Esophageal squamous cell carcinoma (ESCC) ranks among the five most common cancers in China, and has a five-year survival rate of less than 15%. The transcription factor ATAD2 has potential as a therapeutic target in various tumors, and microarray-based gene expression profiling reveals dysregulation of ATAD2 specifically in ESCC. Here we investigated whether ATAD2 could mediate a regulation of cancer stem cell (CSC) biological functions in ESCC. Immunohistochemical staining, reverse

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... on quantitative polymerase chain reaction, and Western blot assays all revealed up-regulation of ATAD2 in ESCC tissues and cell lines, which furthermore correlated with progression of ESCC. In loss-of-function experiments, silencing of ATAD2 inhibited activation of the Hedgehog signaling pathway, as indicated by reduced expression of Gli1, SMO, and PTCH1. Investigations with EdU, Transwell assay, scratch test, flow cytometry and colony formation assay showed that silencing of ATAD2 or inhibiting the Hedgehog signaling decreased the proliferation, invasion and migration abilities along with colony formation, but elevated the apoptosis rate of CSCs. Further, in vivo experiments validated the suppressive effect of siRNA-mediated ATAD2 silencing on tumor growth in nude mice. Thus, down-regulation of ATAD2 can seemingly restrain the malignant phenotypes of ESCC cells through inhibition of the Hedgehog signaling pathway.