Abstract 3930: Oligosaccharyltransferase inhibition reduces glioma cell invasion and migration
Authors: Baro Marta , Sarkaria Jann N. , Contessa Joseph N. 
Published: August 2019

Abstract
Purpose: Glioblastoma (GBM) is the most common and aggressive primary brain neoplasm. Cell migration, invasion, and resistance to therapy lead to a high rate of recurrence in GBM. Glycoprotein receptor overexpression or activation caused by mutation is critical for the development and progression of many tumors including GBM. N-linked glycosylation is an endoplasmic reticulum co- and post-translational modification common to RTKs and other glycoproteins that is crucial for receptor activation. We hypothesized that altering N-linked glycosylation with an oligosaccharyltransferase (OST) inhibitor (NGI-1), could effectively disrupt GBM cell proliferation, migration, and invasion.
Experimental Procedures: The effects of OST inhibition on migration and invasion were assessed in vitro by wound healing assay, Boyden chamber assay and 3D Matrigel assay in glioma cell lines (D54, SKMG3, U251, T98G and 42-MG) and in patient-derived cell lines (GBM6, GBM26 and GBM76) in the presence or the absence of NGI-1. Cell proliferation was determined by the MTT assay over 5 days of drug treatment. Radiation survival was evaluated by clonogenic assay. Cell adhesion molecules were measured by phospho-blot assay.
Results: OST inhibition reduced cell proliferation in a dose-response manner with a significant reduction of 50% or greater over a time course of 5 days. These responses were observed in 6 of the 8 glioma and patient-derived cell lines tested while only small effects were found in the less sensitive U251 and GBM6 cell lines. A 70 to 80% reduction of tumor cell invasion was observed after NGI-1 treatment in T98G, SKMG3 and GBM76 cells with a 40 to 50% reduction in U251, D54 and GBM6 cells. Interestingly, neither 42-MG or GBM26 cells showed a decrement in invasion with the treatment of NGI-1, suggesting this effect is mediated by discrete cell signaling pathways. These results also correspond to a significant reduction of radiation clonogenic survival caused by OST inhibition in SKMG3 and D54 cells. In matrigel assays significant changes in 3D tumor growth and morphology were also observed over a time course of 72h following NGI-1 treatment. Together this work shows that cell lines with ErbB-driven signaling (D54 and SKMG3) and patient-derived cell lines with the A289T EGFR activating mutation (GBM26 and GBM76) are sensitive to OST inhibtion with NGI-1 treatment. Changes in glycosylation of cell adhesion molecules, such as integrins and NCAMs, were also observed and studies to define the glycoprotein targets that regulate glioma migration and invasion are underway.
Conclusion: This study suggests that the inhibition of N-glycosylation with a small molecule OST inhibitor suppresses migration and invasion of glioma cell lines and GBM patient-derived cell lines and supports further preclinical investigation in malignant glioma.
Citation Format: Marta Baro, Jann N. Sarkaria, Joseph N. Contessa. Oligosaccharyltransferase inhibition reduces glioma cell invasion and migration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3930.