Department of Orthopedics, Huangshi Mining Bureau Hospital, Huangshi, 435000, PR China.
Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, PR China.
Chem Biol Interact. 2018 Dec 25;296:1-8. doi: 10.1016/j.cbi.2018.08.020. Epub 2018 Aug 18.
BACKGROUD/AIMS: Abnormal activation of the Wnt/β-catenin signaling, which may be antagonized by the members of secreted frizzled-related proteins family (SFRPs), is implicated in tumor occurrence and development. However, the function of SFRP5 relating to Wnt/β-catenin pathway in chondrosarcoma is not clear yet. This study was undertaken to investigate the potential role of SFRP5 promoter methylation in chondrosarcoma metastasis and invasion through activating canonical Wnt signaling pathway.
The results demonstrated that SFRP5 promoter was hypermethylated and SFRP5 expression was significantly reduced in chondrosarcoma cell lines at the mRNA and protein levels. The canonical Wnt/β-catenin signaling was observably activated with β-catenin stabilization by dephosphorylation and translocation into the nuclear. 5-Aza-2'-deoxycytidine (5-Aza-dC), the DNA methyltransferase inhibitor, significantly inhibited the proliferation of chondrosarcoma cells by cell cycle arrest through repressing the methylation of SFRP5 and promoting its expression. Both 5-Aza-dC treatment and SFRP5 overexpression could significantly inhibited the metastasis and invasion of chondrosarcoma cells by inactivating Wnt/β-catenin signaling pathway and promoting chondrosarcoma cells mesenchymal-epithelial transition (MET). 5-Aza-dC also inhibited the xenograft growth and lung metastasis of chondrosarcoma cells in vivo via suppressing SFRP5 promotor methylation, inactivating Wnt/β-catenin pathway and inducing epithelial markers expression.
All of our results revealed the epigenetic silencing of SFRP5 by promoter methylation plays pivotal roles in chondrosarcoma development and metastasis through SFRP5/Wnt/β-catenin signaling axis. Modulation of their levels may serve as potential targets and diagnostic tools for novel therapeutic strategies of chondrosarcoma.
背景/目的：Wnt/β-连环蛋白信号的异常激活，可能被分泌卷曲相关蛋白家族（SFRPs）成员拮抗，与肿瘤的发生和发展有关。然而，SFRP5 与软骨肉瘤中 Wnt/β-连环蛋白通路的关系尚不清楚。本研究旨在通过激活经典 Wnt 信号通路，研究 SFRP5 启动子甲基化在软骨肉瘤转移和侵袭中的潜在作用。
结果表明，软骨肉瘤细胞系中 SFRP5 启动子高度甲基化，SFRP5 表达在 mRNA 和蛋白水平均显著降低。β-连环蛋白去磷酸化和转位入核导致经典 Wnt/β-连环蛋白信号明显激活。DNA 甲基转移酶抑制剂 5-氮杂-2'-脱氧胞苷（5-Aza-dC）通过抑制 SFRP5 的甲基化和促进其表达，使软骨肉瘤细胞周期停滞，显著抑制软骨肉瘤细胞的增殖。5-Aza-dC 处理和 SFRP5 过表达均可通过抑制 Wnt/β-连环蛋白信号通路和促进软骨肉瘤细胞间充质上皮转化（MET），显著抑制软骨肉瘤细胞的转移和侵袭。5-Aza-dC 还通过抑制 SFRP5 启动子甲基化、抑制 Wnt/β-连环蛋白通路和诱导上皮标志物表达，抑制体内软骨肉瘤细胞的异种移植生长和肺转移。
我们的研究结果表明，SFRP5 启动子甲基化的表观遗传沉默通过 SFRP5/Wnt/β-连环蛋白信号轴在软骨肉瘤的发生和转移中发挥关键作用。调节它们的水平可能成为软骨肉瘤新的治疗策略的潜在靶点和诊断工具。
