Phosphorylation of eukaryotic initiation factor 2-alpha inhibits cisplatin-mediated apoptosis of hepatocellular carcinoma cells / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate whether the phosphorylation (functionally inhibitive) of eukaryotic initiation factor 2-alpha (eIF2-a) affects the molecular mechanism of cisplatin-induced cellular apoptosis in human hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>The human HCC cultured cell lines SMMC-7221 and HepG2 were treated with cisplatin alone (controls; 24 h) or in combination with pre-transfection of a dominant-negative eIF2-a mutant (eIF2aS51A) or pre-exposure to an eIF2-a-specific phosphatase inhibitor (salubrinal) to decrease or increase the phosphorylation level, respectively. Changes in expression of apoptosis markers were quantitatively and qualitatively assessed by flow cytometry and western blot analysis. The significance of differences among groups was assessed by analysis of variance testing and of differences between groups was assessed by t-test.</p><p><b>RESULTS</b>Cisplatin treatment induced the appropriate functional-inhibitive phosphorylation of eIF2-a on serine 51. Cisplatin treatment (10 mg/ml) induced significant apoptosis in the eIF2aS51A pre-transfected SMMC-7721 (control: 21.7 +/- 1.5% vs. 50.7 +/- 2.1%, t = 19.454, P less than 0.05) and HepG2 (21.0 +/- 1.0% vs. 57.3 +/- 2.1%, t = 27.250, P less than 0.05). Salubrinal pre-treatment significantly inhibited the cisplatin (15 mg/ml)-induced apoptosis in SMMC-7721 (control: 50.3 +/- 2.5% vs. 16.3 +/- 2.1%, t = 18.031, P less than 0.05) and HepG2 (42.0 +/- 2.6% vs. 12.0 +/- 2.0%, t = 15.667, P less than 0.05).</p><p><b>CONCLUSION</b>Phosphorylation of eIF2-a may act to inhibit cisplatin-induced apoptosis of HCC.</p>

The role of mir-221/222 in inhibiting endoplasmic reticulum stress-induced human hepatocarcinoma cell apoptosis / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the role of miR-221/222 in inhibiting endoplasmic reticulum stress-induced human hepatocarcinoma cells apoptosis.</p><p><b>METHOD</b>miR-221/222 mimics and inhibitors were used to mimic or block the function of endogenous miR-221/222 respectively. Western blot and flow cytometry were used to test the effects of miR-221/222 on cell cycle and apoptosis under endoplasmic reticulum stress in human hepatocellular carcinoma cells.</p><p><b>RESULTS</b>Endoplasmic reticulum stress resulted in miR-221/222 down-regulation in human hepatocellular carcinoma cells. miR-221/222 mimics and inhibitors inhibited and promoted respectively endoplasmic reticulum stress-mediated p27Kip1 induction. Moreover, p27Kip1 suppression not only resulted in reduction in the fraction of G1 phase cells, but also promoted the endoplasmic reticulum stress-mediated apoptosis in human hepatocellular carcinoma cells.</p><p><b>CONCLUSION</b>miR-221/222 were downregulated by endoplasmic reticulum stress in human hepatocellular carcinoma cells, which subsequently protected human hepatocellular carcinoma cells against endoplasmic reticulum stress-induced apoptosis through p27Kip1 regulation.</p>

Cross-talk between PI3K/Akt and MEK/ERK pathways regulates human hepatocellular carcinoma cell cycle progression under endoplasmic reticulum stress / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the cross-talk between the PI3K/Akt and MEK/ERK pathways and its role in cell cycle regulation under endoplasmic reticulum stress in human hepatocellular carcinoma cells.</p><p><b>METHODS</b>PI3K inhibitor LY294002 and MEK inhibitor U0126 were used to block the PI3K/Akt and MEK/ERK pathways respectively, and constitutively activated Akt mutant construct was used to activate the PI3K/Akt pathway. Western blot was used to study the potential cross-talk between the PI3K/Akt and MEK/ERK pathways under endoplasmic reticulum stress in human hepatocellular carcinoma cells. the role of the cross-talk between the PI3K/Akt and MEK/ERK pathways in cell cycle regulation was investigated by using propidium iodide staining.</p><p><b>RESULTS</b>LY294002 not only blocked Akt activation efficiently but also increased ERK phosphorylation markedly under endoplasmic reticulum stress in SMMC-7721 and Hep3B cells. Furthermore, myr-Akt inhibited endoplasmic reticulum stress-mediated ERK phosphorylation. In contrast, MEK inhibitor U0126 had no effect on endoplasmic reticulum stress-induced Akt activation. It is notable that both myr-Akt overexpression and MEK inhibitor U0126 inhibited endoplasmic reticulum stress-induced G0/G1 phase arrest in SMMC-7721 cells.</p><p><b>CONCLUSION</b>Endoplasmic reticulum stress-induced Akt activation is mediated through PI3K and the PI3K/Akt pathway inactivation is involved in increased ERK activity in human hepatocellular carcinoma cells. The cross-talk between the PI3K/Akt and MEK/ERK cascades plays an important role in endoplasmic reticulum stress-induced human hepatocellular carcinoma cell cycle arrest.</p>

Inhibitory effect of interference hTERT and TRF2 gene on the growth of breast cancer MCF-7 cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the effect of combined gene therapy with interference hTERT and TRF2 gene on the treatment of breast cancer.</p><p><b>METHODS</b>Recombinant adenovirus rAd-hTERT and rAd-TRF2 expressing siRNA-hTERT and siRNA-TRF2 was constructed, and the vectors were transfected into MCF-7 cells. Than the expressions of hTERT and TRF2 proteins were detected by Western blot, the inhibition of MCF-7 cell proliferation by MTT colorimetry, and the changes of MCF-7 cell cycle by flow cytometry and the colony forming ability of MCF-7 cells by clone form test.</p><p><b>RESULTS</b>At 48 h after transfection, the relative expression amounts of hTERT protein of the PBS control group, rAd-blank group, rAd-HK control group, rAd-hTERT group, rAd-TRF2 group and rAd-hTERT and rAd-TRF2 group were 1.00, 0.94 +/- 0.02, 0.95 +/- 0.04, 0.18 +/- 0.04, 0.95 +/- 0.01 and 0.18 +/- 0.04, respectively. The relative expression amounts of TRF2 protein were 1.00, 1.01 +/- 0.08, 0.96 +/- 0.02, 0.95 +/- 0.08, 0.22 +/- 0.01 and 0.26 +/- 0.02, respectively. After transfection of rAd-hTERT or rAd-TRF2 into MCF-7 cells separately, the inhibition rate of cell proliferation was only 54.6% and 48.4%, there was 8.9% +/- 1.2% or 9.2% +/- 2.3% of MCF-7 cells into M phase, 66.4% +/- 1.5% or 64.6% +/- 1.9% of MCF-7 cells was arrested at G(0)/G(1) phase, and the cell colony forming ability was decreased significantly (cell colony number from 100 in PBS control group down to 41.3 +/- 5.1 and 43.7 +/- 6.4). But after transfection by rAd-hTERT and rAd-TRF2 simultaneously, the inhibition rate of cell proliferation was about 82.1%, and M phase cells was significantly reduced to 4.4% +/- 1.2%. Large numbers of cells were arrested at G(0)/G(1) phase (81.4% +/- 1.3%), and the cell colony forming ability was more significantly decreased (cell colony number there were only 29.2 +/- 3.9).</p><p><b>CONCLUSION</b>More effective effect of tumor gene therapy can be achieved by combination of interference hTERT and TRF2 genes as compared with interference by either of the single gene alone.</p>