Dickkopf-4激活Wnt/PCP通路促进肾透明细胞癌的增殖及侵袭

目的研究Dickkopf-4(DKK4)在肾透明细胞癌(clear cell Renal cell carcinoma, ccRCC)组织中的表达及其与ccRCC生物学行为、临床分期分级和预后之间的的相关性。方法采用RT-PCR、免疫组织化学及Western印迹法比较42例肾癌和癌旁正常组织中DKK4的表达水平,观察其表达与肿瘤大小、临床分期、分级之间的关系；使用pCMV6-DKK4表达载体转染786-O和A498人肾透明细胞癌细胞,检测、观察转染后的肿瘤细胞的增殖活性、侵袭力及细胞凋亡水平,检测Wnt/β-Catenin(β-Catenin、Cyclin D1)及Wnt/Planar Cell Polarity信号通路(JNK、Rac1)蛋白表达。结果 28例(66.7%)肾癌组织中,DKK4的表达明显高于正常组织,其表达水平与肿瘤病理分级分期和临床特征之间无明显相关(P＞0.05)；过表达DKK4的肾癌细胞株的增殖活性及侵袭力明显增强；细胞内Wnt经典通路蛋白β-Catenin表达下调而Cyclin D1表达上调；Wnt/PCP通路下游蛋白JNK、Rac1表达上调。结论 Wnt/β-Catenin通路抑制剂DKK4通过激活Wnt/PCP非经典通路促进肾癌细胞增殖,增强肾癌细胞侵袭力。
ObjectiveTo investigate the expression level of DKK4 in clear cell renal cell carcinoma and its association with tumourigenesis and progression of ccRCC. MethodsThe expression level of DKK4 in 42 cases of ccRCC compared with matched adjacent normal kidney tissues were detected by RT-PCR, immunohistochemistry and Western blot, and its correlation to the clinical features were explored. Plasmids that contained the human full-length combinational DNA fragment of DKK4 were used to transfected 786-O and A498 cells. Cell viability, cell invasion and apoptosis of stable transfected DKK4 cells were tested. Downstream target protein of Wnt/β-Catenin pathway(β-Catenin, Cyclin D1)and Wnt/PCP pathway(JNK,Rac1)were detected. ResultsOf the 42 specimens, 28(66.7%)has clearly high expression level of DKK4 mRNA compared to matched adjacent normal kidney tissues. No correlation was found between the overexpressed DKK4 and tumor clinical characters (P＞0.05). β-Catenin was downregulated in stable transfected cells but Cyclin D1, JNK and Rac1 up-regulated. ConclusionDKK4 as Wnt/β-Catenin pathway inhibitor may promote the proliferation and invasion of ccRCC