奥曲肽对结肠癌SW480细胞Wnt通路β-catenin/TCF及下游靶基因表达的影响

The effect of octreotide on Wnt pathway on the expresion of β-catenin /TCF and the downstream genes in SW480 cell line

目的研究不同浓度奥曲肽对结肠癌SW480细胞增殖以及对SW480细胞Wnt／β-catenin信号通路的影响，阐明其抗肿瘤的作用机制。方法采用MTT比色法测定不同浓度奥曲肽对SW480细胞增殖的抑制作用；应用Westernblot法分析不同浓度奥曲肽对SW480细胞核中β—catenin、TCF-4及Wnt信号通路下游靶分子C—myc、CyclinDl蛋白表达的影响。结果奥曲肽可抑制SW480细胞的增殖，并在10-10～10-8M浓度范围内呈剂量依赖性，在48h内呈时间依赖性，浓度为10-8M时抑制作用最强，浓度为10-11M以下对细胞增殖无抑制作用。浓度为10-6、10-8、10-10M的奥曲肽对β—catenin蛋白、TCF-4蛋白、C—myc蛋白及CyclinDl蛋白的表达有明显抑制作用，与未经奥曲肽处理的细胞比较有统计学意义（均P〈0．01）。结论奥曲肽对Wnt／β-catenin信号通路的抑制作用可能是通过减少β—catenin在细胞核内的聚集，抑制TCF-4的激活，从而抑制下游靶基因C—myc及CyclinDl。

Objective To study the effect of octreotide at different concentrations on proliferation in colonic cancer cell line ; explore the effect and mechanism of action of octreotide to Wnt/β-eatenin signal pathway, to e- lucidate furtherly the anti-tumor mechanism of octreotide. Methods MTF assay was used to analyse the effect of oetreotide at different concentrations on the proliferation of SW480 cell. Western blot assay was used to evalu- ate the protein level of β-catenin, TCF-4 and the Wnt pathway downstream genes C-myc and CyclinD1 in SW480 cell treated by different concentrations of octreotide. Results Octreotide could inhibited proliferation of SW480, and in a dose-dependent manner within a range from 10-l~ M to 10-s M, further in a time-dependent manner within 48 hours, the best inhibition concentration of octreotide at 10 -s M, however, there was no effect on the growth of SW480 when octreotide beneath 10-11 M. The protein expression of β-catenin, TCF-4, C-mye and CyclinD1 were significant reduced in treated SW480 cells line within octreotide 10 -6, 10-8, 10- l0 M, sta- tistical differences were noted between them and SW480 without treatment with octreotide. Conclusions Oct- reotide suppresses Wnt/13-catenin signal pathway may prevent β-catenin concentrate to the cell nucleus, and in-hibit the activation of TCF-4, further inhibit the downstream genes C-myc and CyclinD1.