Liver fibrosis is characterized by the excessive deposition of extracellular matrix (ECM) components, and activated hepatic stellate cells (HSCs) are a primary source of ECM. Several studies have revealed that the induction of HSC senescence may reduce liver fibrosis. The effect of interleukin-10 (IL-10) on the senescence of activated HSCs is not fully understood. Therefore, the present study examined its effects and potential mechanisms in activated primary rat HSCs. Collagenase perfusion and density gradient centrifugation methods were used to isolate rat HSCs. HSCs were identified by autofluorescence, Oil Red O staining and immunocytochemical analysis. Activated HSCs were treated with 0, 10, 20 or 40 ng/ml IL-10 for 24 h. Senescence-associated β-galactosidase (SA-β-Gal) staining, flow cytometry analysis and a cell counting kit-8 assay were performed to detect the senescence, apoptosis and viability of rat HSCs, respectively. Reverse transcription-quantitative polymerase chain reaction, western blot analysis and enzyme linked immunosorbent assays were used to detect the expression of senescence-associated proteins and cytokines. Freshly isolated rat HSCs exhibited a striking blue-green autofluorescence and HSC retinoid droplets were stained bright red by Oil Red O. Immunocytochemical analysis demonstrated the cytoplasmic expression of HSC markers desmin and α-smooth muscle actin. The number of SA-β-Gal positive HSCs, the apoptotic rate and the expression levels of p53, p21 and tumor necrosis factor-α were significantly increased following IL-10 treatment. HSC viability and IL-6 and IL-8 expression levels were significantly decreased compared with the control group. In summary, primary rat HSCs were successfully isolated and IL-10 was demonstrated to promote the senescence of activated primary rat HSCs through the upregulation of p53 and p21 expression.
Evidence suggests that peroxisome proliferator activated receptor-γ (PPAR-γ) acts as a tumor suppressor in multiple types of cancer; however, the role of action of PPAR-γ on human epidermoid carcinoma is unclear. The present study investigated the effects of a PPAR-γ agonist, rosiglitazone, on human epidermoid carcinoma cell growth using the A431 cell line. The effects of rosiglitazone on cell viability and proliferation were evaluated with MTS and [H] thymidine incorporation assays. The effects of rosiglitazone on the cell cycle and apoptosis were analyzed by flow cytometry, and western blotting. It was identified that rosiglitazone inhibited A431 cell proliferation in a dose-dependent manner, increased the proportion of cells in the G1 phase, but did not affect apoptosis. Consistently, there was a significant decrease in the expression of cell proliferation-associated proteins, including cyclin D1, cyclin-dependent kinase (Cdk)2 and Cdk4 in A431 cells treated with rosiglitazone. This decrease was rescued by a selective antagonist of PPAR-γ or specific PPAR-γ small interfering RNAs. However, the ratio of B-cell lymphoma 2 (Bcl-2) to Bcl-2 associated X protein, which is associated with cell apoptosis, was not affected by these treatments. The data of the present study suggest that the PPAR-γ agonist rosiglitazone inhibits human epidermoid carcinoma cell growth through regulating the expression of the cell cycle-associated proteins, and that this effect is independent of apoptosis.
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