RESUMO
Background & Aims: Hepatocytic cells found during prenatal development have unique features compared to their adult counterparts, and are believed to be the precursors of pediatric hepatoblastoma. The cell-surface phenotype of hepatoblasts and hepatoblastoma cell lines was evaluated to discover new markers of these cells and gain insight into the development of hepatocytic cells and the phenotypes and origins of hepatoblastoma. Methods: Human midgestation livers and four pediatric hepatoblastoma cell lines were screened using flow cytometry. Expression of over 300 antigens was evaluated on hepatoblasts defined by their expression of CD326 (EpCAM) and CD14. Also analyzed were hematopoietic cells, expressing CD45, and liver sinusoidal-endothelial cells (LSECs), expressing CD14 but lacking CD45 expression. Select antigens were further examined by fluorescence immunomicroscopy of fetal liver sections. Antigen expression was also confirmed on cultured cells by both methods. Gene expression analysis by liver cells, 6 hepatoblastoma cell lines, and hepatoblastoma cells was performed. Immunohistochemistry was used to evaluate CD203c, CD326, and cytokeratin-19 expression on three hepatoblastoma tumors. Results: Antibody screening identified many cell surface markers commonly or divergently expressed by hematopoietic cells, LSECs, and hepatoblasts. Thirteen novel markers expressed on fetal hepatoblasts were identified including ectonucleotide pyrophosphatase/phosphodiesterase family member 3 (ENPP-3/CD203c), which was found to be expressed by hepatoblasts with widespread expression in the parenchyma of the fetal liver. In culture CD203c+CD326++ cells resembled hepatocytic cells with coexpression of albumin and cytokeratin-19 confirming a hepatoblast phenotype. CD203c expression declined rapidly in culture whereas the loss of CD326 was not as pronounced. CD203c and CD326 were co-expressed on a subset of hepatoblastoma cell lines and hepatoblastomas with an embryonal pattern. Conclusions: CD203c is expressed on hepatoblasts and may play a role in purinergic signaling in the developing liver. Hepatoblastoma cell lines were found to consist of two broad phenotypes consisting of a cholangiocyte-like phenotype that expressed CD203c and CD326 and a hepatocyte-like phenotype with diminished expression of these markers. CD203c was expressed by some hepatoblastoma tumors and may represent a marker of a less differentiated embryonal component.
RESUMO
OBJECTIVES: Cell-surface antigen screening was performed on human fetal liver cells using flow cytometry. The goal was to provide proteomic expression data on a number of human fetal liver cell populations that can inform studies on developmental hepatology and hematology. DATA DESCRIPTION: A 21 weeks' gestation liver was depleted of erythrocytes prior to antibody staining. Screening was performed using phycoerythrin-labelled antibodies against 332 antigens. In addition to these antibodies, all samples were stained for CD14, CD45, CD235a, and CD326 (epithelial cell adhesion molecule - EpCAM). Subpopulations of fetal liver cells were identified using the co-stained antigens. Hematopoietic cells were identified by their expression of CD45 and CD235a; non-hematopoietic cells were further subdivided based on CD14 and CD326 expression. CD326++CD14low hepatoblasts and CD14++ liver sinusoidal endothelial cells were analyzed for the frequency and intensity of antigen expression. Analyzed flow cytometry data are presented for the expression of the antigens on hematopoietic cells and on non-hematopoietic cells in the context of CD14 and CD326 expression.