癌干细胞（CSCs）是多种癌症转移、药物抵抗和复发的主要驱动因素。然而，可以调节CSC干性的关键因素尚未明确确定。之前的报道表明核受体亚家族2群E成员3（nr2e3）表达与ER+乳腺癌患者的药物敏感性和临床结果呈正相关。这表明nr2e3的表达可能与此类型肿瘤细胞中的CSC干性呈负相关。本研究旨在研究NR2E3对ER+乳腺癌细胞干性特性的调控作用，并找出其潜在机制。使用来源于癌症基因组图谱数据库的数据进行生物信息学分析。构建nr2e3特异性shRNA和核受体亚家族2群C成员2（nr2c2）过表达质粒，分别沉默和增强nr2e3和nr2c2的表达。使用Transwell和划痕愈合实验评估MCF7细胞的迁移和侵袭能力，而使用集落形成测试评估其克隆性。流式细胞术被用来检测CD44+CD24-/low细胞的百分比。反转录定量PCR和免疫印迹检测技术被用来检测mRNA和蛋白水平的表达。结果显示，与正常乳腺组织和MCF10A细胞相比，ER+乳腺肿瘤组织和细胞系中nr2e3的表达增加。nr2e3沉默促进了ER+ MCF7细胞的迁移、侵袭和集落形成能力。它还增加了上皮间质转化标志物和干细胞相关转录因子的表达，以及CD44+CD24-/low细胞的百分比。nr2e3和nr2c2的表达呈正相关。nr2e3敲降降低了nr2c2的mRNA和蛋白表达水平，而nr2c2的过表达则逆转了nr2e3沉默导致的CD44+CD24-/low细胞比例增加和迁移活性增加的现象。本研究的结果表明NR2E3在调节ER+乳腺癌细胞的干性特性中可能发挥重要作用，其中NR2E3/NR2C2信号可能是ER+乳腺癌的治疗靶点。版权：© Xie等。

Cancer stem cells (CSCs) are major drivers of metastasis, drug resistance and recurrence in numerous cancers. However, critical factors that can modulate CSC stemness have not been clearly identified. Nuclear receptor subfamily 2 group E member 3 (nr2e3) expression has been previously reported to be positively associated with drug sensitivity and favorable clinical outcomes in patients with estrogen receptor (ER)+ breast cancer. This suggests that nr2e3 expression may be inversely associated with CSC stemness in this type of tumor cells. The present study aimed to investigate the regulatory roles of NR2E3 in the stem-like properties of ER+ breast cancer cells and to identify the underlying mechanisms. Bioinformatics analysis was performed using the data derived from the Cancer Genome Atlas database. Nr2e3-specific shRNA and nuclear receptor subfamily 2 group C member 2 (nr2c2) overexpressed plasmids were constructed to silence and enhance the expression of nr2e3 and nr2c2, respectively. Transwell and wound healing experiments were conducted to evaluate the migration and invasion ability of MCF7 cells, while colony formation tests were used to evaluate the clonality. Flow cytometry was used to detect the percentage of CD44+CD24-/low cells. Reverse transcription-quantitative PCR and western blotting were performed to detect expression at the mRNA and protein levels. The results showed that compared with normal breast tissues and MCF10A cells, the expression of nr2e3 was increased in ER+ breast tumor tissues and cell lines. Nr2e3 silencing promoted the migration, invasion and colony-forming ability of the ER+ MCF7 cells. It also increased the expression of epithelial-mesenchymal transition markers and stem cell-related transcription factors, in addition to the percentage of CD44+CD24-/low cells. The expression of nr2e3 and nr2c2 was found to be positively correlated. Nr2e3 knockdown decreased the mRNA and protein expression levels of nr2c2, whereas nr2c2 overexpression reversed the elevated CD44+CD24-/low cell ratio and the increased migratory activity caused by nr2e3 silencing. The results of the present study suggest that NR2E3 may serve an important role in modulating the stem-like properties of ER+ breast cancer cells, where NR2E3/NR2C2 signaling may be a therapeutic target in ER+ breast cancer.Copyright: © Xie et al.