2. Academic Validation
  3. Intracellular BAPTA directly inhibits PFKFB3, thereby impeding mTORC1-driven Mcl-1 translation and killing MCL-1-addicted cancer cells

Intracellular BAPTA directly inhibits PFKFB3, thereby impeding mTORC1-driven Mcl-1 translation and killing MCL-1-addicted cancer cells

  • Cell Death Dis. 2023 Sep 8;14(9):600. doi: 10.1038/s41419-023-06120-4.
Flore Sneyers 1,  Martijn Kerkhofs 1,  Femke Speelman-Rooms 1 2,  Kirsten Welkenhuyzen 1,  Rita La Rovere 1,  Ahmed Shemy 3,  Arnout Voet 3,  Guy Eelen 4 5,  Mieke Dewerchin 4 5,  Stephen W G Tait 6,  Bart Ghesquière 7,  Martin D Bootman 8,  Geert Bultynck 9
Affiliations

Affiliations

  • 1 KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I, Herestraat 49 box 802, 3000, Leuven, Belgium.
  • 2 KU Leuven, Laboratory of Chemical Biology, Department of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I bis, Herestraat 49 box 901, 3000, Leuven, Belgium.
  • 3 KU Leuven, Laboratory for Biomolecular Modelling and Design, Department of Chemistry, Celestijnenlaan 200G, 3001, Heverlee, Belgium.
  • 4 KU Leuven, Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute, Campus Gasthuisberg O&N4, Herestraat 49 box 912, Leuven, Belgium.
  • 5 VIB-KU Leuven, Center for Cancer Biology, Laboratory of Angiogenesis and Vascular Metabolism, Campus Gasthuisberg O&N4, Herestraat 49 box 912, 3000, Leuven, Belgium.
  • 6 Cancer Research UK Beatson Institute, School of Cancer Sciences, University of Glasgow, Glasgow, UK.
  • 7 KU Leuven, Laboratory of Applied Mass Spectrometry, Department of Cellular and Molecular Medicine, Leuven, Belgium - VIB, Metabolomics Core Facility Leuven, Center for Cancer Biology, Leuven, Belgium, Herestraat 49 box 912, 3000, Leuven, Belgium.
  • 8 School of Life, Health and Chemical Sciences, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK. martin.bootman@open.ac.uk.
  • 9 KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, Campus Gasthuisberg O&N I, Herestraat 49 box 802, 3000, Leuven, Belgium. geert.bultynck@kuleuven.be.
PMID: 37684238 DOI: 10.1038/s41419-023-06120-4
Abstract

Intracellular CA2+ signals control several physiological and pathophysiological processes. The main tool to chelate intracellular CA2+ is intracellular BAPTA (BAPTAi), usually introduced into cells as a membrane-permeant acetoxymethyl ester (BAPTA-AM). Previously, we demonstrated that BAPTAi enhanced Apoptosis induced by venetoclax, a Bcl-2 Antagonist, in diffuse large B-cell lymphoma (DLBCL). This finding implied a novel interplay between intracellular CA2+ signaling and anti-apoptotic Bcl-2 function. Hence, we set out to identify the underlying mechanisms by which BAPTAi enhances cell death in B-cell cancers. In this study, we discovered that BAPTAi alone induced Apoptosis in hematological Cancer cell lines that were highly sensitive to S63845, an Mcl-1 antagonist. BAPTAi provoked a rapid decline in MCL-1-protein levels by inhibiting mTORC1-driven Mcl-1 translation. These events were not a consequence of cell death, as Bax/BAK-deficient Cancer cells exhibited similar downregulation of mTORC1 activity and MCL-1-protein levels. Next, we investigated how BAPTAi diminished mTORC1 activity and identified its ability to impair glycolysis by directly inhibiting 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) activity, a previously unknown effect of BAPTAi. Notably, these effects were also induced by a BAPTAi analog with low affinity for CA2+. Consequently, our findings uncover PFKFB3 inhibition as an CA2+-independent mechanism through which BAPTAi impairs cellular metabolism and ultimately compromises the survival of MCL-1-dependent Cancer cells. These findings hold two important implications. Firstly, the direct inhibition of PFKFB3 emerges as a key regulator of mTORC1 activity and a promising target in MCL-1-dependent cancers. Secondly, cellular effects caused by BAPTAi are not necessarily related to CA2+ signaling. Our data support the need for a reassessment of the role of CA2+ in cellular processes when findings were based on the use of BAPTAi.

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