Michelotti Gregory, Jiang Xiaoyin, Sosa Julie Ann, Diehl Anna Mae, Henderson Brittany Bohinc
Division of Gastroenterology, Duke University Medical Center, Durham, North Carolina, USA.
Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA.
Oncotarget. 2015 Oct 27;6(33):34549-60. doi: 10.18632/oncotarget.5330.
Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is a cancer stem cell marker and a down-stream target in Wnt/β-catenin signaling. In human papillary thyroid cancer (PTC), over activation of Wnt/β-catenin has been associated with tumor aggressiveness.
Using established human cell lines (TPC-1, KTC-1, Nthy-ori-3-1), we report LGR5 and R-spondin (RSPO1-3) overexpression in PTC and manipulate LGR5 and Wnt/β-catenin signaling via both pharmacologic and genetic interventions. We test the association of LGR5 tumor expression with markers of PTC aggressiveness using a Discovery Cohort (n = 26 patients) and a Validation Cohort (n = 157 patients). Lastly, we explore the association between LGR5 and the BRAFV600E mutation (n = 33 patients).
Our results reveal that LGR5 and its ligand, RSPO, are overexpressed in human PTC, whereby Wnt/β-catenin signaling regulates LGR5 expression and promotes cellular migration. In two separate cohorts of patients, LGR5 and RSPO2 were associated with markers of tumor aggressiveness including: lymph node metastases, vascular invasion, increased tumor size, aggressive histology, advanced AJCC TNM stage, microscopic extra thyroidal extension, capsular invasion, and macroscopic invasion. As a biomarker, LGR5 positivity predicts lymph node metastasis with 95.5% sensitivity (95% CI 88.8%-98.7%) and 61% specificity (95% CI: 48.4%-72.4%) and has a negative predictive value (NPV) of 91.3% (95% CI 79.2%-97.5%) for lymph node metastatic disease. In human PTC, LGR5 is also strongly associated with the BRAFV600E mutation (p = 0.005).
We conclude that overexpression of LGR5 is associated with markers of tumor aggressiveness in human PTC. LGR5 may serve as a future potential biomarker for patient risk stratification and loco regional metastases in PTC.
富含亮氨酸重复序列的G蛋白偶联受体5（LGR5）是一种癌症干细胞标志物，也是Wnt/β-连环蛋白信号通路的下游靶点。在人甲状腺乳头状癌（PTC）中，Wnt/β-连环蛋白的过度激活与肿瘤侵袭性有关。
我们使用已建立的人细胞系（TPC-1、KTC-1、Nthy-ori-3-1），报告了PTC中LGR5和R-spondin（RSPO1-3）的过表达情况，并通过药理学和基因干预来调控LGR5和Wnt/β-连环蛋白信号通路。我们使用一个发现队列（n = 26例患者）和一个验证队列（n = 157例患者）来测试LGR5肿瘤表达与PTC侵袭性标志物之间的关联。最后，我们探讨了LGR5与BRAFV600E突变（n = 33例患者）之间的关联。
我们的结果显示，LGR5及其配体RSPO在人PTC中过表达，其中Wnt/β-连环蛋白信号通路调节LGR5表达并促进细胞迁移。在两个独立的患者队列中，LGR5和RSPO2与肿瘤侵袭性标志物相关，包括：淋巴结转移、血管侵犯、肿瘤大小增加、侵袭性组织学、美国癌症联合委员会（AJCC）TNM分期进展、显微镜下甲状腺外扩展、包膜侵犯和肉眼侵犯。作为一种生物标志物，LGR5阳性预测淋巴结转移的敏感性为95.5%（95%可信区间88.8%-98.7%），特异性为61%（95%可信区间：48.4%-72.4%），对淋巴结转移疾病的阴性预测值（NPV）为91.3%（95%可信区间79.2%-97.5%）。在人PTC中，LGR5也与BRAFV600E突变密切相关（p = 0.005）。
我们得出结论，LGR5的过表达与人PTC中的肿瘤侵袭性标志物相关。LGR5可能作为未来PTC患者风险分层和局部区域转移的潜在生物标志物。
