Zheng Chenhui, Pan Yue, Lin Bangyi, Li Jin, Chen Qi, Zheng Zhibao
Department of Surgical Oncology, Taizhou Central Hospital (Taizhou University Hospital) Taizhou, PR China.
Department of Ultrasound, Taizhou Central Hospital (Taizhou University Hospital) Taizhou, PR China.
Histol Histopathol. 2025 Jan;40(1):123-131. doi: 10.14670/HH-18-786. Epub 2024 Jun 26.
Our previous study demonstrated that NRF3 (NFE2L3, Nuclear Factor-erythroid 2-related factor 3) could suppress cell metastasis and proliferation in breast cancer. In this study, we investigated the mechanisms underlying its function in breast cancer.
In the present study, NRF3 expression and its clinical characteristics in breast cancer were analyzed using public datasets and clinical specimens. After breast cancer cells were overexpressed NRF3, FACS was used to detect the intracellular ROS levels. The migration and invasion activities of NRF3-ectopic expressed breast cancer cells were determined by transwell assay. To validate the role of ROS/ERK axis in the inhibitory effect of NRF3 in cell metastasis, ROS scavenger NAC was also included.
We found that NRF3 mRNA was highly expressed, while NRF3 protein was extremely lowly expressed in breast cancer tissues compared with their normal counterparts, and low level NRF3 was associated with poorer prognosis in patients with triple negative breast cancer (TNBC). More interestingly, overexpression of NRF3 protein significantly increased cellular ROS production and dramatically decreased p-ERK level and cell migration in TNBC cells. Mechanistically, NRF3 protein was found to be mutually regulated by valosin-containing protein (VCP). Strikingly, VCP-knockdown dramatically increased NRF3 protein expression, but NRF3-knockin also decreased VCP expression in return. Moreover, antioxidant NAC treatment effectively increased the level of p-ERK and VCP expression, as well as cell migration and invasion abilities of TNBC cells.
NRF3, a tumor suppressor downregulated by VCP, could attenuate cell metastasis in TNBC cells by increasing cellular ROS accumulation and subsequently inhibiting the ERK phosphorylation.
我们之前的研究表明，NRF3（NFE2L3，核因子红细胞2相关因子3）可抑制乳腺癌细胞的转移和增殖。在本研究中，我们探究了其在乳腺癌中发挥作用的机制。
在本研究中，利用公开数据集和临床标本分析了NRF3在乳腺癌中的表达及其临床特征。在乳腺癌细胞中过表达NRF3后，采用流式细胞术检测细胞内活性氧水平。通过Transwell实验测定NRF3异位表达的乳腺癌细胞的迁移和侵袭活性。为验证活性氧/细胞外信号调节激酶（ROS/ERK）轴在NRF3对细胞转移抑制作用中的作用，还加入了ROS清除剂N-乙酰半胱氨酸（NAC）。
我们发现，与正常组织相比，NRF3 mRNA在乳腺癌组织中高表达，而NRF3蛋白极低表达，且低水平的NRF3与三阴性乳腺癌（TNBC）患者的预后较差相关。更有趣的是，NRF3蛋白的过表达显著增加了TNBC细胞中的细胞活性氧生成，并显著降低了p-ERK水平和细胞迁移能力。机制上，发现NRF3蛋白与含缬酪肽蛋白（VCP）相互调节。引人注目的是，敲低VCP显著增加了NRF3蛋白表达，但敲入NRF3反过来也降低了VCP表达。此外，抗氧化剂NAC处理有效提高了p-ERK水平和VCP表达，以及TNBC细胞的迁移和侵袭能力。
NRF3是一种被VCP下调的肿瘤抑制因子，可通过增加细胞活性氧积累并随后抑制ERK磷酸化来减弱TNBC细胞的转移。
