Molecular Mechanisms of KDELC2 on Glioblastoma Tumorigenesis and Temozolomide Resistance.

Yu-Ling Tsai,Yu-Chan Chang,Ying Chen,Ying-Chuan Chen,Wen-Chiuan Tsai,Hsin-Han Chang

doi:10.3390/biomedicines8090339

Abstract

The activation of the Notch pathway induces glioblastoma (GBM) development. Since KDEL (Lys-Asp-Glu-Leu) containing 2 (KDELC2) is involved in the Notch pathway, the detailed mechanism is still undetermined. The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases revealed that KDELC2 mRNA was associated with oncologic factors of GBM. U87, LN229, LNZ308, U118MG, and GBM8401 cells showed higher KDELC2 expression than normal brain tissues. The results of MTT, wound healing, and invasion assays proved that KDELC2 knockdown suppressed GBM-aggressive behaviors. The inhibitory properties of GBM stemness and angiogenesis under KDELC2 knockdown were evaluated by tumor spheroid and tube formation assays. Suppression of KDELC2 downregulated Notch factors’ expressions, including KDELC1, pofut1, Notch receptors 1–3, and HES-1. Immunoblot assay showed that KDELC2 knockdown promoted tumor apoptosis by downregulating PI3k/mTOR/Akt, MAPK/ERK, and NF-kB pathways. The combination of KDELC2 knockdown and temozolomide (TMZ) treatment had an optimal therapeutic effect by suppressing MGMT expression. Results of an orthotopic xenograft animal model and human tissue confirmed that KDELC2 correlated with glioma proliferation, advanced grades, and poor prognosis. Therefore, KDELC2 might be a potential pharmacological target to inhibit tumorigenesis, epithelial–mesenchymal transition, angiogenesis, and chemo-resistance of GBM.

Highlights

Among all primary brain tumors, GBM has the most aggressive behavior and worst prognosis [1].The molecular evidence showed the association of various signaling pathways with glioma development, including Notch, phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/rapamycin, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF/kB) signaling pathways [2,3,4].The switch differentiation of neural crest stem cells from neurogenesis to gliogenesis was initiated by transient Notch activation [5]
Compared with the shRNA with luciferase vector (shLuc) group of GBM8401 and U87 GBMs, our results demonstrated lower expression of phosphorylated phosphoinositide 3-kinase (PI3k) (p-PI3k), phosphorylated mTOR (p-mTOR), phosphorylated Akt (p-Akt), phosphorylated MEK (p-MEK), phosphorylated ERK (p-ERK), and phosphorylated NF/kB p65 (p-NF/kB p65) and higher PTEN protein expression in the shKDELC2 GBMs (Figure 9C)
The mammalian Notch signaling pathway can be regulated by O-glucosylation of epidermal growth factor (EGF) repeats of

Summary

Introduction

Among all primary brain tumors, GBM has the most aggressive behavior and worst prognosis [1].The molecular evidence showed the association of various signaling pathways with glioma development, including Notch, phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/rapamycin (mTOR), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF/kB) signaling pathways [2,3,4].The switch differentiation of neural crest stem cells from neurogenesis to gliogenesis was initiated by transient Notch activation [5]. Among all primary brain tumors, GBM has the most aggressive behavior and worst prognosis [1]. The molecular evidence showed the association of various signaling pathways with glioma development, including Notch, phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/rapamycin (mTOR), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF/kB) signaling pathways [2,3,4]. The switch differentiation of neural crest stem cells from neurogenesis to gliogenesis was initiated by transient Notch activation [5]. Notch deregulation was found to impact brain cancer stem. Biomedicines 2020, 8, 339 cell differentiation by Notch intracellular domain (NICD) overexpression [6]. Performed a bio-informative analysis to evaluate the expression of possible genes and signaling pathways in GBM. Compared with normal brain tissue, downregulated KDELC2 expression was identified in GBM patients [7]. The role of KDELC2 in gliomas still needs to be clarified

Methods

Results

Conclusion