Abstract 3605: O-linked N-acetylglucosamine transferase as a potential therapeutic target for metastatic gastric cancer

Introduction

Many cancer types display elevated O-GlcNAcylation and aberrant expression of O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). Here, we describe metabolic reprogramming linked to aberrant increased O-GlcNAcylation, and then inhibition of O-GlcNAcylation as a potential therapeutic target for gastric cancer (GC) treatment.

Methods

We utilized 17 established GC cell lines including 6 primary cell lines (AGS, OCUM-2M, MKN45, SNU1, SNU484, and SNU719), 4 metastatic cell lines (MKN1, MKN28, MKN74, and SNU216), 6 ascite cell lines (SNU5, SNU19, SNU601, SNU620, SNU638, and SNU668), and 1 pleural effusion cell line (KATO III). We collected 21 matched pairs of primary GC and normal gastric tissues and Patient-derived cells (PDCs) (N = 10) at the Samsung Medical Center. PDCs and all cells were grown in RPMI-1640 medium supplemented with 10% FBS. For immunoprecipitation, cells were transfected with pFlag-OGT or siOGT, washed with cold PBS, and lysed in a buffer. Protein extracts (300-500 μg) were incubated with protein G-agarose beads (sc-2002; Santa Cruz)

Results

Cell lines of primary, metastasis and ascites showed expression of O-GlcNAc and OGT. OGT expression is increased in tumor cell and ascites and western blot results showed that OGT expression is more increased in ascites than tumor cell. OGT knockdown inhibited MKN1 cell growth and colony formation. To determine the effect of OGT knockdown on tumor growth in vivo, BALB/c nude mice were injected subcutaneously in the bilateral flank with siC and siOGT transfected MKN1 cells (1 x 107 cells). OGT overexpression enhances O-GlcNAcylation of NFκB p65, c-Myc, and K-Ras. NFκB p65, c-Myc, and K-Ras immunoprecipitates obtained from the cellular extracts were analyzed by immunoblotting for O-GlcNAc. OGT knockdown inhibited PDC (collected from malignant ascites) cell growth. OGT knockdown inhibited GC PDC (1 x 104 cells) cell invasion. Targeting OGT with siRNA in xenograft models decreases the growth of tumors.

Conclusion

Depletion of OGT inhibits cancer cell proliferation and OGT knockdown significantly delays tumor growth in xenograft model. Future work will take advantage of approaches to explain the impact of O-GlcNAc modification on GC.

Citation Format: Joon Young Hur, Jeeyun Lee, Kyoung-Mee Kim, Sun-Ju Byeon, Inkyoung Lee, Won Ki Kang. O-linked N-acetylglucosamine transferase as a potential therapeutic target for metastatic gastric cancer [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 3605.