Objectives: Transcription factor GATA-4 is expressed in early fetal liver and essential for organogenesis. It is also implicated in carcinogenesis in several endoderm-derived organs. Hepatoblastoma (HB), the most common malignant pediatric liver tumor, has features of fetal liver including extramedullary hematopoiesis. We investigated the expression of GATA-4 and its purported target gene erythropoietin (Epo) in liver tumors and the role of GATA-4 in HB pathogenesis.
Patients and Methods: Immunohistochemistry, Western blotting, and reverse transcription-polymerase chain reaction were used for liver samples from patients with HB or hepatocellular carcinoma. To further investigate the role of GATA-4 in pediatric liver tumors, we used adenoviral transfections of wild-type or dominant negative GATA-4 constructs in the human HB cell line, HUH6.
Results: We found abundant GATA-4 expression in both types of liver tumors in children, whereas it was absent in adult hepatocellular carcinoma. A close family member GATA-6 was expressed in a minority of childhood but not adult liver tumors. Epo, present in the fetal liver, was also expressed in childhood liver tumors. Moreover, cell line HUH6 was GATA-4 positive and produced Epo. We found that altering the amount of functional GATA-4 in HUH6 cells did not significantly affect either proliferation or apoptosis.
Conclusions: GATA-4 is abundant in pediatric liver tumors, but unraveling its exact role in these neoplasms requires further investigation.