title: A specific inhibitor of lactate dehydrogenase overcame the resistance toward gemcitabine in hypoxic mesothelioma cells, and modulated the expression of the human equilibrative transporter-1.
abstract: Malignant pleural mesothelioma (MPM) is a very hypoxic malignancy, and hypoxia has been associated with resistance towards gemcitabine. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis. Therefore we investigated the combination of a new LDH-A inhibitor (NHI-1) with gemcitabine in MPM cell lines. Under hypoxia (O2tension of 1%) the cell growth inhibitory effects of gemcitabine, were reduced, as demonstrated by a 5- to 10-fold increase in IC50s. However, the simultaneous addition of NHI-1 was synergistic (combination index < 1). Flow cytometry demonstrated that hypoxia caused a G1 arrest, whereas the combination of NHI-1 significantly increased gemcitabine-induced cell death. Finally, the mRNA expression levels of the human equilibrative transporter-1 (hENT1) were significantly down-regulated under hypoxia, but treatment with NHI-1 was associated with a recovery of hENT1 expression. In conclusion, our data show that hypoxia increased MPM resistance to gemcitabine. However, cell death induction and modulation of the key transporter in gemcitabine uptake may contribute to the synergistic interaction of gemcitabine with the LDH-A inhibitor NHI-1 and support further studies for the rational development of this combination.
authors.affiliation: a Department Medical Oncology , VU University Medical Center , Amsterdam , The Netherlands.|b Cancer Pharmacology Lab, AIRC Start-Up Unit, University of Pisa , Pisa , Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Giovannetti
authors.affiliation: a Department Medical Oncology , VU University Medical Center , Amsterdam , The Netherlands.|b Cancer Pharmacology Lab, AIRC Start-Up Unit, University of Pisa , Pisa , Italy.|c University of La Laguna , La Laguna , Spain.
authors.forename: Leticia G
authors.initials: LG
authors.lastname: Leon
authors.affiliation: a Department Medical Oncology , VU University Medical Center , Amsterdam , The Netherlands.
authors.forename: Valentina E
authors.initials: VE
authors.lastname: Gómez
authors.affiliation: d Department Oncology , Humanitas Cancer Center , Milano , Italy.
authors.forename: Paolo A
authors.initials: PA
authors.lastname: Zucali
authors.affiliation: e Department Pharmaceutical Sciences , University of Pisa.
authors.forename: Filippo
authors.initials: F
authors.lastname: Minutolo
authors.affiliation: a Department Medical Oncology , VU University Medical Center , Amsterdam , The Netherlands.
authors.forename: Godefridus J
authors.initials: GJ
authors.lastname: Peters
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D033721:Equilibrative Nucleoside Transporter 1 / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors*; D000080864:Lactate Dehydrogenase 5; D008654:Mesothelioma / Q000188:drug therapy*; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D033721:Equilibrative Nucleoside Transporter 1; D007211:Indoles; D007527:Isoenzymes; C438649:SLC29A1 protein, human; D003841:Deoxycytidine; D007770:L-Lactate Dehydrogenase; D000080864:Lactate Dehydrogenase 5; D000093542:Gemcitabine
keywords: Anticancer nucleosides; LDH; gemcitabine; human equilibrative transporter-1; mechanisms of action studies; mesothelioma