The role of β-catenin/TCF transcriptional activity in endometrial cancer (EC) recurrence is not well understood. We assessed the impact of Wnt/β-catenin inhibition in EC models. In an analysis of the Cancer Genome Atlas, we confirmed that CTNNB1 mutations are enriched in recurrent low-risk EC and showed that aberrant Wnt/β-catenin pathway activation is associated with recurrence. We studied CTNNB1-wildtype (HEC1B, Ishikawa) and CTNNB1-mutant (HEC108, HEC265, HEC1B-S33Y, Ishikawa-S33Y) EC cell lines. Dose response curves were determined for 5 Wnt/β-catenin pathway inhibitors (Wnt-C59, XAV-939, PyrPam, PRI-724, SM04690). XAV939, Wnt-C59 and PyrPam inhibited function upstream of β-catenin transcriptional activity and were ineffective at inhibiting cell viability. In contrast, PRI724 and SM04690 indirectly inhibited β-catenin transcriptional activity and significantly reduced cell viability in CTNNB1-mutant cell lines. Treatment with SM04690 reduced cell viability (Licor Cell stain) in all EC cell lines, but viability was significantly lower in CTNNB1-mutant cell lines (p < 0.01). Mechanistically, SM04690 significantly inhibited proliferation measured via 5′-bromo-2′-deoxyuridine incorporation and reduced T cell factor (TCF) transcriptional activity. HEC1B, HEC1B-S33Y and HEC265 tumor-bearing mice were treated with vehicle or SM04690. Tumors treated with SM04690 had smaller mean volumes than those treated with vehicle (p < 0.001, p = 0.014, p = 0.06). In HEC1B-S33Y and HEC265 tumors, SM04690 treatment significantly reduced Ki67 H-scores compared to vehicle (p = 0.035, p = 0.024). Targeting the Wnt/β-catenin pathway in CTNNB1-mutant EC effectively inhibited proliferation and β-catenin/TCF transcriptional activity and blunted tumor progression in in vivo models. These studies suggest β-catenin transcriptional inhibitors are effective in EC and particularly in CTNNB1-mutant EC, highlighting a potential therapeutic vulnerability for treatment of CTNNB1-mutant EC.

中文翻译：

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在 CTNNB1 突变的子宫内膜癌中抑制 Wnt/β-连环蛋白

β-连环蛋白/TCF 转录活性在子宫内膜癌 (EC) 复发中的作用尚不清楚。我们评估了 Wnt/β-catenin 抑制对 EC 模型的影响。在对癌症基因组图谱的分析中，我们证实CTNNB1突变在复发性低风险 EC 中富集，并表明异常的 Wnt/β-catenin 通路激活与复发相关。我们研究了CTNNB1 -野生型（HEC1B，Ishikawa）和CTNNB1-突变体（HEC108、HEC265、HEC1B-S33Y、Ishikawa-S33Y）EC 细胞系。确定了 5 种 Wnt/β-连环蛋白通路抑制剂（Wnt-C59、XAV-939、PyrPam、PRI-724、SM04690）的剂量反应曲线。XAV939、Wnt-C59 和 PyrPam 抑制 β-连环蛋白转录活性上游的功能，并且在抑制细胞活力方面无效。相反，PRI724 和 SM04690 间接抑制 β-连环蛋白转录活性并显着降低CTNNB1突变细胞系中的细胞活力。SM04690 处理降低了所有 EC 细胞系的细胞活力（Licor 细胞染色），但CTNNB1突变细胞系的活力显着降低（ p < 0.01)。从机制上讲，SM04690 显着抑制通过 5'-溴-2'-脱氧尿苷掺入和降低的 T 细胞因子 (TCF) 转录活性测量的增殖。用载体或 SM04690 治疗 HEC1B、HEC1B-S33Y 和 HEC265 荷瘤小鼠。用 SM04690 治疗的肿瘤的平均体积小于用载体治疗的肿瘤 ( p  < 0.001，p  = 0.014，p  = 0.06)。在 HEC1B-S33Y 和 HEC265 肿瘤中，与载体相比，SM04690 治疗显着降低了 Ki67 H 分数 ( p  = 0.035，p  = 0.024)。靶向CTNNB1中的 Wnt/β-连环蛋白通路-突变体 EC 在体内模型中有效抑制增殖和 β-连环蛋白/TCF 转录活性并减缓肿瘤进展。这些研究表明 β- 连环蛋白转录抑制剂在 EC 中有效，特别是在CTNNB1突变 EC 中，突出了治疗CTNNB1突变 EC 的潜在治疗脆弱性。