Yu Yuanzi, Yan Wenji, Liu Xuefeng, Jia Yan, Cao Baoping, Yu Yingyan, Lv Youyong, Brock Malcolm V, Herman Jame G, Licchesi Julien, Yang Yunsheng, Guo Mingzhou
Department of Gastroenterology and Hepatology, Chinese PLA General Hospital #28 Fuxing Road, Beijing 100853, China ; Department of Gastroenterology, Provincial Hospital Affiliated to Shandong University 324 Jingwu Weiqi Road, Jinan, 250021, China.
Department of Gastroenterology and Hepatology, Chinese PLA General Hospital #28 Fuxing Road, Beijing 100853, China.
Am J Cancer Res. 2014 Nov 19;4(6):710-24. eCollection 2014.
Dapper, Dishevelled-associated antagonist of β-catenin (DACT), is a key regulator of Wnt signaling pathway. The purpose of this study is to explore the epigenetic changes and the function ofDACT2 in human gastric cancer (GC). Eight human gastric cancer cell lines, 167 cases of primary gastric cancer and 8 cases of normal gastric mucosa were involved in this study. In addition, methylation Specific PCR (MSP), semi-quantitative RT-PCR, colony formation assay, flow cytometry assay, siRNA, immunofluorescence techniques and xenograft mice models were employed. The results indicate that DACT2 is frequently methylated in human primary gastric cancer (55.7%), and that methylation of DACT2 is associated with lost or reduction in its expression (X(2) test, P<0.01). We found that DACT2 expression was regulated by promoter region hypermethylation. Methylation of DACT2 is associated with tumor differentiation, invasion and intravascular cancerous emboli (X(2) test, P<0.05, P<0.05 and P<0.05). In gastric cancer patients treated with 5-FU and cisplatin, the five-year survival rates are higher in DACT2 methylated cases. DACT2 inhibits cell proliferation, migration and invasion in gastric cancer cells and suppresses gastric cancer xenografts in mice. Restoration of DACT2 expression inhibits both canonical and noncanonical WNT signaling in SGC7901 cells. Restoration of DACT2 expression sensitized gastric cancer cells to paclitaxel and 5-FU. In conclusion, DACT2 is frequently methylated in human gastric cancer and DACT2 expression is silenced by promoter region hypermethylation. DACT2 suppressed gastric cancer proliferation, invasion and metastasis by inhibiting Wnt signaling both in vitro and in vivo.
β-连环蛋白相关的整洁相关拮抗剂（DACT）是Wnt信号通路的关键调节因子。本研究旨在探讨人胃癌（GC）中DACT2的表观遗传变化及其功能。本研究纳入了8种人胃癌细胞系、167例原发性胃癌和8例正常胃黏膜。此外，还采用了甲基化特异性PCR（MSP）、半定量RT-PCR、集落形成试验、流式细胞术试验、siRNA、免疫荧光技术和异种移植小鼠模型。结果表明，DACT2在人原发性胃癌中频繁发生甲基化（55.7%），且DACT2的甲基化与其表达缺失或降低相关（χ²检验，P<0.01）。我们发现DACT2的表达受启动子区域高甲基化调控。DACT2的甲基化与肿瘤分化、侵袭及血管内癌栓相关（χ²检验，P<0.05、P<0.05和P<0.05）。在接受5-氟尿嘧啶和顺铂治疗的胃癌患者中，DACT2甲基化病例的五年生存率更高。DACT2抑制胃癌细胞的增殖、迁移和侵袭，并抑制小鼠胃癌异种移植瘤的生长。DACT2表达的恢复抑制了SGC7901细胞中经典和非经典WNT信号通路。DACT2表达的恢复使胃癌细胞对紫杉醇和5-氟尿嘧啶敏感。总之，DACT2在人胃癌中频繁发生甲基化，其表达因启动子区域高甲基化而沉默。DACT2在体外和体内均通过抑制Wnt信号通路抑制胃癌的增殖、侵袭和转移。
