| Objective To investigate the molecular mechanism of Res inhibits the human gastric cancer SGC-7901 cell line in vitro.Methods After human gastric cancer SGC-7901 cell line was cultured in vitro, MTT assay was used to detect the inhibitory effect of Res and GW9662 (specific blocker of PPAR-γ) on cell proliferation.Flow cytometry was used to detect cell cycle,PPAR-γ, Cyclin D1,VEGF mRNA was measured quantitatively by reverse transcription-poly- merase chain reaction (RT-PCR). Expression of PPAR-γprotein was measured quantitatively by Western blot.Expression of Cyclin D1,VEGF protein in gastric cancer cells were measured by immunohistochemistry.Results (1)The result of MTT showed,human gastric cancer SGC-7901 cell line was cultured in vitro and exposed to Res in different concentration(0,25,50,75, 100μmol/L) for 24,48,72h.The proliferation of SGC-7901 was inhibited by Res in a dose-time depended manner,the inhibitory rates of cells trearted with 25,50,75, 100μmol/L Res+ 10μmol/L GW9662 for 48h was significantly decreasing compared with the same concentration Res group(P<0.05).(2)Flow cytometry analysis reavealed the cell cycle was blocked at G1 phase. treated with 50,100μmol/L Res for 48h, the proportion of cells in G1 phase increased and the proportion of cells in S phase decreased in a dose-dependent manner, the proportion of cells in G2 phase had no obvious changes.The percentage of cells in the G1 phase of 100μmol/L Res+10μmol/L GW9662 group was highly reduced than that of 100μmol/L Res group(P<0.05).(3)RT-PCR and Western blot showed that PPAR-γmRNA and protein were expressed in the SGC-7901 cell line. Res could enhanced PPAR-γmRNA expression.After SGC-7901 cells were treated by Res for 48h with the concentration of 25,50,75 and 100μmol/L, the relative percentages of PPAR-γmRNA expression were 122.2%,195.1%,232.9% and 277.1% of those in the control (P<0.05). the relative percentages of PPAR-γmRNA expression treated with 100μmol/L Res+10μmol/L GW9662 group were 261.1% of this in the control,that was significantly different from that of 100μmol/L Res group( P<0.05) .The result of Western blot showed that the total protein of PPAR-γwas not changed. (4)Cyclin D1 mRNA and protien was detected in high levels in SGC-7901 cells, Res significantly decreased the expression of Cyclin D1 mRNA and protein compared with the control group(P<0.05). After SGC-7901 cells were treated by Res for 48h with the concentration of 25, 50, 75 and 100μmol/L, the inhibitory rates of Cyclin D1 mRNA were 11.3%,24.3%,35.4% and 59.5%,respectively,the average value of Cyclin D1 grey were77.57±1.15,54.43±1.78,28.91±2.21,respectively.treated with 100μmol/L Res+10μmol/L GW9662 group, the inhibitory rates of Cyclin D1 mRNA were 40.7% ,the average value of Cyclin D1 grey were 40.56±1.84.that was significantly different from that of 100μmol/L Res group( P<0.05)(5)VEGF mRNA and protien was detected in high levels in SGC-7901 cells, Res significantly decreased the expression of VEGF mRNA and protein compared with the control group(P<0.05). After SGC-7901 cells were treated by Res for 48h with the concentration of 25,50,75 and 100μmol/L, the inhibitory rates of VEGF mRNA were 11.2%,21.8%,27.6%, 49.6%,respectively.the average valu of VEGF grey were 77.57±1.15,54.43±1.78, 28.91±2.21,respectively.treated with 100μmol/LRes+10μmol- /L GW9662 group, the inhibitory rates of VEGF mRNA were 39.0% , the average value of VEGF grey were 40.56±1.84. that was significantly different from that of 100μmol/L Res group( P<0.05).Conclusion Res can significantly inhibit Cyclin D1,VEGF expression partly by activating PPAR-γin gastric cancer cells SGC-7901, which results in the blockage of cell cycle at G1 phase and inhibition of cell proliferation.
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