Inhibition of the Hexosamine Biosynthetic Pathway by targeting PGM3 causes breast cancer growth arrest and apoptosis

Francesca Ricciardiello,Barbara La Ferla,Luca De Gioia,Roberta Pastorelli,Rosa Maria Moresco,Silvia Valtorta,Francesca Tinelli,Alice Paiotta,Roberta Palorini,Giuseppina Votta,Isabella Raccagni,Giuseppe D’Orazio,Laura Brunelli,Ferdinando Chiaradonna

doi:10.1038/s41419-018-0405-4

Abstract

Cancer aberrant N- and O-linked protein glycosylation, frequently resulting from an augmented flux through the Hexosamine Biosynthetic Pathway (HBP), play different roles in tumor progression. However, the low specificity and toxicity of the existing HBP inhibitors prevented their use for cancer treatment. Here we report the preclinical evaluation of FR054, a novel inhibitor of the HBP enzyme PGM3, with a remarkable anti-breast cancer effect. In fact, FR054 induces in different breast cancer cells a dramatic decrease in cell proliferation and survival. In particular, in a model of Triple Negative Breast Cancer (TNBC) cells, MDA-MB-231, we show that these effects are correlated to FR054-dependent reduction of both N- and O-glycosylation level that cause also a strong reduction of cancer cell adhesion and migration. Moreover we show that impaired survival of cancer cells upon FR054 treatment is associated with the activation of the Unfolded Protein Response (UPR) and accumulation of intracellular ROS. Finally, we show that FR054 suppresses cancer growth in MDA-MB-231 xenograft mice, supporting the advantage of targeting HBP for therapeutic purpose and encouraging further investigation about the use of this small molecule as a promising compound for breast cancer therapy.

Highlights

Glycans are the most abundant and complex group of molecules in living organisms
FR054 induces an early proliferation arrest followed by a marked cell death increase in breast cancer cells To examine the ability of FR054 to interfere with cancer cell proliferation and survival, as previously shown with other Hexosamine Biosynthetic Pathway (HBP) and N-GlcNAc inhibitors[21], at first we examined the effect of 48 h FR054 treatment on seven different breast cancer cells
We demonstrate that FR054 acting as a competitive inhibitor for PGM3 enzyme is able to induce an early decrease of intracellular UDP-GlcNAc, and to diminish both HBP branches as confirmed by the reduction of highly branched N-glycans and protein O-GlcNAc

Summary

Introduction

Glycans are the most abundant and complex group of molecules in living organisms. Frequently attached to proteins to form simple and complex glycoconjugates, in a process defined N-glycosylation (N-GlcNAc) and OGlcNAcylation (O-GlcNAc), they regulate several aspects of protein function and participate in many key physiological processes including cellular adhesion, migration, growth, differentiation, signal transduction, receptor activation, and quality control of protein folding[1]. Glycoconjugates play different roles in several steps of Glycan structures and types depend on gene expression, the activities of several enzymes, and the availability of the main donor substrate, uridine diphosphate N-Acetylglucosamine (UDP-GlcNAc). The donor substrate is derived from glucose (Glc), glutamine, AcetylCoA, and uridine-5′-triphosphate as well as from intracellular degradation of glycoconjugates in lysosomes (salvage pathway) through the metabolic route termed Hexosamine Biosynthetic Pathway (HBP) (Fig. 1a). Previous work linked tumor development with an enhanced flux through the HBP5,6. In this regard, complex glycans synthesis, present in integrins and growth factor receptors, and protein O-GlcNAc are Official journal of the Cell Death Differentiation Association

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