Reciprocal expression of CCAAT/enhancer binding proteins α and β in hepatoblastomas and its prognostic significance

Hepatoblastoma is one of the common pediatric solid tumors with frequent mutation of the β-catenin gene which might be an early event of its carcinogenesis. However, the detailed molecular mechanism is still unknown. We studied the expression levels of CCAAT/enhancer binding protein a (C/EBPa) and C/EBPB, which regulate differentiation and growth of embryonic hepatocytes, to establish whether or not they were involved in affecting the clinical behavior of hepatoblastoma. The quantitative real-time reverse transcriptase-PCR revealed that expression of C/EBPa mRNA was significantly up-regulated in tumors 223% (p=0.013) as compared with that in adjacent normal livers, while expression of C/EBPB was down-regulated to 27% (p=0.002). Of interest, the immunohistochemical analysis showed that expression of C/EBPa was higher and that of C/EBPB lower in the poorly differentiated tumor cells than in the well-differentiated cells within the same tumor. Furthermore, high expression of C/EBPa (p=0.047) as well as low expression of C/EBPB (p=0.025) was significantly associated with poor prognosis of the patients. Cox hazard model suggested that expression of C/EBPa and that of C/EBPB were independent indicators to predict the prognosis from age but not from histology. Thus, expression of C/EBP proteins may play an important role in the genesis and clinical behavior of hepatoblastoma probably by inducing different stages of arrest of differentiation.