POSTER PRESENTATION Open Access

Metformin suppresses pediatric acute myeloidleukemia cell viability and clonogenicityAnilkumar Gopalakrishnapillai*, E Anders Kolb, Sonali Barwe

From Metabolism, Diet and Disease 2014: Cancer and metabolismWashington DC, USA. 28-30 May 2014

BackgroundAcute myeloid leukemia (AML) accounts for 15-20% ofchildhood leukemias. Although remission is achievedfollowing treatment with front-line chemotherapy,nearly half of the patients are faced with disease relapseassociated with chemoresistance. Therefore, therapiesthat could sustain the remission phase in pediatric AMLare urgently needed. Metformin is a widely used anti-diabetic drug known to exhibit anti-cancer effect in sev-eral malignancies. Metformin is well-tolerated at veryhigh doses, and its safety has also been demonstrated inclinical trials in diabetic children.

Materials and methodsCell viability was estimated using the Cell Titer Blue assay.Cells were stained with Annexin V-FITC and apoptoticcells were detected by flow cytometry. The activation sta-tus of AMP-activated protein kinase (AMPK) was detectedby immunoblotting for phosphorylated (T172) AMPKasubunit. Metformin-treated cells were plated in methylcel-lulose complete medium containing metformin for clono-genicity assay. The number of colonies were counted after15 days. The AML xenograft model was generated byinoculating metformin-treated cells into NSG-B2m micevia the tail vein. The disease progression was monitoredby flow cytometry.

ResultsTreatment with metformin decreased the viability ofseveral AML cell lines in a dose-dependent manner withIC50 ranging from 1.57 to 12.65 mM. IC50s werereduced when metformin treatment was performed inlow glucose medium or in the presence of a glucoseuptake inhibitor fasentin. Metformin induced G1 cellcycle arrest and apoptosis in these cells. Treatment with

low doses of metformin (0.5 mM) resulted in suppres-sion of colony formation in a clonogenicity assay. Incorrelation with this data, we observed that low dosemetformin treated cells exhibited delayed engraftmentin an AML xenograft mouse model with 50% reductionin the percentage of AML cells in mouse blood. Metfor-min is known to induce AMPK activation in a variety ofcancer cells. This AMPK activation has also been shownto be essential for metformin-induced cell death in cer-tain cell types. Metformin caused AMPK activation inMV4;11 and NB4 cells, but failed to induce AMPKphosphorylation in THP-1 cells, indicating that AMPKactivation by metformin is cell-type specific.

ConclusionsMetformin induced G1 cell cycle arrest and apoptosis inAML cells. At low doses, metformin suppressed clonalgrowth and delayed engraftment in the AML xenograftmouse model. Differential activation of AMPK bymetformin in different cell lines suggests a possibleAMPK-dependent or independent mechanism of met-formin-induced cell death.

Published: 28 May 2014

doi:10.1186/2049-3002-2-S1-P23Cite this article as: Gopalakrishnapillai et al.: Metformin suppressespediatric acute myeloid leukemia cell viability and clonogenicity. Cancer& Metabolism 2014 2(Suppl 1):P23.

Alfred I duPont Hospital for Children, Wilmington, DE, USA

Gopalakrishnapillai et al. Cancer & Metabolism 2014, 2(Suppl 1):P23http://www.cancerandmetabolism.com/content/2/S1/P23 Cancer &

Metabolism

© 2014 Gopalakrishnapillai et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the CreativeCommons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, andreproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.