Differential regulation of Id1 expression by TGF-β1 in HepG2 cells

Introduction: In early stages of hepatocellular carcinoma (HCC) TGF-β is proposed to have a tumour suppressive function whereas in advanced HCC it acts as a tumor promoter [1]. However, the relevance of a potential TGF-β1 target gene, i.e. Id1, is discussed controversial during HCC development and progression [2 – 4]. In HCC cell lines expressing various types of TGF-β receptors and being growth inhibited by TGF-β1, Id1 is suppressed by this ligand [5]. In order to refine the response pattern to TGF-β1 and identify putative regulatory circuits in HCC cells, we analysed the gene activation pattern in the TGF-β re…