Dibutyryl cyclic AMP-induced enhancement of tissue inhibitor of metalloproteinases-3 expression and its possible relation to the invasive activity of the human hepatoma cell line PLC/PRF/5.

The effects of dibutyryl cyclic AMP (DBcAMP) on tissue inhibitor metalloproteinase (TIMP) expression were studied in the human hepatoma cell line PLC/PRF/5 with relation to the invasive activity of the cells. Messenger RNA expression levels of metalloproteinases (MMP)-2 and 9, and TIMP-1, 2 and 3 in the cells were determined by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). MMP-9 and TIMP-2 mRNA expression were not detectable in the cells with or without DBcAMP treatment. Relative MMP-2 and TIMP-1 mRNA expression levels in the cells were not affected by DBcAMP, whereas TIMP-3 mRNA expression was enhanced by DBcAMP. This stimulatory effect of DBcAMP on TIMP-3 expression was confirmed at the mRNA and intracellular protein levels by Northern and Western blotting, respectively. Invasive activity of PLC/PRF/5 cells was determined using the in vitro Matrigel (extracellular matrix extract) invasion model. DBcAMP inhibited the invasive activity of the cells, and this effect was eliminated by addition of an antisense oligonucleotides corresponding to TIMP-3 mRNA. These results suggested that TIMP-3 expression is enhanced by DBcAMP and may play a role in inhibition of the invasive activity of hepatoma cells.