Liver Cirrhosis Research Today is a free monthly online journal that collates and summarizes the latest research about Liver Cirrhosis, including details on alcohol, treatment, drugs, effects, causes.

Overexpression of Bcl-2 by activated human hepatic stellate cells: resistance to apoptosis as a mechanism of progressive hepatic fibrogenesis in humans.

Novo E, Marra F, Zamara E, Valfrè di Bonzo L, Monitillo L, Cannito S, Petrai I, Mazzocca A, Bonacchi A, De Franco RS, Colombatto S, Autelli R, Pinzani M, Parola M

Dip Medicina e Oncologia Sperimentale, University of Torino, Italy.

BACKGROUND AND AIMS: Myofibroblast-like cells, originating from activation of hepatic stellate cells (HSC/MFs), play a key role in liver fibrosis, a potentially reversible process that may rely on induction of HSC/MFs apoptosis. While this possibility has been shown in cultured rat HSC, very limited data are currently available for human HSC/MFs. METHODS: Cultured human HSC/MFs were exposed to several proapoptotic stimuli, including those known to induce apoptosis in rat HSC/MFs, and induction of cell death and related mechanisms were investigated using morphology, molecular biology, and biochemical techniques. RESULTS: In this study we report that fully activated human HSC/MFs did not undergo spontaneous apoptosis and survived to prolonged serum deprivation, Fas activation, or exposure to nerve growth factor, tumour necrosis factor alpha (TNF-alpha), oxidative stress mediators, doxorubicin, and etoposide. Induction of caspase dependent, mitochondria driven apoptosis in HSC/MFs was observed only when protein synthesis or transcription were inhibited. Importantly, the process of HSC activation was accompanied by changes in expression of a set of genes involved in apoptosis control. In particular, activated human HSC/MFs in culture overexpressed Bcl-2. The role of Bcl-2 was crucial as Bcl-2 silenced cells became susceptible to TNF-alpha induced apoptosis. Finally, Bcl-2 was markedly expressed in HSC/MFs present in liver tissue obtained from patients with hepatitis C virus related cirrhosis. CONCLUSIONS: Human activated HSC/MFs are resistant to most proapoptotic stimuli due to Bcl-2 overexpression and this feature may play a key role in the progression of fibrosis in chronic liver diseases.

Published 19 July 2006 in Gut, 55(8): 1174-82.
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