Synergistic interaction of novel lactate dehydrogenase inhibitors with gemcitabine against pancreatic cancer cells in hypoxia |
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Authors: | M Maftouh A Avan R Sciarrillo C Granchi L G Leon R Rani N Funel K Smid R Honeywell U Boggi F Minutolo G J Peters E Giovannetti |
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Institution: | 1.Department of Medical Oncology, VU University Medical Center, De Boelelaan 1117, 1081HV, Amsterdam, Netherlands;2.Department of Pharmacy, University of Pisa, Pisa, Italy;3.Center for Biomedical Research of the Canary Islands, Instituto de Tecnologias Biomedicas, University of La Laguna, La Laguna, Spain;4.Department of Surgery, University of Pisa, Pisa, Italy |
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Abstract: | Background: Hypoxia is a driving force in pancreatic-ductal-adenocarcinoma (PDAC) growth, metastasis and chemoresistance. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis, ensuring supply of energy and anabolites in hypoxic-environments. Therefore, we investigated the molecular mechanisms underlying the pharmacological interaction of novel LDH-A inhibitors in combination with gemcitabine in PDAC cells.Methods: Lactate dehydrogenase A levels were studied by quantitative RT–PCR, western blot, immunofluorescence and activity assays in 14 PDAC cells, including primary-cell-cultures and spheroids, in normoxic and hypoxic conditions. Cell proliferation, migration and key determinants of drug activity were evaluated by sulforhodamine-B-assay, wound-healing assay, PCR and LC-MS/MS.Results: Lactate dehydrogenase A was significantly increased under hypoxic conditions (1% O2), where the novel LDH-A inhibitors proved to be particularly effective (e.g., with IC50 values of 0.9 vs 16.3 μM for NHI-1 in LPC006 in hypoxia vs normoxia, respectively). These compounds induced apoptosis, affected invasiveness and spheroid-growth, reducing expression of metalloproteinases and cancer-stem-like-cells markers (CD133+). Their synergistic interaction with gemcitabine, with combination index values <0.4 in hypoxia, might also be attributed to modulation of gemcitabine metabolism, overcoming the reduced synthesis of phosphorylated metabolites.Conclusion: Lactate dehydrogenase A is a viable target in PDAC, and novel LDH-A inhibitors display synergistic cytotoxic activity with gemcitabine, offering an innovative tool in hypoxic tumours. |
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Keywords: | pancreatic ductal adenocarcinoma hypoxia lactate dehydrogenase inhibitors gemcitabine |
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