(-)-Epigallocatechin-3-gallate reduces vascular endothelial growth factor expression in gastric cancer cells via suppressing activity / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the molecular mechanism involved in the downregulation of vascular endothelial growth factor(VEGF) expression through the suppression of signal transducer and activator of transcription 3(Stat3) by(-)-Epigallocatechin-3-gallate (EGCG).</p><p><b>METHODS</b>After human gastric cancer cells (AGS) were treated with IL-6 (50 μg/L) and EGCG(0, 5, 10, 25 or 50 μmol/L), the expression levels of VEGF, total Stat3(tStat3), and activated Stat3(pStat3) in tumor cells were examined by Western blotting. The influence of the inhibitor of Stat3 pathway on the IL-6-induced VEGF expression was investigated. VEGF protein level in tumor cell culture medium was determined by ELISA and VEGF mRNA expression in tumor cells by RT-PCR. Tumor cell nuclear extract was prepared and nuclear expression of pStat3 was detected. Stat3-DNA binding activity was examined with chromatin immunoprecipitation (ChIP) assay.</p><p><b>RESULTS</b>IL-6 significantly increased VEGF expression in AGS gastric cancer cells. Compared with the group without IL-6, the expression and secretion of VEGF protein, and mRNA expression increased by 2.4 fold,2.8 fold, and 3.1 fold(all P<0.01), respectively. EGCG treatment markedly reduced VEGF protein, release and mRNA expression in a dose-dependent manner. When compared with the control group induced by IL-6, EGCG and AG490(a Stat3 pathway inhibitor) significantly inhibited VEGF expression induced by IL-6 (P<0.01). EGCG dose-dependently inhibited pStat3 induced by IL-6(P<0.05), but not tStat3 (P>0.05). Stat3 nuclear translocation and Stat3-DNA binding activity in AGS cells or that induced by IL-6 were directly inhibited by EGCG(P<0.05).</p><p><b>CONCLUSION</b>EGCG reduces expression of VEGF in gastric cancer cells through the inhibition of Stat3 activity.</p>

Curcumine inhibits migration and invasion of hepatic stellate cells by reducing MMP-2 expression and activity / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the molecular mechanism of the inhibitory effect of curcumine on the migration and invasion of hepatic stellate cells (HSC).</p><p><b>METHODS</b>Rat hepatic stellate cells were cultured and activated with ConA. Matrix metalloproteinase-2 (MMP-2) expression and activity was determined by Western blot and gelatin zymography. Migration and invasion of HSC was assessed by wound healing assay and modified Boyden chamber assay.</p><p><b>RESULTS</b>Curcumine reduced the level and activity of MMP-2 expression in activated HSC in a dose-dependent manner. When treated with 25, 50 or 100 micromol/L curcumine, the expression of MMP-2 was reduced by 21.8%+/-5.1%, 65.5%+/-9.2% or 87.9%+/-11.5% (P < 0.05), and the activity of MMP-2 was also significantly reduced by curcumine. Migration and invasion of activated HSC was also inhibited by curcumine in a dose-dependent way. When treated with 25, 50 or 100 micromol/L curcumine, the migration of activated HSC was reduced by 27.5%+/-5.8%, 54.4%+/-7.6% or 67.1%+/-9.3% (P < 0.05), and the invasion of activated HSC was also significantly reduced by curcumine.</p><p><b>CONCLUSION</b>Curcumine inhibits migration and invasion of activated HSC by reducing MMP-2 expression and activity.</p>

Epigallocatechin-3-gallate inhibits growth and angiogenesis of gastric cancer and its molecular mechanism / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the inhibitory effect of epigallocatechin-3-gallate (EGCG) on growth and angiogenesis of gastric cancer and to explore its molecular mechanism.</p><p><b>METHODS</b>Heterotopic tumor was established by subcutaneously injection with SGC-7901 cells in nude mice. Once the tumor was established, the mice were allocated randomly into two groups and received intraperitoneal injection of EGCG or phosphate buffered saline respectively. Tumor growth was measured by caliper in two dimensions, and angiogenesis was determined with tumor microvessel density (MVD) by immunohistochemistry. Protein levels of vascular endothelial growth factor (VEGF) and activation of signal transducer and activator of transcription 3(Stat3) in tumor cells and tumor tissues were examined by Western blot. VEGF release in tumor culture medium was determined by ELISA and VEGF mRNA expression in tumor cells by RT-PCR.</p><p><b>RESULTS</b>Intraperitoneal injection of EGCG significantly inhibited the growth of gastric cancer[(0.32+/-0.08) g vs(0.81+/-0.12) g, t=7.24, P<0.01], and an average of 60.4% suppression of primary tumor growth was observed. Microvessel density in tumor tissues receiving EGCG treatment was also markedly reduced(15.2+/-4.3 vs 24.6+/-6.6,t=3.41,P<0.01),and an average of 38.2% suppression was observed. EGCG treatment markedly reduced VEGF protein level in vitro and in vivo. Secretion and mRNA expression of VEGF in tumor cells were also suppressed by EGCG in a dose-dependent manner. This inhibitory effect was associated with reduced activation of Stat3. Stat3 activation was dose-dependently suppressed by EGCG in tumor cells, and an average of 53.5% reduction was observed in tumor tissues, but EGCG treatment did not change total Stat3 expression.</p><p><b>CONCLUSION</b>EGCG reduces expression of VEGF in gastric cancer by inhibiting activation of Stat3, thereby inhibits tumor growth and angiogenesis of gastric cancer.</p>