Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China.
Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
Cancer Res Treat. 2020 Oct;52(4):1084-1102. doi: 10.4143/crt.2020.093. Epub 2020 May 27.
Breast cancer stem cells (BCSCs) contribute to the initiation, development, and recurrence of breast carcinomas. β1,4-Galactosyltransferase V (B4GalT5), which catalyzes the addition of galactose to GlcNAcβ1-4Man of N-glycans, is involved in embryogenesis. However, its role in the modulation of BCSCs remains unknown.
The relationship between B4GalT5 and breast cancer stemness was investigated by online clinical databases and immunohistochemistry analysis. Mammosphere formation, fluorescence-activated cell sorting (FACS), and in-vivo assays were used to evaluate B4GalT5 expression in BCSCs and its effect on BCSCs. B4GalT5 regulation of Wnt/β-catenin signaling was examined by immunofluorescence and Ricinus communis agglutinin I pull-down assays. Cell surface biotinylation and FACS assays were performed to assess the association of cell surface B4GalT5 and BCSCs.
B4GalT5, but not other B4GalTs, was highly correlated with BCSC markers and poor prognosis. B4GalT5 significantly increased the stem cell marker aldehyde dehydrogenase 1A1 (ALDH1A1) and promoted the production of CD44+CD24-/low cells and the formation of mammospheres. Furthermore, B4GalT5 overexpression resulted in dramatic tumor growth in vivo. Mechanistically, B4GalT5 modified and protected Frizzled-1 from degradation via the lysosomal pathway, promoting Wnt/β-catenin signaling which was hyperactivated in BCSCs. B4GalT5, located on the surface of a small subset of breast carcinoma cells, was not responsible for the stemness of BCSCs.
B4GalT5 modulates the stemness of breast cancer through glycosylation modification to stabilize Frizzled-1 and activate Wnt/β-catenin signaling independent of its cell surface location. Our studies highlight a previously unknown role of B4GalT5 in regulating the stemness of breast cancer and provide a potential drug target for anticancer drug development.
乳腺癌干细胞（BCSCs）促进乳腺癌的发生、发展和复发。β1,4-半乳糖基转移酶 V（B4GalT5）催化 N-糖基化聚糖中半乳糖与 GlcNAcβ1-4Man 的连接，参与胚胎发生。然而，其在调节 BCSC 中的作用尚不清楚。
通过在线临床数据库和免疫组织化学分析研究 B4GalT5 与乳腺癌干性之间的关系。采用球体形成实验、荧光激活细胞分选（FACS）和体内实验评估 BCSC 中 B4GalT5 的表达及其对 BCSC 的影响。通过免疫荧光和蓖麻凝集素 I 下拉实验检测 B4GalT5 对 Wnt/β-catenin 信号通路的调节。通过细胞表面生物素化和 FACS 实验评估细胞表面 B4GalT5 与 BCSC 的关联。
B4GalT5 与 BCSC 标志物高度相关，与不良预后相关，但其与其他 B4GalTs 无关。B4GalT5 显著增加了干细胞标志物醛脱氢酶 1A1（ALDH1A1）的表达，并促进了 CD44+CD24-/低细胞的产生和球体的形成。此外，B4GalT5 过表达导致体内肿瘤生长明显。机制上，B4GalT5 通过溶酶体途径修饰和保护 Frizzled-1 免受降解，促进 Wnt/β-catenin 信号通路的激活，该信号通路在 BCSC 中高度激活。B4GalT5 位于一小部分乳腺癌细胞的表面，但其并不负责 BCSC 的干性。
B4GalT5 通过糖基化修饰调节乳腺癌的干性，稳定 Frizzled-1 并激活 Wnt/β-catenin 信号通路，与 B4GalT5 的细胞表面位置无关。我们的研究揭示了 B4GalT5 在调节乳腺癌干性方面的一个未知作用，并为抗癌药物的开发提供了一个潜在的药物靶点。
