维生素D受体在肠道肿瘤生长中与β-catenin通路之间的关系

The relationship of vitamin D receptor and β-catenin pathway in intestinal tumor growth

目的探讨维生素D受体（VDR）对肠道肿瘤生长的影响以及与β-catenin信号通路之间的关系。方法体外培养的人类结肠癌SW480细胞株经维生素D处理4h，免疫沉淀法检测VDR和t3-catenin蛋白的交互作用，24h后用Westernblot检测细胞E．cadherin蛋白的表达。体内实验比较APCmin／＋VDR-／-与APCmin／＋小鼠，免疫组化法检测两型小鼠肠道肿瘤VDR、β-catenin和Brdu蛋白的表达，Westernblot检测肿瘤和肿瘤旁组织β-catenin蛋白的表达。结果维生素D处理SW480细胞后，VDR和β-catenin蛋白相互结合，随后E-cadherin蛋白表达增高（对照组灰度值145．57±4．21，实验组109．35±3．56，t=32．63，P〈0．05）。缺失VDR的APCmin／＋VDR-／-小鼠肠道肿瘤中β-catenin蛋白表达免疫组化（灰度值140．51±2．57）及Westemblot（灰度值166．47±2．36）检测均高于APCmin／＋肿瘤（分别为145．41±3．62、182．35±3．24，t=2．65，4．36，P〈0．05）。结论维生素D抑制肠道肿瘤增殖的作用可能通过VDR影响β-catenin信号通路来完成。

Objective To explore the effect of vitamin D receptor （VDR） in intestinal tumor development and the relationship between VDR and β-catenin signaling pathway. Methods The interaction of vitamin D receptor and β-catenin were detected by co-immunoprecipitation assay after human colonic car- cinoma cells SW480 were treated with vitamin D in vitro for 4 hours. The expression of E-cadherin protein was detected by Western blot after treated for 24 hours. To compare APCmin/＋ VDR - / - and APCmin/ ＋ mice in vivo, the expression of VDR, β-catenin and BrdU proteins in intestinal tumor were determined by immunohistochemistry. The expression of β-catenin protein in tumor and adjacency intestinal was further determined by Western blot. Results After SW480 cells were treated with vitamin D, vitamin D receptor and β-catenin protein showed binding, the expression of E-cadherin protein further increased （ Gray value the control group 145.57 ＋ 4. 21, Gray value of the experimental group 109. 35± 3.56, t = 32. 63, P 〈 0. 05 ）. Immunostaining and Western blot detection （ Gray value 166.47±2. 36） showed a marked increase of β- catenin level（ Gray value 140. 51 ±2. 57 ） in APCmin/＋ VDR - / - tumor compared to APCmin/＋ tumor（ 145.41±3.62,182. 35 ± 3.24,t = 2. 65,4. 36, P 〈 0. 05 ）. Conclusions The role of vitamin D suppressing intestinal tumor may be achieved through VDR affectingβ-catenin signaling pathway.