BACKGROUND: Hepatic fibrosis, a common response to chronic liver injury, is characterized by increased production of extracellular matrix components, whose major part is produced by hepatic stellate cells (HSCs). Taurine is a sulfur containing beta-amino acid rich in human body, and our previous experiments showed that it can inhibit the deposition of the extracellular matrix in the damaged liver. This work was to investigate the effects of taurine on proliferation and apoptosis of HSC and its possible mechanism.
METHODS: Cell proliferation was detected by the thiazole blue (MTT) colorimetric assay. Cell apoptosis and cell cycle were assessed via flow cytometry. The morphology of apoptotic cells was observed by phase-contrast fluorescent micrography after orange acridine staining, and the cAMP content was measured by radioimmunoassay. The expression of c-jun and c-fos was determined by the combination of immunocytochemistry and image analysis software.
RESULTS: Taurine dose-dependently inhibited the proliferation of HSCs at the concentration of 5-50 mmol/L, resulting in more cells in the G0/G1 phase and fewer in the S phase. Taurine markedly increased the synthesis of cAMP and suppressed the gene expression of c-jun and c-fos (P<0.01) in addition to the inhibition of the proliferative effect of platelet-derived growth factor BB on HSC. However, taurine had no effect on induction of cell apoptosis.
CONCLUSIONS: Taurine can significantly inhibit the proliferation of HSC, causing a G0/G1-phase arrest. This effect on HSC proliferation is associated with the enhancement of the synthesis of cAMP and inhibition of the gene expression of c-jun and c-fos. However it can not induce the apoptosis of HSC.