Abstract
p21WAF1/CIP1 (p21) plays critical roles in cell-cycle regulation and DNA repair and is transcriptionally regulated through p53-dependent or -independent pathways. Bioinformatic analysis predicated one stress-response element (STRE) implicated in single nucleotide polymorphism (SNP) rs2395655 of the p21 promoter. Here, we investigated the transcriptional regulatory function of rs2395655 variant genotype and analyzed its associations with the p21 expression and clinical outcomes in esophageal squamous cell carcinoma (ESCC) patients. Luciferase assay results showed significantly increased transcriptional activity of the rs2395655 G allele-containing p21 promoter compared with rs2395655 A allele-containing counterpart, especially in ESCC cells with ectopic LEDGF/p75 expression. Furthermore electrophoretic mobility shift assay using the rs2395655 G or A allele-containing probe and chromatin immunoprecipitation assay with specific anti-LEDGF/p75 antibody indicated the potential binding activity of LEDGF/p75 with the STRE element implicated in rs2395655 G allele of the p21 promoter. Subsequent specific RNA interference-mediated depletion or ectopic expression of LEDGF/p75 caused obviously down- or up-regulated expression of p21 mRNA in ESCC cells harboring rs2395655 GG genotype but not cells with rs2395655 AA genotype. Furthermore, rs2395655 GG genotype carriers showed significantly elevated p21 protein expression and conferred survival advantage in both univariate and multivariate analyses in total 218 ESCC patients. Our findings suggest that LEDGF/p75 regulates the p21 expression in ESCC cells through interacting with STRE element implicated in polymorphism rs2395655 and the elevated p21 protein expression and rs2395655 GG genotype may serve as positive prognostic factors for ESCC patients.