3-Bromopyruvate-mediated MCT1-dependent metabolic perturbation sensitizes triple negative breast cancer cells to ionizing radiation

Irini Skaripa-Koukelli; David Hauton; John Walsby-Tickle; Eloïse Thomas; Joshua Owen; Abirami Lakshminarayanan; Sarah Able; James McCullagh; Robert C Carlisle; Katherine A Vallis

doi:10.1186/s40170-021-00273-6

3-Bromopyruvate-mediated MCT1-dependent metabolic perturbation sensitizes triple negative breast cancer cells to ionizing radiation

Cancer Metab. 2021 Oct 14;9(1):37. doi: 10.1186/s40170-021-00273-6.

Authors

Affiliations

¹ Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK.
² Department of Oncology, Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Off Roosevelt Drive, Oxford, OX3 7DQ, UK.
³ Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, OX1 3TA, UK.
⁴ Department of Oncology, Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Off Roosevelt Drive, Oxford, OX3 7DQ, UK. [email protected].

Abstract

Background: Triple negative breast cancer (TNBC) poses a serious clinical challenge as it is an aggressive form of the disease that lacks estrogen receptor, progesterone receptor, and ERBB2 (formerly HER2) gene amplification, which limits the treatment options. The Warburg phenotype of upregulated glycolysis in the presence of oxygen has been shown to be prevalent in TNBC. Elevated glycolysis satisfies the energy requirements of cancer cells, contributes to resistance to treatment by maintaining redox homeostasis and generating nucleotide precursors required for cell proliferation and DNA repair. Expression of the monocarboxylate transporter 1 (MCT1), which is responsible for the bidirectional transport of lactate, correlates with an aggressive phenotype and poor outcome in several cancer types, including breast cancer. In this study, 3-bromopyruvate (3BP), a lactate/pyruvate analog, was used to selectively target TNBC cells that express MCT1.

Methods: The cytotoxicity of 3BP was tested in MTT assays using human TNBC cell lines: BT20 (MCT1⁺/MCT4^-), MDA-MB-23 (MCT1^-/MCT4⁺), and BT20 in which MCT1 was knocked down (siMCT1-BT20). The metabolite profile of 3BP-treated and 3BP-untreated cells was investigated using LC-MS/MS. The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of BT20 and MDA-MB-231 cells treated with 3BP were measured using a Seahorse XF96 extracellular flux analyzer. The impact of ionizing radiation on cell survival, alone or in combination with 3BP pre-treatment, was evaluated using clonogenic assays.

Results: Metabolomic analyses showed that 3BP causes inhibition of glycolysis, disturbance of redox homeostasis, decreased nucleotide synthesis, and was accompanied by a reduction in medium acidification. In addition, 3BP potentiated the cytotoxic effect of ionizing radiation, a treatment that is frequently used in the management of TNBC.

Conclusions: Overall, MCT1-mediated metabolic perturbation in combination with radiotherapy is shown to be a promising strategy for the treatment of glycolytic tumors such as TNBC, overcoming the selectivity challenges of targeting glycolysis with glucose analogs.

Keywords: 3-Bromopyruvate; Ionizing radiation; Metabolism; Triple-negative breast cancer.

Abstract

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