Article Text
Abstract
Background and aims: α-Fetoprotein (AFP), a tumour marker for hepatocellular carcinoma (HCC), is associated with poor prognosis. Using cDNA microarray analysis, we previously found that ephrin-A1, an angiogenic factor, is the most differentially overexpressed gene in AFP producing hepatoma cell lines. In the present study, we investigated the significance of ephrin-A1 expression in HCC.
Methods: We examined ephrin-A1 expression and its effect on cell proliferation and gene expression in five AFP producing hepatoma cell lines, three AFP negative hepatoma cell lines, and 20 human HCC specimens.
Results: Ephrin-A1 expression levels were lowest in normal liver tissue, elevated in cirrhotic tissue, and further elevated in HCC specimens. Ephrin-A1 expression was strongly correlated with AFP expression (r = 0.866). We showed that ephrin-A1 induced expression of AFP. This finding implicates ephrin-A1 in the mechanism of AFP induction in HCC. Ephrin-A1 promoted the proliferation of ephrin-A1 underexpressing HLE cells, and an ephrin-A1 antisense oligonucleotide inhibited the proliferation of ephrin-A1 overexpressing Huh7 cells. Thus ephrin-A1 affects hepatoma cell growth. cDNA microarray analysis showed that ephrin-A1 induced expression of genes related to the cell cycle (p21), angiogenesis (angiopoietin 1 and thrombospondin 1), and cell-cell interactions (Rho, integrin, and matrix metalloproteinases) in cultured hepatoma cells. These ephrin-A1 induced genes are also activated in HCC tissues that overexpress AFP.
Conclusion: These findings suggest that the poor prognosis of patients with AFP producing HCC is partially caused by ephrin-A1 expression, which induces expression of genes related to tumour cell growth, angiogenesis, invasion, and metastasis.
- AFP, α-fetoprotein
- HCC, hepatocellular carcinoma
- RIA, radioimmunoassay
- IGF-II, insulin-like growth factor II
- TGF-β, transforming growth factor β
- BMP, bone morphogenetic protein
- TSP-1, thrombospondin 1
- MMP-2, matrix metalloproteinase 2
- SDS-PAGE, sodium dodecyl sulphate-polyacrylamide gel electrophoresis
- cDNA microarray
- EphA1
- p21
- thrombospondin 1
- matrix metalloproteinase 2
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