Inhibition of proliferation of hepatic stellate cells by taurine is mediated via regulating cell cycle proteins / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To explore the possible mechanism(s) of taurine-inhibiting the proliferation of hepatic stellate cells (HSC), this study investigated the effect of taurine on the HSC cell cycle and its regulatory protein expression.</p><p><b>METHODS</b>Cell proliferation was assessed by MTT assay. Cell cycle was analyzed by flow cytometry. Cell cycle regulatory protein Cyclin D1 and P21waf1 expression were determined by immunocytochemistry and image-analysis system, and real-time quantitative PCR.</p><p><b>RESULTS</b>HSC proliferation was markedly inhibited when HSC were treated with taurine at concentrations of 5, 10, 20, 30, 40 and 50 mmol/L for 48 hours, and the inhibition rates were 6.7%, 14.4%, 23.3%, 32.2%, 36.7% and 45.6% respectively (P < 0.05-0.01). In the flow cytometry analysis, it was found that taurine could block HSC in the G0/G1 phase from entering the S phase, resulting in more cells in the G0/G1 phase and fewer in the S phase. The percentage of the cells in the G0/G1 phase and the S phase at the dosage of 40 mmol/L were 68.2%+/-1.4% and 26.2+/-1.3% respectively, which was significantly different in comparison to the controls (56.2%+/-1.7% and 38.5%+/-0.8% respectively, P < 0.01). HSC expressed cyclin D1 and P21waf1. Taurine inhibited cyclin D1 expression and induced P21waf1 expression. The cyclin D1 protein and mRNA in the HSC treated with 40 mmol/L taurine were significantly reduced compared with the controls [protein (optical density value): 0.13+/-0.02 versus 0.18+/-0.02, P < 0.01; mRNA: 5776.7+/-3345.0 versus 18,400.6+/-1374.8 copies/10(6) GAPDH, P < 0.01]; and the P21waf1 protein and mRNA were markedly increased compared with the controls [protein (optical density value): 0.19+/-0.02 versus 0.14+/-0.01, P < 0.01; mRNA: 44,866.7+/-3910.7 versus 16,933.3+/-960.9 copies/10(6) GAPDH, P less than 0.05].</p><p><b>CONCLUSIONS</b>Cyclin D1 and P21waf1 were cell cycle regulatory proteins in HSC, and taurine can inhibit the HSC cyclin D1 expression and stimulate P21waf1 expression, facilitate arresting cells in G0/G1 phase, and suppress cell proliferation.</p>

Effects of ribozyme targeting platelet-derived growth factor receptor beta subunit gene on the proliferation and apoptosis of hepatic stellate cells in vitro / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Activation and proliferation of hepatic stellate cells (HSC) is essentially involved in the development and progression of hepatic fibrosis. The most potent growth factor for HSC is platelet-derived growth factor receptor (PDGF) and PDGF receptor beta subunit (PDGFR-beta) is the predominant signal transduction pathway of PDGF which is overexpressed in activated HSC. This study investigated the cleavage activity of hammerhead ribozyme targeting PDGFR-beta mRNA in HSC and the effect on biological characteristics of HSC.</p><p><b>METHODS</b>Expression vector of anti-PDGFR-beta ribozyme was constructed and transfected into rat activated HSC with lipofectamin. The positive cell clones were gained by G418 selection. The expression of PDGFR-beta, alpha-smooth muscle actin, and typeI and type III collagen were detected by using Northern blot, Western blot and immunocytochemical staining, respectively. The cell proliferation was determined with MTT colorimetric assay. The cell apoptosis was analyzed by using flow cytometry, acridine orange fluorescence vital staining and transmission electron microscopy.</p><p><b>RESULTS</b>The expression of PDGFR-beta at mRNA and protein level was markedly reduced in ribozyme-transfected HSC by 49% - 57% (P < 0.05 - 0.01). The proliferation and alpha-smooth muscle actin expression of ribozyme-transfected HSC were significantly decreased (P < 0.05 - 0.01), and the type I and type III collagen synthesis were also reduced (P < 0.01). In addition, the proliferative response of ribozyme-transfected HSC to PDGF BB was significantly inhibited. Otherwise, the apoptotic cells were significantly increased in ribozyme-transfected HSC (P < 0.01), and typical apoptotic cells could be found under transmission electron microscopy.</p><p><b>CONCLUSIONS</b>The anti-PDGFR-beta ribozyme effectively cleaved the target RNA and significantly inhibited its expression, which blocked the signal transduction of PDGF at receptor level, inhibited HSC proliferation and collagen synthesis, and induced HSC apoptosis. These results suggest that inhibiting PDGFR-beta expression of HSC may be a new target for the therapy of liver fibrogenesis, and ribozyme may be a useful tool for inhibiting PDGFR-beta expression.</p>

Effect of ribozyme against platelet-derived growth factor receptor beta subunit mRNA on the biological characters of hepatic stellate cells / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To study the cleavage activity of hammerhead ribozyme targeting at platelet-derived growth factor receptor beta subunit (PDGFR- beta) mRNA in hepatic stellate cells (HSCs) and its effect on the biological characters of HSCs.</p><p><b>METHODS</b>Expression vector of anti-PDGFR- beta ribozyme was constructed and transfected into rat-derived HSC-T6 cells with lipofectin. The positive cell clones were gained by G418 selection. The expression of PDGFR- beta, alpha-smooth muscle actin (alpha-SMA), and type I and type III collagen was detected by means of northern blot, Western blot and immunocytochemical staining respectively. The cell proliferation was determined with MTT colorimetric assay. The cell apoptosis was demonstrated with flow cytometry, acridine orange fluorescence vital staining and transmission electron microscopy.</p><p><b>RESULTS</b>The expression of PDGFR- beta at mRNA and protein level was markedly reduced in ribozyme-transfected HSCs only 43% to 51% of that in control cells (t > or = 3.957, P < 0.05), and alpha-SMA expression level, type I and type III collagen synthesis ability were also reduced (t > or = 6.790, P < 0.01). The proliferation of ribozyme-transfected HSCs was significantly decreased (t > or = 3.858, P < 0.05), and the proliferation response to PDGF BB was markedly inhibited. However the apoptotic rate was significantly increased in ribozyme-transfected HSCs (chi2 > or = 14.157, P < 0.01), and typical apoptotic cells could be found under transmission electron microscopy.</p><p><b>CONCLUSIONS</b>The anti-PDGFR- beta ribozyme can be expressed stably in HSCs, cleave the target RNA effectively, inhibit HSCs proliferation and collagen synthesis, and induce HSC apoptosis. The results suggest that inhibiting PDGFR- beta expression in HSCs may be a new therapy for liver fibrosis.</p>

Effect of intracellular-free calcium changes on the process of pancreatic cancer cell line apoptosis induced by As2O3 / 第二军医大学学报

Objective: To study the effect of intracellular-free calcium and the expression of Fas and Fas L on the process of pancreatic carcinoma cell apoptosis. Methods: Apoptosis induced by 2 μmol/L arsenic trioxide in pancreatic cancer cell lines SW-1990 was investigated.Concentration of intracellular-free calcium （［Ca2+］i） was determined by Fura-2a fluorescein load technique. Fas and FasL were determined by flow cytometry. Results: Pancreatic cancer cells treated with 2 μmol/L arsenic trioxide presented apoptotic features: intact cell membrane, chromatin condensation, nucleic fragmentation and apoptotic body formation; agarose electrophoresis showed marked ladder; flow cytometery analysis showed a sub-G1 cell peak. In the process of pancreatic carcinoma cell apoptosis Fas and FasL and the ［Ca2+］i were significantly higher than that in the control. Conclusion: The pancreatic cancer cell apoptosis induced by arsenic trioxide is related to Fas and FasL expression by the cancer cells and the ［Ca2+］i increase in the cancer cells.

Detecting telomerase activity of gastrointestinal tract cancerous cell lines by TRAP-ELISA / 第二军医大学学报

Objective: To select the telomerase positive cancer cell lines of gastrointestinal tract and to provide a convinced methodology for future telomerase study. Methods: Fifteen cancer cell lines (carcinoma of stomach 4, of liver 6, of pancreas 2, of colon 3) were cultured and telomerase activity were detected by TRAP-ELISA. The normal hepatic cells were taken as control. Results: Thirteen cell lines were telomerase positive in the 15 lines(86.7%). Conclusion: Most of gastrointestinal tract cancer lines express telomerase, indicating the detection of telomerase activity has clinical potential.

Effect of intracellular-free calcium changes on the process of pancreatic cancer cell line apoptosis induced by As2O3 / 第二军医大学学报

Objective: To study the effect of intracellular-free calcium and the expression of Fas and Fas L on the process of pancreatic carcinoma cell apoptosis. Methods: Apoptosis induced by 2 μmol/L arsenic trioxide in pancreatic cancer cell lines SW-1990 was investigated.Concentration of intracellular-free calcium （［Ca2+］i） was determined by Fura-2a fluorescein load technique. Fas and FasL were determined by flow cytometry. Results: Pancreatic cancer cells treated with 2 μmol/L arsenic trioxide presented apoptotic features: intact cell membrane, chromatin condensation, nucleic fragmentation and apoptotic body formation; agarose electrophoresis showed marked ladder; flow cytometery analysis showed a sub-G1 cell peak. In the process of pancreatic carcinoma cell apoptosis Fas and FasL and the ［Ca2+］i were significantly higher than that in the control. Conclusion: The pancreatic cancer cell apoptosis induced by arsenic trioxide is related to Fas and FasL expression by the cancer cells and the ［Ca2+］i increase in the cancer cells.

Detecting telomerase activity of gastrointestinal tract cancerous cell lines by TRAP-ELISA / 第二军医大学学报

Objective: To select the telomerase positive cancer cell lines of gastrointestinal tract and to provide a convinced methodology for future telomerase study. Methods: Fifteen cancer cell lines (carcinoma of stomach 4, of liver 6, of pancreas 2, of colon 3) were cultured and telomerase activity were detected by TRAP-ELISA. The normal hepatic cells were taken as control. Results: Thirteen cell lines were telomerase positive in the 15 lines(86.7%). Conclusion: Most of gastrointestinal tract cancer lines express telomerase, indicating the detection of telomerase activity has clinical potential.