Hepatocarcinoma cell lines down-regulate matrix metalloproteinase-2 expression in human hepatic myofibroblasts

Matrix metalloproteinases (MMPs) are a family of proteases that degrade extracellular matrix components and are involved in tumor progression and metastasis. We studied the pattern of expression of MMP-2 by human hepatoma cell lines and human hepatic myofibroblasts and its regulation in co-culture between these cell types. MMP-2 expression was studied by zymography and semi-quantitative RT-PCR. The expression of MT1-MMP (involved in MMP-2 activation) was studied by Western blot analysis and RT-PCR and the secretion of TIMP-2 by ELISA and RT-PCR. Myofibroblasts expressed high levels of MMP-2, MT1-MMP and TIMP-2. The hepatoma cell lines HepG2, HuH7 and Hep3B did not express MMP-2 and weakly expressed TIMP-2 and MT1-MMP. In co-culture, no modulation of MT1-MMP or TIMP-2 expression was observed. A strong decrease in myofibroblast MMP-2 expression was seen in the presence of hepatoma cell lines. This was partly reproduced by their conditioned media. We conclude that hepatoma cell lines down-regulate the expression of MMP-2 by myofibroblasts.