Genetic Variants And Functional Studies On S100A14 In Esophageal Squamous Cell Carcinoma

S100 proteins play important roles in tumorigenesis and metastasis.Our previous study by semiquantitative RT-PCR showed that the expression level of sixteen members of S100 family including S100A14 was significantly altered in Esophageal Squamous Cell carcinoma(ESCC).In order to further characterize expression pattern of S100A 14 and the relationship with clinicopathological features,Western blot and immunohistochemical analysis were performed in primary tumors and matched normal tissues and tissue microarray respectively.The results indicated that the expression of S100A14 was downregulated in ESCC samples compared with matched normal counterparts.Statistical analysis revealed that there was significant correlation between S100A14 expression and differentiation grade in ESCC.Functional studies indicated that S100A14 overexpression promoted cell adhesion to Fibronectin-coated wells and invasive capabilities,but inhibited cell motility capability.In accordance with above results,S100A14 RNAi promoted KYSE150 cell motility capability.Molecular mechanism studies showed that E-cadherin was up-regulated whereas N-cadherin was down-regulated in S100A14 RNAi cells. However,the precise mechanism still needs further investigation.In the second part,we examined whether there are functional genetic variants in the S100A14 locus,and assessed their association with susceptibility to esophageal squamous cell carcinoma(ESCC).Thirty individual DNA samples were sequenced to search for genetic variations,and the function of the variants was investigated by a series of biochemical assays.Four single nucleotide polymorphisms,-43A＞G,461G＞A,1493A＞G and 1545A＞T were identified in the S100A14 locus,and all were in absolute linkage disequilibrium.The 461G＞A change was found to be a functional variant affecting p53 binding,which might abolish negative feedback loop in the p53 regulation.A case-control analysis was performed in 1021 patients with ESCC and 1253 control subjects.Odds ratios(ORs) and 95%confidence intervals(CIs) were estimated by logistic regression.The results showed that the 461A allele is associated with an increased susceptibility to ESCC compared with the 461G allele(OR = 1.23,95%CI = 1.04-1.46).A joint effect between the 461A and smoking was also observed.Taken together,we conclude that S100A14 plays an important role in cell adhesion, invasion and migration of esophageal squamous cell carcinoma.Functional genetic variant in S100A14 may affect p53 regulation and play a role in mediating susceptibility to esophageal squamous cell carcinoma.