liang Yan, Guan Xingying, Bai Yun, Xiong Gang
Department of Medical Genetics, Army Medical University (Third Military Medical University) Chongqing, PR China.
Department of Ultrasound, The 309 Hospital of People's Liberation Army Beijing, PR China.
Int J Clin Exp Pathol. 2017 Nov 1;10(11):11006-11013. eCollection 2017.
The single nucleotide polymorphism (SNP) rs2257440 in exon 1 of the gene is known to be significantly associated with susceptibility to esophageal squamous cell carcinoma (ESCC). In the present study, bioinformatics analysis indicated that the SNP might influence the binding of a transcription factor, metal regulatory transcription factor 1 (MTF-1), to its target gene. We further investigated whether the polymorphism rs2257440 could regulate expression as a functional SNP via MTF-1.
Luciferase reporter assay indicated that MTF-1 elevated the expression of luciferase in the presence of the T allele of rs2257440 while no change in the expression was associated with the C allele of the polymorphism. Chromatin immunoprecipitation further evaluated the binding between the locus harboring the T allele and MTF-1. In the case of the TC genotype, over-expression of MTF-1 elevated expression, which in turn promoted the invasion capacity of KYSE450 cells. However, there was no significant change in the invasion capacity of EC109 cells, which had the CC genotype. In the cancer cells of the ESCC patients, the expression of was higher in the case of the TC or TT genotypes in comparison to the gene expression associated with the CC genotype. Over-expression of MTF-1 also decreased apoptosis of EC109 and KYSE450 cells, but the decrement was more in KYSE450 cells than in EC109 cells.
Our finding indicates that rs2257440 is a functional SNP. The T allele of rs2257440 can increase expression as it promotes binding of the gene with the specific transcription factor MTF-1. Therefore, the T allele of this polymorphism can decrease apoptosis and promote the invasion capacity of the cells in ESCC.
已知基因外显子1中的单核苷酸多态性（SNP）rs2257440与食管鳞状细胞癌（ESCC）的易感性显著相关。在本研究中，生物信息学分析表明该SNP可能影响转录因子金属调节转录因子1（MTF-1）与其靶基因的结合。我们进一步研究了多态性rs2257440是否可通过MTF-1作为功能性SNP调节表达。
荧光素酶报告基因检测表明，在rs2257440的T等位基因存在时，MTF-1可提高荧光素酶的表达，而该多态性的C等位基因与表达变化无关。染色质免疫沉淀进一步评估了携带T等位基因的位点与MTF-1之间的结合。在TC基因型的情况下，MTF-1的过表达提高了表达，进而促进了KYSE450细胞的侵袭能力。然而，具有CC基因型的EC109细胞的侵袭能力没有显著变化。在ESCC患者的癌细胞中，与CC基因型相关的基因表达相比，TC或TT基因型情况下的表达更高。MTF-1的过表达也降低了EC109和KYSE450细胞的凋亡，但KYSE450细胞中的降低幅度比EC109细胞更大。
我们的发现表明rs2257440是一个功能性SNP。rs2257440的T等位基因可增加表达，因为它促进了该基因与特定转录因子MTF-1的结合。因此，这种多态性的T等位基因可减少ESCC细胞的凋亡并促进其侵袭能力。
