SP1 is required for basal activation and chromatin accessibility of CD151 promoter in liver cancer cells

CD151 plays an important role in liver cancer metastasis. The mechanism on how CD151 is expressed remains unclear. Here we have identified SP1 is a protein functioning in constitutive activation of CD151. Applying a PCR-based chromatin accessibility assay, an open chromatin conformation was discovered localized around the transcription start site of the CD151 gene. Deletion constructs of the 5′ flanking region were fused to a luciferase reporter gene. After transient transfection in HepG2 and Hep3B cells, a minimal region −171/−53 bearing three SP1-binding sites was identified as the core promoter. Results obtained from electrophoretic mobility shift and chromatin immunoprecipitation assays demonstrated that SP1 is bound to the core promoter. Deletion of SP1 consensus sequence resulted in the total loss of the promoter activity. Moreover, knockdown of SP1 reduced both CD151 promoter activity and chromatin accessibility. Conclusively, SP1 is pivotal to CD151 transcription partly via the construction of a local open chromatin configuration across the promoter.