Identification Of Target Genes Of Transcription Factor AP-2γ In Breast Cancer Cells

Activator protein 2gamma(AP-2γ) is a member of the transcription factor activator protein-2(AP-2) family,which is developmentally regulated and also plays a role in human neoplasia.The AP-2γprotein,in particular,has been shown to be overexpressed in a high percentage of breast tumors and has a dual role in different mammary tumorigenic stages:inhibition of tumor initiation and promotion of proliferation.To identify the gene targets that mediate its effects,we performed chromatin immunoprecipitation(ChIP) to isolate AP-2γbinding sites from human breast cancer cell line MDA-MB-453.Cloning and sequencing of AP-2γ-ChIP-derived DNA fragments identified 20 novel potential AP-2γtarget loci that were proximal to genes involved in the regulation of carcinogenesis,metabolism and others.A combination of sequence analysis,reporter gene assays,quantitative real-time PCR,electrophoretic gel mobility shift assays and immunoblot analysis led to the identification and validation of unknown AP-2γtarget genes.Our results were consistent with the previous reports that ErbB2 was the target gene of AP-27.Decreased expression and overexpression of AP-2γin human breast cancer cells significantly altered the expression of the genes (ErbB2,CDH2,IGSF11,and HPSE) associated with AP-2γbinding sites, indicating that AP-2γdirectly regulates their expression.The data suggested that AP-2γcan coordinate the expression of a network of genes, involving in carcinogenesis,especially in breast cancer.These novel AP-2γtarget genes,involving in carcinogenesis,could serve as a therapeutic target for anticancer therapy.These findings show the biological importance of AP-2γtranscription factors and they have great potential as tumor targeting reagents.