Notch3 Transactivates Glycogen Synthase Kinase-3-Beta and Inhibits Epithelial-to-Mesenchymal Transition in Breast Cancer Cells

Abstract

As a critical transformational process in the attributes of epithelial cells, epithelial-to-mesenchymal transition (EMT) is involved in tumor invasion, metastasis, and resistance to treatment, which contributes to the ultimate death of some patients with breast cancer. Glycogen synthase kinase-3-beta (GSK3β) is thought to be an EMT suppressor that down-regulates the protein, snail, a zinc finger transcription inhibitor, and regulates E-cadherin expression and the Wnt signaling pathway. Our previous studies have shown that Notch3 also inhibits EMT in breast cancer. In mammary gland cells, GSK3β physically bound and phosphorylated the intracellular domain of two Notch paralogs: N1ICD was positively regulated, but N2ICD was negatively regulated; however, the relationship between Notch3, GSK3β, and EMT in breast cancer is still unclear and crosstalk between Notch3 and GSK3β has not been widely investigated. In this study, we revealed that Notch3 was an essential antagonist of EMT in breast cancer cells by transcriptionally upregulating GSK3β. In breast cancer, MCF-7 and MDA-MB-231 cell lines, the silencing of Notch3 reduced GSK3β expression, which is sufficient to induce EMT. Conversely, ectopic Notch3 expression re-activated GSK3β and E-cadherin. Mechanistically, Notch3 can bind to the GSK3β promoter directly and activate GSK3β transcription. In human breast cancer samples, Notch3 expression is positively associated with GSK3β (r = 0.416, p = 0.001); moreover, high expressions of Notch3 and GSK3β mRNA are correlated to better relapse-free survival in all breast cancer patients via analysis in “the Kaplan–Meier plotter” database. In summary, our preliminary results suggested that Notch3 might inhibit EMT by trans-activating GSK3β in breast cancer cells. The suppression of Notch3 expression may contribute to EMT by transcriptionally downregulating GSK3β in breast cancer.

A Signaling Crosstalk Links SNAIL to the 37/67 kDa Laminin-1 Receptor Ribosomal Protein SA and Regulates the Acquisition of a Cancer Stem Cell Molecular Signature in U87 Glioblastoma Neurospheres

“…Here, we establish, for the first time to our knowledge, a signaling axis requiring the functions of RPSA upstream of SNAIL. Pertinent to our study, Notch3 was found to transactivate GSK3β and to inhibit EMT in a breast cancer cell model [ 50 ]. GSK3β regulates EMT and CSC properties in triple-negative breast cancer [ 51 ].…”

NOTCH3 inhibits transcription factor ZEB1 expression and metastasis of breast cancer cells via transcriptionally upregulating miR-223

“…Previously, it has been reported that the expression of NOTCH3 is positively correlated with a lower Ki-67 index and the incidence of involved lymph node status in breast cancer patients, and predicts a better recurrence-free survival rate of breast cancer patients 38 . In addition, NOTCH3 up-regulates the expression of GSK3β, which is related to better recurrence-free survival rate of all breast cancer patients 14 . NOTCH3 is very weakly expressed in breast cancer cells, which prevents tumor occurrence through HeyL-mediated inhibition of Mybl2 (an important cell cycle regulator), and is related to good prognosis 15 .…”

“…In the NOTCH signaling pathway, when a ligand (DLL1、DLL3、DLL4、Jagged1 and Jagged2) binds to a NOTCH receptor (NOTCH1-4), it induces the release and nuclear translocation of NOTCH receptor intracellular domain (NICD), which interacts with the transcription factor CSL, leading to the transcriptional activation of its target genes. Different from the oncogenic role of NOTCH1/2/4 in breast cancer, which promotes the transformation of ductal carcinoma in situ to invasive breast cancer [11][12][13], NOTCH3 is considered to be a tumor suppressor in breast cancer [14,15]. In breast cancer cells, NOTCH3 can activate the Hippo/YAP pathway by up-regulating Kibra, thereby inhibiting EMT [16], and NOTCH3 inhibits EMT in breast cancer by transcriptionally up-regulating the expression of GATA-3 [17], suggesting that NOTCH3 inhibits the progression of breast cancer mainly through transcriptional activation of downstream target genes.…”