PK-M2-mediated metabolic changes in breast cancer cells induced by ionizing radiation
- 113 Downloads
Radiotherapy (RT) constitutes an important part of breast cancer treatment. However, triple negative breast cancers (TNBC) exhibit remarkable resistance to most therapies, including RT. Developing new ways to radiosensitize TNBC cells could result in improved patient outcomes. The M2 isoform of pyruvate kinase (PK-M2) is believed to be responsible for the re-wiring of cancer cell metabolism after oxidative stress. The aim of the study was to determine the effect of ionizing radiation (IR) on PK-M2-mediated metabolic changes in TNBC cells, and their survival. In addition, we determine the effect of PK-M2 activators on breast cancer stem cells, a radioresistant subpopulation of breast cancer stem cells.
Glucose uptake, lactate production, and glutamine consumption were assessed. The cellular localization of PK-M2 was evaluated by western blot and confocal microscopy. The small molecule activator of PK-M2, TEPP46, was used to promote its pyruvate kinase function. Finally, effects on cancer stem cell were evaluated via sphere forming capacity.
Exposure of TNBC cells to IR increased their glucose uptake and lactate production. As expected, PK-M2 expression levels also increased, especially in the nucleus, although overall pyruvate kinase activity was decreased. PK-M2 nuclear localization was shown to be associated with breast cancer stem cells, and activation of PK-M2 by TEPP46 depleted this population.
Radiotherapy can induce metabolic changes in TNBC cells, and these changes seem to be mediated, at least in part by PK-M2. Importantly, our results show that activators of PK-M2 can deplete breast cancer stem cells in vitro. This study supports the idea of combining PK-M2 activators with radiation to enhance the effect of radiotherapy in resistant cancers, such as TNBC.
KeywordsPyruvate kinase Radiation therapy Breast cancer Metabolism
Fibroblast growth factor 2
Cancer stem cell
Epidermal growth factor
Glyceraldehyde 3-phosphate dehydrogenase
Hypoxia inducible factor
Nicotinamide adenine dinucleotide phosphate
M2 isoform of pyruvate kinase
Pentose phosphate pathway
Reactive oxygen species
Triple negative breast cancer
We would like to acknowledge Dr. William McBride for his careful editing of the manuscript and thoughtful feedback and comments.
LZ and JB performed most of the experiments and data analysis and assisted with editing of the manuscript. TY, KD, DS, AD, LG, DN, KB, CA, and MBD assisted with experiments and data analysis. FP assisted with experimental design and editing of the manuscript. EV designed all experiments, oversaw data analysis, and wrote the manuscript.
EV was supported by a Junior Faculty Award (JFA) from the American Society for Radiation Oncology (ASTRO) and the UCLA SPORE in Brain Cancer (P50 CA211015). FP was supported by grants from the National Cancer Institute (CA137110, CA161294).
Compliance with ethical standards
Conflict of interest
All authors declare that they have no conflicts of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
- 1.Sjostrom M, Lundstedt D, Hartman L, Holmberg E, Killander F, Kovacs A, Malmstrom P, Nimeus E, Werner Ronnerman E, Ferno M et al (2017) Response to radiotherapy after breast-conserving surgery in different breast cancer subtypes in the swedish breast cancer group 91 radiotherapy randomized clinical trial. J Clin Oncol 35:3222–3229PubMedCrossRefGoogle Scholar
- 19.Warburg O (1924) On the metabolism of carcinoma cells. Biochem Z 152(309–344):309Google Scholar
- 28.Boxer MB, Jiang JK, Vander Heiden MG, Shen M, Skoumbourdis AP, Southall N, Veith H, Leister W, Austin CP, Park HW et al (2010) Evaluation of substituted N, N’-diarylsulfonamides as activators of the tumor cell specific M2 isoform of pyruvate kinase. J Med Chem 53(3):1048–1055PubMedPubMedCentralCrossRefGoogle Scholar
- 37.Walsh MJ, Brimacombe KR, Anastasiou D, Yu Y, Israelsen WJ, Hong BS, Tempel W, Dimov S, Veith H, Yang H et al (2010) ML265: a potent PKM2 activator induces tetramerization and reduces tumor formation and size in a mouse xenograft model. In: Probe Reports from the NIH Molecular Libraries Program. BethesdaGoogle Scholar
- 46.Muramatsu S, Tanaka S, Mogushi K, Adikrisna R, Aihara A, Ban D, Ochiai T, Irie T, Kudo A, Nakamura N et al (2013) Visualization of stem cell features in human hepatocellular carcinoma reveals in vivo significance of tumor-host interaction and clinical course. Hepatology 58(1):218–228PubMedCrossRefGoogle Scholar
- 53.Warburg O (1925) On the formation of lactic acid with growth. Biochem Z 160:307–311Google Scholar
- 60.Cheng TY, Yang YC, Wang HP, Tien YW, Shun CT, Huang HY, Hsiao M, Hua KT (2018) Pyruvate kinase M2 promotes pancreatic ductal adenocarcinoma invasion and metastasis through phosphorylation and stabilization of PAK2 protein. OncogeneGoogle Scholar
- 63.Palsson-McDermott EM, Curtis AM, Goel G, Lauterbach MAR, Sheedy FJ, Gleeson LE, van den Bosch MWM, Quinn SR, Domingo-Fernandez R, Johnston DGW et al (2015) Pyruvate kinase M2 regulates Hif-1alpha activity and IL-1beta induction and is a critical determinant of the warburg effect in LPS-activated macrophages. Cell Metab 21(2):347PubMedCrossRefGoogle Scholar