转化生长因子-β1的Smad4非依赖性途径对胰腺癌细胞生长的影响

目的探讨转化生长因子(TGF)-β1过表达对Smad4纯合性缺失的胰腺癌细胞生长的影响。方法将含TGF-β1的真核表达载体转染到人胰腺癌细胞BxPC3中,通过流式细胞仪、生长曲线以及细胞迁移试验观察其对BxPC3生物学行为的影响。用Western印迹法检测TGF-β1对BxPC3细胞中p21WAF/CLIP1表达的影响。结果转染TGF-β1基因的BxPC3细胞的形态发生明显改变,其生长速度自第4天开始较转染空载体pcDNA3的阴性对照组减慢。发现BxPC3细胞组S期细胞(27.53±0.02)%与pcDNA3组(26.32±0.01)%的比例均高于TGF-β1组(17.01±0.03)%,P<0.01,表明TGF-β1阻止细胞进入S期。细胞迁移试验表明转染的细胞运动能力明显增加。Western印迹法检测表明p21WAF/CLIP1的表达也相应增高。结论TGF-β1的Smad4非依赖性途径通过增强p21WAF/CLIP1的表达使细胞阻滞于G-G期,从而抑制细胞生长,并且该通路能诱导上皮细胞向间叶细胞转变。

Influence of Smad4-independent pathway of transforming growth factor beta1 on the biological activity of pancreatic cancer cells

OBJECTIVE: To study effects of the expression of transforming growth factor (TGF)-beta1 on the growth of Smad4-null pancreatic cancer cells. METHODS: TGF-beta1 eukaryotic expression vector was transfected into pancreatic cancer cell line BxPC3. Effects of the expressison of TGF-beta1 was studied by growth curve analysis and flow cytometry. Cell motility was monitored by wound-healing assay. Western blot was used to estimate the expression level of p21(WAF/CLIP1), a cyclin-dependent kinase inhibitor. RESULTS: Transfection of TGF-beta1 changed the morphology of BxPC3 into spindle shaped cells. The growth rate of BxPC3 began to decrease after the fourth day of TGF-beta1 transfection, compared with the control groups. Flow cytometry showed that the percentages of cells in the S phase were (27.53 +/- 0.02)%, (26.32 +/- 0.01)% and (17.01 +/- 0.03)% in na?ve BxPC3, vector-control group and TGF-beta1 transfection group respectively. Lesser cells entered the S phase after TGF-beta1 transfection (P < 0.01), but no difference was seen between the BxPC3 and vector groups (P > 0.05). The expression of p21(WAF/CLIP1) increased upon the expression of TGF-beta1. CONCLUSION: The Smad4-independent pathway of TGF-beta1 not only induces epithelial-mesenchymal transition in pancreatic cancer BxPC3, but also inhibits its growth through the up-regulation of p21(WAF/CLIP1).