Effect Of Quercetin On Proliferation Of Human Colorectal Cancer Cell Line And On Wnt/β-catenin Signaling Pathway

Objective: Effects of quercetin on proliferation, cell cycle and apoptosis of colon carcinoma cell line SW480 were investigated. To investigate the regulation effect of quercetin on the Wnt/β-catenin signaling transcription, a Wnt/β-catenin signaling pathway reporter gene model was build, and the influence of quercetin on mutuality gene of Wnt/β-catenin signaling pathway was studied. By these analysis, the probable molecular mechanisms of quercetin on SW480 cell was analyzed, and maybe provide some theoretical evidences for developing quercetin as an anti-tumor drug.Methods:1. Effect of quercetin on proliferation of SW480 cells was analyzed by MTT assay.2. Cell cycle and apoptosis rate of SW480 cells induced with quercetin were detected by flowcytometry.3. After treatment with quercetin, protein expression of cyclin B1 in SW480 cells was analyzed by Western blot analysis.4. We Build a Wnt/β-catenin signaling pathway reporter gene model. The regulation effect of quercetin on the Wnt/β-catenin signaling transcription was investigated by using the reporter gene model.5. Effects of quercetin on expression ofβ-catenin/TCF downstream target genes, cyclin D1 and survivin, of Wnt/β-catenin signaling pathway were detected by Semi-quantitative RT-PCR and Western blot analysis.6. Statistics Methods: Statistic analysis was performed with SPSS 12.0. All experiment data were indicated Mean±STD.Results:1. Quercetein can inhibite the proliferation of SW480 cells By MTT analysis, it is shown that proliferation of SW480 cells was significantly inhibited by quercetein at concentrations of 40, 80, 160μmol/L (P < 0.01), and showing a dose- and time-dependent manner.2. After treatment with 40, 60, 80μmol/L quercetin for 48 h, the percentages of SW480 cells at G0/G1 phase were decreased, and those at G2/M phase were increased markedly (P<0.01). After incubated with 80μmol/L quercetin for 48 h, apoptosis rate of SW480 cells increased from 2.68%±1.04% of control group to 13.32%±4.62% (P<0.01).3. Expression of cyclin B1 in SW480 cells could be down-regulated by quercetin in a dose-depedent manner (r=0.999, P=0.001).4. Quercetin can down-regulate TCF-4 reporter gene We built a Wnt/β-catenin signaling pathway reporter gene model. Activities of TCF-4 reporter gene was significantly down-regulated by quercetin analyzed by using the reporter gene model (P<0.05), and showing a dose- and time- dependent manner.5. Expression of cyclin D1 and survivin in SW480 cells were down-regulated markedly by quercetin in a dose-dependent manner.Conclusions: Quercetin can inhibit proliferation, induce apoptosis and block the cells at G2/M phase of SW480 cells. Cyclin D1 and survivin expression,β-catenin/TCF downstream target genes, in both mRNA and protein level could be down-regulated markedly by quercetin. The anti-tumor mechanism of quercetin may be related to the inhibition of Wnt/β-catenin signaling pathway.