Characterization of 3-bromopyruvate uptake in breast cancer cells
-
1
University of Minho, Portugal
-
2
CICS - Centro de Investigação em Ciências da Saúde, Instituto Superior de Ciências da Saúde-Norte (CESPU), Portugal
-
3
300 Redland Court, Suite 212, MD 21117, United States
-
4
Department of Biological Chemistry, School of Medicine, John Hopkins University, United States
Background and aim. In contrast to normal cells, cancer cells rely more on glycolysis for ATP to support their growth even in the presence of oxygen (“Warburg effect”). This results in a dependence on the sugar glucose and the formation of the end product, lactic acid, a monocarboxylic acid. As a result, this cancer phenotype is marked also by a significant over-expression of monocarboxylate transporters (MCTs) to export the lactate. MCTs (especially 1 and 4) are known to transport monocarboxylic acids across the membrane in a proton-linked manner and have been described as potential markers in different tumors [1]. Recent work in breast cancer cells showed that MCTs may be involved in the uptake of 3-bromopyruvate (3BP) [2], a potent anti-tumor agent. This anti-cancer effect is achieved by 3BP’s selective inhibition of cancer cells’ two power plants, glycolysis, and oxidative phosphorylation, leaving normal cells unharmed. Significantly, 3BP has been shown to eradicate advanced cancers in a rodent model without any damage to normal tissues [3].
Methods. In work reported here, we characterized the differences in 3BP uptake in three breast cancer cell lines known to exhibit different sensitivities to 3BP as follows: ZR-75-1 >MCF-7 > SK-BR-3 [2]. Transport assays were conducted at different pHs using radiolabeled [14C]-3BP and kinetic and bioenergetic parameters were evaluated.
Results. The results showed that the initial uptake rates of 3BP at pH 6.0 are linear between 5 to 30 min in all cell lines with 15 min being the time-point chosen for further studies. The uptake of 3BP occurred via a mediated-transport in all cell lines, ZR-75-1, MCF-7 and SK-BR-3, although at pH 6.0 different Michaelis-Menten constants (Km), 0.57, 1.1, 2.1 mM, respectively, were found. At pH 7.4 all cell lines presented similar Km values, i.e., 1.2 mM, 1.3 mM, and 1.6 mM respectively, for ZR-75-1, MCF-7, and SK-BR-3. The influence of the protonophore CCCP and the ionophores, monensin and valinomycin on 3BP uptake implicate the ZR-75-1 and MCF-7 cell lines as sharing the same or very similar transport mechanism, i.e., one dependent on protons and sensitive to only CCCP while in the SK-BR-3 cell line 3BP uptake is sensitive to the sodium transport inhibitor monensin.
Conclusions / Discussion. These results show that the different sensitivities of the three cancer cell lines for eradication by 3BP may be related to the different affinities of their respective MCTs for 3BP. Moreover, in the cell lines ZR-75-1 and MCF-7 (more sensitive to 3BP) the uptake is proton-dependent, typical of MCTs, while in the more resistant SK-BR-3 cell line a sodium-dependent mechanism is present. The data reported here provide evidence for the important role that MCTs play in the selective anticancer effect of 3BP.
Acknowledgements
Fundação para a Ciência e Tecnologia ( PhD Grant SFRH/BD/76038/2011)
References
[1] Pinheiro C., Longatto-Filho A., Azevedo-Silva J., Casal M., Schmitt F.C., Baltazar F. (2012) Role of monocarboxylate transporters in human cancers: state of the art. J Bioenerg Biomembr. 44(1): 127-39.
[2] Queirós O., Preto A., Pacheco A., Pinheiro C., Azevedo-Silva J., Moreira M., Pedro M., Ko Y.H., Pedersen P.L., Baltazar F., Casal M. (2012) Butyrate activates the monocarboxylate transporter MCT4 expression in breast cancer cells and enhances the antitumor activity of 3-bromopyruvate. J Bioenerg Biomembr. 44(1): 141-53.
[3] Ko, Y.H., Smith B.L., Wang Y., Pomper M.G., Rini D.A., Torbenson M.S., Hullihen J., Pedersen P.L. (2004) Advanced cancers: eradication in all cases using 3-bromopyruvate therapy to deplete ATP. Biochem Biophys Res Commun. 324(1): 269-75
Keywords:
Warburg effect,
Tumor Microenvironment,
monocarboxylate transporters,
3-Bromopyruvate,
proton transport
Conference:
4th Annual Meeting of the International Society of Proton Dynamics in Cancer, Garching, Germany, 10 Oct - 12 Oct, 2013.
Presentation Type:
Abstract
Topic:
2. Membrane transporter in intracellular and extracellular pH-control
Citation:
Azevedo-Silva
J,
Queirós
O,
Ko
YH,
Pedersen
P,
Preto
A and
Casal
M
(2014). Characterization of 3-bromopyruvate uptake in breast cancer cells.
Front. Pharmacol.
Conference Abstract:
4th Annual Meeting of the International Society of Proton Dynamics in Cancer.
doi: 10.3389/conf.fphar.2014.61.00003
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
20 Jan 2014;
Published Online:
07 Feb 2014.
*
Correspondence:
Dr. João Azevedo-Silva, University of Minho, Braga, Portugal, joaosilva@bio.uminho.pt