Limits...
Glucose transporter 1-mediated glucose uptake is limiting for B-cell acute lymphoblastic leukemia anabolic metabolism and resistance to apoptosis.

Liu T, Kishton RJ, Macintyre AN, Gerriets VA, Xiang H, Liu X, Abel ED, Rizzieri D, Locasale JW, Rathmell JC - Cell Death Dis (2014)

Bottom Line: This reduced glucose transport capacity, however, was sufficient to metabolically reprogram B-ALL cells to decrease anabolic and increase catabolic flux.Cell proliferation decreased and a limited degree of apoptosis was also observed.Importantly, Glut1-deficient B-ALL cells failed to accumulate in vivo and leukemic progression was suppressed by Glut1 deletion.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710, USA [2] Department of Immunology, Duke Cancer Institute and Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA.

ABSTRACT
The metabolic profiles of cancer cells have long been acknowledged to be altered and to provide new therapeutic opportunities. In particular, a wide range of both solid and liquid tumors use aerobic glycolysis to supply energy and support cell growth. This metabolic program leads to high rates of glucose consumption through glycolysis with secretion of lactate even in the presence of oxygen. Identifying the limiting events in aerobic glycolysis and the response of cancer cells to metabolic inhibition is now essential to exploit this potential metabolic dependency. Here, we examine the role of glucose uptake and the glucose transporter Glut1 in the metabolism and metabolic stress response of BCR-Abl+ B-cell acute lymphoblastic leukemia cells (B-ALL). B-ALL cells were highly glycolytic and primary human B-ALL samples were dependent on glycolysis. We show B-ALL cells express multiple glucose transporters and conditional genetic deletion of Glut1 led to a partial loss of glucose uptake. This reduced glucose transport capacity, however, was sufficient to metabolically reprogram B-ALL cells to decrease anabolic and increase catabolic flux. Cell proliferation decreased and a limited degree of apoptosis was also observed. Importantly, Glut1-deficient B-ALL cells failed to accumulate in vivo and leukemic progression was suppressed by Glut1 deletion. Similarly, pharmacologic inhibition of aerobic glycolysis with moderate doses of 2-deoxyglucose (2-DG) slowed B-ALL cell proliferation, but extensive apoptosis only occurred at high doses. Nevertheless, 2-DG induced the pro-apoptotic protein Bim and sensitized B-ALL cells to the tyrosine kinase inhibitor Dasatinib in vivo. Together, these data show that despite expression of multiple glucose transporters, B-ALL cells are reliant on Glut1 to maintain aerobic glycolysis and anabolic metabolism. Further, partial inhibition of glucose metabolism is sufficient to sensitize cancer cells to specifically targeted therapies, suggesting inhibition of aerobic glycolysis as a plausible adjuvant approach for B-ALL therapies.

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In vivo Glut1 deletion decreases leukemic tumor burden. (a) Schematic diagram showing tamoxifen treatment to induce Glut1 deletion in vivo. (b) Glut1fl/fl CreER B-ALL were transferred and hosts treated with vehicle or tamoxifen on day 3, and purified B-ALL cells were analyzed by immunoblot from individual mice. (c) Flow cytometry from representative spleen and bone marrow on day 10 of recipient animals that received WT Cre-ER or Glut1fl/fl Cre-ER and were treated with vehicle or tamoxifen. (d) Percentages and numbers of GFP+ transferred B-ALL cells on day 10 in individual mice treated as indicated with vehicle or tamoxifen. Means and S.D. from n=5 mice/group for WT CreER group and n=10 mice/group for Glut1fl/fl CreER group are shown. ****P<0.0001. NS, not significant
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fig6: In vivo Glut1 deletion decreases leukemic tumor burden. (a) Schematic diagram showing tamoxifen treatment to induce Glut1 deletion in vivo. (b) Glut1fl/fl CreER B-ALL were transferred and hosts treated with vehicle or tamoxifen on day 3, and purified B-ALL cells were analyzed by immunoblot from individual mice. (c) Flow cytometry from representative spleen and bone marrow on day 10 of recipient animals that received WT Cre-ER or Glut1fl/fl Cre-ER and were treated with vehicle or tamoxifen. (d) Percentages and numbers of GFP+ transferred B-ALL cells on day 10 in individual mice treated as indicated with vehicle or tamoxifen. Means and S.D. from n=5 mice/group for WT CreER group and n=10 mice/group for Glut1fl/fl CreER group are shown. ****P<0.0001. NS, not significant

Mentions: Despite sharply curtailed growth and proliferation in vitro, how B-ALL progressed in vivo without Glut1 remained unclear. Presence of in vivo nutrients and stromal cell support may allow B-ALL cells to persist and proliferate even without Glut1 and with reduced glucose uptake. Control UbiCreERT2 and Glut1fl/flUbiCreERT2 B-ALL cells were, therefore, transferred into immunocompromised hosts that were treated with vehicle or tamoxifen to activate CreERT2, and in vivo and B-ALL growth was assessed with or without Glut1 expression (Figure 6a). B-ALL cells were monitored by IRES-driven GFP expression from the BCR-Abl expressing retroviral vector. Two days after cell transfer, recipients were treated with tamoxifen to delete Glut1 in transferred B-ALL cells. Animals were then analyzed for B-ALL cell number after an additional week. Glut1 was efficiently deleted in vivo, and Glut1 protein levels were sharply reduced in B-ALL cells purified from splenocytes of tamoxifen-treated recipient animals (Figure 6b). Both UbiCreERT2 control and Glut1fl/flUbiCreERT2 B-ALL cells were present in high levels in both spleen and bone marrow of vehicle-treated mice (Figures 6c and d). Importantly, B-ALL cells did not accumulate in vivo and disease did not rapidly progress after Glut1 deletion (Figure 6c) and numbers of Glut1-deficient B-ALL cells were significantly reduced in spleen and bone marrow (Figure 6d), relative to vehicle-treated or control B-ALL. These data indicate that Glut1 deletion suppresses B-ALL progression, and B-ALL cells are dependent on Glut1 even in physiological conditions.


Glucose transporter 1-mediated glucose uptake is limiting for B-cell acute lymphoblastic leukemia anabolic metabolism and resistance to apoptosis.

Liu T, Kishton RJ, Macintyre AN, Gerriets VA, Xiang H, Liu X, Abel ED, Rizzieri D, Locasale JW, Rathmell JC - Cell Death Dis (2014)

In vivo Glut1 deletion decreases leukemic tumor burden. (a) Schematic diagram showing tamoxifen treatment to induce Glut1 deletion in vivo. (b) Glut1fl/fl CreER B-ALL were transferred and hosts treated with vehicle or tamoxifen on day 3, and purified B-ALL cells were analyzed by immunoblot from individual mice. (c) Flow cytometry from representative spleen and bone marrow on day 10 of recipient animals that received WT Cre-ER or Glut1fl/fl Cre-ER and were treated with vehicle or tamoxifen. (d) Percentages and numbers of GFP+ transferred B-ALL cells on day 10 in individual mice treated as indicated with vehicle or tamoxifen. Means and S.D. from n=5 mice/group for WT CreER group and n=10 mice/group for Glut1fl/fl CreER group are shown. ****P<0.0001. NS, not significant
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4237255&req=5

fig6: In vivo Glut1 deletion decreases leukemic tumor burden. (a) Schematic diagram showing tamoxifen treatment to induce Glut1 deletion in vivo. (b) Glut1fl/fl CreER B-ALL were transferred and hosts treated with vehicle or tamoxifen on day 3, and purified B-ALL cells were analyzed by immunoblot from individual mice. (c) Flow cytometry from representative spleen and bone marrow on day 10 of recipient animals that received WT Cre-ER or Glut1fl/fl Cre-ER and were treated with vehicle or tamoxifen. (d) Percentages and numbers of GFP+ transferred B-ALL cells on day 10 in individual mice treated as indicated with vehicle or tamoxifen. Means and S.D. from n=5 mice/group for WT CreER group and n=10 mice/group for Glut1fl/fl CreER group are shown. ****P<0.0001. NS, not significant
Mentions: Despite sharply curtailed growth and proliferation in vitro, how B-ALL progressed in vivo without Glut1 remained unclear. Presence of in vivo nutrients and stromal cell support may allow B-ALL cells to persist and proliferate even without Glut1 and with reduced glucose uptake. Control UbiCreERT2 and Glut1fl/flUbiCreERT2 B-ALL cells were, therefore, transferred into immunocompromised hosts that were treated with vehicle or tamoxifen to activate CreERT2, and in vivo and B-ALL growth was assessed with or without Glut1 expression (Figure 6a). B-ALL cells were monitored by IRES-driven GFP expression from the BCR-Abl expressing retroviral vector. Two days after cell transfer, recipients were treated with tamoxifen to delete Glut1 in transferred B-ALL cells. Animals were then analyzed for B-ALL cell number after an additional week. Glut1 was efficiently deleted in vivo, and Glut1 protein levels were sharply reduced in B-ALL cells purified from splenocytes of tamoxifen-treated recipient animals (Figure 6b). Both UbiCreERT2 control and Glut1fl/flUbiCreERT2 B-ALL cells were present in high levels in both spleen and bone marrow of vehicle-treated mice (Figures 6c and d). Importantly, B-ALL cells did not accumulate in vivo and disease did not rapidly progress after Glut1 deletion (Figure 6c) and numbers of Glut1-deficient B-ALL cells were significantly reduced in spleen and bone marrow (Figure 6d), relative to vehicle-treated or control B-ALL. These data indicate that Glut1 deletion suppresses B-ALL progression, and B-ALL cells are dependent on Glut1 even in physiological conditions.

Bottom Line: This reduced glucose transport capacity, however, was sufficient to metabolically reprogram B-ALL cells to decrease anabolic and increase catabolic flux.Cell proliferation decreased and a limited degree of apoptosis was also observed.Importantly, Glut1-deficient B-ALL cells failed to accumulate in vivo and leukemic progression was suppressed by Glut1 deletion.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710, USA [2] Department of Immunology, Duke Cancer Institute and Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA.

ABSTRACT
The metabolic profiles of cancer cells have long been acknowledged to be altered and to provide new therapeutic opportunities. In particular, a wide range of both solid and liquid tumors use aerobic glycolysis to supply energy and support cell growth. This metabolic program leads to high rates of glucose consumption through glycolysis with secretion of lactate even in the presence of oxygen. Identifying the limiting events in aerobic glycolysis and the response of cancer cells to metabolic inhibition is now essential to exploit this potential metabolic dependency. Here, we examine the role of glucose uptake and the glucose transporter Glut1 in the metabolism and metabolic stress response of BCR-Abl+ B-cell acute lymphoblastic leukemia cells (B-ALL). B-ALL cells were highly glycolytic and primary human B-ALL samples were dependent on glycolysis. We show B-ALL cells express multiple glucose transporters and conditional genetic deletion of Glut1 led to a partial loss of glucose uptake. This reduced glucose transport capacity, however, was sufficient to metabolically reprogram B-ALL cells to decrease anabolic and increase catabolic flux. Cell proliferation decreased and a limited degree of apoptosis was also observed. Importantly, Glut1-deficient B-ALL cells failed to accumulate in vivo and leukemic progression was suppressed by Glut1 deletion. Similarly, pharmacologic inhibition of aerobic glycolysis with moderate doses of 2-deoxyglucose (2-DG) slowed B-ALL cell proliferation, but extensive apoptosis only occurred at high doses. Nevertheless, 2-DG induced the pro-apoptotic protein Bim and sensitized B-ALL cells to the tyrosine kinase inhibitor Dasatinib in vivo. Together, these data show that despite expression of multiple glucose transporters, B-ALL cells are reliant on Glut1 to maintain aerobic glycolysis and anabolic metabolism. Further, partial inhibition of glucose metabolism is sufficient to sensitize cancer cells to specifically targeted therapies, suggesting inhibition of aerobic glycolysis as a plausible adjuvant approach for B-ALL therapies.

Show MeSH
Related in: MedlinePlus