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| 1 | Correlation of thymidylate synthase,thymidine phosphorylase and dihydropyrimidine dehydrogenase with sensitivity of gastrointestinal cancer cells to 5-fluorouracil and 5-fluoro-2′-deoxyuridine显示文摘AIM:To determine the expression levels of three metabolic enzymes of fluoropyrimidines:thymidylate synthase (TS),thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) in seven human gastrointestinal cancer cell lines,and to compare the enzyme levels with the sensitivity to 5-fluorouracil (5-FU) and 5-fluoro-2′-deoxyuridine (FdUrd).METHODS:TS,TP and DPD mRNA levels were assessed by semi-quantitative RT-PCR,TP and DPD protein contents were measured by ELISA. Fifty percent inhibitory concentrations of growth (IC50),representing the sensitivity to drugs,were determined by MTT assay.RESULTS:IC50 values ranged from 1.28 to 12.26μM for 5-FU,and from 5.02 to 24.21μM for FdUrd,respectively.Cell lines with lower DPD mRNA and protein levels tended to be more sensitive to 5-FU (P<0.05), but neither TS nor TP correlated with 5-FU IC50 (P>0.05).Only TS mRNA level was sharply related with FdUrd sensitivity (P<0.05),but TP and DPD were not (P>0.05).A correlation was found between mRNA and protein levels of DPD (P<0.05),but not TP (P<0.05).CONCLUSION:DPD and TS enzyme levels may be useful indicators in predicting the antitumor activity of 5-FU or FdUrd,respectively. | TaoMa Zheng-GangZhu Yu-BaoJi YiZhang Ying-YanYu Bing-YaLiu Hao-RanYin Yan-ZhenLin | 2004 | World Journal of Gastroenterology2004，10，2： | 17 |
| 2 | Signal pathways involved in emodin-induced contraction of smooth muscle cells from rat colon显示文摘AIM: To investigate the effects induced by emodin on single smooth muscle cells from rat colon in vitro, and to determine the signal pathways involved.METHODS: Cells were isolated from the muscle layers of Wistar rat colon by enzymatic digestion. Cell length was measured by computerized image micrometry. Intracellular Ca^2+ ([Ca^2+]i) signals were studied using the fluorescent Ca^2+ indicator fluo-3 and confocal microscopy. PKCα distribution at rest state or after stimulation was measured with immunofluorescence confocal microscopy.RESULTS: (1) Emodin dose-dependently caused colonic smooth muscle cells contraction, (2) emodin induced an increase in intracellular Ca^2+ concentration; (3) the contractile responses induced by emodin were respectively inhibited by preincubation of the cells with ML-7 (an inhibitor of MLCK) and calphostin C (an inhibitor of PKC), (4) Incubation of cells with emodin caused translocation of PKCα from cytosolic area to the membrane.CONCLUSION: Emodin has a direct contractile effect on colonic smooth muscle cell. This signal cascade induced by emodin is initiated by increased [Ca^2+]i and PKCα translocation,which in turn lead to the activation of MLCK and the suppression of MLCP. Both of them contribute to the emodininduced contraction. | TaoMa Qing-HuiQi JianXu Zuo-LiangDong Wen-XiuYang | 2004 | World Journal of Gastroenterology2004，10，10： | 11 |
| 3 | Contractile effects and intracellular Ca^(2+)signalling induced by emodin in circular smooth muscle cells of rat colon显示文摘AIM: To investigate whether emodin has any effects on circular smooth muscle cells of rat colon and to examine the mechanism underlying its effect.METHODS: Smooth muscle cells were isolated from the circular muscle layer of Wistar rat colon and the cell length was measured by computerized image micrometry.Intracellular Ca2+([Ca2+]i) signalling was studied in smooth muscle cells using Ca2+ indicator Fluo-3 AM on a laserscanning confocal microscope.RESULTS: Emodin dose-dependently induced smooth muscle cells contraction. The contractile responses induced by emodin were inhibited by preincubation of the cells with ML-7 (an inhibitor of MLCK). Emodin caused a large, transient increase in [Ca2+]i followed by a sustained elevation in [Ca2+]i.The emodin -induced increase in [Ca2+]i was unaffected by nifedipine, a voltage-gated Ca2+-channel antagonist, and the sustained phase of the rising of [Ca2+]i was attenuated by extracellular Ca2+ removal with EGTA solution. Inhibiting Ca2+release from ryanodine-sensitive intracellular stores by ryanodine reduced the peak increasein [ca2+]i.Using heparin, an antagonist of IP3R, almost abolished the peak increase in [Ca2+]i.CONCLUSION: Emodin has a direct excitatory effect on circular smooth muscle cells in rat colon mediated via Ca2+/CaM dependent pathways. Furthermore, emodin-induced peak [Ca2+]i increase may be attributable to the Ca2+release from IP3 sensitive stores, which further promote Ca2+ release from ryanodine-sensitive stores through CICR mechanism.Additionally, Ca2+ influx from extracellular medium contributes to the sustained increase in[Ca2+]i. | TaoMa Qing-HuiQi Wen-XiuYang JianXu Zuo-LiangDong | 2003 | World Journal of Gastroenterology2003，9，8： | 7 |
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