Global metabolic alterations in colorectal cancer cells during irinotecan-induced DNA replication stress
Date issued
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
License
Abstract
Background: Metabolic adaptations can allow cancer cells to survive DNA-damaging chemotherapy. This unmet
clinical challenge is a potential vulnerability of cancer. Accordingly, there is an intense search for mechanisms that
modulate cell metabolism during anti-tumor therapy. We set out to defne how colorectal cancer CRC cells alter
their metabolism upon DNA replication stress and whether this provides opportunities to eliminate such cells more
efciently.
Methods: We incubated p53-positive and p53-negative permanent CRC cells and short-term cultured primary CRC
cells with the topoisomerase-1 inhibitor irinotecan and other drugs that cause DNA replication stress and conse‑
quently DNA damage. We analyzed pro-apoptotic mitochondrial membrane depolarization and cell death with
fow cytometry. We evaluated cellular metabolism with immunoblotting of electron transport chain (ETC) complex
subunits, analysis of mitochondrial mRNA expression by qPCR, MTT assay, measurements of oxygen consumption and
reactive oxygen species (ROS), and metabolic fux analysis with the Seahorse platform. Global metabolic alterations
were assessed using targeted mass spectrometric analysis of extra- and intracellular metabolites.
Results: Chemotherapeutics that cause DNA replication stress induce metabolic changes in p53-positive and
p53-negative CRC cells. Irinotecan enhances glycolysis, oxygen consumption, mitochondrial ETC activation, and
ROS production in CRC cells. This is connected to increased levels of electron transport chain complexes involving
mitochondrial translation. Mass spectrometric analysis reveals global metabolic adaptations of CRC cells to irinotecan,
including the glycolysis, tricarboxylic acid cycle, and pentose phosphate pathways. P53-profcient CRC cells, however,
have a more active metabolism upon DNA replication stress than their p53-defcient counterparts. This metabolic
switch is a vulnerability of p53-positive cells to irinotecan-induced apoptosis under glucose-restricted conditions.
Conclusion: Drugs that cause DNA replication stress increase the metabolism of CRC cells. Glucose restriction might
improve the efectiveness of classical chemotherapy against p53-positive CRC cells.