title: Inhibition of glucose metabolism prevents glycosylation of the glutamine transporter ASCT2 and promotes compensatory LAT1 upregulation in leukemia cells.
abstract: Leukemia cells are highly dependent on glucose and glutamine as bioenergetic and biosynthetic fuels. Inhibition of the metabolism of glucose but also of glutamine is thus proposed as a therapeutic modality to block leukemia cell growth. Since glucose also supports protein glycosylation, we wondered whether part of the growth inhibitory effects resulting from glycolysis inhibition could indirectly result from a defect in glycosylation of glutamine transporters. We found that ASCT2/SLC1A5, a major glutamine transporter, was indeed deglycosylated upon glucose deprivation and 2-deoxyglucose exposure in HL-60 and K-562 leukemia cells. Inhibition of glycosylation by these modalities as well as by the bona fide glycosylation inhibitor tunicamycin however marginally influenced glutamine transport and did not impact on ASCT2 subcellular location. This work eventually unraveled the dispensability of ASCT2 to support HL-60 and K-562 leukemia cell growth and identified the upregulation of the neutral amino acid antiporter LAT1/SLC7A5 as a mechanism counteracting the inhibition of glycosylation. Pharmacological inhibition of LAT1 increased the growth inhibitory effects and the inactivation of the mTOR pathway resulting from glycosylation defects, an effect further emphasized during the regrowth period post-treatment with tunicamycin. In conclusion, this study points towards the underestimated impact of glycosylation inhibition in the interpretation of metabolic alterations resulting from glycolysis inhibition, and identifies LAT1 as a therapeutic target to prevent compensatory mechanisms induced by alterations in the glycosylating process.
authors.affiliation: Pole of Pharmacology and Therapeutics, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Florence
authors.initials: F
authors.lastname: Polet
authors.affiliation: Pole of Pharmacology and Therapeutics, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Ruben
authors.initials: R
authors.lastname: Martherus
authors.affiliation: Pole of Pharmacology and Therapeutics, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Cyril
authors.initials: C
authors.lastname: Corbet
authors.affiliation: Pole of Pharmacology and Therapeutics, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Adan
authors.initials: A
authors.lastname: Pinto
authors.affiliation: Pole of Pharmacology and Therapeutics, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Olivier
authors.initials: O
authors.lastname: Feron
mesh_terms: D026962:Amino Acid Transport System ASC / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D027283:Large Neutral Amino Acid-Transporter 1 / Q000096:biosynthesis*; D007938:Leukemia / Q000378:metabolism*; D015778:Minor Histocompatibility Antigens / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D026962:Amino Acid Transport System ASC; D027283:Large Neutral Amino Acid-Transporter 1; D015778:Minor Histocompatibility Antigens; C420506:SLC1A5 protein, human; D005973:Glutamine; D005947:Glucose
keywords: ASCT2; LAT1; glycosylation; leukemia; metabolism