eRF3b-37 inhibits the TGF-β1-induced activation of hepatic stellate cells by regulating cell proliferation, G0/G1 arrest, apoptosis and migration.

The therapeutic management of liver fibrosis remains an unresolved clinical problem. The activation of hepatic stellate cells (HSCs) serves a pivotal role in the formation of liver fibrosis. In our previous study, matrix‑assisted laser desorption/ionization time‑of‑flight mass spectrometry (MALDI‑TOF MS) was employed to identify potential serum markers for liver cirrhosis, such as eukaryotic peptide chain releasing factor 3b polypeptide (eRF3b‑37), which was initially confirmed by our group to serve a protective role in liver tissues in a C‑C motif chemokine ligand 4‑induced liver cirrhosis mouse model. Therefore, eRF3b‑37 was hypothesized to affect the activation state of HSCs, which was determined by the expression of pro‑fibrogenic associated factors in HSCs. In the present study, peptide synthesis technology was employed to elucidate the role of eRF3b‑37 in the expression of pro‑fibrogenic factors induced by transforming growth factor‑β1 (TGF‑β1) in LX‑2 cells that were treated with either control, TGF‑β1 and TGF‑β1+eRF3b‑37. 3‑(4,5‑Dimethyl‑2‑thiazolyl)‑2,5‑diphenyltetrazolium bromide and flow cytometric assays, and fluorescent microscope examinations were performed to evaluate the effects of eRF3b‑37 on proliferation viability, G0/G1 arrest, apoptosis and cell migration. The results of the present study indicated that eRF3b‑37 inhibited the activation of HSCs. The increased mRNA and protein expression of the pro‑fibrogenic factors collagen I, connective tissue growth factor and α‑smooth muscle actin (SMA) stimulated by TGF‑β1 were reduced by eRF3b‑37 via the following mechanisms: i) Inhibiting LX‑2 cell proliferation, leading to G0/G1 cell cycle arrest and inhibition of DNA synthesis by downregulating the mRNA expressions of Cyclin D1 and cyclin dependent kinase‑4, and upregulating the levels of P21; ii) increasing cell apoptosis by upregulating the mRNA level of B‑cell lymphoma-2 (Bcl‑2)‑associated X protein (Bax) and Fas, and downregulating the expression of Bcl‑2; and iii) reducing cell migration by downregulating the mRNA and protein expression of α‑SMA. In addition, eRF3b‑37 is thought to serve a role in HSCs by inhibiting TGF‑β signaling. Therefore, eRF3b‑37 may be a novel therapeutic agent for targeting HSCs for hepatic fibrosis.