State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑Sen University, Guangzhou, Guangdong 510060, P.R. China.
Oncol Rep. 2019 Sep;42(3):1214-1224. doi: 10.3892/or.2019.7233. Epub 2019 Jul 15.
Tetramethylpyrazine (TMP; an extract of the Chinese herbal medicine, Chuanxiong) has been shown to exert remarkable antiretinoblastoma (RB) effects. Based on our previous study, the target gene was found to be C‑X‑C chemokine receptor type 4 (CXCR4). CXCR4 is a prognostic marker in various types of cancer, but the exact mechanisms underlying the regulation of CXCR4 expression by TMP in WERI‑Rb1 cells have yet to be fully elucidated. In the present study, it was revealed that TMP significantly downregulated CXCR4 expression and inhibited CXCR4 promoter activity in WERI‑Rb1 cells, indicating that TMP inhibits CXCR4 expression in WERI‑Rb1 cells through transcriptional regulatory mechanisms. Among the numerous transcription factors involved in CXCR4 function, including Yin Yang 1 (YY1), nuclear respiratory factor‑1 (Nrf‑1), Krüppel‑like Factor 2 (KLF2), specificity protein 1 (SP1), and nuclear factor‑κB subunit 1 (NF‑κB1), only TMP led to a significant downregulation of Nrf‑1 expression. Chromatin immunoprecipitation assays further indicated that Nrf‑1 directly binds to the promoter region of CXCR4, and silencing Nrf‑1 via siRNA transfection notably inhibited CXCR4 expression in WERI‑Rb1 cells. In addition, the expression levels of both Nrf‑1 and CXCR4 increased concomitantly with WERI‑Rb1 cell density. Furthermore, the downregulation of Nrf‑1 and CXCR4 expression in RB by TMP was confirmed in vivo. Taken together, the results of the present study have uncovered a novel mechanism in which CXCR4 expression is regulated by Nrf‑1 in WERI‑Rb1 cells, thereby identifying novel potential targets for the treatment of RB, and providing evidence for the clinical application of TMP in adjuvant retinoblastoma therapy.
川芎嗪（TMP；一种中药川芎的提取物）已被证明具有显著的抗视网膜母细胞瘤（RB）作用。基于我们之前的研究，发现靶基因为 C-X-C 趋化因子受体 4（CXCR4）。CXCR4 是各种类型癌症的预后标志物，但 TMP 调节 WERI-Rb1 细胞中 CXCR4 表达的确切机制尚未完全阐明。在本研究中，发现 TMP 可显著下调 WERI-Rb1 细胞中 CXCR4 的表达并抑制 CXCR4 启动子活性，表明 TMP 通过转录调控机制抑制 WERI-Rb1 细胞中 CXCR4 的表达。在参与 CXCR4 功能的众多转录因子中，包括 Yin Yang 1（YY1）、核呼吸因子 1（Nrf-1）、Krüppel 样因子 2（KLF2）、特异性蛋白 1（SP1）和核因子-κB 亚单位 1（NF-κB1），只有 TMP 导致 Nrf-1 表达显著下调。染色质免疫沉淀试验进一步表明，Nrf-1 直接结合 CXCR4 启动子区域，通过 siRNA 转染沉默 Nrf-1 可显著抑制 WERI-Rb1 细胞中 CXCR4 的表达。此外，Nrf-1 和 CXCR4 的表达水平随着 WERI-Rb1 细胞密度的增加而增加。此外，TMP 下调 RB 中 Nrf-1 和 CXCR4 的表达在体内得到了证实。综上所述，本研究结果揭示了一种新的机制，即 Nrf-1 调节 WERI-Rb1 细胞中 CXCR4 的表达，从而为 RB 的治疗提供了新的潜在靶点，并为 TMP 在辅助视网膜母细胞瘤治疗中的临床应用提供了证据。
