Targeting the hexosamine biosynthetic pathway and O-linked N-acetylglucosamine cycling for therapeutic and imaging capabilities in diffuse large B-cell lymphoma

Abstract

The hexosamine biosynthetic pathway (HBP) requires two key nutrients glucose and glutamine for O-linked N-acetylglucosamine (O-GlcNAc) cycling, a post-translational protein modification that adds GlcNAc to nuclear and cytoplasmic proteins. Increased GlcNAc has been linked to regulatory factors involved in cancer cell growth and survival. However, the biological significance of GlcNAc in diffuse large B-cell lymphoma (DLBCL) is not well defined. This study is the first to show that both the substrate and the endpoint O-GlcNAc transferase (OGT) enzyme of the HBP were highly expressed in DLBCL cell lines and in patient tumors compared with normal B-lymphocytes. Notably, high OGT mRNA levels were associated with poor survival of DLBCL patients. Targeting OGT via small interference RNA in DLBCL cells inhibited activation of GlcNAc, nuclear factor kappa B (NF-kB), and nuclear factor of activated T-cells 1 (NFATc1), as well as cell growth. Depleting both glucose and glutamine in DLBCL cells or treating them with an HBP inhibitor (azaserine) diminished O-GlcNAc protein substrate, inhibited constitutive NF-kB and NFATc1 activation, and induced G0/G1 cell-cycle arrest and apoptosis. Replenishing glucose-and glutamine-deprived DLBCL cells with a synthetic glucose analog (ethylenedicysteine-N-acetylglucosamine [ECG]) reversed these phenotypes. Finally, we showed in both in vitro and in vivo murine models that DLBCL cells easily take up radiolabeled technetium-99m-ECG conjugate. These findings suggest that targeting the HBP has therapeutic relevance for DLBCL and underscores the imaging potential of the glucosamine analog ECG in DLBCL.

The Nutrient-Sensing Hexosamine Biosynthetic Pathway as the Hub of Cancer Metabolic Rewiring

“…The latter is a tremendously interesting field, since HBP is involved in all the cancer hallmarks [ 226 ]. In fact, as some recent publications clearly highlighted [ 26 , 227 , 228 ], the inhibition of HBP or one of its two branches, controlling N -glycosylation or O- Glc N Acylation respectively, may help to develop new therapies for human cancer. Undoubtedly, these approaches will bring a substantial value to the field of cancer metabolic rewiring, but, in perspective, they could also be applied to other human diseases, such as neurodegeneration or aging.…”

“…As previously described for glucose, for glutamine availability the effect on protein O -Glc N Acylation has also been well described. In fact, either in several diffuse large B-cell lymphoma cell lines or murine embryonic fibroblasts, an increased protein O -Glc N Acylation following the glutamine addition to cell culture has been observed [ 23 , 26 ], supporting the ability of HBP to adapt its flux in function of the intracellular glutamine availability.…”

Leflunomide/teriflunomide inhibit Epstein-Barr virus (EBV)-induced lymphoproliferative disease and lytic viral replication

“…In addition to decreasing the amount of pyrimidine-based nucleotides available for DNA/RNA synthesis, drugs that inhibit DHODH activity globally decrease the level of O-linked GlcNAcylate-modified proteins through an “on-target” effect [ 18 ]. Diffuse large B-cell lymphoma (DLBCL) cell lines and primary DLBCL tumor cells have higher levels of nuclear O-GlcNAcylate-modified proteins than do normal B-cells, and the levels of these proteins correlate with DLBCL cell growth and survival [ 19 ].…”

Hexosamine Biosynthetic Pathway Inhibition Leads to AML Cell Differentiation and Cell Death

“…This results in increased uptake of glucose (21–25). Cancer cells also consume large amounts of glutamine, a precursor amino acid for the synthesis of glucosamine, initiator in the hexosamine biosynthetic pathway (HBP) (26, 27). Glutamine–fructose-6-phosphate amidotransferase (GFAT), a rate limiting enzyme of HBP combines Fructose-6-phosphate from the glycolytic pathway with glutamine to produce glucosamine-6-phosphate (28–30).…”