19q13 KRAB zinc-finger protein ZNF471 activates MAPK10/JNK3 signaling but is frequently silenced by promoter CpG methylation in esophageal cancer

Zinc-finger proteins (ZFPs) are the largest transcription factor family in mammals, involved in the regulation of multiple physiologic processes including cell differentiation, proliferation, apoptosis and neoplastic transformation. Approximately one-third of ZFPs are Krüppel-associated box domain (KRAB)-ZFPs. Methods: ZNF471 expression and methylation were detected by reverse-transcription PCR and methylation-specific PCR. The impact and mechanism of ectopic ZNF471 expression in esophageal squamous cell carcinoma (ESCC) cells was evaluated in vitro and in vivo. Results: We identified a 19q13 KRAB-ZFP, ZNF471, as a methylated target in ESCC. We further found that ZNF471 is significantly downregulated in ESCC tissues compared with adjacent non-cancer tissues, due to its aberrant promoter CpG methylation, and further confirmed by methylation analysis and treatment with demethylation agent. Restoration of ZNF471 expression in silenced ESCC cells significantly altered cell morphology, induced apoptosis and G0/G1 arrest, and inhibited tumor cell colony formation, viability, migration and invasion. Importantly, ZNF471 was found to activate the expression of MAPK10/JNK3 and PCDH family genes, and further enhance MAPK10 signaling and downstream gene expression through binding to the MAPK10/JNK3 promoter. Conclusion: Our results demonstrate that ZNF471 is an important tumor suppressor and loss of ZNF471 functions hampers MAPK10/JNK3 signaling during esophageal carcinogenesis.