NOTCH2 negatively regulates metastasis and epithelial-Mesenchymal transition via TRAF6/AKT in nasopharyngeal carcinoma

Abstract

BackgroundClinically, distant metastasis after primary treatment remains a key problem in nasopharyngeal carcinoma (NPC). Thus, identification of the underlying mechanisms and development of novel therapeutic strategies are urgently needed. NOTCH has been shown to function as a tumor promotor that enhances angiogenesis, cancer invasion and metastasis in NPC. However, the precise roles of the four individual NOTCH receptors and their mechanisms of action are unclear.MethodsWe used Western blot analysis, immunofluorescence, immunohistochemical analysis, phalloidin staining, mouse tumor metastatic dissemination models, gene set enrichment analysis, immunoprecipitation assays and a series of functional assays to determine the potential role of NOTCH2 in regulating NPC metastasis.ResultsNOTCH2 expression in the NPC tissues of patients with cervical lymph node metastasis was lower than that of patients without cervical lymph node metastasis. Correspondingly, NOTCH2 expression was low in metastatic and poorly differentiated NPC cells. NOTCH2 expression correlated negatively with survival time in patients with NPC. Suppression of NOTCH2 expression promoted NPC cell metastasis, whereas NOTCH2 overexpression inhibited this process. Furthermore, NOTCH2 attenuated the TRAF6–AKT signaling axis via an interaction between the NOTCH2 intracellular domain (N2ICD) and TRAF6, which inhibited epithelial–mesenchymal transition (EMT) and eventually suppressed NPC metastasis.ConclusionsThese findings reveal that loss of NOTCH2 activates the TRAF6/AKT axis and promotes metastasis in NPC, suggesting that NOTCH2 may represent a therapeutic target for the treatment of NPC.

The IRF2/CENP-N/AKT signaling axis promotes proliferation, cell cycling and apoptosis resistance in nasopharyngeal carcinoma cells by increasing aerobic glycolysis

“…Our previous studies also confirmed that AKT is widely involved in the regulation of biological behaviors such as proliferation, cell cycling, apoptosis and invasion in NPC cells [24,32]. In the present study, we found that AKT1, AKT2, and AKT3 expression was downregulated after knockdown of CENP-N in NPC cells.…”

“…The procedure for the cellular protein immunoprecipitation assay was described in a previous study [32]. Cells were collected and lysed in RIPA lysis buffer (Beyotime) containing a protease inhibitor cocktail (Roche Diagnostics).…”

Metastasis of nasopharyngeal carcinoma: What we know and do not know

“…Based on our findings and other reports, the metastatic ability of NPC cells correlates with EMT [31,37,55,56]. Suppressing EMT by CLCA2 and NOTCH2 can inhibit NPC metastasis in animal models [35,57]. However, direct evidence of NPC metastasis inhibition by reversing EMT or inducing mesenchymal-to-epithelial transition is unconvincing, which is part of the much larger dilemma in cancer biology studies [58].…”

MAPK and Notch-Mediated Effects of Meso-Xanthin F199 Compounds on Proliferative Activity and Apoptosis of Human Melanocytes in Three-Dimensional Culture

“…Considering that Notch-1 and Notch-2 receptors are typically overexpressed in solid tumors [33], while the inhibition of Notch-1 by the γ-secretase complex, oppositely, results in apoptosis [34], one can assume that this event is a starting point in the enhanced proliferative activity. However, evidence exists that overexpression of Notch-2 receptor prevents metastasis and tumor growth [35] and can induce apoptosis making it an attractive target for cancer therapy [36]. In contrast, the constitutive expression of Notch-1 and silencing of Notch-1 by siRNA result in the decrease in proliferative activity and enhance apoptosis [33,34].…”